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I thought I saw a pic somewhere else where you had your PCV hooked into the intake and brake booster into the carb. Reverse that. .... http://www.ebay.com/itm/CHEVY-INLINE-6-C...fb5&vxp=mtr$60. Cheap and works well. The vac advance is adjustable with this one. You use an allen wrench in the vac line hole in the canister and you can change it. I played with mine to get it right. Don't recall the settings. Regardless going this route made a HUGE difference in how mine idles. Smoothed it out a lot. After all that I also had to go to mid grade gas to keep from pinging. Hi gbauer, Well,I've got the vacuum lines all hooked up differently. The upper vacuum line only gets vacuum after idle when the throttle is opened. I'll need to advance more to get idle smooth. I like the HEI, but I'm really gun-shy of China equipment after a terrible experience with brakes and front end. That seems the only way it could be such a good price. Are any made in USA anymore? Really just looking for quality regardless of where it was made. Look at your broken float arm. Thanks!! Mark
Mark '67 Camaro L6-250
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I thought I saw a pic somewhere else where you had your PCV hooked into the intake and brake booster into the carb. Reverse that.
Your times are doggedly slow. My 1bbl, stock set up was faster than that. You should be MUCH faster with a 4bbl. gbauer, Per the above, did you maybe stopwatch or GTECH your Camaro at some point? (Stock and as now with 4bbl, Langdons)? Recall last fall I had predicted what it would do with the Gonkulator: https://www.inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=81951&page=allBut, I don't have any actual times in my database so wondered if I missed any actual testing you did (always interesting to compare to the predictions!) My 0-60mph predictions for your car were 11.9 sec 153hp, bone stock 10.4 sec 174hp, 4bbl & Langdons Haven't timed it yet. I'll download an app and do it with my phone next weekend. Do you really think I only gained 20hp? Feels like a heck of a lot more than that! On hills I used to have to floor the gas to get up now I'm at 1/2 throttle. Might be more advanced timing and good scavenging in the exhaust (going with a single 2.5" as opposed to dual 2.25")
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The broken float arm was because it was lord knows how many years old before I got it. I'll wager it was made right here in the US of A. As to the distributor: I'm sure it's made in China. Just like the American brands. Nothing is made here anymore thanks to the EPA and NAFTA. Here's a review of their V8 distributor: http://www.hotrodders.com/forum/skip-whi...4/topics/179906Digging further it's a "clone" (probably made in the same factory) as a MSD Streetfire. Your choice, obviously, but I can't see buying a $200 distributor when a $60 one is exactly the same distributor probably made in the same factory.
Last edited by gbauer; 06/17/15 06:51 PM.
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gbauer, Well that's what the Gonkulator said, gain of 21hp. BUT - that's a 15% gain. So that's like taking a 300hp 2bbl v8, adding a 780cfm 4bbl, and getting 345hp - sounds about right compared to lots of dyno stuff.
Headers are the same way, on a mild v8 headers only add about 5% across the board - 15ftlb, 15hp, etc. So if they add 5% to an inline, it's comparable. Our old obsolete numbers are all smaller, but the "eye candy" of any inline is catching on, for all makes. Good to see.
Curious to see what app you use and how it works out - Dynolicious for iPhone was a little erratic, better than nothing but not as good as a GTECH. A bargain for $10 though.
I still wonder if mshaw may be measuring 0-70mph or so when the needle reads 60mph. I have had the old ones do that - the speedo is right on steady state, but when you accelerate, it "lags", then lurches and catches up after you get OFF the throttle, which is a hint. I used to use speedometer & stopwatch when these cars were only 10 years old or so, but after 50 years the speedos get kinda sticky.
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Well now we've thoroughly hijacked poor mshaw's thread...
What is the fabled gonculator and is it something publicly available to play with?
Also how much will a mild cam, oversized valves and lumps help? That's this winter's project (along with a 200r4).
