[tremo]

Hey All,

I have a '69 Custom S built-out to RA-IV specs (details below) with a rebuilt TH-350. The car runs well and will do high 14's in the 1/4 at 5,400' alt. However, I've never been able to get any rubber from a dead stop, around a right hand turn (um, on concrete, in the rain!) or even spooling it up to 2000 rpm and letting go of the brakes. It'll break lose a bit when power braking, but in no way can I light 'em up. It would be so much more fun on the street if I could get more of that power to the rear tires...

While it could be a number of things, I'm just wondering if my 2000 rpm torque converter may be the culprit and I was curious what the stall speed was for a stock '69 GTO with a RA-IV engine and TH-400?? i.e. Since I've modeled the car after the RA-IV, it would be good to know if the stall speed was higher (like say 2200??) so I can perhaps duplicate that as well.

Thanks in advance for any advice...

Jim.

[69goatboy]

If you indeed have a 3.90 posi with a that motor and only run high 14's: I'd say that you're on the right track with the converter. You should be able to get rubber with what you list.

Also, a 650 carb at a mile elevation? I'm no expert, but I think you may also be a bit lean in the fuel delivery area.

[tremo]

Thanks Goatboy! Good to know that I'm heading in the right direction. Since you have a '69 Goat, is it a RA-IV with a TH-400? Even if it's not a RA-IV, what is the stall speed on your converter (assuming you have an automatic)?

Re the 650cfm Q-Jet, this is a guess on my part. Had a Holley (4160) 750cfm and I never could get that thing tuned right over a ~2 year period. I finally took my mechanics advice and let him build a Q-Jet for my car. He didn't have any worthy Pontiac versions available so we used a Chevy version - I think it's like a '72 or '73? Hence the guess that it's a 650cfm. Bottomline is once I installed it the difference in throttle response was incomparable vs. the Holley. I said to myself "Geeez, I must have gained 30 horse!" and then I took him for a drive and he said the same damn thing!

Soooo, while it seems that the smaller carb runs better on my engine, perhaps it's the *type* of carb that has given me the increase in performance? i.e. A Q-Jet built specifically for GM cars vs. a Holley built for 'any' car. Given my altitude, maybe I could go up in cfm with another Q-Jet to get even more power?

I keep looking for a "silver bullet" for my lack of power on the street, so this may be something to consider as well. That silver bullet may very well be incremental, but I can't help think that there's still some power on the table somewhere (and this is after going through "everything" over the last few years)...

Thanks again!

Jim.

[69goatboy]

A Q-Jet is obviously a very good choice for your motor, I'm just wondering if 650 cfm's is enough with your elevation. I would think that the thinner the air, the more air you would need. I believe our beloved 400's came with 750's.

I think you're looking at a combination of cfms and the converter. A properly built TH-350 is no slouch.

My car is in a bunch of pieces in process of converting from a auto to a manual plus a new motor. The converter I do have is probably a worn out factory one.

I would re-post you situation over in the street section and let the guru's over there diagnose your issues.

A well tuned 400 with 3.90's out back should run a hell of a lot quicker than high 14's.
Also, what were your 60 ft times?

[goatless]

Originally Posted by 69goatboy

A well tuned 400 with 3.90's out back should run a hell of a lot quicker than high 14's.
Also, what were your 60 ft times?

That's what I was thinking. I am aware that the elevation is having a negative effect on ETs, but still... A 400 with 3.90 gears should should be able to obliterate the tires even with a stock converter.

[Ron Landis]

a 2400 stall would hit the tires harder. That is what GM put into a 396/375 car from the factory. The RA IV cam makes NO bottom end power. That is why GM offered it with 3.90s or stiffer gears. Personally, I'd go with a 2700-3000 unit myself. Folks are intimidated by the numbers but the converters are advertising flash stall...not brake stall. You would realize @ 2200 or so on the footbrake with a 3000 stall converter. We ran a Super Street Fighter which is 3500-3800 and could only hold the car to @ 3000 on the footbrake. This was a 3400# car with four wheel discs!!! Pulled thru the lights at 3100 rpm. We had 4.10 gears. A buddy of mine ran a 396 in a '66 Chevelle with the same converter and 3.55 gears on the street. No problem with heat or slippage. Again...don't take the numbers too seriously...you'll never realize what they advertise. Good luck. Ron

[goatless]

Ron, without a doubt a higher stall is going to help off the line, but...
I can scarcely move my car around in the drive way with out chirping the tires. I know it's a 455 and all but it's only got 3.73s in it.

The way he's making it sound is like my Lemans was back when it had a 350 and 2.56 gears.

[69goatboy]

Sounds more like his converter is not working at all and he has almost total slippage.

Shot in the dark here, but have you check your tranny fluid lately? Is there the proper amount? Is it the proper color?

What were your 60' times? Final speed?

[Ron Landis]

Originally Posted by goatless

Ron, without a doubt a higher stall is going to help off the line, but...
I can scarcely move my car around in the drive way with out chirping the tires. I know it's a 455 and all but it's only got 3.73s in it.

