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i have a 69 400 that i had built and added the tri power intake setup. diagram for this is the distributor gets vacuum from center carb which theres always vacuum compared to the original intake where i had the ported vac switch. im running the points distributor also and no ac, is this ok or do i make a change at the distributor canister? im not a wizard in this area
The reality is that the factory initial timing and advance curves (vacuum and mechanical) were designed for a STOCK engine running on the gasoline available at the time of manufacture. Obviously a tricarb intake is not stock on your 69, and since we have no idea what went into an engine that you "had built", we can only assume it is not factory stock. The only certainty is that the original advance curves in your distributor will not be correct for your current setup. Will it run? Probably. Will it be optimized? Definitely not. This is where people come back and complain that their new engine doesn't make the power they thought it should.
As JP said, you will need to fine tune to your application..I put a pontiac tripower, ( basic same set up as Olds with the exception a pontiac center carb is manifold not carb ported vacuum.) on a 421 with forged pistons, xe268h cam, ported heads etc. to fine tune it in I used bigger jets on center carb and end carbs, clipped one ring off the power piston spring and used a adjustable vacuum can to keep messing with it..Pertronix billet distributor as well.. Got it so it ran pretty good. I am not a tune up specialist, just tried things etc so you may meed to be prepared to go down that road. Your question was vacuum source, it is-ported on olds tricarbs.
thank you gentleman! i figured its gonna b trial/error , it now has a bigger cam and edelbrock heads so its more than stock. i love these forums , been a major help with my different toys! u guys r great!
thank you gentleman! i figured its gonna b trial/error , it now has a bigger cam and edelbrock heads so its more than stock. i love these forums , been a major help with my different toys! u guys r great!
Hey Paul
Did you get the issue resolved? If you need any help please let me know
Mike
Hey Paul
Did you get the issue resolved? If you need any help please let me know
Mike
hi mike yes the linkage is all working as intended, i used a bb chevy truck throttle cable and bracket i had and its working but i am waiting on a another bracket for a return spring,
hi mike yes the linkage is all working as intended, i used a bb chevy truck throttle cable and bracket i had and its working but i am waiting on a another bracket for a return spring,
Is it idleing and running ok now that the linkage is correct?
so my vac advance engages at an idle, is this proper? will an adjustable vac can fix this?
Vacuum advance simply reacts to manifold vacuum. If you have it connected directly to manifold vacuum (as opposed to ported vacuum), it will "engage" anytime manifold vacuum is more that 0. Ported vacuum is sourced from ports above the throttle blades in the carb. When the blades are in the idle position, ported vacuum is zero. As soon as the throttle is opened enough for the blades to uncover those ports, then ported vacuum is exactly the same as manifold vacuum.
The reality is that the factory initial timing and advance curves (vacuum and mechanical) were designed for a STOCK engine running on the gasoline available at the time of manufacture. Obviously a tricarb intake is not stock on your 69, and since we have no idea what went into an engine that you "had built", we can only assume it is not factory stock. The only certainty is that the original advance curves in your distributor will not be correct for your current setup. Will it run? Probably. Will it be optimized? Definitely not. This is where people come back and complain that their new engine doesn't make the power they thought it should.
a new cam and heads were added, edelbrock performer heads #61025, with roller rockers, 9.850'' push rods
Vacuum advance simply reacts to manifold vacuum. If you have it connected directly to manifold vacuum (as opposed to ported vacuum), it will "engage" anytime manifold vacuum is more that 0. Ported vacuum is sourced from ports above the throttle blades in the carb. When the blades are in the idle position, ported vacuum is zero. As soon as the throttle is opened enough for the blades to uncover those ports, then ported vacuum is exactly the same as manifold vacuum.
my timing is advancing at an idle and it shouldnt be..i thought i mentioned this to mike
The Olds tri carb center carb has a direct vacuum port below the throttle plates that go directly to the vacuum advance port on the fuel bowl. FYI The GTO center carb does not have this port as they don't use a vacuum port on the fuel bowl.
Funny thing is the original 67 W30 tuning guide tells you to omit the vacuum hose to the distributor and block the carb plus set the timing differently.
On an engine with vacuum advance, the correct procedure to set initial timing includes removing the vacuum hose to the distributor and plugging the nipple at the carb. That way you set the mechanical initial advance without added vacuum operated advance. At an idle, there will be vacuum and thus a lot more timing when the vacuum advance is attached.