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gbauer, well I hope its a friendly hijack - what strikes me is this is kind of a "build a budget inline and measure its performance" thread as you, me, and mshaw (at least) are all doing that - all with a powerglide so far! I don't know if the Gonkulator is fabled or not, but it is pretty well regarded over on fordfe.com (in fact that is where it got named the Gonkulator). I started writing it almost 40 years ago, about the same time Dynosim and a few others did. I have not put it in a user-friendly form but it is an engine/driveline/dragrace program like others. So I use it on a few forums, make predictions to help, and in return appreciate the real world data that folks go out and get, whether stopwatch or timeslip. So I appreciate mshaws stopwatch data and yours too when you get it! Well last fall I made some of those predictions for your ride- https://www.inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=81951&page=allGot as far as 228hp with 9.5cr, lump port, valves, and a mild 194-204 cam 2.62 11.00 at 68.3 16.87 at 82.7 I did not Gonkulate a 200-4r, will have to go back and do that. On my own car, the Gonk said almost a full second quicker vs that doggy powerglide.
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Gbauer & DeuceCoupe, I don't mind the hijack at all! It's interesting, a lot to learn. I was thinking about another thread for the electronics, but really, this is my personal engine build thread! Come one, come all, digressions welcome. I'll keep this thread alive over the next six months as I stumble my way through... Oh yeah, I think a 200r4 is right for the upgrade (vs. 700r4), but don't know too much about that either. The broken float arm was because it was lord knows how many years old before I got it. I'll wager it was made right here in the US of A. As to the distributor: I'm sure it's made in China. Just like the American brands. Nothing is made here anymore thanks to the EPA and NAFTA. Here's a review of their V8 distributor: http://www.hotrodders.com/forum/skip-whi...4/topics/179906Digging further it's a "clone" (probably made in the same factory) as a MSD Streetfire. Your choice, obviously, but I can't see buying a $200 distributor when a $60 one is exactly the same distributor probably made in the same factory. Taking some vacay, visit the respective families in the heartland, no ability to try swapping the vacuums, etc. I suspect you're right about everything coming from China. I have more than a little professional experience with Chinese electronics manufacturers (EE by trade). The tendency is to use cheaper, lower efficiency parts in designs whenever possible. I've heard horror stories in the industry of counterfeit capacitors wiping out entire production builds but haven't experienced that. You can find "quality" platings with thickness that vary all over the map. The only way you know you have a problem is if you accidently have more moisture and humidity than you expected. Then boom, corrosion city. I'm convinced the only way to get something really good is to buy a brand that you have confidence that they perform regular monitoring of the factories. My experience with brakes and suspension is that most people have good experiences, but lucky me (Murphy is my middle name) I replaced two ball joints, one caliper, and pads. So I know that the quality control epidemic has hit car parts also. But I digress and perhaps say too much. I really want to publish a research paper on those experiences, but lack of time... I'm really tempted to buy the lower-cost stuff because chances are like gbauer, it'll work just fine. But I have precious little spare time and really do not appreciate replacing brand new hardware like I did this spring. The above treatise gets me to my philosophy that worked really well when I had the '32 Chevy: "Touch it once". Meaning, don't settle for intermediate solutions, choose a path, go all-in and then forget about it for the next twenty years. On the '32 it meant take the time and replace every danged nut and bolt I removed because they just don't make iron like they do steel. Back to my own hijacking of the thread. I'll probably go with a better name-brand, new dizzy that is more likely to have superior quality control over the electrical components used. Given all that, which vendors have a good reputation and have you used successfully? Which have a bad reputation and have you had bad experiences with? We've got Gbauer's experience. I read somebody on another thread with good luck with Langdon's. Others? Thanks! Mark
Mark '67 Camaro L6-250
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I read on another forum about a 200R4 swap from a Powerglide transmission.
It is a direct swap, but you would need a trans crossmember for a TH400 & it bolts right up w/out having to change the driveshaft.
MBHD
12 port SDS EFI
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I read on another forum about a 200R4 swap from a Powerglide transmission.
It is a direct swap, but you would need a trans crossmember for a TH400 & it bolts right up w/out having to change the driveshaft.
MBHD I've read that you can re-use the crossmember. You may need to drill new mounting holes but you don't need to spend money on a new crossmember. Some cars have the holes already there. I suspect that's the case for our Camaros. I'm all for saving a buck as long as it's not sacrificing safety or quality.
