distributor recurve?

[suburban4x4]

im lookin to put a recurve kit in my hei distributor that i installed in my 73 caddy 500 cid the engine is unrebuilt but has headers and an edelbrock 750
my question is what am i lookin for in total timing and which springs do you recomend

[Andy V]

I'd shoot for 34 to 36 degrees total timing without vacuum advance hooked up.
w/ the vacuum advance it will likely be over 45-50 total, which is ok.

For springs, you can start about it 2 ways....start light and if it pings work progressively stiffer till it stops. Or start with the heaviest and work down till it pings then go back one step.
Depending on the combo you can probably go pretty light (weaker springs I mean, which bring in the advance quicker).

[Morella]

The Crane kit comes with complete instructions, if that helps.

-denise

[suburban4x4]

I'd shoot for 34 to 36 degrees total timing without vacuum advance hooked up.
w/ the vacuum advance it will likely be over 45-50 total, which is ok.

For springs, you can start about it 2 ways....start light and if it pings work progressively stiffer till it stops. Or start with the heaviest and work down till it pings then go back one step.
Depending on the combo you can probably go pretty light (weaker springs I mean, which bring in the advance quicker).

would it be better to run the vacuum line direct or through the carb

[SMITH29]

I'd shoot for 34 to 36 degrees total timing without vacuum advance hooked up.
w/ the vacuum advance it will likely be over 45-50 total, which is ok.

For springs, you can start about it 2 ways....start light and if it pings work progressively stiffer till it stops. Or start with the heaviest and work down till it pings then go back one step.
Depending on the combo you can probably go pretty light (weaker springs I mean, which bring in the advance quicker).

would it be better to run the vacuum line direct or through the carb

xxxx
Direct is the best for economy and cooling when in traffic at idle stopped in gear.

[suburban4x4]

thanks

[curtis73]

Not sure exactly what is meant by direct or through the carb, but you definitely want ported vacuum, not manifold, but it also depends on your vac advance canister. If you have an early canister (usually switched over by about 72-ish) then it will not actuate properly with the weaker ported source. Conversely if you have a later vac advance canister designed for ported vacuum and you give it a strong manifold source, it will be sucked on fully everywhere but WOT.

I agree with what has been said otherwise, though. 34-36 total, then ported vacuum on an adjustable vac advance canister. Most advance spring kits come with a key to tell you which springs will give you advance at what RPM, but they are highly unreliable. I put 3400 RPM springs on mine and when we tested it on the Sun tester, it was all in by 1800; no joke. The best way is to put it on a sun tester with the different springs.

Shoot for all mechanical to be in by 3000 RPMs or so. You could have it all in by 2600 for all out peformance, but you may end up with headaches on hot days or during winter when fuel is sometimes oxygenated. Then hook up your vac advance to ported and start with it the whole way in (least amount of advance). Test it on a hill on a hot day with as much load as you can put on it. Keep testing and backing the adjuster out one turn at a time until you get ping. It could be several turns (mine was 6) so don't get discouraged. Once you get ping, take it back in a half. Over the next several days you may notice that certain loads will produce some ping, in which case you can go another half back in.

[Nashalac]

I'm not familiar with the Sun tester but could the 1800 prm be dist rpm, not engine rpm. If so wouldn't the dist. total adv actually be at 3600 rpm???

[curtis73]

A sun tester is just a "kleenex" name for a distributor tester. You clamp in your distributor, hook up some wires, and then it spins and strobes all of your sparks on a wheel.

Unfortunately, my springs were in fact at 900 dist RPM for 1800 crank RPM. That's a far cry from where they should have been.

[suburban4x4]

ok now im getting a little backfire out of the exhaust when i floor it and let go is this normal as the engine sounds a bit healthier i am runningthe vacuum direct off the manifold

[curtis73]

Nope, not normal. Get that vacuum off the manifold and onto a ported source. It also sounds like you are getting a sticking weight. Something's not right.

[suburban4x4]

timing was a few degrees off