Mac

I have a 91 camaro RS and it had about a 140,000 miles and it got a rod knock, so I threw out the old 305, rebuilt a 350, stock compression pretty much. Its a 96 motor from a marine. Its built stock except for a comp cam 218 duration 454 lift, 1500-5500 power band, a holley 600 4 barrel, with vacuum secondarys. The thing is I left the stock intake on, which is a quadrajet intake, so I bought an adapter plate so i could put the holley on. The motor runs just a little better than stock. It runs 16.3s with stock exhaust and rear end. (2.73)yuck. My freinds keep on telling me its cause the air flow is messed up cause holley is a square board, and the power band of the intake is idle to 4000. Im sure the intake would make a difference, but would it really do anything all that drastic? Need help, i want to compete with the new ls1s, and prove a third gen can play with the big boys

The ODB

I suspect the exhaust is your problem. Try taking care of that first.

Mac

yeah its pretty much bone stock, i do have flowtech headers, but the y pipe is stock and very thin, i have a brand new cat which is non performance and probably restrictive. then it runs a 2 1/2 pipe back with no muffler

FastBroker

Change the intake for sure. It'll give you 25-50 hp if you clean up the exhaust/cat restriction.

EDIT: and make sure your carb and distributor ignition cureve are tuned right!!! Gotta have 32-36 degrees advance at about 3000rpm with vac advacne disconnected! Check at 2000-3000rpm in the driveway with adjustable timing light and friend to see if/how the curve changes for you. Carb tuning is self explanatory and make sure there are no vacuum leaks around the adapter plate(s)/gasket(s).

[This message has been edited by FastBroker (edited March 01, 2001).]

five7kid

iTrader: (14)

Let's take one step back: What distributor did you use? You need a vacuum/mechanical advance type, the stock one from your 305 will not do.

If you've got that covered, then it comes back to "The Package". The pieces have to work together: Carb, intake, heads, cam, exhaust. Stock intake & exhaust manifolds just don't do it with higher rev'n cams. Marine engines are made to run a constant but not necessarily high RPM, so the heads typically have small ports and valves. Spreadbore/squarebore adapters are all over the place, but I have yet to see one work decently.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

Mac

The heads are 76cc, the ignition was taken care of, its an accel distributor. I do have flowtech headers for the car, but the exhuast after is complete crap. it goes into one 2 1/4 pipe out the back with a restrictive cat of course, and no muffler out the back, just straight pipe

FastBroker

Did you ckeck the ignition curve??? Total timing??? Check it!!!

A single 2-1/4" exhaust is WAAAAAAAAAAAAAAAY TOOOOOOOOOOOO SMALLLLLLLL!!!!!!!!!!! And, you need performance 3"-outlet y-pipe MINIMUM dia, less-restrictive 3" true inlet/outlet cat converter and good 3" muffler. w/o these, you are choking the motor TERRIBLY. Do it NOW but do it RIGHT!!!

[This message has been edited by FastBroker (edited March 02, 2001).]

super83Z

i would suggest picking up some new heads (preferably aluminum) with 64cc chambers this will raise your compression ratio about a full point. heads and a complete makeover in the exhaust will wake that motor right up.

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LONG LIVE THE MUSCLE CAR!!!!! MAY ITS REIGN NEVER END

1983Z28 350w/ edelbrock performer RPM power package with 64cc aluminum heads, flowtech shorty headers, 700R-4 with shift kit, 750cfm carb, edelbrock 3" exhaust systemm, ASCD SS hood, 16" IROC rims.

future mods:
completely done over suspension, black paint with flames, B&M shifter, dakota digital gauge package, procharger supercharger.

FastBroker

Don't listen to that guy. you dOnt need new heads! you should make 325+ hp with whatcha got, if you do what I suggest:


buy better Intake Manifold
do you have Good headers??? 1-5/8" min
Fix exhaust, ie make dual or 3" single min!
tune carb, Do IT, don't assume!!!
Make sure HEI has correct timing, don't assume!!!

Mac

Well my budy let me borrow his weiand intake and so we slaped it on tonight, and the thing still doesnt pull after 3 grand, ran exactly the same as it did before. I didnt notice any kind of change, i dunno maybe because of the exhaust, and the lame 2.73 rear end.

Bort62

Its the Exhuast.

What Goes in, Must Come out.




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

Mac

Does anyone have any suggestions for exhuast I should be running. I thought of doing what my freind did and run side pipes, so i can run duals nice and easy. Any catback system that wont choke my 350

FastBroker

I already posted it above... Intake change will not help AT ALL with you rpresent exhaust. It may, in fact, hurt you!!!

You gotta do what I said above if you're gonna run SINGLE EXHAUST or run true duals of AT LEAST 2-1/4"dia with H-pipe and free flowing brand-name mufflers. And hope you have nice headers, too.

[This message has been edited by FastBroker (edited March 05, 2001).]

Mac

Yeah, i have the hooker headers, but unfortanately their 1/2 primarys. So I probably need better headers. I was thinking of getting those flowmaster y pipes right after the cat and running dual 2 and a 1/4s with no mufflers out the back. Hopefully then some things will be improving.

FastBroker

I don't think you understand what I meant by "do it right". Don't waste your time and especially MONEy on half-butt cures that won't do anything and don't fix the problem.

For single exhaust (cheapest) you'll need:

GOOD headers
High-flow Y-pipe that leads to 3" collector
3" pipe to cat converter
3" TRUE inlet catalytic converter
3" pipe to muffler
GOOD 3" Muffler (Dynomax, Borla, etc)
good 3" tailpipe.

This will add approximately 50hp IF YOUR CARB AND IGNITION are spec'd like I sated above. Should cost less than $500 if you put the headers on yourself and drive to custom muffler shop for the rest.

DON'T WASTE your time on a fake dually after a restrictive header/y-pipe/cat cnfiguration. IT WILL BE AS BIG A WASTE OF TIME AS THE INTAKE SWAP!!!!!!!!!!!

94-6spd

I definitely think that you should change exhaust. Also, I have another suggestion. This may seem obvoius but have you checked to make sure you fuel line isn't crimped in any way? I think I know which cam you are using. Is it the comp 268? I have one in my 83 camaro right now and am using heddman hedders, custom y-pipe and 2 1/2 inch pipe all the way back to the flowmaster. It pulls to 5500 easy. I am using an Edelbrock 600 carb and performer rpm intake. I also have 3.73's and a posi. It has run a 14.10 in the 1/4 with a crappy stock converter so I know your motor has alot of potential.
What do you have your initial timing set at?

94-6spd

I do think that your exhaust is restrictive but somehow I don't think that would cause you not to turn over 3000 rpm's UNLESS your cat is plugged up. Now that I think of it I've seen this before. Hope this helps.

Mac

Im starting to think its alot of little things. Like the exhaust, the intake, the rear end. From what I keep on hearing, everthing has to match. Like this weekend, i notice their was a short in my coil, which would be robbing my motor of voltage and power espeically at higher rpms. So i fixed that, bumped up the timing to 10 degrees adavanced at idle, with the vacuum disconected. I noticed it pulled alot harder, i thought the car was cured cause it really started to launch a whole lot better, but after around 3800 it stoped pulling instead of 3000. So I figure i need exhuast, to help free up, and keep the new intake i got on there, but I was wondering, i had the carb jetted for the best performing settings before, but if I change the intake which i did, and later when i change the exhuast, will i need different jets. Cause right now the motor has the smallest jets in front i think 64s, and 74s in the back, which still seems to tiny to me, but thats where it performced best with the ****y coil, restrictive exhuast, and quadrjunk intake.