I'm having one heck of a time setting timing on my new 350.

When I put the timing light on it, it seems to be jumping 4-6 degrees as it's running.

Specs are as follows
350 bored .030 over, new heads, 1.6 roller rockers, lunati voodoo cam 60103LK, lunati lifters, hardened pushrods, brand new Procom distributor, holley 650cfm 4150 carb, 700r4 trans

I pull the vacuum line going from the timed vacuum port on the carb to set time. While the line is disconnected it seems to jump around way too much - like anywhere from 4* to 10* BTC. I go the plug in the vacuum line and it jumps up another 8-10 degrees.

Please help!!!! This is getting very annoying.

 

maybe not a lot of help, but i was having a similar problem with my TPI and bumped up the idle to about 1200 rpm to set it. after all the adjusting i was doing, i had to rebase it again yesterday, but she runs like a raped ape now! somehow or another, though, it seemed to be advancing and ran like crap (duh) but it's good now.

 

What RPM is it running while you are setting the timing? It may be on the edge of starting mechanical advance. Normally I'd mention a loose distributor, but you say it's new. The other possibility is a walking cam.

 

We've been setting time around 1000 - 1200 rpm w/ vacuum advance disconnnected.

Walking cam isn't a good thing!

Any suggestions on the major change in timing after plugging in the vacuum advance line?

 

rev the motor to 3500 rpm set it at 34-36 degrees and do it that way. also if you're setting timing the RPM needs to be under 800 or else you'll start getting mech. advance

 

bigblock, do you have worked over 601 heads on that 350? with a lunati 60103 cam? boy, that's almost exactly what i'm building.
let me know how it runs, when you get it set up right


pull the vacuum advance plug off your distributor, and plug the line. Then set your timing at 800RPM or lower.

Or yea, rev to 3500RPM and set timing to 34* say. Then when you're at idle, just double check your timing. You should be able to get a good idle with that.

what distributor is it?

 

it sounds like as stated above your hitting the begining of your mechanical advance...try getting the idle down as low as possable, and than timing it, try for below 750-800 RPM. Hope that helps

 

Thanks for the help guys. This board is loaded with tons of info and alot of smart people!

I'll try setting time at 3500 rpm and see what happens....