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Gbauer & DeuceCoupe, I don't mind the hijack at all! It's interesting, a lot to learn. I was thinking about another thread for the electronics, but really, this is my personal engine build thread! Come one, come all, digressions welcome. I'll keep this thread alive over the next six months as I stumble my way through... Oh yeah, I think a 200r4 is right for the upgrade (vs. 700r4), but don't know too much about that either. The broken float arm was because it was lord knows how many years old before I got it. I'll wager it was made right here in the US of A. As to the distributor: I'm sure it's made in China. Just like the American brands. Nothing is made here anymore thanks to the EPA and NAFTA. Here's a review of their V8 distributor: http://www.hotrodders.com/forum/skip-whi...4/topics/179906Digging further it's a "clone" (probably made in the same factory) as a MSD Streetfire. Your choice, obviously, but I can't see buying a $200 distributor when a $60 one is exactly the same distributor probably made in the same factory. Taking some vacay, visit the respective families in the heartland, no ability to try swapping the vacuums, etc. I suspect you're right about everything coming from China. I have more than a little professional experience with Chinese electronics manufacturers (EE by trade). The tendency is to use cheaper, lower efficiency parts in designs whenever possible. I've heard horror stories in the industry of counterfeit capacitors wiping out entire production builds but haven't experienced that. You can find "quality" platings with thickness that vary all over the map. The only way you know you have a problem is if you accidently have more moisture and humidity than you expected. Then boom, corrosion city. I'm convinced the only way to get something really good is to buy a brand that you have confidence that they perform regular monitoring of the factories. My experience with brakes and suspension is that most people have good experiences, but lucky me (Murphy is my middle name) I replaced two ball joints, one caliper, and pads. So I know that the quality control epidemic has hit car parts also. But I digress and perhaps say too much. I really want to publish a research paper on those experiences, but lack of time... I'm really tempted to buy the lower-cost stuff because chances are like gbauer, it'll work just fine. But I have precious little spare time and really do not appreciate replacing brand new hardware like I did this spring. The above treatise gets me to my philosophy that worked really well when I had the '32 Chevy: "Touch it once". Meaning, don't settle for intermediate solutions, choose a path, go all-in and then forget about it for the next twenty years. On the '32 it meant take the time and replace every danged nut and bolt I removed because they just don't make iron like they do steel. Back to my own hijacking of the thread. I'll probably go with a better name-brand, new dizzy that is more likely to have superior quality control over the electrical components used. Given all that, which vendors have a good reputation and have you used successfully? Which have a bad reputation and have you had bad experiences with? We've got Gbauer's experience. I read somebody on another thread with good luck with Langdon's. Others? Thanks! Mark Keep in mind that "made in America" probably only means "assembled" in America. I sell water and wastewater equipment for a living. Even our American manufacturers don't get their castings made here much less electronic components. They can get around the "made in America" clause by assembling the units here. It's all about the quality. For the corrosion resistance: I take off the cap every couple months and spray WD-40 in it. I don't think I need to do it but I do anyway.
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The 2.74 first gear on the 200-4R would really help get the car moving. Second gear is 1.57 not too far from FIRST gear (1.82) in a power glide. The overdrive let's you run higher gears without buzzing down the freeway. Even my nova with 2.73 gears and a th350 seems like it needs to "shift one more time " when on the freeway. Jay 6155.
