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Old 08-09-2022, 03:45 PM
dv657172 dv657172 is offline
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Default What should it be running?

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

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Old 08-09-2022, 03:59 PM
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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.

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Old 08-09-2022, 04:13 PM
dv657172 dv657172 is offline
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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.

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Old 08-09-2022, 05:08 PM
grandam1979 grandam1979 is offline
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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?

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Old 08-09-2022, 05:19 PM
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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.

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Old 08-09-2022, 05:36 PM
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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

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Old 08-09-2022, 05:49 PM
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Well you have yourself a good start, enjoy!

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Old 08-09-2022, 06:32 PM
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25stevem,

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

thanks
DV

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Old 08-09-2022, 10:34 PM
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I would also believe your carb is a bit small. I believe an 850 is the minimum for a 455.

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Old 08-10-2022, 01:35 PM
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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.

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Old 08-10-2022, 04:06 PM
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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.

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Old 08-10-2022, 05:06 PM
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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.

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Old 08-10-2022, 05:13 PM
grandam1979 grandam1979 is offline
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Are 100% sure it’s a stroker and is not a 400 still?

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Old 08-10-2022, 05:23 PM
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The OP stated it’s now a 455 so he has been told.

If it’s a factory crank looking at the flexplate side of the crank could prove that, he could also remove a plug and stick a pencil in a bore to find out what the motor has for stroke.

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Old 08-10-2022, 05:38 PM
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Should be running 11.60's to 70's... carb is too small for sure. Any high compression 455 ( 12.5-1 with 16#s ) should be mid 11's... if not, there is definitely a problem

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Old 08-10-2022, 06:27 PM
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OK unless it has been bored a 400 block and 455 stroke is 449 ci.

I differ and think his times show no more than about 400 FWHP.

You say it has cranking compression of 160 psi. To get an idea of the cam / CR. At what RPM does it idle at smoothly?

Stan

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Old 08-10-2022, 06:46 PM
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Quote:
Originally Posted by Stan Weiss View Post
OK unless it has been bored a 400 block and 455 stroke is 449 ci.

I differ and think his times show no more than about 400 FWHP.

You say it has cranking compression of 160 psi. To get an idea of the cam / CR. At what RPM does it idle at smoothly?

Stan
U gonna type that rpm in ur computer and get him an answer?

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Old 08-10-2022, 07:31 PM
dv657172 dv657172 is offline
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Thanks for all the comments and ideas thus far...

Stan - the idle is 1,000 rpm

Grandam1979 - not 100% sure on crank being a 455 but will try to confirm as per 25stevem's idea but lets assume that it is

Haven't noticed any fuel starvation issues when I have run it, I have an electric pump pushing at 97 GPH (rating) and a mechanical pulling at 110 GPH so it should be consistent I would think

While the engine was run on a dyno stand before I bought the car (engine in car but no plumbing or wiring) I do not have the info as I bought from a guy flipping car from original owner/builder

In terms of carb size I wondered about it being a bit too small for 100% racing as original owner wanted to make it a street/strip car.

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Old 08-10-2022, 07:46 PM
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Quote:
Originally Posted by dv657172 View Post
Thanks for all the comments and ideas thus far...

Stan - the idle is 1,000 rpm

Grandam1979 - not 100% sure on crank being a 455 but will try to confirm as per 25stevem's idea but lets assume that it is

Haven't noticed any fuel starvation issues when I have run it, I have an electric pump pushing at 97 GPH (rating) and a mechanical pulling at 110 GPH so it should be consistent I would think

While the engine was run on a dyno stand before I bought the car (engine in car but no plumbing or wiring) I do not have the info as I bought from a guy flipping car from original owner/builder

In terms of carb size I wondered about it being a bit too small for 100% racing as original owner wanted to make it a street/strip car.
I would say a 750 is too small.. get a decent carb.. 850 or so...AED sells great carbs. Give them all the info u have and they will set u up...
I have an 850 pro carb of thiers... I have it apart.. gonna have them rebuild and test it.. if u don't have one to try, I'll send u this one once it's done... pm me if u want to try it.. just understand I have to have it rebuilt... may take a couple weeks..
Glad to send it to u to try when it's done. Won't be the first time I mailed out parts to try

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Old 08-10-2022, 07:51 PM
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Scott that is very generous of you. I will get in touch with you soon

I have also attached a pic to put the story with if anyone is interested in seeing the car. Hopefully it worked
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