Inliners International Forums General Discussion Engines My 230/250 Build

You went to Skyline Drive? It starts 10 minutes from my house

Entered in the North entrance and drove down to the tunnel, turned around and exited at Luray.

I've lived in Front Royal since 2010 and STILL have not driven it. Been waiting for the Nova to be ready, and this summer it is on the road.... it's time

Drive the whole thing once. There's a nice winery down on the south end called Veritas. Get their "3".

Make sure to bring your camera and an Ipod or something for music because you won't get a phone signal to run Pandora or radio stations worth a darn.

I'd be happy (and nervous) just listening to the engine....

Hi, more updates.

Adjusted idle to 900 RPM, idle mixture screws to 1-5/8th where the vacuum is 16 lbs. The accelerator pump is set to be almost full at full throttle. Later while out driving I swapped the vacuum advance from ported to non-ported (full) and the RPM popped up to what sounds like 1100. I haven't done more settings yet. Over 120 miles on the car, I think the break-in is pretty much done. Except for the oil change at 300-500 miles.

With these settings and moderate throttle, the outcome is 0-60MPH in under 12 seconds (26 sec when I bought the car). I was surprised when the rear tires spun and the tires chirp shifting from 1st to 2nd. Yeah! I can't wait for full throttle.

I've still got a ways to go, though. There is a big hesitation upon acceleration even at moderate speeds. Moving the vacuum advance to always-on reduced the hesitation. Full throttle sounds awful with less oomph than mid-throttle and I've experienced a backfire through the carb. So I'm shy of the throttle. I'm back to the original 1/4" gas line from the fuel pump to the carb, don't know if that would affect this.

Next steps are to mess with the accelerator pump external setting.

For the starter, I ended up making a cleaner ground from the engine to the starter through the right angle bracket by cleaning off paint. It seemed to crank faster. But I found it to still crank slowly one time when it was hot.

We're getting there!

I'm wondering if the advance should be ported or non-ported too? I have the assembly manual to the 1978 Camaro, and the Monojet vacuum hose routing diagram shows the Thermac hose and advance hose hooking to the tee on the throttle body base for full manifold vacuum. The ported vacuum just goes to the purge valve on the Evap cannister.

I believe my original carb was non-ported. It idles faster with non-ported, so it must be better, eh? I just have to watch for knocking upon acceleration. I'm running premium.

I did some adjustments on the accelerator pump today. I tightened up the nut on the plastic lever which should cause the pump to back off more and maybe have more total throw. Almost all hesitation at low throttle is gone. There is still some hesitation at mid-throttle and WOT still runs like a dog. The jets are 51. The nut is much tighter than gbauer's suggestion of WOT with just a little left on the pump. The new adjustment should leave a lot more swing on the pump.

Additional tips on setting the accelerator? Do I just try turning it tighter and then looser and see which works best?

Thanks!

Silly me, I keep forgetting about youtube. There are a lot of good videos out there, here are three.

Yeah, you had a much older 1bbl than my Monojet. I have one ported vacuum on mine and it runs to the Evap canister. Two full manifold on a tee on the carb, two full manifold on the intake on a tee, and one full vacuum for the EFE (no power brakes). Sounds like the inline 6 has always run the advance off full manifold vacuum. I have an adjustable advance canister I put on my HEI too.

To clarify when I said "just touching" I meant at WOT the plunger should be just short of full extension.

To change duration, etc, you change the cam or cam screw location. I've played around with them and, to be honest, they don't seem to make a lot of difference. Some but not a lot.

Found an article that is claimed to be written by a GM engineer explaining vacuum advance. In it, he says that the vacuum advance should be connected to full manifold not ported:

http://chevellestuff.net/tech/articles/vacuum/port_or_manifold.htm

I wonder why the Holley instructions tell you to connect the advance to the ported nub?

