351 cam in a 302

[Dutton]

I just rebuilt my 302 and installed a 351w cam shaft in it. I set the firing order up for a 351 and I am running the Pertronix HEI distributor. I finally got it to run but my timing is about 30 degrees without the vac advance. If I set it at 14 it will not run. I have a new balancer and set up the bottom end with everything at TDC. It seems to run ok but i am concerned that the timing is that far advanced. Has anyone else had this happen?

 

[sp71eb]

have you verified your timing marker is correct? I would pull your 1 plug and put it at tdc and check your balancer marks. Sounds to me like something isn't giving you a accurate timing reading.

 

[needabronco]

Bill, did the Pertronix distributor come with different weight advance springs like an MSD does? If so I'd change out to the tightest springs and see what you get.

 

[blubuckaroo]

Are you sure you're using the correct cylinder for #1? Wouldn't be the first time a Chevy man tried to work on a Ford.

 

[jckkys]

The timing mark on the vibration damper, the pointer, or the timing chain are off. Do what sp71eb suggested to find the true TDC of cylinder #1. If the timing mark and pointer line up, you'll need to pull the passenger side valve cover to check the valve timing. The vacuum advance has no effect at idle. The initial advance is what the engine will tolerate without pre-ignition. That can easily be 20 degrees and be correct for that engine in that truck. The so called specs for timing are at best a starting point. However if your engine wont run with 14 degrees advance, something's wrong.
The centrifugal advance is not part of cranking or idle unless the springs are missing.

 

[Broncobowsher]

Hint:
The keyway in the crank points straight up with #1 at TDC. Pull the balancer bolt and look at the keyway and get it pointing straight up. Then check your balancer timing marks for alignment.

I bet they don't line up. There are at least 3 different alignments for timing marks on a small block ford. I am guessing that with the new balancer things are no longer lining up correctly. Coat hanger makes for an easy way to make a new timing pointer. No using a piston stop, it sucks when they bend or break (it has happened many times). The coathanger and eyeballing the keyway will have some error, but when you are mixing and matching parts then you are on your own for tuning anyway. At that point the numbers are just reference marks. You can figure how much advance change, but just not a perfectly accurate starting or ending point.

 

[Dutton]

Thanks everyone for the suggestions. I will go through everything again to see what I can find.

 

[Dutton]

I installed a curve kit and it cured it up. The old girl is running pretty good now.

 

[needabronco]

Let me know if you need help tuning the carb. I'm thinking you'll only need a couple of rods, the jets should be fine.