73 455 timing questions?
April 28th, 2013, 08:37 AM
#1
My 73HO
Thread Starter
Join Date: Jul 2009
Location: Zooo Jersey/ Retired Now Florida
Posts: 277
73 455 timing questions?
I have been reading and rereading post all over the net to come up with a bench mark for my timing!!!
I have read a hundred pages here on this topic and Im still not comprehending it unfortunately to fit my HEI install.
1973 455 Cutlass with rebuilt Q-jet.
1. I have a Pertronix Flame Thrower HEI distributor. The instructions say it preset with 16 degrees of advance.
http://www.pertronix.com/support/manuals/pdf/hei.pdf
2. My engine was reset when it was rebuilt to 0 at tdc. So my timing from what I understand should be at the 8-12 mark correct?. (not taking into consideration the hei yet)
3. My cam card will be attached in case that make a difference.
4. So this is my estamate: 8 base timing plus 16 = 24. So with an advance timing gun I set to 24 on zero.
a. From what I read it should be done at 3500 rpms?
b. I cant get my asz to stay under the hood to f with the timing light and distributor with it roaring that high!
Everywhere I read it say 32-34 advance at 3500 rpms because most HEI's are preloaded around 20 plus the normal 12 they are factory set at??
Any help is always appreciated....!
I have read a hundred pages here on this topic and Im still not comprehending it unfortunately to fit my HEI install.
1973 455 Cutlass with rebuilt Q-jet.
1. I have a Pertronix Flame Thrower HEI distributor. The instructions say it preset with 16 degrees of advance.
http://www.pertronix.com/support/manuals/pdf/hei.pdf
2. My engine was reset when it was rebuilt to 0 at tdc. So my timing from what I understand should be at the 8-12 mark correct?. (not taking into consideration the hei yet)
3. My cam card will be attached in case that make a difference.
4. So this is my estamate: 8 base timing plus 16 = 24. So with an advance timing gun I set to 24 on zero.
a. From what I read it should be done at 3500 rpms?
b. I cant get my asz to stay under the hood to f with the timing light and distributor with it roaring that high!
Everywhere I read it say 32-34 advance at 3500 rpms because most HEI's are preloaded around 20 plus the normal 12 they are factory set at??
Any help is always appreciated....!
April 28th, 2013, 09:15 AM
#2
Administrator
Join Date: Oct 2009
Location: Poteau, Ok
Posts: 41,081
Ok, your distributor has 16 degrees of mechanical advance, that is the amount of advance you will get in addition to your initial. So if you set your initial at 18 at idle with vacuum disconnected, and you set your timing light to 34, rev the engine to 3500, you should read "0" on the timing mark to the tab. If it reads higher or lower, then raise or lower your initial that many degrees to compensate. Most engines can stand up to 36-38 BTDC depending on fuel quality.
Please note, monitor your engine for pinging at mild throttle with you vacuum advance connected.
Please note, monitor your engine for pinging at mild throttle with you vacuum advance connected.
Last edited by oldcutlass; April 28th, 2013 at 09:19 AM.
April 28th, 2013, 05:02 PM
#3
Registered User
Join Date: Jun 2008
Location: Near Muskegon Michigan
Posts: 1,015
My Summit HEI has 20 degrees advance. My timing is at 17 initial coming out @ 37 degrees total. I have tried more and less but this is where she likes to run. Of course this is depending alot of variables with your engine.
May 5th, 2013, 06:49 AM
#6
My 73HO
Thread Starter
Join Date: Jul 2009
Location: Zooo Jersey/ Retired Now Florida
Posts: 277
Ok so I set the timing at 18 and it works good! I still cant get myself to stay that close to the motor while reving at 3500 to see if it hits 32-36 degrees at that rpm! No pinging.... I think when I have time ill bump it up and see at what point I get pinging and back it off...
Thanks again!
Thanks again!
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