Inliners International Forums General Discussion Engines original 76 camaro i6 250 need help please

i just bought a 1976 camaro that is original with the original 250 it runs as is but its not a perfect i dont know to much about these cars so i would like to know information about maintenance and issues with this car my goal for this car is to possibly turn it into a low grade drag car to play with at the track on weekends so any tips for performance or ways i can upgraded it would be nice i am keeping the engine as is not swapping it since a i6 with power is unique i am young and in college so i am kinda on a limited budget and dont know to much about this subject but i appreciate older cars and would like to keep it as original as i can but also with more power, thank you in advance any help or information will be greatly appreciated

College? ...and no punctuation whatsoever? What is this world coming to?....slow down, and take a breath. ....

Wow didnt think i was writing a research paper thanks for the help

A video under the hood starting up would be great to give these old geezers a baseline.

Don't take us too seriously!! We got used to corrected spelling and punctuation when we were your age and it never wore off!! It does make finding the important stuff a little easier!!

Are you planning on lightening that Camaro to compensate for having less engine and are you planning on extensive modifications to the drivetrain??

Some of us are old racers and have lots of tricks that we can pass along to make your build more rewarding and successful!!

Pics are a great way to start!!

Welcome to the forum!! Do it like you want and we'll try to help!!

edit: Just noticed that you're in Memphis. I'm outside of Nashville and there are several good folks within a half days drive from you!!

For old guys like us, its hard to read without sentence breaks and spaces. Welcome aboard!

Here are some quick pictures and a video that I took today. I apologize for the bad quality.







Underhood video

DANGIT!!! I'd forgotten how cluttered those cars were under the hood!! One of my buds bought a '78 Z28, new that year!! It took me month to clean up and rearrange that spaghetti under the hood!!

There's a lot of potential there!! GO FOR IT!!

Wow, what a perfect college car. Nicer than what i had (much less rust). Thanks for the pictures.

FWIW you'll find these car forums littered with middle aged guys regretting having sold their college cars.

These engines are really sturdy. To start with, question to those who know. All that smog gear can be taken off legally, right? That seems the place to start.

This depends on your location, (state and local laws)!!

Technically, It is a federal offense to tamper with or render inoperative the emissions components on a car in any state. But the feds are few and far between and largely leave it up to the states to regulate and enforce the laws to suit their own objectives.

Speaking of federal laws that are still on the books, did you know it is a federal offense to have flame throwers on your exhaust system? The law dates back to prohibition era. They were considered evasion devices.

Of course it is also against the law to exceed the speed limit - but sometimes I do 56 in a 55 MPH speed zone.

It's against the law to cary pliers (wire cutters) in Texas or to shoot camels in Nevada. It's hard to do anything without breaking a law or at least doing something that someone thinks should be against the law. There aren't many cops out there these days who would have any idea of what should be under that car's hood but many will take an extra look if what is under the hood is prettier than what is outside.
That is a nice car and it is good to see a young guy that is interested to keep it inline. S strong 250 has to make few apologies.

Mathew welcome, nice ride.
AS for the ?old" comments gents lets be politically correct, and just say seasoned members LoL.

One of the ways folks out here get around emissions is by changing the status of their car/truck to classic status. It has it's limits of how much you can drive it etc. but The vehicle has to be atleast 25 years old and you cant drive it more than about 2,500 miles a year. But I know a lot of serious street car racers that do this to get around the emissions stuff. Not a six but for instance a good friend has a late 80's camaro with 6.3 truck motor in it and no smog stuff. Drives it to shows and cruises.

You're probably safe in Memphis if you do the Classic/Antique thing. If you take it through the emissions test stuff, you COULD get into a hassle. In my part of Tennessee, they don't test, but three blocks away, some folks are required to go through "MARTA" when they renew their tags.

Well i know Tennessee doesn't do inspections, and i think im going to start with the differential first. I would start to pull things out from under the hood but im not too sure what is necessary and what can be removed. It looks like it has a lot of extra parts built in, like all the wires and tubing as i think Blackwater said.

Oh snap!!!! I can't believe I missed this thread. Another inline 2nd Gen Camaro owner. Same year as my first and second Camaro too. I have a '78. Differences between mine and yours are minor. I have posted on the PCV, EGR, THERMAC, EVAP, and EFE hookups up in other threads.

