'77 308 Engine Question

1. Do you have an aftermarket muffler that truly separates the exhaust flows from each banks? If not (i.e., you have the stock muffler), I wouldn't put too much significance on what is happening at the tailpipes (i.e., the flows are mixed inside the stock muffler).

2. If you have two distributors with mechanical advance mechanisms, you should ensure both are still quasi-working (i.e., with a timing light confirm the ignition event advances with RPM).

3. It's not impossible to have all carb barrels mistweaked on one bank and all carb barrels tweaked well on the other -- but until you confirm/deny #2 (if you have two distributors) I wouldn't worry about that yet.

Can you give more description about your ignition and exhaust systems?

 

Agree with Steve:

1. First ensure working ignition: both distributors and advance mechanisms are working, good caps and rotors, recent sparking plug and coil wires, good coils and good plug extenders.

2. Next is carbs (should not dwiddle with the carbs until the ignition function is known to be good): check sychronization; if symptoms continue, ensure the jets are all clean and no air leaks around the carbs - look inparticular at the shaft bearings.

3. If you are sure the ignition and carbs are good, the last thing I would do is check cam timing. Were the belts just replaced? Do they need to be replaced?

As Steve said, tell a little more about your car.

 

I cant help you out but I'm sure all of us want to see pics of the car and engine

 

+1

 

Hooker Headers makes headers for a 308? Thats interesting.

I built a high geared car when I was 17. 65 Pontiac GTO, BIG motor and a high geared rearend (low numerical ratio, 2.78:1) with a manual trans. So I understand what your asking. But the truth is that the engine dont care about actual gearing, just what it has to push against. No matter what you have for gears, the lowest gear should behave the same as the car would with some different kind of final drive gearing with the gearbox in a higher gear.

In any case, the engine should perform appropriately if the selected gear allows the engine to run out to max revs. That old Pontiac was hard to get moving from a stop. The big cam didnt help either, even at 20 mph it was pretty gutless. But once it started to breath it really woke up and flew, 1st would pull to like 60 mph! But of course, 2nd it would lump along again before it pulled hard. I would suspect overgearing a 308 would have the same nasty effect, however the 308 has a much broader powerband and wouldnt dog out so bad.

Just like anyone else trying to sort out engine tuning problems, IMHO you must always start from scratch and work forward from the beginning. In this case, I would first verify valve timing before doing anything else, simply because so many other things depend on it. If you jump in in the middle, making assumptions about things you passed by, those could be killing you. Next in order would be ignition, and make sure you have full advance. Stock 77 carbed 308 motors are set 34 degrees advance at 5000, but continue advancing to 44 degrees. If your not advancing fully you will lack power in the top end where these engines really come alive. Once you have the timing and ignition all sorted, and only then, go through the induction system.

If you have some kind of gearing that could hypothetically allow the car to reach 200 mph, acceleration will be slow and the shifts will be more widely spaced. A well tuned 77 was good for nearly 160 in the top end if they were tuned right and had enough road. But with only a measily 240 HP, the only way it could really go much faster would be on a downhill grade. Even then, air drag would have a much greater effect than gravity unless it was quite a grade. So in practical terms a car geared like that, 5th gear would be almost useless, relegating the car to more of a four speed. In that case 2nd gear gearing would probably fall between 2nd and 3rd in a stock geared car, in which case the car should really move out.

I ditto those above, some pics would be a treat.

 

My fouled plugs were caused by a combination of a bad/weak condensor & ignition wires that were crossfiring.
ps lets see the pics!!!!!

 

Why change motor orientation? Was the chassis stretched also? It would have to be, no?

Greg

 

+1. Love to see the pics!

Every power/fuel problem I've had always seems to come back to ignition... There's always some minor tweaking with the carbs, but big power issues always seem to be electrical.... Food for thought. (This is of course assuming proper timing, which should NEVER be overlooked. That did bite me in the arse once. These cars are definitely a learning experience!)

 

If you are looking for some big jump in power at a certain RPM, I don't think it will happen -- the intake tract on a carbed 308 is so short that the hp vs RPM curve is fairly linear and just flattens a little as you approach redline.

