timing jumps from 12btc to 20btc and back again

Performance mods and Advanced Stroker discussion.
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bkernes
Posts: 2
Joined: September 20th, 2019, 5:14 am
Stroker Displacement: 4.6L
Vehicle Year: 1992
Vehicle Make: jeep
Vehicle Model: Wrangler

timing jumps from 12btc to 20btc and back again

Post by bkernes »

I recently finished my 4.6L stroker project but I'm having difficulty getting the engine to run correctly.
Problem is when it starts it idles for several seconds at about 800 rpm, then drops to about 400 rpm for a second or two, and stalls but doesn't die. It recovers and goes back to 800 rpm only to repeat the cycle.
I put on a timing light and it shows 12 btc @ 800, 20 btc @ 400, then drops and recovers to 12 btc again.
Any ideas about what is causing this to happen?

The bare head, block, oil pan and valve cover are the only original parts on this engine.
The stoker kit is from Clegg Engines, their Stage 3, 4.6L, 9.3:1 with #24 injectors.
I added a Comp Cams 68-232-4 which has a built-in 6 deg advance and I went through the cam break-in procedure.
Used Comp Cams beehive springs with new valve train components and had the head ported.
Using Autolite 3923 spark plugs and added two cans of Royal Purple Max Boost to get my full tank of 87 up to 93.
The distributor, MAP sensor and injectors are new. I changed the FPR to 49 psi to no avail and I'm about out of ideas.

I would appreciate your thoughts...
Thanks
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