I worked on the accelerator adjustment. I changed the holley CAM from 2 to 1. I tightened up the CAM adjustment (hopefully I didn't stretch the diaphram). But still it hesitates and occasional backfire.

The accelerator jet is only 25. I'll increase it. They recommend by three, so .028. What is yours set at?

Thanks!

When you adjust the cam follower (spring etc)- tighten it until there is end play between the follower and the cam with the throttle closed - then carefully back it off until the end play is gone but no looser.

If it still pops when you stomp on it - either you need a bigger squirter or a different cam. Holley has an cam assortment.

28 is probably still too small. I recommend buying a 28 and a 32 at the same time. 28 was too lean for me.

My main jets are 52's.

Thanks efi-diy, Thanks for the tip. I tried this adjustment last night. I'm a bit concerned that I've stretched the diaphram, because I've tightened the nut all the way and it still seems to be engaging a bit. I never adjusted it when it was new and it was a quite a bit further out. When I order new nozzles, I'll order a new diaphragm just in case I damaged mine.





Hmmmm, I was going to order both 28 and 31's. Maybe save the $12 and order only 31's. I'm thinking this also was (a small) part of the backfiring issue previously.

My main jets are 51's now. Since I need to order the nozzles and they're cheap, i'll order 52's for down the road.

Thanks for the tips!

51 is probably about perfect. 31 squirter is also about perfect.

Backfires are caused by timing and/or lean conditions.

Update on the starter. I had already purchased the Summit brand direct replacement which has the ignition bypass built in. No muss, no fuss. It even came with a full load line curve of torque, amps, RPMS.

The RPMs were significantly higher at cold start than the old starter! I assume that the hit starts will be better as well.

Thanks for the suggestions, always learning experience!

Put in a 35 accelerator nozzle and a 8.5 power valve (6.5 originally). I forgot to order 52 jets, so still 51.

Low end acceleration is really good now. Full throttle acceleration is much improved, but not quite where it could be.

But wow, what a difference! The roads ended up a little wet and I was spinning and fish tailing like crazy! Woohoo! Looking forward to dry roads.

Still dinking around with the transmission, but almost done with that.

I doubt you'll see any difference going from a 52 to a 51 jet. A 35 nozzel is pretty big, though.

Top end would be more on the spring selection you have for the secondary. The primaries can only do so much. I think that's where you need to play next. For me the second weakest spring is the one that works best. Secondary spring kits are cheap. If you really want to play around with it Holley makes a quick change kit for the secondary spring that you might find useful.

Sounds like you have the primaries sorted out. Time to go and play with the secondaries.

Well, uh, I was going to try the 32 nozzle first, but after dropping the gasket, nozzle, and screw down into the throat and ever so gingerly removing the carburetor, I did the work on the bench. Since the hesitation was still sizeable with the 31, it seemed unlikely that 32 would do the job so went straight to the next size up, 35. I didn't want to take the carb off again! You'll note that I have the high compression engine and larger intake valves with porting done on the head (no lumps though). I think I have the same CAM as your new one. But I think the combo leads to bigger nozzle.

Just watched a youtube video on changing the secondary spring kit. Looks like I can do it easy without removing the carb and with tiny risk that I shoot the spring into the carburetor throat. :-)

I never remove the carb to change the squirter. Just use a screwdriver and a pair of needle nose pliers.

As to changing the spring: you'll need to remove the carb. Too much going on not to. You'll want to do it on a bench. That's why they make the quick change kit.

The secondary spring is in that part that hangs off the carb by the choke. You have to remove the choke to get to the last screw to remove the secondary actuator.

Have you pulled your plugs yet after driving it normally? Drive it around (don't flog it because you'll get into your secondaries) and shut it down as soon as you pull into your garage. Let it cool a bit (or don't let it cool like me...) and pull a plug to get a reading. That'll tell you if you're too rich or lean. Also tells you about your timing.

Thinking it out a bit it could also be your vacuum advance. Either one will result in poor power.

