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Old 12-22-2012, 06:33 PM
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looking for the perfect converter

I have a 1967 c10 tubbed race truck. I have had it about 8 months and had little success so far due to chasing many issues with it. The truck weighs 3150 with me and a full tank of 112 octane. I have a Chrysler 8 3/4 full spool and 4.87 gear with disc brakes. The tires are 32x14.5 hoosier slicks. I've tried a powerglide trans 1.76 with a 10in 4000 stall and went 12.60@104 then tried a turbo 350 with a 4600 9in stall and ran 11.71@108. I switched to a 5000 8in stall and went 7.24@95. I decided to switch back to the powerglide now I'm looking for the perfect converter for my setup. I currently have an 8inch Hughes "5200" stall. The motor is a 350 .60 over gm crank, hbeam rods, speedpro 12.5 forged pistons, world sportsman 2 heads 58cc around 13.1 compression with a lot of port and valve work they are 2.08 not sure on flow specs. 12-908-9 comp cam..630 solid roller .306 duration @.50. Victor Jr intake port matched. Apd 750 carb and 2inch Apd billet spacer. The motor made 540hp@7000 and 500tq@5000 any suggestions would be appreciated I'm also looking for more power I want to run low 10s I know I could have run low 11s but I only had 1/8 mile passes on my last setup. Any other questions on things I left out just ask

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Old 12-22-2012, 06:51 PM
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Quote:
Originally Posted by dougleadfoot View Post
I have a 1967 c10 tubbed race truck. I have had it about 8 months and had little success so far due to chasing many issues with it. The truck weighs 3150 with me and a full tank of 112 octane. I have a Chrysler 8 3/4 full spool and 4.87 gear with disc brakes. The tires are 32x14.5 hoosier slicks. I've tried a powerglide trans 1.76 with a 10in 4000 stall and went 12.60@104 then tried a turbo 350 with a 4600 9in stall and ran 11.71@108. I switched to a 5000 8in stall and went 7.24@95. I decided to switch back to the powerglide now I'm looking for the perfect converter for my setup. I currently have an 8inch Hughes "5200" stall. The motor is a 350 .60 over gm crank, hbeam rods, speedpro 12.5 forged pistons, world sportsman 2 heads 58cc around 13.1 compression with a lot of port and valve work they are 2.08 not sure on flow specs. 12-908-9 comp cam..630 solid roller .306 duration @.50. Victor Jr intake port matched. Apd 750 carb and 2inch Apd billet spacer. The motor made 540hp@7000 and 500tq@5000 any suggestions would be appreciated I'm also looking for more power I want to run low 10s I know I could have run low 11s but I only had 1/8 mile passes on my last setup. Any other questions on things I left out just ask
There are many people on this forum that would know a lot more about this than I do but, I take it that your 7.24@95 was your 1/8th mile time and the 12's and 11's are 1/4 mile times. Your running a 4.87 rear gear and only picking up 13 MPH in the last 1/8th mile and it takes you 4 to 5 seconds to get that 13 MPH...do you think you might have to much gear and the converter is OK. Maybe try a 4.10 or so rear gear..Just thinking?

Ray
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Old 12-22-2012, 07:07 PM
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The 1/8 mile time was a different setup converter wise... I'm assuming just by how the truck responded I would have been around 115-118 mph I've been told to go with a higher gear to try 5.13-5.38 but I'd rather not even change that part..
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Old 12-22-2012, 07:23 PM
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Like I mentioned, many people would know more than I would but, what RPM are you going through the traps at on the 12.60 and 11.71 runs?

I had a Firebird years ago, 400, with a 4.88 rear gear, similar horsepower and torque but at a lower RPM and more weight. I was running consistent 12.3's @ 109, went to a 4.11 and ran high 11's @ 117 MPH. I ran out of motor before I ran out of track with the 4.88 rear gear, now that might be the the RPM difference, your running peak at 7,000 and I was at just under 6,500. I did notice that I wasn't coming out of the hole as quick but sure made it up at the big end.

