Tuning 454 - Chevelle Tech
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post #1 of 46 (permalink) Old Apr 7th, 20, 1:06 PM Thread Starter
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Tuning 454

Hi Everyone, After 13 Yrs w/ 71 elky restoration. I am finally in the test & tune stage and this big block should light up the tires w/o having to raise the rpms and dump the clutch but will not.
454,.30 over, GM perf aluminum head semi-open chamber 2.25 Exh and 1.88 int, speed pro pistons a pprx 9:1 Gm perf rods, Crane cam & kit 226/236 - 534/553, dual roller chain, pertronix flame thrower dist & coil, Holley 770 street avenger on winters LS 6 manifold, Timing 16 intial 34 total @ approx 3000rpm. R 44TS @ .045. I just adjusted floats and idle circuit and idles good for cam. 10 In vacuum @idle steady needle, cannot adjust any higher w/ idle screws. Ceramic coated hedmans and 2-1/2 SS exhaust. Backed by m22 w/ 323 gear.
I feel I am missing something w/ tune it should be more responsive. I did change vac secondary spring to yellow that help a little when you hit it. But dumping the clutch just ignites the tires and begins wheel hop. You know I had 7 SS BBs mostly 4 spds maybe the 30 years w/o it making me forget. Needs some tuning help.
thanks, Tony
Clarkridge,AR
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post #2 of 46 (permalink) Old Apr 7th, 20, 1:21 PM
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Eric
 
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Re: Tuning 454

Wheel hop is not caused by your tune, its suspension related.

You're just jealous because you can't hear the voices!

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post #3 of 46 (permalink) Old Apr 7th, 20, 2:13 PM Thread Starter
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Re: Tuning 454

yeah , I gonna get under and make sure all bolts are torqued correctly w/ weight on car. after a restoration stuff just gets loose.
Thanks Tony
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post #4 of 46 (permalink) Old Apr 7th, 20, 2:20 PM
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Vince
 
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Re: Tuning 454

If your gauge is right , 10 of vac is low - tells me something is off. What is your idle rpm?

I ran a 454 with those heads and carb, and a 231/239 cam and got about 11.5 of vac at about 850 rpm I believe. Manual trans also. Was a great running 11 sec car.

Personally I think you need more initial timing. Id try around 20* and see if response improves. If it does and you like it, you will need to shorten the mechanical curve a bit.
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post #5 of 46 (permalink) Old Apr 7th, 20, 4:30 PM Thread Starter
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Re: Tuning 454

Hi Vince, at first I had 17" then realized I should be taking vacuum f/ under carb small port. when I did that I got a reading of=f 10". Ok you saying 20 deg initial timing w/ dist vac off and plugged. Then I reattach vac line and check total @300 0? I,m missing something about backing off total. You can only back it off by turning dist. won't that effect initial also?
Tony
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post #6 of 46 (permalink) Old Apr 7th, 20, 5:15 PM
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Re: Tuning 454

Change the advance bushing in the distributor to shorten the amount of centrifugal advance, to around 16. And put advance springs in that will full advance before 3000 rpm, about 2600. Then unplug your vacuum advance, set the initial timing to 20, rev the engine until it stops advancing, you are looking for 36. Then connect your vacuum advance to full manifold vacuum NOT ported. Reset idle speed.

If you can post the part number of the distributor we can look up the instructions to see what bushing/springs to use.
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post #7 of 46 (permalink) Old Apr 7th, 20, 5:21 PM
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Re: Tuning 454

Where did you have it hooked up that you had 17"?

Jim

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post #8 of 46 (permalink) Old Apr 7th, 20, 7:09 PM Thread Starter
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Re: Tuning 454

will try, thanks
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post #9 of 46 (permalink) Old Apr 7th, 20, 7:10 PM Thread Starter
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Re: Tuning 454

I had it hooked up to multiport in front of dist that screws into manifold.
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post #10 of 46 (permalink) Old Apr 7th, 20, 7:45 PM
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Re: Tuning 454

Quote:
Originally Posted by urleycay View Post
Hi Vince, at first I had 17" then realized I should be taking vacuum f/ under carb small port. when I did that I got a reading of=f 10". Ok you saying 20 deg initial timing w/ dist vac off and plugged. Then I reattach vac line and check total @300 0? I,m missing something about backing off total. You can only back it off by turning dist. won't that effect initial also?
Tony
I would suggest as a simple test, before even having to pull that distributor out, is to crank in a little bit more timing first to see if the car even likes it. Get your timing light out And set your base timing to say 20 to 22, And reconnect your vacuum advance. You may have to lower your idle speed a little bit. Yes your total time it is now higher, but you were not gonna be doing any wide-open blasts, You are just seeing if the car responds favorably In terms of throttle response and power. If it likes it, you will Then have to shorten the mechanical Curve However that distributor requires. This way you can keep your current total timing with the extra added initial. Make sense ?

*69 SS 502 EFI /224-228* HR/9.8:1/T56/3.90/ 4000lbs RW 11.5/124mph
*96 Stang 6.0 turbo 10.5/135mph (9.13 ET w/E85 and 16psi) **SOLD**
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post #11 of 46 (permalink) Old Apr 7th, 20, 8:19 PM
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Re: Tuning 454

I would disconnect the vac advance until you get done playing with your mechanical advance. Once you establish your advance curve then work on the vac advance.

You're just jealous because you can't hear the voices!

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1963 Plymouth Fury 440/Torqueflite
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post #12 of 46 (permalink) Old Apr 8th, 20, 8:01 AM
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Vince
 
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Re: Tuning 454

And what was the idle speed?

*69 SS 502 EFI /224-228* HR/9.8:1/T56/3.90/ 4000lbs RW 11.5/124mph
*96 Stang 6.0 turbo 10.5/135mph (9.13 ET w/E85 and 16psi) **SOLD**
*2011 Mustang GT premium
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post #13 of 46 (permalink) Old Apr 8th, 20, 8:13 AM Thread Starter
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Re: Tuning 454

Idle 1000 rpm
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post #14 of 46 (permalink) Old Apr 8th, 20, 8:29 AM
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Vince
 
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Re: Tuning 454

If the vac gauge is correct, 10" of vac at 1000rpm tells me something is not right. Try a little more timing first. After that may want to do a carb tune, valve adjustment, compression test. I would think at least 12-13" at 800-850. 1000 is way too high, especially for a manual trans. Burning a lot of unnecessary fuel.
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*69 SS 502 EFI /224-228* HR/9.8:1/T56/3.90/ 4000lbs RW 11.5/124mph
*96 Stang 6.0 turbo 10.5/135mph (9.13 ET w/E85 and 16psi) **SOLD**
*2011 Mustang GT premium
*61" Scag Kohler 22hp 7mph
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post #15 of 46 (permalink) Old Apr 8th, 20, 8:31 AM
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Re: Tuning 454

With 10" of vacuum at idle and a clutch you might want to run straight timing and remove the vacuum advance..
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