Did I do it right ?
Thread Starter
Drifting
Joined: May 2005
Posts: 1,909
Likes: 6
From: Lake Arrowhead - Georgia > 72 Base Coupe & 74 BB Roadster
Did I do it right ?
I recently converted my points to an HEI. Today I used the "long thread" on Timing to set up my distributor.
I understand "basics" of what I did but would like to be sure I did it right.
74 LS4....454
Unplugged / sealed vacuum advance.....rubber banded centrifugal weights......set timing to 10*.....removed rubber bands....confirmed timing was still at 10*.
After installing ONE weaker spring, I was able to max at 36* @ 2900 RPM with no vacuum advance.
I then connected the vacuum advance....timing shows 36* at IDLE.....600.
With vacuum advance connected....RPM @ 2900 - timing shows 50*.
I'm so confused.........
I understand "basics" of what I did but would like to be sure I did it right.
74 LS4....454
Unplugged / sealed vacuum advance.....rubber banded centrifugal weights......set timing to 10*.....removed rubber bands....confirmed timing was still at 10*.
After installing ONE weaker spring, I was able to max at 36* @ 2900 RPM with no vacuum advance.
I then connected the vacuum advance....timing shows 36* at IDLE.....600.
With vacuum advance connected....RPM @ 2900 - timing shows 50*.
I'm so confused.........
Former Vendor
Joined: Nov 2006
Posts: 2,482
Likes: 3
From: Carmichael ca
Sounds like you hooked up the vacuum advance to manifold vacuum, so now you're getting full vacuum advance at idle. If you hook it to a ported vacuum source you won't get vacuum advance until you're off idle.
Did you by-pass the balast resistor. HEI needs a full 12 volts.
Did you by-pass the balast resistor. HEI needs a full 12 volts.
Thread Starter
Drifting
Joined: May 2005
Posts: 1,909
Likes: 6
From: Lake Arrowhead - Georgia > 72 Base Coupe & 74 BB Roadster
My vacuum line is hooked to the upper - right front of the Q-Jet. I could use the lower passenger SIDE.
Which is best?
Yes....gave it the full 12 V supply.....good point though!
Which is best?
Yes....gave it the full 12 V supply.....good point though!
Last edited by fotyfobravo; Jul 12, 2010 at 07:36 PM.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Sounds like you got it right. You now have 24 deg of centrifigul advance, plus 10 deg of initial equals the 36 total. 50 is ok at cruise because the vacuum advance will retard it during acceleration.
On mine I limited the centrifigul to 20 deg so I could run higher initial. Depending on you cam, yours should be fine.
On mine I limited the centrifigul to 20 deg so I could run higher initial. Depending on you cam, yours should be fine.
Last edited by '75; Jul 12, 2010 at 09:46 PM.
