Vacuum distributor or not? - Team Camaro Tech
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post #1 of 7 (permalink) Old Mar 22nd, 08, 07:09 AM Thread Starter
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Don
 
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Vacuum distributor or not?

Hey guys;

Looking to pick up a Unilite for the ol' small block and I see a gob of them for sale with mechanical advance.

Is it really critical to have vacuum advance for street use?

I am going to run: 350, .060 over, flat tops, (Probably) Patriot 202-160 aluminum heads (64 cc) Lunati VooDoo 268 cam, full roller rockers, 650-750 (Vac. secondaries) carb, Weiand Stealth or Stealth Air Strike manifold.

Which distributor would you choose and why??

Thanks......

Don

My 68 coupe that I begged for since age 6..350, 4 speed, new paint
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post #2 of 7 (permalink) Old Mar 22nd, 08, 07:15 AM
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Re: Vacuum distributor or not?

I can't think of any reason not to have an operating vacuum advance system on a street car.
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post #3 of 7 (permalink) Old Mar 22nd, 08, 07:26 AM
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Jim
 
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Re: Vacuum distributor or not?

Not only that, but there are many reseaons TO use a vacuum advance on a street car.





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post #4 of 7 (permalink) Old Mar 22nd, 08, 07:29 AM
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Dave
 
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Re: Vacuum distributor or not?

For a street car, I would definitely go with vacuum advance dizzy. Under light loads (which will be 99% of the time on street), the optimum timing may be as much as 50 to 55 degrees. Mechanical advance only allows up to about 36 degrees, the extra timing comes from the vacuum advance.

Here's a couple of links with good details on vacuum advance. You truly benefit by it for street IMHO.

http://www.popularhotrodding.com/tec...iew/index.html

http://www.highperformancepontiac.co...ech/index.html

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970
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post #5 of 7 (permalink) Old Mar 22nd, 08, 07:44 AM
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Tim
 
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Re: Vacuum distributor or not?

For a streetcar I would have the vac advance if for no other reason than something to grab for twisting timing. Also I have seen some distributors with the oil annulus irregular shaped, the vac can would guarantee it is positioned correctly. Most of the aftermarket units I've seen have a symmetrical annulus though.

If the vac adv bugs you all you have to do is omit the hose. If it really bugs you, you can remove it from the distributor.

This is from somebody with locked out timing.

Edit: With your .060 oversize, you want all the anti-overheating medicine you can get and that's one thing vac advance helps on. Not trying to scare you, just based on the 350's history. Lots of .060's do fine but a few cause grief.

Tim Smith
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post #6 of 7 (permalink) Old Mar 22nd, 08, 08:23 AM
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Tom
 
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Re: Vacuum distributor or not?

Quote:
Is it really critical to have vacuum advance for street use?
YES unless you OWN an Oil company.

Vacuum advance NEVER hurts performance in anyway shape or form.
It only operates when you are driving at part throttle.

71 Camaro 355 NA
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post #7 of 7 (permalink) Old Mar 22nd, 08, 09:17 AM Thread Starter
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Don
 
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Re: Vacuum distributor or not?

Well the jury certainly has answered that one in basic unanimous fashion!

I suppose my goal was not say that I did not want it, but rather how much difference.........

I will continue the search for a vacuum advance dizzy............

Thanks guys........the usual free sharing of sage knowledge.......

Appreciate it.

Don

My 68 coupe that I begged for since age 6..350, 4 speed, new paint
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