The column shifter on the new 200-4R was super sloppy loose. On the hypothesis that it was due to two ball joints in the linkage kit, I cut down and reformed the linkage from the original power glide. It's not quite as sloppy, but I can't get the letters to all line up, but it's good enough. Park is P and Over Drive is the first D. Everything else is off.

Hey George & others,

To address the bogging at lower RPMs with the foot down hard, I swapped in the light secondary vacuum spring (original was medium). To my surprise, I got many more backfires and worse bogging. I checked the vacuum to see if I introduced a leak, but it looked fine. Timing 12 BTDC w/o vacuum, 36 w/vacuum and 43 or 46 revving up, if I remember the last two correct. Premium gas.

I think the plugs look alright, this is from 4 and 6 cylinders. The base of the plugs are still black, so shouldn't be too lean.

Engine seems to run great at higher RPMs, so maybe the secondary is opening too soon. I didn't see any check ball in the unit, but not all of them have that. Did yours? Holley.com says to start with heavier springs, move lighter until it "kicks", then back off to the next higher spring. Can somebody explain what a "kick" feels like?

Ideas other than put in a heavier spring?

Plugs look lean or a hot plug.

Do you have a O2 wide band reader yet? Takes out all of the guess work plus save a lot of time tuning/trouble shooting.
MBHD

Hi, no I do not, just heard about them. Do you have recommendation for sensor and reader?

I changed to heavier spring, brown color, one off of the heaviest and the worst of the bogging and backfire is gone! The engine didn't like the secondaries opening so soon. Upper RPMS are awesome. But lower RPMS still not living up to potential. Probably need different jets, but I'd like to try the O2 sensor, be more scientific and less experimental.

Thanks!

yup looks lean to me.

Just a heated O2 sensor is enough for a temporary tuning session, remove and use a metal plug when not needed. A regular narrow band is sufficient to get you in the ballpark, and you can read it with a digital multimeter. No need to spend money on a wide band setup. I've been doing this for 20 years with a regular O2 before "Wideband" became a buzz word.

That said, wideband kits have come down in price so much that if you DO decide to get a permanent setup, they are now the way to go.

Note that cheap LED gauges need a voltage regulator to eliminate system voltage fluctuation, or the gauge will lie. Some DIY kits have this included but still get affected by system voltage changes. For kicks I built a couple of those to see if they were any good. In older cars the fluctuation was too great for the electronics to "clean" the voltage sufficiently.

I use Innovate products for Air Fuel ratio readings. They have a long wire harness so you can install it temporary at the end of the tailpipe. So you use it on other cars also.

After thinking about it, I think I'll ask the muffler shop to install an O2 sensor when I take it in for some work sometime this summer. I can run a multi-meter on it. In the meantime, I'm going to continue the shot-gun tuning approach.

My primary jets are stock 51. Gbauer's got 52's. My larger valves seem to be a bit thirstier than his, so maybe I'll try 53 next.

For the Power Valve, my understanding is that the rating is for the point at which the vacuum needs to drop to open and not for the amount of fuel that comes out, correct? The summitracing tuning video says there are two ways to think about power valve size selection. First is the same as Holley, take the vacuum at idle in gear, divide by two. Second is to take the vacuum and subtract two. My idle vacuum is 13 PSI, meaning 6.5 (came stock in the carb). My vacuum at full throttle was something like 2 PSI, measured before I adjusted the secondaries. I had put in 8.5 which had shown a marked improvement. I've got a 9.5 on the bench. The engine seems to run so well at upper RPMs (assume with secondary's open) that I don't want to touch anything more on the secondary's.

How much risk to bump to 53's and 9.5 power valve?

Best to not make multiple changes. You will not know what is or not working.
I would up the primary jets.

P.S. Vacuum is measured in inchs of mercury, not PSI

AEM uses the latest wideband sensor - require minimal warmup - like 5 seconds so it can be used to set up cold start.

