69 Z, Headers, VS Stock Manifold and Chambered

[NEW]

I have a 69 Z, it has now a completely rebuilt engine,
0.3 overbore,with standard GM pistons standard Camshaft
and the standard 2.02, 1,60 Heads, The engine has been slightly top decked.

I have for now the oiginal intake, but has also been running it with my Crossram.

Anyway now the qusetion::::

Has anyone here tried swithcing from stock exhaust manifoilds, and chambered exhaust to something like Hooker headers and a little bigger exhaust system like 2,3/4" or 3".???
What is your experiences, there is no punch in the engine and i am thinking it could be the manifoilds that is to restrictive?

And does anyone know what jet sizes is best to run in the stock Z carb, aaaaaaaaand some more, does anybody have recomandations regarding crossram intake, and jetting, maybe it also would be better switching for 1.st design camshaft...

Any tips, or info from people that has tried diffrent things, or people in the know of something pls. Reply..


In advance, THANKS

NEWs,,,
and i know it is not like a Super Super car but it is a super car

[COPO PETE]

I don't believe you will see that much of a gain with headers, but there will be some, nothing really seat of the pants. Sounds like it is geared wrong. What tranny you got???? If it's a M21, you'll need at least 4:88 gears. If it's a M20 4:11 minimum to 4:56. Maybe Mark will chime in on the crossram jetting???
Peter

[Keith Tedford]

Back in '69 Nurse Chev-Olds installed a track cam and cross ram setup on a Z/28. With the stock 3:73 gears there was absolutely nothing below 4000 rpm. 4:56 gears would be the minimum for this combination on the street. The M21 might have been the ticket on the road courses but it didn't do the street car any favours. Tony Pizzi showed what terrors these cars could be on the strip when set up properly. On the stock 780 Holley with power valves front and back #73 primary and #76 secondary jets would be a good start.

[NEW]

Me Again!

I am running M21, and 4,10 in the rear.

Its the 780 carb, but i∆m running 78 on the primary, and 80 on the secondary now.

What timing would be suggested? i∆ve read abt. people doing sometimes like 42 total.

I once had a L88 with stock manifoilds, and stock type exhaust, once i put headers and some less restrictive system on that engine it was like a diffrent engine.

It also have a tendency to get sligthly hot on the exhaust side, LH side.

Has anyone had any problems with the smog system leaking in, and making the engine backfire?,

NEW

thanks for the replys [img]/ubbthreads/images/icons/smile.gif[/img] [img]/ubbthreads/images/icons/smile.gif[/img] [img]/ubbthreads/images/icons/smile.gif[/img]

[COPO PETE]

Stick some 72's or 73's in the front, give it 42 degrees timing, put some 4:88 in it and call me in the morning [img]/ubbthreads/images/icons/smirk.gif[/img] L88 with headers will pick you up over 50 horse over manifolds, you will not see anywhere near that on a 302. Do run something like an ultraflow muffler on it.
Peter

[JoeC]

Also try the lightest springs you can find in the carb and dist.

[JohnF]

I am by no means an expert but I have been playing with different set-ups on my Z/28 for almost 24 years. Here is what has worked for me. I run 72 jets on the primary side and 76 secondary side; yellow secondary spring and 25 squirter. Headers do make a difference! I currently run the 1 3/4" Hooker Super Comps, 2 1/4" pipe to a cross flow muffler, and 2" tail pipes. The only muffler, other than stock, that performs better (and is not too loud) is a DynoMax cross flow that is listed for the Buick GN. It is a bit shorter than stock but looks good under the car and seems to flow quite well. As far as timing advance, I run 10 to 12 initial and 36 total, all in by about 2200 rpm. I have never felt that going over 38 did much to create any more power. These are not racing modifications but work very well for me on the street. I have tried everything over the years including the original manifolds, etc. With the quick timing advance you will need good gas. You may want to visit the Camaro.net site and do a search under the name JohnZ. He has studied the original 30/30 cam and gives very detailed instructions on how it should be adjusted. Again, just my opinion, but this works very well on the street.

[NEW]

Hi,,
Basically what you people are saying is ::

72/73 jets front, 76- secondary,
timing 38-42, light springs,
carb light springs.
I∆ll try sometime during christmas or slightly in to the new year..

But back to the Chambered, good, or acceptable or just nice sound?

Smog system, anyone had trouble with this?,


THANKS Great info......

NEWs [img]/ubbthreads/images/icons/smile.gif[/img] [img]/ubbthreads/images/icons/grin.gif[/img]

[COPO PETE]

Chambered ain't bad, maybe Rob will chime in since he changed his. It is one of the best sounding though! I honestly think to get the best seat of the pants improvemnet is to put a M20 in it. With the M21 you will ring out first gear till your going about 50 MPH. With a M20, you will think you have woke up about 50 horse. I'll put my reputation on that!!!!...what ever my reputation is! [img]/ubbthreads/images/icons/confused.gif[/img]
Peter

[Chevy454]

Well, since you asked, Pete:

Factory chambered = Crap

It all depends on what your are going after. Nothing beats the sound of chambered, but the factory system is restrictive...and I mean WAY RESTRICTIVE! Flowmaster offers a 2.5" mandrel system which uses it's own "interpretation" of a transverse muffler, or Dynomax sells a really good transverse muffler that looks fairly close to stock and flows really well, but you'll have to bend the rest of the system yourself. BUT, if I was gonna put exhaust on something that won't be submitted to a tech inspection(!), I would buy the chambered system they offer for the new Camaros/Firebirds. The system is mandrel bent, but is a LOT bigger than the original chambered of the '60s. It supposedly adds power to the late model F-bodys, and is supposed to sound AWESOME, so it must be pretty good, because those late model guys won't buy ANYTHING without seeing what it did on a chassis dyno. That, to me, would be the best of both worlds: the sound and look of chambered, but built using today's technology.

As for tips for your Z-28...I have no idea about tuning it, but don't be afraid to REV THE PISS OUT OF IT! Don't worry, your ET's will thank you for it!