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The 2.74 first gear on the 200-4R would really help get the car moving. Second gear is 1.57 not too far from FIRST gear (1.82) in a power glide. The overdrive let's you run higher gears without buzzing down the freeway. Even my nova with 2.73 gears and a th350 seems like it needs to "shift one more time " when on the freeway. Jay 6155. Hi Jay, That sounds pretty good after the rebuild. It would be great for giddyup, can run longer and faster in 2nd gear. Right now, I think the car would drag to a crawl in overdrive. I was thinking about 200r4 versus 700r4. The 700r4 sounds like overkill. Mark
Mark '67 Camaro L6-250
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Back home and finally taking her out for a run. Zero backfires, zero hot engine lights even though temperature was upper 80's. Yeah! I had advanced timing even further to 17 degrees. Risk it's too much, but didn't hear any knocking. I'll take it back a bit. Drove her to the VCCA (vintage chevy club) garage night. The car is probably running rich and the advanced timing is dealing better with the richness. It starts with black smoke then blue to burn off the valve drippings. At the VCCA meeting, I got tips on how easy it is to replace the valve guide seals. A home brew tool was described and method using a magnet. But I prefer to use a regular tool. Below is a loaner tool, but it's not obvious how to use it. (Probably will be once I get it) http://www.autozone.com/loan-a-tools/valve-spring-compressorTips on how to replace the valve guides? How to use this tool? Should I get a tool like this? http://www.napaonline.com/Catalog/Catalo...R912_0405868448Looking at Napa, there's a pile of valve guides available. Tips for those too? Thanks! Mark
Last edited by mshaw230; 07/09/15 02:25 AM.
Mark '67 Camaro L6-250
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Ive used the autozone style but I loathe it, always cuss a lot. Advantage is you don't need compressed air, but so clunky to use.
The napa style works good on just about all stud rockers. I've had mine for 36 years. Really easy but you do need compressed air. Even a little compressor will do, you don't need CFM's, just 90-100psi and it goes fast. Make sure each cylinder is right at TDC first or the air will spin the crank, Surprise! Some use this tool without air, just stuff a rope in the spark plug hole, again that works but not my favorite way.
Good to hear the timing worked out.
I like the Ford umbrella valve seals if you have the room. That's the best you can do I think without pulling the head and machining it.
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Hi Gbauer, Thanks a heap, that explains nearly everything. It looks pretty straight forward. I plan to do a compression test this weekend, hopefully a blow-down test. See what sort of shape the valves and rings are doing. Mark
Mark '67 Camaro L6-250
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Today's update. I took it out for a 0-60MPH run, first time since setting the timing way up to 17 BTDC. Each run was under 20 seconds! A couple of backfires, hesitation still at moderate acceleration. I know it's running rich, likely needs smaller jets. I also did a compression and leakdown test. In all cases, I couldn't hear any hissing from the carburetor or the exhaust, but plenty from the valve cover meaning the rings. To confirm that it was from the rings, the first cylinder I did, #1, blew smoke out of the valve cover. Cylinders 1-4 aren't that bad, 5 is worse, 6 is the worst. The manual says compression should be 130, so they're all a bit low. Cyl, Compr, Leakdown %loss 1, 105, -14% 2, 105, -15% 3, 108, -17% 4, 110, -18% 5, 105, -26% 6, 100, -40% Looking at the plugs, 5&6 look the best. Maybe the valve seals are leaking the least, maybe they're just the hottest cylinders (typical from my limited experience). #4's oil is the worst. Looking at this, it seems that 1) valve seals are bad, 2) valves look to be fine, 3) rings in two cylinders were noticeably worse than the others, 4) compression is a little low all around. Bottom line: rings/pistons need work in addition to valve seals. Your thoughts are always appreciated. Mark
Mark '67 Camaro L6-250
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Before tearing anything apart try adjusting the valves. https://www.youtube.com/watch?v=U65dTaEn62QJust like that. I had a similar problem and after reading your thread I thought it might be my seals. Pulled the valve cover and figured I'd see smoke coming from the valve seals when it was running. No smoke. Decided to readjust my valves since the cover was off. I had a misfire at idle on the #6 cylinder. It was because one of the valves was not adjusted right. fixed the problem and now I have a smooth idle again plus no more black smoke.
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Before tearing anything apart try adjusting the valves. https://www.youtube.com/watch?v=U65dTaEn62QJust like that. I had a similar problem and after reading your thread I thought it might be my seals. Pulled the valve cover and figured I'd see smoke coming from the valve seals when it was running. No smoke. Decided to readjust my valves since the cover was off. I had a misfire at idle on the #6 cylinder. It was because one of the valves was not adjusted right. fixed the problem and now I have a smooth idle again plus no more black smoke. Hey, certainly worth a try. Service manual basically says do this engine not running, back off until lash (rods move side to side with fingers), tighten until lash is removed. Then turn one full turn tighter. Obviously, the video shows the tried and true backyard mechanic's method. They don't say much in the video. Do you back off until you get lash, then tighten until the push rod quits turning and back off again? I was going to run both a dry and wet leakdown on cylinders 5 & 6. Doh! should've done it then as it would have been one more hint about the shape of the rings. Thanks, Mark
Mark '67 Camaro L6-250
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I back off until you hear a ticking then tighten 1/2 turn. That's what some of the guys here recommended.
