Tuning a tripower
Thread Starter
Racer
Joined: Sep 2011
Posts: 444
Likes: 35
From: Michigan
Tuning a tripower
I've read lots of threads on tuning BBs and vacuum advance. Can someone tell me what port on the tripower manifold should I use to check manifold pressure when I'm attempting to check total time vs base timing. Has anyone found a paper written specific for a tripower tune up?
I've got a 400hp with a mild cam and slightly higher compression.
I've got a 400hp with a mild cam and slightly higher compression.
Last edited by Jims427400; Apr 20, 2016 at 09:05 AM. Reason: Left out information
Race Director
Joined: May 2006
Posts: 18,690
Likes: 2,572
why are you trying to determine manifold vacuum when checking initial and total mechanical advance? You are supposed to disconnect the vacuum line going to the distributor advance mechanism when setting either the initial or attempting to set total timing. There is nothing different as far as timing whether you have a 4bbl or tripower. If you are attempting to modify the advance curve you are trying for 36 degrees total mechanical advance at approx. 2,800 rpm.
Last edited by MelWff; Apr 20, 2016 at 11:01 AM.
Thread Starter
Racer
Joined: Sep 2011
Posts: 444
Likes: 35
From: Michigan
Well I'm showing my lack of knowledge on this topic. I understand now what I have to do. Now I hope you can tell me how simple it is to modify the advance curve. I'll google this next.
Thank you
Thank you
why are you trying to determine manifold vacuum when checking initial and total mechanical advance? You are supposed to disconnect the vacuum line going to the distributor advance mechanism when setting either the initial or attempting to set total timing. There is nothing different as far as timing whether you have a 4bbl or tripower. If you are attempting to modify the advance curve you are trying for 36 degrees total mechanical advance at approx. 2,800 rpm.
Le Mans Master
Joined: Mar 2001
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From: Lincoln, CA
Instructor
Joined: Apr 2016
Posts: 104
Likes: 7
From: Denver Colorado
For street engines running on 87 to 91 octane I recommend no more than 30-31 degrees total advance in by 3000 rpm. And even then the engine could ping a little bit under a heavy load in high gear. The "standard" 36 degrees was fine and dandy for 100 octane gasoline but with the lower octane gasoline we have today it's much better to give up a few horsepower for the sake of reliability. I have a 10 to 1 cr big block with 31 degrees of advance in by 2500 rpm and it will rattle a bit when climbing steep hills in 4th gear at around 2000 rpm.
Race Director
Joined: May 2006
Posts: 18,690
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Mountainoakie:
Aren't some of the limitations you site based on you cant get 93 octane in Colorado plus you have an altitude factor that doesn't require more advance? At sea level and using 93 octane 36 degrees isn't causing an issue.
Aren't some of the limitations you site based on you cant get 93 octane in Colorado plus you have an altitude factor that doesn't require more advance? At sea level and using 93 octane 36 degrees isn't causing an issue.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
There are distributor spring and weight kits out there consisting of a set of weights, maybe 3 sets of springs, and instructions. It seems Mr Gasket made them, it's been a while. The kit is installed under rotor. What you are doing mostly is altering how fast mechanical advance comes in. Changing the weights may give you a little more advance but not a lot. The kit has nothing to do with vacuum advance. It can be a trial and error thing changing weights and springs. You would be checking progress with kit by watching at what rpm full mechanical advance occurs. Then driving car to see how it performs. Your total advance(including vacuum advance) should still be 34-36 degrees@3k
Melting Slicks
Joined: Oct 2003
Posts: 2,162
Likes: 813
From: Chapel Hill NC
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There are HOURS of reading regarding timing on the forum. I have a 68 BB tripower NOM of unknown displacement, cam, compression ( it does have mechanical lifters). Bubba was into my distributor big time and after moving the dist. one notch and fixing some other issues what worked for me was 22-24 initial advance, all in 36 at 2800 which required closing up some of the advance slot. With my vacuum advance I'm at 52 but will reduce this with home made limiter probably to 48. I obtained all my info from the forum and there was a lot of trial and error.
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