[yragat]

are the advance springs from a HEI the same as the older delco with the window on the side?
SBC total advance without vac connected is around 36*all in at 2500 RPM
What should it be for a 1960 stock 390 Cadillac?
Thanks

[F-BIRD'88]

Having the mechanical advance come in so fast is usually no ideal on these
older high compression motors with mild "stock" cam timing.
Some of these old stock motors had quite high compression.

Slow it down a bit with stiffer advance springs.
All in by 2500 rpm is pretty agressive for this "stock motor"

If this is a high compression ratio motor it will probably need something better than crap 87 octane gas.

If its 10:1+ use 92+ octane gas.

[yragat]

I use 93 octane
What total would you recommend and all by what rpm?
I have a bunch of HEI springs---can I use them in the older dist?
Compression reads at 150 --was 165 from factory
Millage on engine is unknown,but runs good

[yragat]

This thing is driving me nuts! It runs good,so I probably should just leave it alone,but I know it ain't right. I set the timing at 5 btdc with the vacuum disconnected and plugged. then I hook up the vacuum and the timing goes to 30 btdc,and stays there whether idling or when I rev it. I don't think by the look of the very heavy springs that the centrifugal advance is working at all and the vacuum canister is pulling too much (i think)---so basically Its running at 30 advance all the time??? Any suggestions??

[SSedan64]

You can change the Vac Can.
HEI Cans towards bottom of Pg. >> http://www.corvette-restoration.com/...c_Adv_Spec.pdf
Does your Carb have a Ported/Timed Vac Port?

[yragat]

Its not a HEI its the old style Dist with the window in the cap No more points--have pertronix conversion. No vac port on carbs (Stromberg 97s)
1960 Caddy engine (stock 390 c i)

[yragat]

Looks like I should get the B1 Vac canister?,and probably a set of different centrifugal advance springs The ones in there now are very heavy ones,I don't think they are letting the weights move at all

[PatM]

I know it isn't 1964 any longer, but some folks do have distributor machines still in their shop, or even in their garage (I bought one from a guy in Carson City, NV a couple of years back). A distributor machine makes playing around with this stuff all so much simpler. You could put points in to test it and build the curve you want right on the bench, then switch back to pertronics right before reinstalling. If you are really lost, and uncertain about the parts you have, this is a great way to test each compnent. You can characterize the vacuum canister and the mechanical advance, both in terms of rate and limits. Then, adjust as needed.

[yragat]

Thanks
Tried to find someone who had one in my area couple years ago and no luck

[cobalt327]

Originally Posted by yragat

Looks like I should get the B1 Vac canister?,and probably a set of different centrifugal advance springs The ones in there now are very heavy ones,I don't think they are letting the weights move at all

With the vacuum advance, what you see while sitting in the shop w/o any load on the engine is not what you would see if you had a timing light on the engine while under a load. But the vacuum gauge should drop immediately when the throttle is quickly opened, then come way back up when the engine decelerates w/the throttle closed. If there's any delay in the action, be prepared to remove the distributor for a thorough cleaning.

I agree it sounds like the springs are too stiff to allow advance at the RPM where you need it, so use lighter springs to bring the mechanical advance in sooner. How soon depends on several things, like gear ratio, vehicle weight, gas quality, how you drive it, compression ratio, air/fuel ratio, etc. There are weight/spring kits for points or HEI-type distributors. Use just the springs, not the weights. I would also suggest you get an adjustable vacuum can for that distributor. The Crane points-type kit w/can, springs and limiter plate is HERE.

The stock timing is 5º BTDC. I would raise that to about 10º BTDC to see if this improved off idle throttle response, but remember to take away any initial you add from the total so the total doesn't go too high. You will want to experiment w/using ported and manifold vacuum to see which works best for you.

[yragat]

Thank you very much
DARN,I already ordered the B1 canister from NAPA and a spring kit (with the junk weights) & some other stuff from Summit. I know that with SBC I always had good luck with one light spring and one medium one. But this isn't a SBC. Its just a stock Caddy 390 running 2 Stromberg 97's at the same time (it has 6,but 4 are blocked off)
With the SB I would run 36 total (without vac hooked up) all in at 2500 rpm,but I really don't know what would be a good setting with the Caddy. It is a light car (30 roadster) with turbo 350 and 2.79 gears. NOT a race car,just a drivable hot rod

[cobalt327]

No worries- the B1 can should be fine and the springs will get you to total quicker.

While this isn't a SBC, I suspect in the light car it's in the timing curve will not be too much if any different from the SBC set-up's you're used to.

I would say to start on the conservative side (less initial and total timing, total in later) and work your way up from there. Just use the same technique as you're prolly used to using- listen carefully for detonation and keep the engine out of it, keep an eye on the plugs for signs of a lean air/fuel ratio and use good fuel at least to start with until you're sure of what you can "get away with".

Good luck.

[yragat]

Yeh,it likes the expensive gas

[yragat]

Well today I installed the B1 canister,and put in 1 medium spring and 1 light spring. Set the initial timing (without vac connected) at 10. at Idle with vac it is at 28 . I don't have a tach,but revved it pretty good and timing went up to 30 with vac disconnected. Have idle set at 800rpm in park and 600 in gear.
Does that sound about right?

[cobalt327]

Originally Posted by yragat

Well today I installed the B1 canister,and put in 1 medium spring and 1 light spring. Set the initial timing (without vac connected) at 10. at Idle with vac it is at 28 . I don't have a tach,but revved it pretty good and timing went up to 30 with vac disconnected. Have idle set at 800rpm in park and 600 in gear.
Does that sound about right?

First, you really need a tach so you know when it's all in by.

I'd say to try it where it is and judge for yourself. But I believe you will find that you can use more initial AND total timing. I'd up the initial to 14º, this will put the total at 34º. Try it there and compare this to the earlier setting. You can also try a lighter spring package to see if it will take the timing sooner- just be aware of any detonation.

With the vacuum advance hooked up and you driving it, if you feel it surge under light throttle cruise conditions, you can make a limiter plate to set the total vacuum advance where you want it- usually around 10º-15º degrees. Use THIS as a pattern to limit the vacuum advance. It's for an HEI, so the spacing will be different for your older distributor I do believe.