I'm in Illinois, so no-one sniffs my car. The previous owner had removed the exhaust from the catalytic converter on back, only the header pipe present. So I replaced that with a 2.5" pipe and the cat-back from the '77-'81 Z28 with dual resonators. I'm considering going with the Holley 390cfm, Offy intake, and Langdon cast headers. So the EFE valve to the exhaust manifold will be gone, and I just remove the steel vac lines that lead to the other side of the block and plug the temp valve hole there. It is replaced by the water heat from Langdon's Heat Plate on the Offy intake. There's no EGR provision, so I have to take the vac line leading to that off. But it is part of a line going to the EVAP canister, so I have to remove the tee that leads to the EGR and keep that line and the temp valve on the side of the water neck. I will replace the EVAP canister so that it has fresh carbon in it. There is a second valve on the EVAP this is in the carbs on V8s, but this one collects fuel vapor from the carb while the engine is off and directs it to the EVAP. The Holley is an open bowl design, so it does not have a hookup for this line. I may just put a port on the bottom of the air cleaner for it to hook to, or just delete those lines and use a V8 EVAP canister instead. To keep the air intake (I've created a secret ram air vent through the left parking lamp) which uses cool air instead of hot underwood air, I will use a baseplate off a 10"x2" open air filter and mount it to the bottom of the stock 10"x2" unit with the middle cut out. So my THERMAC vac line will still be attached and I'll use the filter in the air cleaner for the PCV system. And lastly there is the vac line to the advance which passes through the temp valve on the water neck, gotta keep this obviously.

I will find a diagram of your system and see if it is the same as mine. I assume this is a federal car and not a CA car with AIR injectors? I'll post some photos on the lines to show how it all goes together later.

BTW you have the first version of the integrated cylinder head and intake that they used in '75 and '76. Mine is the second version used on the last of the inline car engines from '77 to '78 (went back to the non-integrated head and intake in '79 for the last year the Camaro and Nova had an inline). So our two top ends might be a little different. It will be interesting to compare the two. I know their valve covers are different from each other and the non-integrated cover.

Also, your's has AC and PB, but mine doesn't. Mine is a manual, is your's and auto?

Ok, if you need to pass visual inspection and sniff test at some point, you will have to work on a build that retains all those items. It's tough without just using almost all stock parts off the HD 292 top end. It might be doable even with the Holley/Offy/Langdon with lump port non-integrated head. EGR and the EVAP are a problem. And I don't know if they accept a swap from vacuum actuated EFE valve on the exhaust to the Langdon water heated manifold as within compliance. If these are put back on for show and not working, will it still pass sniff without them I wonder? Certainly you have to put a free flowing catalytic converter on it then.

If you don't, then that's a lot of monkeying around avoided. You can just delete the cat, EGR, part of the EVAP, EFE, and swap the THERMAC air cleaner with an open element one if you like.

Did a check on Illinois out of curiosity and the IL EPA has a testing program for Chicago and East St Louis for 1996 and newer cars. Anything built before 1995 in those areas I guess has to be unmodified, but won't be tested otherwise. Anywhere else in the state no one is watching. If it is a 1992 or older vehicle in Chicago and East St Louis, and has an antique plate or expanded use antique plate (mine does, unrestricted driving from April through October) is exempt from testing.

Since the Chevy inline six was done with the last 250 Varajet and 292 full size trucks in I think 1987, all inlines are exempt from inspection and testing here for antique plates. Since regular plates are annual $101, and the two antique plates are cheaper at $30/5yr and $51 annual, and our winters are no place for old rear wheel drive cars, there's no reason not to register them that way here.

I was inspired and amended these diagrams and photos to illustrate the emissions system layout and what changes can be made to it:




Here's the modifications to be made when swapping in a non-integrated head with Offy intake (or Clifford) with Holley 390cfm carb (or Edelbrock 500cfm) and either Langdon Stovepipe headers or Clifford shorty headers (using the 2.5" outlet 292 HD exhaust manifold without the flapper valve, exhaust will still heat the manifold):




Here's how the hoses run on my '78 integrated Monojet 250:




For the Holley 390cfm carb, I'm not familiar with the Edelbrock 500cfm carb so I'm not sure what ports these would plug into for that:




Keeping the EVAP system for the fuel tank is preferable to removing it and venting the gas to the atmosphere, and your garage smelling like gasoline. Not to mention not venting all that gasoline you paid for into the air. The PCV doesn't hurt performance, and just scavenges the blow-by gases in the crankcase instead of venting them to the atmosphere. These two things were the first emissions controls added to cars and made a huge dent in the smog in urban areas. Then of course you need to have your vacuum advance hooked up on the HEI too.

