it has nothing off idle in fact it wont even spin the tires it runs great after that. any ideas. i told him i'd post it and see what the experts thought


81 Z-28
350 w/flat tops
comp magnum 280
230/230 @50
480/480 lift
110 lsa
performer intake
performer 600 cfm carb
world sportsman II 64cc heads
342:1 10 bolt posi
headers

That's a really good combo! Should make about 375+hp. What is his timing curve like?

He needs a 2500+ torque converter. Heck I run a 3000 with my 408 in my 69 Chevelle with less cam.

3500 stall here same cam 280H
my car leaves like a rocket....
shane

Might wanna experiment with the timing curve. A lazy curve will make a slug out of any engine. It sounds like a decent combo, maybe it just needs a little tuning.... smile.gif Oh, and if he can put the car on a diet, that would help too. Those late-70's/early-80's camaros were no lightweights. My 79 w/t-tops weighed 3800 lbs! My 68 chevelle is only 3500.....

chris

Check the tune first and foremost. That can range from free to cheap.

After that...I'd like to see more gear with that cam. How tall are the rear tires, btw?

What size headers?

What size converter? If it's a stock stall, then he's gonna have to step up a couple of notches.

I'd say he can either step up the gear, converter, maybe even go to a Performer RPM manifold and 650-750cfm carb (tho what he has now isn't terrible, just not good for more than 5000-5500 rpms).....

....or go the other way and keep what he has, but slip a smaller cam in there. His choice. That might be the cheapest way to go, but he'd have to tear into the engine just a bit.

Race weight and street trim weight would be helpful to us as well.

I agree. The 3.42's will work out allright, but it woulda been better with something between a 3.73 to 4.10 gear. And, if its a stock converter, that would further aggrivate the situation, cause as the others have depicted, youd want a 2500 converter minimum to really help that cam out. Also, start with the tunuep for sure. You never know what you will gain from that til you get into it. Next, if it doesnt have a descent converter, that would be the next step. Im not so sure Id say jump on a gear change, unless you really made it worth it. Like I said, when he put the car together, a little more gear woulda been better, but consider the cost of a gear swap. If you did decide gears were a good next step after the other stuff, Id jump right for a 4.10 gear. Cause really, a swap from a 3.42 to a 3.73 is only gonna make a minimal difference and I personally dont see it completely worth it(maybe you will see different though). However, going from a 3.42 to a 4.10 is a little bit more justified so thats where I would be going if you did decide on a gear swap so you get a little bit of a bang for your buck.

Yep..sounds like a way to tight converter to me. When I had my old 350 with a 286 comp it ran ok with the 2000 stall. But when I finally stepped up to the 3000 stall it freakin made a HUGE difference. So I say go at least 2800 stall to as high as 3500 if your at the track alot.

I had that problem for a while and it turned out to be my accellerator pump linkage had a little slack in it. just a thought.

lets see......carb and timing tune off.......convertor to tight.......and the darn weight of the camaro's ( that year not uncommon to see 3700+ with driver)...that all adds up to a big slug off the line........

the engine even in the worst case is going to have 9.7 to 1 compression. (i figured .020 deck,.039 gasket,64 cc head,6cc on the flat top brows)

so the cam is ok with that compression, heads are good for some rpm's......intake is ok, carb is ok......but i would bet the tune is really off on the carb for sure.....as well as the timing, and curve.......crank the timing up on that motor and get it around 16 initial if not more and get total in at 36 by 2500 rpms.at least for a baseline..........and work it from there.....engine like that i would sure put a block in the rear of the carb with jets...( even tho it has really nothing to do with off line performance)..if it has choke best be looking into is operation and make darn sure its working like it should...if it was mine it would be trashed and choke horn cut off....but that me...lol......make sure the secondary's are opening do the paper clip trick on the vacuum rod.......make sure full throttle is there...........get a stall in the car.....like has been said min. of 2500 but i would shoot for a 2800-3000 stall at least jmo this would make up some for lack of gearing weather some believe it or not......

wow you guys are great. it sounds like converter is the answer. what is the best ignition for this set up. i told him you guys would help him out!

The type/brand of ignition setup doesnt' really matter that much. I like MSD due to ease of adjustment in the distributor, and the rev limiter in the ign box. But a properly set up HEI, or any other brand of electronic ignition will be just fine.

The trick is to set up the timing curve to come in at the right time, and advance the right amount. Only experimenting will tell you exactly where that particular engine wants it to be. Dennis' guidelines are a good starting point, aim for about 36 deg total, and 12-16 initial, and see what happens. Usually higher baseline settings (like 12-16) will make an engine perkier at lower rpms (like off idle). Try to get the total timing in by 2500-3000 rpm, and it should feel pretty good.

Wouldn't hurt to experiment with accelerator pump tuning as well.

I can't help you with a convertor, I'm a stick guy. But playing with the timing and accelerator pump is pretty much free. I'd try that and see what happens before removing the trans and replacing the convertor. If tuning doesn't help much, then you know where to look next! smile.gif

chris

Conservative ignition advance is another benefit of running a 2500-3000 converter. With a real tight converter, you often have to compromise having the timing flutter on idle due to using the weak springs to get the timing in early. With a higher stall converter you can stabilize the timing and shoot for a smooth transition at 1800+ and still be at full advance when the converter hits.

thanks again for your help. we'll start w/ tuning and go from there. TC IS THE BEST

In a nut shell, the cam is too big!!

He needs a 268/270 cam, imho!!

His ECR figures out to be 7.61!! Low for the 280 cam!!

A CC 270 Magnum cam along with a set of Fel-pro's, PN 1094, .015" thick rubber coated, steel shim headgaskets will give right at an 8.1 ECR which is just about right, imho...

pdq67

PS., I used a 350 motor, .025" down in the hole, a .039" headgasket, the 6 cc's and 64 cc chamber ed heads...