Obviously, your car is highly modified, but you really didn't give any specifics about the ignition system -- is it the stock system (or a system where the two banks are quasi-separate in ignition function), or is it now a single aftermarket system running all 8 cyl? If the later, I would find it unlikley that it could be the source of your "one bank fouls, one bank doesn't" problem.

As Russ suggested, having a cam off a tooth would certainly hamper the mid-upper end power -- would you have an opportunity to drive a stock '73-'77 US 308 to compare with (after all, a normally-aspirated 3 liter is never going top feel like a Viper)?

 

As the old saying goes, "Most carburetor problems are ignition."

 

Interesting...

 

So does that include verifying that both ignition systems are working well, and properly, at all RPM (i.e., advance vs RPM is in spec and firing is occurring reliably at high RPM)? Are you running just the R1 points or something aftermarket? (I don't mean to be critical, but it would be better to relocate the 1-4 coil so the coil wire going to the 1-4 cap and the "point" wires running between the coil and the "points" weren't so long).

The cam cover on the 1-4 bank (with the cast-in torque brace mount) is actually off a 1978-1979 model -- is there a story behind that, or is it a later engine (with the milder cams)? With your mounting it might not be easy to see, but is the engine family marked (near the water pump) as F106A or F106AE?
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Giade
Wow what a car! I do tend to agree based on my experience that the ignition is the first thing to ensure works well.


Your writing style is very familiar - your initials wouldn't be A.C. of Faza/Abarth Exhaust fame would it? Some of us old guys remember.

 

I shouldn't have stated this with such certainty -- i.e., I should've typed: "I think the cam cover..." -- but the engine family marking should answer the question (if you can see it).

 

Thats a Car! You need a 360 motore!!!!Que Bella Machina.Grazie Fchat for these presentations,ps I had a 64GTO,I caddied for a pro that had a pontiac dealership.The 64 pontiac GTO engine is absolutly identical to the engine in a 1959 Sedan de Ville,Cadillac.

 

Giade, your car just begs for twin turbo and EFI, look at all that room! What is the point of rotating the engine anyway and doing nothing to it, wheelbase seems unchanged. A matter of preference but I am leaving the 308 badge on my GTO-lookalike. Those who don't know Ferraris think it's an expensive car anyway and those who know Ferraris will see it is not a GTO.

 

Wow. that is awesome.

 

PLEASE GET RID OF THE FRAM OIL FILTER!!!!!!!


cool color by the way. get a Baldwin filter... the Frams will do bag things to your engine....... we have threads with pics.

 

What Steve M is eluding, is the engine typo number would indicate what camshafts would have come in the engine. Better would be to identify the part numbers stamped on the camshafts (located behind the cam belt sprockets on the camshaft boss. The cam cover indicates a later model engine, 78 and later, and if it is, and if it has "those" cams, its a pretty underpowered engine. Actually it shares the same distinction as the 2V injected cars as being the most underpowered of all the 308's (205 HP with mediocre torque. The cars were slow to begin with, so with higher gearing could make it almost impossible to get anywhere.

If you are really looking for lag free high performance, a supercharger would be the best way to go. Mk e had a 308 with a blower, and claimed over 500 HP. And he didnt even have an intercooler, mostly because there is no room. You have more room than you know what to do with. Better yet, twin turbos AND a blower. Blow the low end and boost the top end, no lag, broad power band, uber HP. Well, it sounds good on pixels anyway.

Its amazing that the motor was turned and the axles remained perpedicular without stretching the wheelbase. Do you have any better pictures of the drivetrain looking straight down?

 

Sounds like its running way rich, fouling plugs & washing down the cylinders causing the blue then black smoke.

 

Giade,

There are all sorts of crazy ways to get a rough estimate of the gearing. Any competent shop should be able to tell you approximately what the ratio is. If you have some sort of freak Porsche 915 box, why not replace it. The cost of a gearbox shouldnt be more than 2-3K.


Artvonne,

"Its amazing that the motor was turned and the axles remained perpedicular without stretching the wheelbase. Do you have any better pictures of the drivetrain looking straight down?"

I bet they are at some funky angle. I guess that means the CV's would need to be replaced once in a while.

Cheers,
Paul