I also checked in Florida, my other home during the winter months, even tho I don't take my Camaro with me when I go. And there are no emissions inspections at all in the state.

Before we discuss anything let's start with budget...

Being a college kid you're probably on the cheap bigly (as our new President would say) so removing weight would be the cheapest. That said you're in college so you might actually want to take a girl on a date so don't go too nuts. They're not really into bare-bones cars that smell like gas and run like crap so first things first: sort it out so it runs well and doesn't leave you smelling like a used oil drum.

Then onto the fun stuff: Gearing: Not sure which rear you have. 10 bolts: 8.2? 8.5? Either one will be fine for the car to start with. Do you know the gearing?

I'm looking at gear changes in my 8.2. Right now they're extremely tall. Combined with my powerglide means 60 mph in 1st gear. Sure she moves pretty good to get there but still...

So rear end would be cheapest. If you just swap gears yourself you're looking at $200 in parts and tools. If you plan to add posi: $600 all-in for a kit (assuming 8.2).

Next would be the head situation. We have to fix your head. It's all wrong! Wrong I tell you!

You have an integrated head. Meaning you can't put the fun stuff on it. You can't swap in a 4bbl or aftermarket headers.

So get a head. You can probably find one with the stock manifolds too. Should be easy enough to change out to start and won't add any hp but will make it so you can add it later. I'm sure someone around here has one laying around or you can go on Craigslist or just ask around locally. A lot of people have pulled these engines and have them sitting out back. You might even score it for free!

Then once you get your head straight move on to exhaust headers. That made a HUGE difference for me and was the start of my addiction.

I went with Langdon headers and a single 2.5" exhaust. Runs well and sounds great! Added quite a bit of punch too! Figure about $700-800 all in once you add in new exhaust. Get someone who knows what they're doing or it'll cost you another $300 to fix it later. Ask how I know...

Now you're onto the intake side. Offy intakes are cheapest and have great streetability. You'll want to heat it, though.

a 390 CFM carb or FiTech EFI would sit on top. I got my 390 used and had to rebuild it. Good learning experience, sure, but I plan on going EFI and would have skipped the carb had it not been $2,000+ plus when I did mine. Now Holley Sniper and FiTech are both around $1,000 for the setup. Expensive on a college budget but it'll eliminate the gas smell and give you better MPG's so...

You can also do a cam. I went too mild on mine. Wishing I had gone more aggressive but I digress...

Another cheap way to free up 15 hp is to ditch the mechanical cooling fan and go electric. I did an electric pusher fan and the car is much quieter, cooling is fine and I have free hp. All in you're around $120 there. I bought a cheap replacement fan from Autozone, a relay, and push-through temp sensor (the type that you push between the vanes on your radiator) and it works well.

You didn't say what trans you have.


Now want to get serious? Start with the head again. This time lump ports and oversized valves. Probably about $800 to have a machine shop do it.

Next pistons: get flatties and you just upped your compression.

Really want to get serious? SPI makes a turbo exhaust manifold. Now you're talkin!



I know this will be sacriledge to say here but it's a fortune to build a 6. It's satisfying as all heck, to be sure, but if you really want to go cheap get a junkyard 350 and rebuild it yourself. It'll be the same or more HP than everything I mentioned above (except maybe turbo) and be about $5,000 less in costs.

Don't discount the 6 though. She's a neat little engine that can surprise people.

Here's mine:

http://i.imgur.com/MRxtWKE.jpg?1

See? No spaghetti!

Ok, this is second gen Camaros here, so that’s my field of expertise. Especially ‘75-’81s.

Yeah, he didn’t say what transmission he had. All Camaro automatic L6s had the TH350 with 2.52:1 first gear, and 1.52:1 second. Prior to 1975 the standard 3spd manual transmission with L6s in the Camaro was the Saginaw standard ratio unit with 2.85:1 first and 1.68:1 second. From ‘75 to ‘77 they equipped them with a Saginaw wide ratio unit with 3.11:1 first and 1.84:1 second (‘78 and ‘79 had a super wide of 3.5:1 and 1.89:1, 3 notches on spline). So if you have an auto you have a TH350, more rare is the 3spd which would be a Saginaw 3.11 unit (2 notches on the spline).

