[dv657172]

I bought a 65 GTO at a swap meet awhile ago from a guy who was flipping it from the previous owner. He didnt have any details about the work done to the engine other than its a 68 400 (verified) with a 455 crank #16 heads and Harland Sharp roller rockers. Engine had only been run on a dyno before being put in car. I bought it needing wiring, plumbing and race set up. The engine has a Torker II intake, Wilson tapered combo 1" aluminum spacer, Holley 750 double pumper (#74/#84). It has Hedman headers with 1.75" pipe and 3" collectors into a 3 foot long head pipe and turn downs (no mufflers) from previous owner. Also has a Holley mechanical and electric (red) fuel pump along with a MSD 6 AL box and Blaster 2 coil. Tranny is a TCI TH400 with a TCI 10" 3500 stall converter. Moser spool rear end with 3.90 gear and M/T slicks 26 x 10. Front shocks are 90/10, rear 70/30 and a PS rear air bag at 10 lbs. The car has been down the track about a dozen times (my only experience on a track also), I launch off a transbrake at 3500-4000 rpm and shift at 5500 the car has no traction issues. The best time so far is 1.672 / 7.705 @88.80 / 12.163 107.92 at basically sea level (South FL) but has run a similar 1/8 mile at Knoxville Dragway in TN (1,000 ft elev.) where I live now. Total timing is 36 degrees and cylinder compression is 160 lbs +/- 5 lbs on all cylinders. I do still have front stabilizer bar on the car but will be taking that off soon.

I know not having knowledge about cam and headwork, if any, makes this a tough question but does initial performance before any tuning sound about right or slow for a starting point? Any guess about what size cam it might have? What is weak spot or limitation of combo?

Thanks for any thoughts

[25stevem]

There’s a pretty big void in your post since you gave no cam info, so taking a guess as to how the car should perform can’t be done.

There are 400 cid number 16 heads and 455 SD number 16 heads , which do you have.

[dv657172]

68 400 #16 heads

I dont know what cam is in it. That's the issue, I know it makes judging it difficult but just trying to get an idea of what might be in it based on combo and initial time and whether the configuration is any good.

[dv657172]

Thanks!

[scott70]

Hmmm....my 750 qjet by cliff made about 5-7 more hp than the dyno 850 they had,,,even tried rejetting it. I will say they did use a adapter to put the holley on the cast intake . Maybe that hurt the 850.

[grandam1979]

So from your post it’s a 400 with a 4.21 or 4.25 crank so it’s a 455-468 with just what you have listed it should be faster your mph is down also. I think first I would do is verify your carb is opening all the way. You said it had dyno time do you have any of the information from that run?

[25stevem]

Does the car still have its stock steel fuel line running up from the tank?
If you have a dial caliper you should pull a valve cover to see what you have for intake and exh lift.

So now there’s two guys who don’t know what’s been done to this motor.

I hope that modified crank holds up for you with the racing that your doing if it’s a factory crank.

[dv657172]

The dyno run was done with engine on a stand as per previous owner (not the guy that I bought it from who was just flipping it).

I have an AN-8 fuel line from tank to carb installed.

I bought it because I have always wanted to built a GTO racecar but the ones I have and run across are all numbers matching and this one was basically a blank sheet of paper to start with...although a blank sheet on engine info also unfortunately

[dv657172]

TC

I havent done any tuning on it yet in terms of launch or shift rpm or air bag pressures. Still just trying to get seat time and a good base line for the car.

I would be interested in hearing why lowering the launch rpm below the stall rating might improve the performance? I would think a harder launch provided traction isnt an issue would be better although maybe harder on parts

Thanks

[tc]

Originally Posted by dv657172

I would think a harder launch provided traction isnt an issue would be better although maybe harder on parts

Thanks

I agree with this, but a harder launch is from a lower rpm launch than stall rpm. A lightweight car with more horsepower probably will launch 800 below stall rpm and I think cars like ours ( factory weight , less hp ) will have better 60ft with much lower launch rpm.

The 60 ft and 1/8 mile time looks good for a small ( street ) cam, street/strip car. The 1/4 mile time is ok, but the mph a little low. Those last two should improve with your 'tuning'.

I like you car and the color. What color ( name ) is it. Looks similar the the color I want for my '68 Firebird.

[25stevem]

Well you have yourself a good start, enjoy!

[dv657172]

25stevem,

Is your crank concern due to launch technique, shift rpm, or inherent issue in modifying a factory crank? just curious

thanks
DV

[dv657172]

TC

Thanks for the info. I will definitely try a lower rpm launch in the future to see what impact it has. The car sat for a few years between running it in FL and finally running it again this year in TN so my first few runs were with a lower rpm and my 60 foot times were definitely slower 1.80 - 2.0 range but will try it again once everything is sorted out more formally.

Thanks on the compliments and the color is claimed to be PPG Silver Mist. Never checked it but I like it too.

[quick67bird]

I would also believe your carb is a bit small. I believe an 850 is the minimum for a 455.

[Scott Stoneburg]

It's hard to say, but the performance seems a little soft. The fuel system may be an issue. A Holley Red pump pushing through a mechanical pump, may not be up to the task. Carb is a little on the small side. My 428 ran better with an 830 over the 750.

[dv657172]

I would guess around 3500 + driver weight (too much, lol).
Car is missing the back seat but the Moser rear end (Ford 9") is definitely heavier than a Pontiac unit and it has a TH400

[mchell]

Oh oh….if the back seats out someone’s tying to go fast….what else is “missing “…lol

Might want to weigh it sometime…always interesting.

Weighed mine a couple months ago and it tripped the scales at 4008… had more gas in it or I’m growing, probably a little of both.

[JLMounce]

If the engine was run on the dyno did the previous owner provide the power numbers? Since we're making assumptions, if we assume this is a 462-468cid engine at or near 9.0 to 9.5:1 compression, with stock heads and something like a comp 280H in it, the power it's making to motivate a 65 GTO to nearly 108 mph in the 1/4 mile might be right on the number. You need around 370rwhp to do that which would put the engine somewhere between 460-480hp.

If it has a much healthier cam, head work and a flat top piston which would put it above 11:1 compression, then I'd say the performance is probably soft.

[25stevem]

My concern is that if it’s factory 455 crank in there that there’s two ways to do that. One way is sound and the other way is a ticking time bomb.

This can be done the right way with a modified Olds thrust bearing, or it can be done by welding the cast iron crank which is bad

Even a guess of just 460 Hp, no less 480 Hp is a very rosy guess when if we are talking about stock heads and a 280H cam.

[grandam1979]

Are 100% sure it’s a stroker and is not a 400 still?