I did mine while running. Gets a little messy but not too bad.
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I back off until you hear a ticking then tighten 1/2 turn. That's what some of the guys here recommended.
I did mine while running. Gets a little messy but not too bad. Today I ran another leak down test on cylinders 5&6. 1) results were about the same as before 2) loosened valves, they seemed a bit tight, but no change 3) with valves loose, put oil in chamber. I don't think there were changes. I tightened the valves not running, startup tomorrow. Inconclusive results today. Mark
Mark '67 Camaro L6-250
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I back off until you hear a ticking then tighten 1/2 turn. That's what some of the guys here recommended.
I did mine while running. Gets a little messy but not too bad. Today I ran another leak down test on cylinders 5&6. 1) results were about the same as before 2) loosened valves, they seemed a bit tight, but no change 3) with valves loose, put oil in chamber. I don't think there were changes. I tightened the valves not running, startup tomorrow. Inconclusive results today. Mark If nothing else it was worth a try. Free is always better than paying...
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If nothing else it was worth a try. Free is always better than paying... Yes, definitely worth the try, thanks for the suggestion! The thing that's got me scratching my head about is that three shots of oil from my little oil can didn't change the readings. "Wet" tests are said to improve due to getting oil down to the rings. Maybe I needed to spin by hand. When from sound the leak is primarily coming from the rings. I did use my rubber mallet and lightly popped each intake and exhaust valve when the lifters were loose. No effect. But today I remember that there's a cup on these pistons. maybe, just maybe I didn't put in enough oil and that it pooled in the cup and didn't make it to the rings. No matter, I'll rebuild it. HEI arrives this week, hope to install this weekend. Hey, at the Chevy All Camaro show this weekend, she stood proud amongst her peers. Lots of interest in the 6-cylinder. There were two other 6's, both completely stock engines and transmissions. Next year I'll be the only one with a souped-up six. :-) Funny thing, though, half the first gen cars there were "stock" V8's. But the book says 51% of '67 were 230's. Hmmmmm, it seems statistically improbable, but maybe the types to bring their car shows are the ones who keep their cars stock and the others just show-off around town... Mark
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Installed HEI this week. Set timing to 9BTDC. It was hot out, upper 80's when I was driving around. It seemed to have less stall at moderate acceleration than before, but after it got good and warm, behaved much like before, backfiring, stalling in traffic. You can either idle or hit WOT to make it go. And one might think WOT would be a danger. But when you have almost no performance, it's not that bad. I had previously set the timing on the old distributor to 17bTDC and it seemed better. I didn't want to go that high with the nice new HEI system. It even backfired on the interstate. I didn't notice any wobble in the old distributor shaft.
Here's where I stand: - Old carb, new carb. Backfire when hot. - Old distributor, new HEI. Backfire when hot. - No broken springs or obviously sticking valves. Compression low, leak-down test sounds like rings leaking, cylinders 1-4 about the same, #5 worse, #6 twice as worse as 1-4. Tester was low pressure (15 PSI) Harbor Freight model.
It could be that I'm running too rich with the new carb. The paper with the carb claimed jets were OK for this engine. The old carb literally dripped gas when running.
I've checked and see the accelerator pump squirts gas right away, but looking at the Holley website, it looks like there is a whole lot of tuning that can be done on this carb. I was trying to stay away from changing the jets until after the engine gets rebuilt.
I don't know if I'm asking a question or if I'm just talking... :-)
Mark
Mark '67 Camaro L6-250
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I don't think running too rich will make it backfire. IMHO it's a vacuum leak somewhere. Valve springs are possible, so is a timing problem . Could there be an internal leak in the carb? Jay
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Backfires only happen from lean conditions. You have a vacuum leak.
