[stroker444]

I just did a thorough test to try to get the conditions of when the car bucks. Ive noticed that it will buck in all gears except for 6th. Also it will stop bucking in all other gears if the rpms are over 2000. Its done this with the holley 750 i have now and the edelbrock 750 i had before. I did not do this when i had the automatic in it. What are some things that could make the car buck so much? Also could it just be the cam?

[SDLuck]

More info what are we dealing with,motor ,car,gears etc.

[stroker444]

87 Trans am

383 stroker

t56

3.42 posi rear end

[SDLuck]

Cam,dist ,timing,static and total ,comp ratio,cylinder heads.

[stroker444]

Originally Posted by SDLuck

Cam,dist ,timing,static and total ,comp ratio,cylinder heads.

Comp camshaft 510/520 lift 230/236 Duration 112 LSA

Msd HEI distributor with accel high output coil

14 initial 36 all in at 3k

didnt build engine so i didnt check it myself, but person who did said its at 10:1 compression

PBM Aluminum Heads, 220cc runners 2.02 and 1.60 valves 58cc chambers

[SDLuck]

58 cc heads mean dished pistons to get the compression that low .What is cranking compression?

[406 bug]

I would concentrate on the rear gear 3.42. when you changed to manual I would have maybe changed the gear . 220 runners too much for that mtr.

[stroker444]

Originally Posted by 406 bug

I would concentrate on the rear gear 3.42. when you changed to manual I would have maybe changed the gear . 220 runners too much for that mtr.

The rear end and transmission are from a fourth gen firebird. Its a good match to each other.

[406 bug]

Originally Posted by stroker444

The rear end and transmission are from a fourth gen firebird. Its a good match to each other.

does the Firebird use the same rear gear for both the Auto and manual trans?

The reason I think you need more gear (lower) is because of the fact you mentioned all is fine above 2k. Your rear./ trans may be a good match to each other as you say, but maybe not that good of a match with your eng.
I just think you may need additional r's at the lower speeds..

[stroker444]

Originally Posted by 406 bug

does the Firebird use the same rear gear for both the Auto and manual trans?

The reason I think you need more gear (lower) is because of the fact you mentioned all is fine above 2k. Your rear./ trans may be a good match to each other as you say, but maybe not that good of a match with your eng.
I just think you may need additional r's at the lower speeds..

It could be. The rear end is from an ls1 with a t56 and the transmission is for an lt1. You see lots of guys in 4th gen firebirds with a bigger cam and etc with the same powertrain i have. There really isnt much difference between an lt1 and sbc.

On acceleration and decelleration theres no jerking whatsoever, smooth as can be (except for the tires spinning! jk), its only when im doing part throttle the engine bucks. When i had to much vacuum advance it made it alot worse, but now im running low total mechanical so it shouldnt be that. Also in 4th gear which is direct gear, its the worst. It feels like im slamming on the brakes quickly then letting off.

[2old2fast]

You Might Want To Check Your Power Valve. If The Diaphram Is Blown It Will Make Make You Pig Rich At Partial Throttle. Ask Me How I Know.

[1BAD80]

Change the power valve to a lower number, if it is blown it would be flooding out.

If expect a blown power valve, use this simple test.
TEST: At idle turn your idle mixture screws
(found on the side of the metering block) all the way in.
If your engine dies the power valve is not blown.

[stroker444]

Originally Posted by 1BAD80

Change the power valve to a lower number, if it is blown it would be flooding out.

If expect a blown power valve, use this simple test.
TEST: At idle turn your idle mixture screws
(found on the side of the metering block) all the way in.
If your engine dies the power valve is not blown.

Would the powervave really have any effect? Its all under 2000 when the engine is running off the idle circuit anyway

[1BAD80]

Well it helped mine, what do you have to loose except the bucking.
It feels like the torque converter going in & out.
I like a lower PV anyways, I run 3.5 in my carbs now.

[stroker444]

Originally Posted by 1BAD80

Well it helped mine, what do you have to loose except the bucking.
It feels like the torque converter going in & out.
I like a lower PV anyways, I run 3.5 in my carbs now.

Alrighty, ill give it a try. Im pulling about 10-12 vacuum right now. When choosing the powervalve do i just take the lowest vacuum i get at idle, then take half of THAT for the valve?