All Camaros from 1971 to 1981 came with the GM corporate 8.5” 10 bolt rear end. I know L6 Novas came with a light duty rear end in early ‘70s, but had the 8.5” by the end of its production, but Camaros always had the heavier duty one. Starting in 1976, and also in 1977, the standard ratio for L6 with either trannie was 2.73:1 on the rear end. Only these two years did they offer the performance axle option for the L6 which was a 3.08:1 rear (standard 2.85 Saginaws, the wide 3.11 in 1975, and the autos prior to ‘76 all had 3.08 rears, ‘78 had a 2.73 rear with the 3.5 Saginaw & TH350, and in ‘79 they gave all L6s the 2.56 rear gear for the final year of the L6 in cars). Positraction was available too. So if you’re lucky you got the 8.5” 10 bolt with Posi and performance 3.08 gears; but that’s pretty rare. You probably have a TH350 or 3.11 Saginaw with 2.73 open rear end.

Standard tires for the L6 were the FR78-14 blackwalls (P205/75R14 in ‘79) on 14”x7” wheels, available in white stripe or raised white letters. There was a downgrade option of E78-14 bias ply tires with 14”x6” wheels available through ‘78 and in blackwall or white stripe (my first ‘76 had a tire placard for the radials, my second ‘76 and my ‘78 had the bias ply tires). I have an original E78-14 on rally wheel, and it is 26” tall, the FR78-14 may have been 26.1” tall. So if you reuse the stock wheels (no reason not to unless you want to go to 15”, especially if they are rally wheels), and want the retro white letter look, the Cooper Cobra Radial G/T are the only ones left now that make a P215/70R14 (25.75”) and P225/70R14 (26.26”) that will fit either the 7” or 6” wheels. In 15” flavor you can’t go wrong with P235/60R15 (26.1”) on 15x7” or 8” wheels. If you’re not worried about your speedo and raising your gear ratio, you can stick anything up to a P275/60R15 (28.07”) in the rear wheel wells.

http://us.coopertire.com/Tires/Passenger/COBRA-RADIAL-G-T.aspx

On the engine gbauer said it, the ‘75 and ‘76 L6 was an integrated cylinder head and intake (‘77 and ‘78 were a different casting integrated). So the whole top end has to be swapped out to get lumps and a 4bbl. The water neck, engine lift brackets, rocker arms, and probably pushrods can all be swapped over to a non-integrated head. But you will need a new valve cover as the non-integrated is different from both the ‘75/’76 and ‘77/’78 integrated versions. MrHotRod6 has several heads listed on ebay, but they bare except for T6 lumps installed. Still need the valves increased to 1.84” intake and 1.6” exhaust, with exhaust seat hardened, plus any casting cleanup with a grinder and polish on the exhaust and chamber if you can, in addition to rocker-arms/springs/seals/retainers/locks.

http://www.ebay.com/itm/201582242441?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT Lump Head

On the intake side gbauer is right, the Offy intake with Holley 390cfm carb is the cheapest option, unless you want to get ahold of a non-integrated Monojet manifold and add the 292cid HD 250cfm Monojet (stock 250cid is 210cfm), or get an adapter for a 2bbl, or try to fabricate multiple one-barrel carbs on it. I haven’t looked at the FiTech EFI, maybe a cheap option? Make sure you get the Offy manifold that includes the linkage for the Holley carb, and at least a half inch spacer:

https://www.summitracing.com/parts/ofy-5416 Offy 4bbl w/ linkage
https://www.summitracing.com/parts/mor-64945 Moroso 1/2” spacer
https://www.summitracing.com/parts/hly-0-8007 Holley 390cfm
https://www.summitracing.com/parts/hly-162-523 Holley fuel filter
https://www.summitracing.com/parts/hly-20-88 Holley throttle cable brackets
https://www.summitracing.com/parts/spe-4708 Spectre Perf throttle return spring brackets
https://www.summitracing.com/parts/trd-2174 Trans-Dapt Perf air filter assembly stud
https://www.summitracing.com/parts/pro-66802 Proform air cleaner 10”x2” round

The integrated exhaust manifolds for ‘75 thru ‘78 had a 2.25” outlet (2” prior to that, and the 292 SD 2.25: manifold in ‘79). But the cheapest option is to take advantage of all the tractors out there with 292 engines that need replacement 2.5” HD manifolds. It will need some test fitting an grinding to make it snug up with the Offy intake, but you will have passive exhaust heat to warm the intake (no EFE flapper). Just run a single 2.5” exhaust out the back.

http://www.ebay.com/itm/400750523442?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT 292 Tractor manifold