Mine was a hard one to find. It was the vac line to the trans. The rubber hose down right at the trans.
Another time it was the grommet on the brake booster. Another time it was the booster itself. Yet another time it was the vac advance canister.
The best way to find it is to disconnect each vacuum hose one at a time and plug it. Eventually you'll find the culprit. If it's not a hose try the old carb cleaner trick.
I had the same problem. Took me months to find it.
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I'm re-reading through the thread to see what I'm missing and what I've learned. DeuceCoupe, I see your worn 250 engine with compression from 130-155. Mine measured 100 on the worst cylinder and got up to 110 on the best. The leakdown test confirmed #6 is the worst. It was the Harbor Freight tester, so I'm using it as a gauge to see how the cylinders in comparison to each other and not as a definitive test. Cyl, Compr, Leakdown %loss 1, 105, -14% 2, 105, -15% 3, 108, -17% 4, 110, -18% 5, 105, -26% 6, 100, -40% mshaw, For me, I don't think U need HEI yet - all my tests so far have used the old 1960s single-point distrib, no problems yet.
You might need to use a weaker spring in place of the stronger one down below in the distrib - but first need a tach to see what your timing curve is for sure. 30 total is getting close though, if you just try 12 initial for 32 total you'd be basically "there".
As far as tired, I find that tired engines actually run FASTER if anything, just cuz they're "looser". Unless of course the valve or ring seals are giving up. Not sure if you did a compression test next but that for me is the best "tired" indicator. Here is what I got from the 250cid that ran all the carb "shootouts" a couple years back: 135 155 142 130 145 138 I consider this a "tired" engine, not the greatest results even on compression but it still ran good and gave decent times in the shootout - after all the car ran "high 10s" (0-60mph that is!!!)
I would definitely do these steps before you tear into the engine, that way you will have a before & after. Also find out where the big Powerglide is shifting - mine was shifting about 4500 or so, probably a little lower than the 4bbl wanted but I didn't want to abuse it so left it there - I was looking for improvements and comparisons, not the last tenth by revving the old six higher.
Thanks for all the photos you are posting it makes for some interesting threads! Integrated j 78, I think you're onto something here, read on... I don't think running too rich will make it backfire. IMHO it's a vacuum leak somewhere. Valve springs are possible, so is a timing problem . Could there be an internal leak in the carb? Jay Gbauer, I realize I made the terrible mistake of changing two things at the same time when I put in the HEI. I tried the idle mixture, leaned it up just a bit. An earlier post I'd made it richer. I'll back it off to where it was before, maybe even make it a little richer. One of the things I'd done before was to really pop the timing up, on the points to 17BTDC. I'm at 9 now, maybe I'll take it to 12 since that seemed OK before. With HEI, i'm nervous about advancing too much. You guys keep coming with great advice. You're all pointing now to some sort of vacuum leak (or valves). Before the HEI, one of the tests I ran was to block off every vacuum line. Yes, I even ran without power brakes. It backfired like nobody's business due to not having enough timing advance. That's one reason why I've still got the vacuum advance on the lower carburetor line to keep it advanced as much as possible. I will try swapping the lines after I try the other fixes. But notice that I've tested fully removing every vacuum line with no improvement. If everything else were OK, here's what I think the list of potential leaks, listed from most probable to least: 1) Intake manifold gasket 2) Carburetor base and 1" spacer 3) Carburetor itself (brand new) I should be able to discover these with carb cleaner, right? Mark Backfires only happen from lean conditions. You have a vacuum leak.
Mine was a hard one to find. It was the vac line to the trans. The rubber hose down right at the trans.
Another time it was the grommet on the brake booster. Another time it was the booster itself. Yet another time it was the vac advance canister.
The best way to find it is to disconnect each vacuum hose one at a time and plug it. Eventually you'll find the culprit. If it's not a hose try the old carb cleaner trick.
I had the same problem. Took me months to find it.
