Yes! You answered your own question. I was battling the timing on my '73
pickup after I installed HEI (350 with Edelbrock products and a stock HEI
installed). I pulled the HEI off a camero, slapped it in and expected
miracles. Very wrong to assume so on my part. After a year of fiddling
around, I ended up going to a friend who works for a local shop that does
custom curving (it's amazing what a 12 pack will do). The original one I
put in was completely wrong for my pickup. In the end, we set the
distributor up at 10 to 12 initial (timed vacuum), 42 total and (I think) a
15 degree vacuum can. Selecting the proper shaft for the distributor (note
that the shaft and weights are a matched set) was the key and the expert
knew exactly what to do. [I don't want to discourage anyone from trying
this themselves, but it turned out to be a lot more complicated, or I should
say more science involved, than I originally thought. I suppose I could
have figured it out if I had some my homework.]. We selected a shaft based
on where the motor timing was (and using the part number on the existing
shaft), the timing of the cam, and where we wanted to end up. Look in the
GM parts book for HEI shafts...I think we counted 42...? In the end,
mileage increased by 30% (no kidding) and the motor simply WOKE UP. I was
extremely disappointed with the performance before - but am happy now. In
the end, we replaced the shaft, bushings, module, pick up coil, cap, vacuum
canister and wires (and of course cleaned everything up sparkly) for around
$100 in genuine GM parts.
I practiced on the '73 so that now I can apply the same process to the HEI
for the 261.
Good luck.
Allen in Seattle.
'50 3100
----- Original Message -----
From: "William Gray" <william.gray@snet.net>
To: <oletrucks@autox.team.net>
Sent: Wednesday, January 16, 2002 1:28 PM
Subject: [oletrucks] Ignition Timing Question
> This is my 1st note to this net - I hope I'm doing it right.
>
> Does anyone have the ignition timing specs for a pre-computer 350 in a
> 3/4 or 1 ton truck? I need to know initial, centrugal and vacuum
> advance numbers.
>
> What I've got is a fairly modern crate 350 with an HEI distributor from
> who-knows-what in a '59 Gumman-Olson van - 3/4 ton Chev forward control
> chassis, 10K lb. GVW.
>
> Maybe I should write to the shops that do custom curving of distributors
> - they should have most specs.
>
> Bill Gray
> william.gray@snet.net
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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