Thread: 78 Trans Am getting some love

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Yes, it was a bad example, it's not the first time I lit them up for him though. When they were younger when I would give them a ride it was always " DO A SQUEALY DAD! PLEASE!" LOL

This car had an aftermarket 8 track in when I bought it, I sure wish I would have kept it.

I need some exhaust advice here. Trans am motor is hopped up a bit, exhaust says potato potato potato but I don't remember the details of what I've done besides a larger cam and higher compression pistons. My old boss helped me out with it and he does know his motor stuff , he wasn't just throwing arrows in the dark. The problem was I could never fit headers on it because of my four speed linkage, and It really seems to get choked off when the RPMs come up. I would like to get some RAM air exhaust manifolds, , but I'm wondering how far I need to go with this. They offer standard ones, and oversize which they claim have 15% more flow. Exhaust I was looking at has a built in x pipe and it's two and a half inch mandral bent. What I'm wondering is, it starts getting expensive with that stuff, and I know it's more free flowing but I'm not sure my motor is putting out that much horsepower.Standard ram air manifolds with regular bent exhaust without an x pipe is a fair amount cheaper, Would the mandral bent pipes and the larger manifolds be of any noticeable difference with regular street driving? I know it's kind of an open-ended question, just looking for some experience advice. The exhaust I was looking at is from ram air restorations

JMHO, give us some more details on the motor, i.e. ignition, carburetor, rear gears exc.. may just need tuning more than exhaust. Unless you want to change the sound...

you made me do something that I swore I would never do again, and that was talked to my former boss lol. We did not leave on good terms. Anyhow, 15 years later I did get the cam specs from him. It is a comp cam 51-223-4 .224 int. 230 ext with 480 lift 110 lobe separation. I have 323 gears, HEI ignition, quadrajet, factory intake. It has the factory heads with 2.11 intake valves and 1.66 exhaust Right now it has stock manifolds going into 2-in down pipes which then goes into 2 1/4-in exhaust

I don't think your exhaust is a problem - there's a lot of opinions about headers and how they will add "xx horsepower" but in reality, a set of stock cast iron exhaust manifolds running into 2 or 2-1/4 inch pipe and through Flowmaster 40 series mufflers is a great combination. An "H" or "X" pipe will help some and balances the sound.

Have you checked the exhaust riser dampener(s)? They were designed to retain exhaust until the engine warms up and then a bimetallic spring open a butterfly to allow straight through. I've usually just removed them (or wired them wide open) as they do stick.

Another thought is the air cleaner. The factory units are designed to be quiet and are restrictive. A big open element job is in order for any performance modifications. We used to flip the lid over to give better flow.

Let us know how things develop,
Glenn

I have the dampener removed the factory air filter on it has a upside-down design to it already and the rear of the shaker iscoop is open. I guess the best way to describe it is the 4 barrel had a lot of howl but no go.

15 years and he remembered THAT cam? Wow.

When I actually had my birds, I spent lots of time on line reading and I recall that the consensus was that the power gains on a poncho big block were minimal at best upgrading to headers. The best gains are to be had down stream and sounds like you are already there. Also, big blocks a misnomerfor Pontiac, as the block sizes are externally comparable. (Didn't look back in the thread to see what CID you are running, sorry.)

Originally Posted by firebird77clone

15 years and he remembered that cam )

He had a record of it in his computer, it was 1997 when I did it, but I think it was about 15 yrs since I talked to him.

I'm with Glen and Firebird, headers are nice and they look cool, but tuning is where the horsepower is gonna be for the street. Your motor should run great with what you have, so lets get some more details;
What is it doing through the RPM range (bogs, hesitations, sputters, falls on its face, peaks out to soon, exc.)?
What do the plugs look like?
What is the fuel pressure?
What is initial and total timing?
When does total timing come all in?
How much timing does the vacuum advance add?
How much vacuum at idle?

And as Glen said, lets get some air into the motor, at least flip the cleaner cover over. No mater how larger your exhaust, it will do nothing if air ain't gettin' in. Gears are good, they'll perform well with your cam and still cruise down the highway.

Originally Posted by 53 Chevy5

I have the dampener removed the factory air filter on it has a upside-down design to it already and the rear of the shaker iscoop is open. I guess the best way to describe it is the 4 barrel had a lot of howl but no go.

I missed this sorry.

Originally Posted by 53 Chevy5

I guess the best way to describe it is the 4 barrel had a lot of howl but no go.

Do you have the stock mufflers on it?

Here is a link to an excellent guide to tuning your quadrajet;
http://corvette-restoration.com/wp-c...arb_Tuning.pdf

Originally Posted by 36 sedan

Do you have the stock mufflers on it?

No, it has some brand of turbo mufflers on it. I replaced the carb base gasket and that seemed to help the vacuum to shake around 13 , still a bit low I think. I have 9 at idle, and 39 total , not quite sure of the rpms cause I couldn't see the tack, it sounded like around 4ish. The part that I think is not right is when I hook it to manifold vacuum the timing goes all the way to 34, that seems like a lot. I moved the line to port vacuum now. The carb base gasket may have helped a fair amount, the A/C doesn't seem to bother it quite as bad and now when It's pulling hard I feel it surging a bit so I'm wondering if my fuel pump is getting weak. Here is a link of me running it, turn the volume up.I will check out the tuning link you gave me. https://www.youtube.com/watch?v=EahCVj8TEMI

Originally Posted by 36 sedan

Here is a link to an excellent guide to tuning your quadrajet;
http://corvette-restoration.com/wp-c...arb_Tuning.pdf

Holy crap, the only thing I got from that was buy Holley Sniper It's a bit overwhelming, but I'll check some of those things out.

Surging is usually lean, you really do not want it lean at WOT (very bad for the motor). Pull the plugs and take a look at the ring, porcelain tip and way down inside, the plugs tell all (post pictures). Right now we don't need to do any throttle chops, guys will tell you you need to do them to read the plugs, but for right now we just need to see generalities of the combustion. I have a plywood rack that holds my plugs (tip up) marked for each cylinder, you can do the same using cardboard to hold them (I'm a little anal), mark each cylinder so you can see what's happening in each cylinder.

Vacuum is too low for your cam, should be around 15hg, bringing initial timing up to 12-16° will help the vacuum but you're already over the top at 39° total. With that much total timing your surging may actually be detonation (really bad for the motor). Your motor will probably like 12-16° initial and 34 -36 total (36° max) and all in by 2200-2500rpm, but to do this you'll need to limit your mechanical advance to 18- 20° and change the springs (maybe weights too). 20-25° of vacuum advance is what we see in stock vacuum advance set ups, but it's too much for your motor, I would bring it down to 10° additional (15 max if it likes it).

For now (I know this is gonna sound oxymoron, but I'm trying to protect your motor), I would drop initial timing down 3-4 degrees bringing total down to a safer margin, then use manifold vacuum on your advance to bring the idle timing up (should get your vacuum up). See if it takes the WOT surging out, then work on tuning the carb, next the distributor. I put it in this order to keep your motor safe.

Get the total timing down to a safe place to prevent detonation, then tune the carb to get rid of too lean or rich conditions (error on the side of a little rich), once the carb is tuned, tune the distributor. You get this all done and you'll find you'll really need to HOLD ON, cause you will not believe the difference in power.