Mark '67 Camaro L6-250
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Ya gotta remember that these only had at Most from factory 8.5.1 compression.....that's NOT alot of compression. My 292 had 95 pounds in all cylinders and ran perfectly fine. Here's some general specs for setting timing: 8-10 degrees advanced No vaccum 20-25 degrees at idle with vacuum. And no more than 38 degrees full load. You said you had it set 17 Btdc? That tells me 17 degrees retarded.....you should have it Advanced not retarded. Try 8 degrees advanced and see what happens. Heck I had my 292 at almost 16 degrees advanced with no problem because the compression was so low. With my new 292 I'll be starting at 8 without vacuum and tuning from there.
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Ya gotta remember that these only had at Most from factory 8.5.1 compression.....that's NOT alot of compression. My 292 had 95 pounds in all cylinders and ran perfectly fine. Here's some general specs for setting timing: 8-10 degrees advanced No vaccum 20-25 degrees at idle with vacuum. And no more than 38 degrees full load. You said you had it set 17 Btdc? That tells me 17 degrees retarded.....you should have it Advanced not retarded. Try 8 degrees advanced and see what happens. Heck I had my 292 at almost 16 degrees advanced with no problem because the compression was so low. With my new 292 I'll be starting at 8 without vacuum and tuning from there. Tonight's experiments, had success, or at least I'm back to where I was before. The first two experiments yielded an awful running engine, no power at all, tons of backfires. 1) Backed idle mixture from 1-3/4 to 2-1/4. Previous setting was 2. No change, lots of backfires. 2) Swapped top and bottom vacuum lines off the carb so that advance is on the top, transmission on bottom. Idled worse, no change, lots of backfires. 3) Bumped timing up 17 no vacuum 40 with vacuum! 50 with vacuum at higher RPMs! it could be that the timing light is a little bit off, it's one of those with the knobs to measure the advance where you set it to the number and the strobe lights at 0. I know it's not retarded because I watch the advance go up when I connect vacuum and increase the RPM. The great news is that there were zero backfires and only small hesitation. The performance was markedly better than the previous runs. I didn't hear any knocking, but then again, only took a short run around the block. I think I'll try backing off the valves on all the cylinders like suggested in the other thread. But this weekend i'll try my 0-60 to see if the HEI made a difference. The most troubling of all is that my friend's college-bound son, who's a big old car buff, stated afterwards he wants an old Mustang. I've gotta work on that boy... Mark
Mark '67 Camaro L6-250
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Backfiring can also be from running to lean. Had that problem with the single barrel on my 292. Rev it and pow pow pow! lol! Had to pull the mixture screw out 1 full turn and it ran ok. You may have your light set wrong....but it won't backfire with a little to much advance. Retarding it to much with cause major hesitation and backfiring...too far advanced it will be hard to start or won't start at all.
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The outer ring on the pulley/balancer has slipped. You only think that it is 17 degrees advanced when it really is retarded. Try this. Make a piston stop from a old spark plug, put in the number one spark plug hole. Pull the other plugs out, disconnect the battery for safety. Turn the engine BY HAND til the piston hits the stop. Mark the place on the balancer, turn it backwards til it hits the stop and mark it again. In the middle of the two lines is TDC. Not perfect but close. Put the plugs back In and time the car with the new TDC mark and see how it runs. If the factory mark is not real close replace the balancer. Jay 6155
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The outer ring on the pulley/balancer has slipped. You only think that it is 17 degrees advanced when it really is retarded. Try this. Make a piston stop from a old spark plug, put in the number one spark plug hole. Pull the other plugs out, disconnect the battery for safety. Turn the engine BY HAND til the piston hits the stop. Mark the place on the balancer, turn it backwards til it hits the stop and mark it again. In the middle of the two lines is TDC. Not perfect but close. Put the plugs back In and time the car with the new TDC mark and see how it runs. If the factory mark is not real close replace the balancer. Jay 6155 Yikes, that would be an issue. Do you think it would also work to look for the point where the exhaust valve closes and the intake opens? It would require the cam to be symmetric around bottom dead center. For the plug, do you mean break the ceramic out of a plug and add a bolt to hang down into the cylinder? Thanks, Mark
Mark '67 Camaro L6-250