I've checked the digital innovate and aem against a reference (lab quality) wideband. AEM is faster and a bit more accurate. The digital innovate is a close 2nd.

Cruise - aim for 15:1
WOT - aim for 12.8 to 12.9:1

Tune for part throttle cruise with jet size. Then adjust the PVCR to get WOT.

AEM uses the latest wideband sensor - require minimal warmup - like 5 seconds so it can be used to set up cold start.

I've checked the digital innovate and aem against a reference (lab quality) wideband. AEM is faster and a bit more accurate. The digital innovate is a close 2nd.

Cruise - aim for 15:1
WOT - aim for 12.8 to 12.9:1

Tune for part throttle cruise with jet size. Then adjust the PVCR to get WOT.

A 9.5" PV will bring in WOT enrichment sooner - down side is your mileage will suffer.

If your pull 2" of vac @ WOT and the sec. throttle blades are 100% open. The carb is too small.

Great info, efi-diy. I'll ask guys in the local club if they have the O2 sensor. But I'm a gonna try the shotgun approach for now. With all luck, the package arrives tomorrow and I can try Sunday. Here's the experiments to run with installed values and (new parts values). It may rain this weekend, slow things down...

Power Valve 8.5 (9.5 on the bench, I could try that tomorrow)
Main Jets 51 (54, 53 in delivery)
Squirter 35 (37 in delivery)

Gbauer, I found your last year's thread. You put in 10.5 power valve, 37 squirter and I think 53 main jet. did you stick with those?

I checked my notes on vacuum. at 25MPH I had 12", 35,45,55 all had 13" or 15". Reverse 13, idle 19. Power valve 9.5 probably will work okay, but 10.5 would violate the Summit racing recommendation to remain 2 below the lowest value. But if it's working in George's, another data point that maybe 9.5 is fine over 8.5.

I'd start with the main jets. You must have a vacuum gauge, awesome for tuning a carb. Notice how with any acceleration the vac will drop to 5 or lower? That is when the PV is open. That fuel circuit is separate from the main jets.
Get your hands on a WBO2 as has been talked about.

I have a extra that could be rented out. It is the Innovate unit with the long wire. I recommend the bung be put within 3 feet of the engine.

I changed my settings long ago. It's 6.5, 52, and 32 now.

Thanks for the update. Parts did not arrive yesterday (couldn't bring myself to pay $43 for overnight:-)).

I'll try the 54 jet first. While bowl is off, I'll pop the secondary bowl to find out what jets are in there.

And I'll try the timing according to vacuum (max - 2"). If it still stumbles, I'll try the 37 squirter.

Thanks for the tips! Can't wait for next weekend!

Put in a 54 today, runs really well now! I've got 35 accelerator squirter, 8.5 power valve, secondary is one spring tighter than medium stock.

I did the 2" vacuum thing. Took it all the way up to 36BTDC with vacuum disconnected, got a little more than 20" vacuum. Then backed off to 18", which was at 16.4BTDC. Surprised it's that high. Then adjusted the idle mixture, got the vacuum to raise to 19". Test drove and off to chopping springs.

Starter solenoid did something weird. Cranked slowly, I would hear that slow crank every 10 or so cranks, the next one is always fast. But this time when I let off on the key, the motor went spinning full RPM without engaging the starter. Even with the key off. I removed the quick disconnect from the battery. I removed the wire from the switch and the starter cranked full speed. I cut power again, tapped with a hammer a few times and got it to work.

Seems that it must be a bad solenoid. Thoughts?

How long were you holding the key in the "start" position? Solenoid contacts easily overheat and weld themselves together if left "on" for too long.

It was only a few seconds, five at most. When I hear it turn slowly, I try to stop and try again to see if it's still slow, which is what I did.

I had just finished the long tuning process. The starter was certainly warm. Maybe natural cooling freed it or maybe the hammer.

No chance it's the ignition switch, right?

If you can't fix it with a hammer you have an electrical problem mate. lol