If you don't want to change the rear gear, I don't know if a converter is going to do it for you, but let's see what the guys say that really know what their talking about...because I don't profess to be the ultimate expert on this stuff.

Ray
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Old 12-22-2012, 07:36 PM
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I'm at 6800 at the lights. The 12.60-11.71 et difference was based on a bad converter.. I run 1.52 60ft spinning a little I know the truck should run 10.50s just haven't had time to fine tune... I'm running alky next season
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Old 12-22-2012, 08:02 PM
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If your hitting the traps at 6,800 wouldn't a 5.13 or 5.37 rear gear be a bit much? At what RPM do you make your peak torque and horsepower on the power curve? If your spinning out of the hole and running a 1.52, 60 foot, is there anything you can do suspension wise to cure getting a bit loose at launch? What are you doing for rear suspension?
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Old 12-22-2012, 08:11 PM
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I thought going to a higher gear would be to much also that's why I don't wanna change that part.. I run ladder bars with adjustable coil overs I've changed a little bit but not sure what to do
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Old 12-22-2012, 09:17 PM
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I prefer a 4 link but ladder bars are generally not a bad set up...what kind of adjustment have you got on the coil overs?
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Old 12-23-2012, 04:53 PM
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The stall speed should be as close to the torque peak of the engine as you can get.

I think you're a little too heavy for a PG, but it might be more consistent if that is important.

Ever consider a TH-type input so you could try all the converters you have for them?

It seems the trap speed is not showing the amount of HP that would be happening so high in the rev range. Because of this I tend to believe you need less rear gear, too.
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Old 12-23-2012, 06:26 PM
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So you suggest around 5,000?
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Old 12-23-2012, 07:57 PM
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Give or take, yes.
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Old 12-23-2012, 08:04 PM
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Using the 1/8 mile et and mph of 7.24 seconds/95 mph, the 1/4 et is estimated at 11.39/117.80 mph. The rear gears are killing you for the quarter.
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Old 12-23-2012, 11:22 PM
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Your 7.24@95 MPH in the 1/8th indicates a 11.35@121MPH in the 1/4.
Your horsepower and car weight and mph corrilate.
You do not have near enough gear in the car.
The engine is not reving high enough thru the traps.
You re riding the converter too far down the track.
you need to trap around7500-7700rpm.
8 to 10% higher than peak power rpm
You need some 5.57 gears. (32" tire.) put the turbo back in with the 8" converter too. ( assuming its not wounded.
Now you will be applying all the engines' power.
Now the converter will lock up and function as designed.
Now the ladder bars and slicks will work a lot better
Now the car will launch, ET and MPH as it should for a 540HP engine in a 3200lb car.
Check for fuel starvation in the top end too.

Now get a tunnel ram like the Edelbrock Steet tunnel ram and another matching 750carb.
It will pick up enough additional power to get in the 10's high 10's@122-123MPH
The Tunnel Ram, two 750's and Methanol will work really well.

Be sure the spark advance is not over advancing in the top end .
Be sure the valve springs are right and not worn out so the engine can rev and trap properly.
I trust your distributor is locked out and timing is accurate and not acattering.
I trust the trans and or converter is not wounded or the motor is running out of fuel in the top end.

Last edited by F-BIRD'88; 12-23-2012 at 11:51 PM.
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Old 12-23-2012, 11:34 PM
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but I'd rather not even change that part.. The car and engine don't care what you want.

You are not reving this engine near high enough thru the traps. Get some 5.57's

Now try some tighter valve lash on that cam. try around .020-.022" in .022-.024" ex. set cold.
should pick up a bit more top end.

Last edited by F-BIRD'88; 12-23-2012 at 11:58 PM.
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Old 12-24-2012, 06:40 AM
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The highest gear set I've found for an 8 3/4 is a 5.38. What about switching to a set of brodix 23 degree spreadport -11x heads cnc ported would that be to big of a head for it?
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