I have a totally stock '78 350 engine (from a full size car) in my '71 Chevelle. The only mods it has is a 600 cfm Holley on top of it and a set of what looks like full length 1 5/8 headers which feed thru dual 2.25 inch pipes with glasspacks. The engines bolted to a stock TH350 with stock converter and sends the power to a 12 bolt rear with 4.10 gears and a posi.

When you stomp it off the line the engine bogs and then takes off but sort of slugglishly. I mean I can't even get this car to squeak a tire, not even with the 265/60's out back! If you hold it in gear before shifting to 2nd it does seem to have some good uummpphh to it but then you can't seem to get the car to run over 55 mph w/o it loosing power. Perhaps the engine's tached out?

I tried checking the timing and at first the engine had no timing tab so I bought a tab for it but now I can't manage to find the timing mark on the balancer when checking timing.

I've not raced anyone but I'm willing to bet it wouldn't run any better than maybe a 15 sec. 1/4 pass.....if I'm lucky to even have that.


I wanted to go bbc but now I think I'm going to try and keep the sbc and later stroke it. But for now I want to give it the performance edge it so deserves. Any pointers on how to perk up this dog of an engine?

Thanks.

Bigger carb, performer RPM intake, new cam, headers, 2-1/2" mandel bent exhaust, super turbo mufflers.

If you're not on a budget, then higher compression pistons, and new heads will really wake it up.

I suggest you make these items pretty big (not for much use in the lower rpms)... otherwise if you stroke the engine, you'll have to get all new parts. Then your new 377/383/400/etc, will have some low end grunt and tons of midrange power.

A shift kit in the TH350 would also make the car much more enjoyable to drive.

You have enough gear , carb , headers, and mufflers. You need an intake and a cam next. I would try to really think about your intended use before buying these items!. How is your ignition system condition?

With a 4.10 gear, you should be coming out of the hole nicely. What kind of Holley is it? Before you start tearing into the motor, play with your timing and accelerator pump nozzles. Might want to go pick up a few books on holley tuning also. Even things such as the throttle plates not opening fully will make huge differences that cost little to no cash.

The car will be used for street/strip duty. It's a 4160 series 600 Holley model 1850S.

Originally posted by Junkyard Dawg:
I have a totally stock '78 350 engine (from a full size car) in my '71 Chevelle.

Any pointers on how to perk up this dog of an engine?

Thanks. Nitrous the crap out of it until it breaks.

Good luck!

You will have to ask yourself if you want to tear the motor apart now or just get it runnin good. 4160's can work well if you tune the vac secondaries and the accelerator pumps. If you are not familiar with these, check out the many holley books out there and learn to maximize your current combo. It wont cost much now to tune it, but you will know how to do it when you spend some serious cash on heads and cams.

Also, even a smog 350 with a good tune will be alot of fun with 4.10 gears and a shift kit.

Whoa, start with basics 'bro. Buy an $8 piston stop and get true TDC marked on the balancer. If you dont have a dial back timing light, spend another $6 on a 6" timing tape to put on the balancer.

Set the timing, check your advance curve. Start tuning. Dont Do ANYTHING before you set the timing, then focus ont eh carb. Set floats, and then buy a spring kit for the secondary.

Dumb q. but what's a piston stop?

A piston stop is a thing (never used one) that you stick into the spark plug hole. When the piston reaches TDC the it will hit the piston stop. I'm not sure if i'm correct but i think you turn the engine clockwise until it hits the stop, mark damper in relation to where 0 is on the timing tab. Then turn the engine one more rotation until it hits again and mark this position. TDC is supposed to be exactly half way between the two marks you made. (Caution: ask which way you turn it the second rotation, i dont know if it's CW or CCW).

I run an 8.3:1CR 355. Holley 600cfm 4160, Hooker 1 5/8s headers (dented collectors. not good), 2.5 duals/tails, flowmasters, , q-jet manifold, 1inch spacer, GM HEI, 8.8wires, AC Delco plugs, small cam (206/212@.050), TH350 and open 2.73gears. It runs a best of 10.17 in the 1/8th or about 15.9x in the 1/4mi.

In my opinion, if it feels like a dog off the line, something is out of tune. Even with the 2.73 my engine doesnt feel too doggish, it's responsive. I think you need to tackle the timing first. My engine is NOT responsive if the timing isnt right. Mine runs best (so far, still tuning) with about 14-16 intial, anything under that and it feels like my old 305 off the line. My carb is bone stock except i changed the vac sec spring.

