To determine the correct amount of idle timing, you do this simple 5 min test:
- engine warmed up to operating temp, mixture adjusted as best as possible, engine idling in gear.
- slowly rotate dist CW [ advances the timing ].
- keep going until you get the highest rpm/smoothest idle. Toggle the dist to make sure.
- now check what the timing is.
Report back with the result & we go from there....
Yep done 'relatively' the same thing on all my motors,
MoPar Buick Pontiac Chevy Olds, doesn't matter
I see some that always say 32* (or 34*
) max all in at 2500 etc.
or
it won't live it will detonate it to death etc.
If that's what your specific engine/motor combo needs yeah
otherwise, Vacuum advance or not, can do it without too
if you drive it on the street the VA will be a smoother transition to cruise
AFRs are better too
&
I do like you said above, very similar, I disconnect the VA,
set the idle speed at 2000+ turn the distributor/advanced
until I get the best vacuum &/or highest RPM gain
re-hook VA back up & do a test drive, adjust the distributor if needed
usually like maybe 2*- 4* retarded, from what it was max,
before the VA was hooked up
been doing it since 1974, street or racecars VA or no VA, didn't matter
old trick my old' Pontiac S/S racer stepdad Bob told me,
his engine guy crew chief Wes, got from Mickey Thompson "allegedly"
& it never fails
I have a 4.290" 0.040"over-bored 383/392cid, Street/Strip was,
now just street beast
No tracks within 200 miles now
(forget what at 50) doesn't matter 278*/284* 0.528/0.540 hydr. roller Crane,
w/Crane Super-Gold 1.6:1 roller rockers
closed chamber 84 cc Edelbrock RPMs mild ported & Pocket ported, 1-7/8" step headers
(now it has
ported HP manifolds, chokes it down a lot, long story 'steering rack' in the way)
near zero deck, old forged Venolia flattops with .120" intake .100" exhaust valve reliefs,
.039" torqued FelPro 4.40" perma-torque gaskets,
should've use a Cometic 0.025" gasket, a lil' smaller bore 4.35" diam. in the Cometic too
a lil' down on compression for what I'd like, I'm at altitude too...
I have sold my 479cid zero deck 11:1 race short-block, to a racer buddy in need,
all this stuff was on & put all my top end & camshaft stuff on this
thing/OE #s 1968 short-block,
runs pretty well for a lil' 383, w/trick 6bbl dual plane
usually around 40*- 42* total with mechanical advance, I have a limiter from FBO,
use the 16* slots, so the VA doesn't over do it, ping to death while part throttle up hill loads
(as high as 52*-54*+ total with the VA activated) 24*- 26*+ at idle, (no VA)
plug back in it's smooth & great at 900-950 rpm, lower (like 850) it is fat, so I keep it up a tad
doesn't tug on the converter, much if any, crispy throttle, very responsive, drives nice
even for using 'Calif. swill/pump gas 91 octane'
it's a tad bit low on compression, for at altitude, but it's OK...
If I go out for a beat run, I bump it up to to like 28* initial & have at it...
probably over 120+hp down from the old motor, oh well
depends on the engine needs, it will tell you what it wants
nothing near the 34* total everyone tells you,
every engine needs to be
no it doesn't