The Langdon’s will cost more, but allow a dual 2” exhaust, or just Y them to a single 2.5”. But it requires water heat like gbauer has set up on his, with the two brass plumbing connectors on the water heater hoses at the fire wall.

http://www.langdonsstovebolt.com/store/#!/Stovebolt-Cast-Exhaust-Headers-for-GM194-230-250-292-engines/p/1395980/category=18665955 Langdon Stovebolt cast headers
http://www.langdonsstovebolt.com/store/#!/Heat-Plate-for-GM194-230-250-292-Inlet-Manifold/p/1222036/category=18665977 Langdon's heat plate for intake manifold water

Other non-integrated head Camaro stuff:

A cheaper option than the electric fan is the later 250 and 292 truck fan which is a three blade clutch unit. It will free up more HP than the fixed unit, but not as much as the electric fan.

Flat tops for a 250 are tough to find. You either have to locate factory original 307 pistons (rebuilders had a chamfer around the edge which makes them no better than the stock dish, no quench). Or try to find a set of the forged 307 flat tops L2314F. You can’t take too much off the 250 block to get zero deck, so the taller 307 pistons help get you to quench. Zero deck is the only cheap possibility of getting quench out of it as the only rebuilder head gaskets are 0.040”. Pricier options are Ross pistons, and/or Cometic MLS head gasket which requires specific prep of the deck surfaces of block and head.

To keep Dynamic Compression Ratio up near 8.5:1 for premium with quench (8.25:1 failing that), you need to keep the stock 48 degree intake ABDC. So either the stock cam (172/188 duration, .389/.406” lift) or one like the CompCams 61-113 (192/200 duration, .455” lift) with stock springs, or something like the CompCams 61-232 (206 duration, .474” lift) with some Z28 valve springs.

Stock 3.875” bore by 3.53” stroke, with 0.040” by 3.88” rebuilder gasket, with stock 5.7” connecting rod, deck block to zero, deck head to 70cc, with 307 flat-tops with 2.5cc……….equals quench with a DCR of 8.47:1 (SCR of 9.5:1) on premium gas. That is what I am aiming for on mine. If you want to go with 87reg, more CCs on the head will be needed or avoid the quench. My ‘78 does 20mpg in the city right now stock, not sure about highway. The 4bbl is actually more efficient than the Monojet. So I expect it to go up, but if I get more the gearing in my 4spd and posi swaps, it may just stay the same or drop a little.

But I’ve run the numbers, and to convert an L6 Camaro to a 350 V8 costs more than just building it up with the most basic natural aspirated build (lumps, valves, Offy, Holley, 292 HD exhaust, 307 pistons, cam). Even with a rebuilt 350 bottom end; getting Vortec heads, headers, intake, carb, cam is more expensive than the L6 parts. After that is all the changes that have to be made to the car and drivetrain. Beefing up the TH350 or replacing the Sag with a T10. The cooling system is different, smaller radiator on the L6, and the front frame area is not cut to accept the larger V8 radiator so it has to be swapped or modified. The only parts that swap over between the L6 and V8 are the bottom motor mounts, the fuel pump, and if you re-clock the alternator that can be swapped to. Every bracket, hose, pulley, connector….every part has to be replaced. That nickles and dimes the project to death. I’ve run the numbers many times…...unless I swap a stock running 350, with maybe intake and headers upgrade, out of another donor Camaro so I have all the parts…….it just can’t come in cheaper than a naturally aspirated tweak of my 250. And it will just be another small block V8 Camaro in a sea of them at cruise night…….would hardly get any attention.

If you are on a very limited budget, and have to keep it more or less stock, then gearing and possibly a looser torque converter would be the easiest things to think about. As for the intigrated head, those are interesting if you really look at them, but not so much for peak performance. with the one barrel model, you could remove the sleeve under the carb, and open things up a bit, of you intend to add an adapter and larger carburetor. Also from observation some of these heads had smaller runners on one side of the plenum area than the opposite side. I have seen two and on them they were on opposite sides, so it wasn't something intentional, just sloppy foundry work. That said you can open them up to match them if desired, and also open them up around the boss for the bolt holes at the top end where the runners curve to feed the center cylinders. But on the exhaust side there is little room to open things up. Or you could look for a two barrel head in the junk yard. Those came with a dual exhaust manafold on them, which were joined further downstream. As for bigger valves, you would have to talk to a maichine shop to know what is possible. The same would apply to milling them. And of course there is a camshaft option too. With something around 3 to 1 for gears, don't go nuts here, you need the help at the bottom end.
Good Luck!