I think your problem is tuning, and those 4.10 gears. The gears themselves should be awesome to have, but i bet that cam/compression can't keep up with them. Tune your timing as best you can, it'll help a ton, but with those gears and a stock hydraulic cam, you're zipping right past any usable power. Like you say it's "tach'd out". I vote for a cam swap.

do a compression test and report back, some smaller chamber heads would really wake it up, I'm sure it's only an 8.5-1 motor so don't stab a big cam in unless you bump the compression. The 600 will be fine, what intake is on now?

badbob is right, but on a low compression motor you can advance the snot out of the timing to get better rip.

Piston stop is literally that, a rod you screw into the spark plug hole, roll the motor over BY HAND GENTLY one way, hits the stop, mark it, now back it up and go the other way, hits the stop mark it, split the difference and you have TDC.

A timing tape is just a tape marked off in degrees you stick on the balancer. Measure the balancer dia to be sure, I assume 6".

I would also reset the valve lash to 1/4 turn after the clacking stops, ie., a bit looser than you might have it now, use 40-45 total advance, and then get into the Holley last. You should find a marked improvement in rip.

First and foremost we must decide what exactly a RAPED APE runs like.
Is it faster than greased lightning?
or faster than a New York minute?
Faster than a scolded dear?

Once this question is answerd then we can proceed.

Lets say when I stomp the gas I want the tires to go up in smoke as the car lunges foward with brutal strength and just keeps going with no hestitation. Right now a ricer could probably beat me in a race and that's sad. graemlins/sad.gif

First do like said and do your tuneup and timing check..

Then, no more then a good set of double-hump heads to up your CR some up around 9.75 to almsot 10 to 1 CR. and a good old CC 268HE cam up to Crane's 274H06), will really wake her up..

AND I would pull the cover on the rearend and count the teeth to double check it is really a 4.10 gear set IF you didn't give the set to the guy that installed them if it was my car..

I did it to my car after I got it back to make darn sure I still had my original 3.31 geared 12 bolt posi which I do......

Even a stock, 230" 6-banger will turn tires over with 4.10's!!!!

pdq67

JD,
I agree on starting with a compression test.Just wanted to add this even though it may not apply to your motor.Many Chevy 350 and 305's of the mid to late 70's and early 80's had cams where 1 or 2 lobes went flat over a period of time.I had a 79 305 with a flat intake on cyl #8.Idled and ran OK till you got on it,then you knew something was wrong.Replaced the cam woke the little motor up but it was still a 305 graemlins/sad.gif

pull all of the spark plugs and prop the carburetor throttle blades open so you don't pull an excess amount of fuel from the idle circuit, then disconnect the ignition so you won't have any sparks. put the compression tester in each cylinder one by one and have someone crank it over till she pumps 5 or so times and record the readings for each cylinder. I'm crossing my fingers hoping for about 150 ish psi for that stock motor. Anything less would mean the rings and or valves are going downhill. Add a small amount of motor oil in the cylinders and recheck, if the compression goes up a lot it means the rings are worn. If the oil doesn't bring the reading up and it's below 150 you may have some leaky valves. Applying air pressure at TDC will show what valves are leaking-you'll hear it hissing through the intake or exhaust. If the compression test proves the internal condition of the engine's cylinders is ok then your ready for a cam, headers, and smaller chamber heads IMO

So insert compression tester in all 8 plug holes and let someone revolve the engine over 5 or 6 times eh?

Thanx I will have to try this and report back. graemlins/thumbsup.gif

one hole at a time

Well, I did find out this morning my HEI is sticking....the springs are fine but they don't return the base back to where it's supposed to be....if you grab it you can turn it but it's sticking like if some grease or something has gummed it up making it harder to turn.....I wonder if I can shoot some penetrating lube in there and free it up?

Your best bet on that is to pull it out, take it apart and clean it real well. The put it back together with a little grease on the bushings. Lube the weights with a very small amount of slicon grease. You don't want anything flinging around inside the cap. Let us know if it helps.

BTW - Make sure you take note of where your rotor is pointing before pulling it out so you can stab it back in the right place. Then recheck your timing after you get it working properly.

Troy.