[3tas4me]

Originally Posted by Zirconia

We are actually in agreement. As I mentioned previously, W72 is about "a tick" slower or 1 sec. slower.

Ok, got it. Too tired to think today....

[3tas4me]

Originally Posted by ta man

More compression would help..have the heads been milled?

Engine is stock. I am trying to maximize what I have without pulling the engine apart or getting into expensive mods.

[ta man]

When you had your heads off would have been the time...for the price of some gaskets something to consider.

[ta man]

Originally Posted by 3tas4me

I appreciate the replies, but as I stated originally, I do not want to get into changing the cam at this time. I am looking to maximize what the factory gave me with simple timing and jetting changes. HO Racing used to offer a kit for these cars that consisted of carb jets and distributor weights/springs. As Warbird said, if someone could find the HO article and post it that would help.

I know with my stock 400 T/A's I have had,opening the hood scoop,installing the medium moroso advance kit springs to have timing all in by 3000,installing decent headers,dual exhaust and maximizing the total timing until pinging and back down a few degrees made a big difference.The low compression engines will take alot of timing.This was back twenty years ago in my younger days,I actually have an old book "Supertuning Your Firebird Trans Am" by Joe Oldham..which actually got me into tuning Pontiacs.

[David Holmberg]

Get the air in and get the exhaust out.

Back in 79, my 78 Y88 WS6/W72 TA, auto, stock ran 15 teens.
I added stock 74 head pipes into the factory resonators and tailpipes. A flex fan replaced the factory clutch fan, I opened the hood scoop and installed LR 60 radials. The car ran 14.20's in the fall of 79.

A friend had a bone stock RAIII 70 TA, 3.73 automatic, no options. We ran many times and I always pulled him by a car or more. (man it drove him crazy)

I installed a 455 right after that, but had I continued an HO or RAIII cam would have been next with a set of headers and an earlier factory intake.

The motor is an air pump, the easier you get it in and out the more power it will make.

[77 Canamman]

My W72 Can Am has run a best of 15.1@91. Mods include timing, slightly fatter mixture, open scoop, and 2" dual exhaust. Race weight is 4300. No changes to the long block at all as delivered from PMD.

[phil400]

A couple of years ago my friend's 78 w72 4-speed ran 14.8@95 with just true duels best of 5 runs,I posted this on another t/a site and was pretty much called a liar,nice to see people aknowledge these cars made good power and could post OK times considering the relatively small cam,and low compression.

I too own a 78 w72 4-speed in '92 the PO installed a comp 268H and headers to me it pulls pretty hard,in '04 I ran it, after a couple of runs, I couldn't get it to hook, I've never ran it since.

I can only imagine what 10-1 400 must feel like.

My friend liked the way my car went so much that we just installed the same cam in his with a recurve and heddman 28150 headers,the cam REALY wakes up these engines.

Don't mean to put you all to with my rambling

[rad400]

3tas just leave that factory cam in it. With this post you got me wanting a bone stock 79 400 So i can do the same mods.

[hada76]

Originally Posted by mechanic17

RE: exhaust. Have to disagree with 2ManyTAs. Log manifolds are a definite hindrance in the midrange+. I hate headers myself, and the RAREs with 2.5" outlets work well! Would love to have long-branches.

agree, logs are the worst, you will not get the full benefit of duals if you keep stock logs on

[Skip Fix]

Some of the FAST guys are running as quick with logs as RA manifolds. If you look at a cross section one hole is pretty small on the RA. RARE has soem cut up at one PSN and when they all join together one hole is really small.

Liek others said air in air out. Open the scoop, get a wide band and use it to dial in carb jetting, quicker advance curve and check timing it wants at the track or a chassis dyno.

Without tearing down the motor 1.65s might or might not rub, you could use offset trunnion Crowers to get more ratio/more lift without grinding on the heads.

Rear gears will make the biggest change you can feel.

