68 427 real world timing
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
32-36 degrees total timing, at your preferred rpm, generally around 3000-3500.
you could try 32, see how it is, ensure no pinging, try 36 see how it is, and ensure no pinging.
timing is definitely a diminishing return(you would gain more from raising timing from 10 to 15 than you would 30 to 35) so I wouldn’t stress about finding the absolute highest you can run without pinging.
32 is great for street driving.
you could try 32, see how it is, ensure no pinging, try 36 see how it is, and ensure no pinging.
timing is definitely a diminishing return(you would gain more from raising timing from 10 to 15 than you would 30 to 35) so I wouldn’t stress about finding the absolute highest you can run without pinging.
32 is great for street driving.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Closed chamber 427/390 will want about 38 degrees total.....the chamber is very inefficent compared to the second design open chamber stuff......you will need 93 octane fuel minimum if it is stock.....
This puts initial in the 16 degree range......hook vacuum advance to full manifold vacuum.....stock will be hooked to ported. Full manifold vacuum at idle will improve response, idle better and run cooler.
Jebby
This puts initial in the 16 degree range......hook vacuum advance to full manifold vacuum.....stock will be hooked to ported. Full manifold vacuum at idle will improve response, idle better and run cooler.
Jebby
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Closed chamber 427/390 will want about 38 degrees total.....the chamber is very inefficent compared to the second design open chamber stuff......you will need 93 octane fuel minimum if it is stock.....
This puts initial in the 16 degree range......hook vacuum advance to full manifold vacuum.....stock will be hooked to ported. Full manifold vacuum at idle will improve response, idle better and run cooler.
Jebby
This puts initial in the 16 degree range......hook vacuum advance to full manifold vacuum.....stock will be hooked to ported. Full manifold vacuum at idle will improve response, idle better and run cooler.
Jebby
First, use a set of springs in the distributor that will allow full centrifugal to come in at 2800 - 3000 rpm. The 427 with stock iron heads produces best torque and power when full centrifugal timing is set to about 38 at the noted peg-out rpm (as long as you're running gas with enough octane to avoid detonation). This should put initial timing (without vacuum) in the mid- to high-teens. 16 to 18 initial works well - fabricate a limit bushing to achieve this spec. Limit your vacuum advance to 10-12 degrees and run it off manifold vacuum. All these specs, and how to achieve them, are outlined in detail in my "How to set your Timing" paper, available from me via e-mail request.
Lars
V8FastCars@msn.com
Last edited by lars; Jan 26, 2022 at 12:16 PM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
The first L-88's and ZL-1's were Closed Chamber and made peak power with 38 degrees lead....in mid 69' the open chamber was released and made peak power with 36. The open chambers quench was just that good.....the second design heads were also worth about 30 horsepower.......which explains the wide gap in quoted numbers from 530 to 560 when talking about these engines........
My 427/400 ran better with 38 degrees but you better make sure you have some octane......the open chamber is more detention resistant.
FWIW...the open chamber is so good that even the aftermarket suppliers offer their BBC heads with this chamber largely unchanged some 53 years later!
Jebby
Last edited by Jebbysan; Jan 26, 2022 at 12:26 PM.
Drifting
Joined: Oct 2005
Posts: 1,528
Likes: 148
From: East London/SW Essex UK
I simply installed a Moroso bob weight and spring kit to my L36 4 speed (3.08 rear) - set initial for 16 degrees and 36 (or 38 total - can't remember) all in with full centrifugalat 2100 rpm. It ran sweet - no pinking at all.
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