A NEW timing issue

Hey all! Well I'm back with another timing issue with my monte. I previously had an MSD pro billet distributor that was modified and locked out, and had some issue with it losing timing (and some other issues). There was an iron gear on it as well (pretty worn down), and I've since replaced it with a melonized gear and things seemed better.

Since this is primarily a street car that I'll be taking to the track sometimes, I decided to get an MSD pro billet 8360 with vacuum advance and get it running right on the street. Based on recommendations from the guy who put together my engine and the one who helped tune it previously, I put the black bushing (to add 18 degrees of mechanical advace) and 2 light blue springs (to all come in by 2500rpm) in it. Switched the gear to it, and dropped it in. I set the idle timing (plugged all vacuum advance stuff for now to get this right) to 18 degrees (since I want 36 total) and idle seemed great.

Here's the problem: as I rev the motor up, the timing raises to about 25 degrees...and just stops. It kind of bounces around, almost like it goes above it for a second but then settles back to around 25. This is a brand new distributor/bushing/springs/etc. and the weights are not sticking. I'm using an MSD timing light (NOT dial back) that should work with the distributor/6al box/blaster 2 coil.

Any ideas??? This is driving me nuts...

I should probably add it's a 355 sbc with a comp hydraulic roller cam, holley 750, afr heads, no computer/egr stuff.

jcelk said:

at what rpm did you get 25 deg i take it 18 initial + 7 deg mechanical =25 and how high of an rpm did you go up to ?

Click to expand...

It seemed to get there by 2500ish, and I went up to 4000 and no change (if anything it went down a bit). Could this be cam walk? I'd have to call the guy who put the motor together to ask about a cam button, etc.

565bbchevy said:

The black MSD bushing adds 18 degrees plus initial.

Click to expand...

Yea, that's why I'm stumped as to why the initial is 18 and it's only advancing to 25 total.

jcelk said:

what is your idle rpm the weights might be starting to swing out at idle . try lowering idle rpm if that makes a difference with initial timing then you know the weights are swinging out early ...also i could be wrong but i think there are different size vibration dampers so they would have a different tape

Click to expand...

Idle is around 800

565bbchevy said:

I am curious why you didn't just get the 8361 since you already have a 6al, the 8360 is a "ready to run" distributor that does not require a box since it has an internal module.

Click to expand...

I would have, but the way this wiring was set up was with another 8360 (but it was locked out, vac advance gone, etc) with the 6al and blaster 2, so I wanted to just put the same distributor in there to not rewire everything (connectors and what not are different for the 61 and 60). I talked to an MSD tech and he said it should all work perfectly together.