The way he's making it sound is like my Lemans was back when it had a 350 and 2.56 gears.

Don't ASK me to explain your car....that thing is phenominal!!! Anyway...you're right. It could be as simple as a timing issue. Maybe advance the cam phasing by 2-4 degrees. A chassis dyno would tell the tale. Tough call without being there to observe. Ron

[270win]

my 68 has a stock 400 with 2.93's and a 400TH and it'll roast the tires if you nail it from a dead stop. It has a stock converter...sounds like either the converter is going bad or there's another issue here....JMO

[71 T/A]

I use a B&M Holeshot 2000 in my 69 GTO. I have been told that in a Pontiac, this converter stalls closer to 2200-2400.

[68WarDog]

My 68 has a 406 with # 96 heads and RAIV cam adv 4 degrees,B&M 22-2400 stall with 3.90 gear.If I foot brake it then floor it the car will light up the tires in such a way I have to either shift out to 2nd(and still burning rubber) then into third with a small bark. But the point is, 3.90's should be an animal in any TORQUE Pontiac from a standstill.Runs 1/8 mile in 8.4 on 87 octane.

[mechanic17]

I suspect cam mismatch too. Notice 68wardog has his 4 degrees advanced. Your converter is not flashing up to the torque curve the engine makes.

You can test for little to no money by installing a set of 1.5 rockers--you may have the old ones still around--effectively making the cam smaller. If you feel an improvement off the line, keep going in that direction. You can advance the cam for zero $. Remember that Pontiac didn't use that cam with d-port heads. Finally, Rhoads lifters should make it better down low, for $100.

Just throwing out alternatives to a new (good) converter, which is going to cost you some.

[68WarDog]

[QUOTE=mechanic17;3767423]I suspect cam mismatch too. Notice 68wardog has his 4 degrees advanced. Your converter is not flashing up to the torque curve the engine makes.

Good point Mechanic. I also noticed you're running approx 10.6:1 c/r with iron heads. Are you running 100 octane fuel? Was the cam degreed/ installed to ward off detonation (retarded) for pump gas? IMHO your cam is not too large IF you c/r is indeed 10.5:1. Still should be a "stoplight" animal with 10.5:1 c/r 413/RAIV cam ci/ 3.90 gear.Something has gone amiss. May want to post this in the "Street Section" to find out what's missing.

[mechanic17]

oh yeah, make sure your HEI vacuum advance is plugged into ported vacuum--not manifold vacuum. Some "tuners" make this mistake and then end up with retarded initial timing, which just kills the bottom end. Very common problem.

In case you don't know, ported vaccuum will show "0" on a gauge at idle and go up as you rev the motor. Right front of a q-jet, as you're looking from the nose of the car, if I remember right.

[69gtocv]

Originally Posted by mechanic17

oh yeah, make sure your HEI vacuum advance is plugged into ported vacuum--not manifold vacuum. Some "tuners" make this mistake and then end up with retarded initial timing, which just kills the bottom end. Very common problem.

Huh? I would hope that most of us would plug the vacuum advance before adjusting the initial timing. And whether or not you use ported or full manifold vacuum (debated on these forums ad nauseum), it will not affect your initial timing once set.

[fredjchavez]

I had a 1971 cutlass convert with a 455 and 3.55 gears and auto. Granted, 455 torque is something to behold (pontiac or olds or buick) and because of this, ANYTIME a downshift to 1st took place, watch out cuz it would go side ways if you were paying attention (read, anything below 35 or 40 mph). Interesting to note that traction was not a big issue from a stand still (w30 cam does not wake up till around 2400 or so). Anyway, it ran 14.60 which was a very respectible time at 5200 ft elevation in summer heat. I do not know what the actual correction but suspect it was around 1.1 or 1.2 seconds which puts it down in the low mid 13's (as expected...w30 build). This combination was very consistent and surprised many and required less skill to lauch mainly due to the cam not waking up. Brake stall was around 1900 with this combo.

Anyway, my 68 convert has never been to the track but according to my handy dandy electronic timer, does 15.20 (I now live at sea level). However, it is 2.93 and open. It will grab rubber at anything less then around 30. Even with less torque, I would fully expect similar behavior with a 3.55 rear end and more problems launching then my 455 cutlass. The 067 cam will wakes up as low as 1700 rpm and my convertor brake stalls at 2300 so you have the formula for smoke if that is what you want.

The point of all this is, do you want a show or do you want to go (or want a car that is consistent and easy to launch)? I have always prefered auto cars to come on gradually after a launch but that is just me. A 455 with 3.55, and 2700 convertor, and 068 and smaller cam would get ould pretty fast!

Just my 2 pennies...

[270win]

personally, I prefer a car that hits really hard off the line and hooks...if we're talking drag strip runs...on the street it's tough to hook. So a car that doesn't hit hard from idle is going to do better on the street. But for me, I don't care much for waiting for the cam to "come on"...I want tire shredding power as soon as I hit the loud pedal!