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#1
06-03-2007, 01:15 PM
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do i need a different vac advance with 4spd?
the hei i'm using is out of a 76 or 77 grand prix with a 400 and auto. is there a difference between the vacuum advance units between autos and manual transmissions? the number on the vac advance i have now is 635-25. so if there is a difference, what's a good part number to use with a 350/m21, and where to get it? also, would i need a different one because of engine modifications?
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#2
06-03-2007, 05:58 PM
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That vacuum advance can pulls 25* of advance. Depending on your engine set up it may be too much and could put into detonation. Without more info I won't say more than that.
Stewart
__________________
1976 TA, nose converted to 1970 style, 406, ported #13 Heads, '70 iron intake without crossovers, Q-Jet - Cliff style, RARE OS manifolds, Pypes duals w/crossflow, UD 230/238 custom HR 4/7 swap cam with solid roller lifters  , Hydro-Boost 4-wheel discs, 4 Speed, 3.23 posi.“Nothing in life is so exhilarating as to be shot at without result.” - Winston Churchill |
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#3
06-03-2007, 06:46 PM
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my combo is a 350 with #16 heads(the t37 ones), summit 2801 cam, comp lifters, bored .030 over, heads cut, decked, quadrajet, cast iron intake, split water cross over, gasket matched head and intake, comp roller timing set, flat top pistons with small reliefs. m21 muncie, 11" clutch, 3.73 posi.
Last edited by heff; 06-03-2007 at 10:06 PM. |
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#4
06-03-2007, 07:21 PM
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with the dist modified to complement the other things in the combo a good number to shoot for on a vac adv is 10-15 crank degrees and be sure it is non operational below say 6-7 in hg. of vac.
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#5
06-03-2007, 08:15 PM
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Agreed. Something on the level of 15* is about right. It will take some tuning to find the proper amount of VA necessary so I'd suggest an adjustable can like the one from Crane. It could be anywhere from 12* - 18*, I'd think. I did similar things to the 400 in my TA. But now I'm going to change the cam and start all over again.
 Sounds like you will have a great combination when you get the details sorted out. Good luck. Stewart
__________________
1976 TA, nose converted to 1970 style, 406, ported #13 Heads, '70 iron intake without crossovers, Q-Jet - Cliff style, RARE OS manifolds, Pypes duals w/crossflow, UD 230/238 custom HR 4/7 swap cam with solid roller lifters , Hydro-Boost 4-wheel discs, 4 Speed, 3.23 posi.“Nothing in life is so exhilarating as to be shot at without result.” - Winston Churchill |
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#6
06-04-2007, 09:00 PM
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so where should i set the vacuum at? do those adjustable vacuum advance deals come with good instructions? also, i've rebuilt the distributor and used the weights and center plate i've read were the best to use, along with on heavy spring and one med spring
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#7
06-04-2007, 09:30 PM
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Quote:
Stewart
__________________
1976 TA, nose converted to 1970 style, 406, ported #13 Heads, '70 iron intake without crossovers, Q-Jet - Cliff style, RARE OS manifolds, Pypes duals w/crossflow, UD 230/238 custom HR 4/7 swap cam with solid roller lifters , Hydro-Boost 4-wheel discs, 4 Speed, 3.23 posi.“Nothing in life is so exhilarating as to be shot at without result.” - Winston Churchill |
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