[3tas4me]

I have a question about timing advance. I have a timing light with the advance dial on it. When checking my timing advance with the stock weights and springs, it will show well over 40 degrees of timing advance at 3000 rpm. In fact, it may even be considerably more than that, just don't remember for sure since it has been a while since I checked it. I see that most people say to have 36 degrees all in by 2000 or 2500 RPM. Does the 36 degrees include the base timing of 16 degrees or is that added to get a total of about 52 degrees (which seems to be about where total timing is when I check these cars).

[68bird400HO]

Originally Posted by 3tas4me

I have a question about timing advance. I have a timing light with the advance dial on it. When checking my timing advance with the stock weights and springs, it will show well over 40 degrees of timing advance at 3000 rpm. In fact, it may even be considerably more than that, just don't remember for sure since it has been a while since I checked it. I see that most people say to have 36 degrees all in by 2000 or 2500 RPM. Does the 36 degrees include the base timing of 16 degrees or is that added to get a total of about 52 degrees (which seems to be about where total timing is when I check these cars).

Jeff,

36* all in by 3000 includes the initial timing. Make sure you disconnect the vacuum advance when checking this....

[3tas4me]

I am pretty sure it was disconnected. That is why I was shocked at how much timing I was seeing. It wasn't just on this car that I noticed that. It was also on the '78 W72 I used to own. I will have to check it again.

[hada76]

50* sounds a bit much to me

[Skip Fix]

50 would probably be right with the vacuum hooked up and cruising

[2manyT/A'S]

Originally Posted by Skip Fix

Rear gears will make the biggest change you can feel.

AGREED!

ALL W72's came with 3:23's,except 78 4 speeds which were 3:42's....

ALL other (well MOST) 77-79 T/A's came with 2:41's or 2:56's....

That 3 series (W72) gear set made the W72's extra 20 or 40 HP feel like 75 HP!

Definately one of the most significant W72 "power adders" & it had really NOTHING to do with engine.....

Pontiac was still being SNEAKY even in the late 70's.... I LIKE IT!

[autobahn]

after watching Zorconia's test drive utube and hearing the B&Ws T 10 s, I really appreciate MY TREMEC 5 speed

[77 Canamman]

None of my M20's are that loud...

[Alvin]

BTT: 3tas4me Looking back to your original post I remembered and dug up for you the reference material I used to “Super Tune” on my original TA and those to follow (including our current 1978 & 1979 W-72 4-spd’s). Click on the images here and they will link to the med versions of each “how to” page.

FWIW & IIRC: Our 1979 Y-84 W-72 4-spd TA has had HO Racing HCO2(?) Cam, Factory Q-Jet Jet Kit, Tri-Y Headers, Performer RPM intake, and Pontiac #96 (1971 GTO 400) heads installed. Some other HO Racing recommended “tricks” were used too. However - The factory A/C, Shaker Scoop, 3:23 gear, etc. all function as normal.



The vacuum routing shown below is also used:


The original Thunder Am and HPP articles were reprinted in a compilation titled “Pontiac Power from the Editors of High Performance Pontiac Magazine”

Cover


Article included (2) pages how to “Street-Tuning The Trans Am”

Page 1

Page 2

Re-routing hoses full size blowup here


Important Note on Layout:

If objectionable surge occurs at idle, connect distributor to ported source & reset idle speed.

Hope this helps you!

[Alvin]

1978 W-72 4-spd TA

Equipment
Original (closed) Shaker Scoop
Stock exh manifolds
3:42 Gear
245/60/16 Radial T/As
Only mods are Cat removed and cheapo N. TX installed H-pipe dual through Turbo muffs on old 2” exhaust system thru factory splitters.
Neat feature is: The over the rear axle tubes pipes were crushed “fitted” by installer back in the 90’s.
This has never slowed this car down!

Our only drag strip runs with this stock TA @ Baytown NHRA track netted timeslips of:

1st try was something like 15.10 @ 95mph
2nd try was 14.89 et @ 96mph