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The outer ring on the pulley/balancer has slipped. You only think that it is 17 degrees advanced when it really is retarded. Try this. Make a piston stop from a old spark plug, put in the number one spark plug hole. Pull the other plugs out, disconnect the battery for safety. Turn the engine BY HAND til the piston hits the stop. Mark the place on the balancer, turn it backwards til it hits the stop and mark it again. In the middle of the two lines is TDC. Not perfect but close. Put the plugs back In and time the car with the new TDC mark and see how it runs. If the factory mark is not real close replace the balancer. Jay 6155 I set the timing up a couple more degrees and went for a nice long drive. Ran very well, still low power, only a single small backfire. Tried a friend's timing light, it seemed like I was still set high, but not as high as the HF light. But his light didn't have the advance feature. Considering my HF light may have been defective (the timing on my '32 was also best run higher than anybody else's), so I bought a nice expensive Bosch digital light. Turns out the HF wasn't that far off, a couple of degrees at most. I was running at 20 BTDC, which is too high. So I backed it off to 15.5 BTDC and the backfires are back. I need to run 18 BTDC to prevent the backfires. Of course, if the outer ring has slipped, it's all funny business. I haven't checked that yet. But I also bought some carb cleaner and tried to spray all the gaskets. Somewhere around the center intake manifold if I hit it just right, the idle RPMs drop. If I squirt from a direction where I can really see what I'm doing, no drop. I tried tightening up everything, same result. I think it's a vacuum leak. I'll bump the timing back up to prevent the backfires and just hold tight for another two months until I pull the engine. I'll do the diagnostics then. I was going to try loosening the valves, but what's the point on dinking with it any further. It's a busy couple of months, I won't get to drive it much anyways. Thanks everyone for your help! Mark
Mark '67 Camaro L6-250
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Yes put a long bolt or something in the center of the spark plug after the porlcin is gone that will hang into but not fall into the cylinder for the piston to hit very gently. Even if a vacuum leak is the problem you will know for sure if the balancer is ok. Jay 6155
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The outer ring on the pulley/balancer has slipped. You only think that it is 17 degrees advanced when it really is retarded. Try this. Make a piston stop from a old spark plug, put in the number one spark plug hole. Pull the other plugs out, disconnect the battery for safety. Turn the engine BY HAND til the piston hits the stop. Mark the place on the balancer, turn it backwards til it hits the stop and mark it again. In the middle of the two lines is TDC. Not perfect but close. Put the plugs back In and time the car with the new TDC mark and see how it runs. If the factory mark is not real close replace the balancer. Jay 6155 I set the timing up a couple more degrees and went for a nice long drive. Ran very well, still low power, only a single small backfire. Tried a friend's timing light, it seemed like I was still set high, but not as high as the HF light. But his light didn't have the advance feature. Considering my HF light may have been defective (the timing on my '32 was also best run higher than anybody else's), so I bought a nice expensive Bosch digital light. Turns out the HF wasn't that far off, a couple of degrees at most. I was running at 20 BTDC, which is too high. So I backed it off to 15.5 BTDC and the backfires are back. I need to run 18 BTDC to prevent the backfires. Of course, if the outer ring has slipped, it's all funny business. I haven't checked that yet. But I also bought some carb cleaner and tried to spray all the gaskets. Somewhere around the center intake manifold if I hit it just right, the idle RPMs drop. If I squirt from a direction where I can really see what I'm doing, no drop. I tried tightening up everything, same result. I think it's a vacuum leak. I'll bump the timing back up to prevent the backfires and just hold tight for another two months until I pull the engine. I'll do the diagnostics then. I was going to try loosening the valves, but what's the point on dinking with it any further. It's a busy couple of months, I won't get to drive it much anyways. Thanks everyone for your help! Mark Sounds like you found it. Get a new intake/exhaust gasket when you pull it apart. Also some on here recommend bronze RTV.
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Aye, a vacuum leak also can be the cause. That's another thing that sucks. lol Sometimes the leak is sooo small. but enough to cause problems. My old 292 had some leaks...idle RPMs fluctuated like crazy...and sometimes they were fine. Lot of times the valve adjustments fixed those issues. But for an old goat That was a great running inline 6. Just to bad she was worn out so bad. But it gave a good excuse to hop another one up!
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