BPE HEI Distributor

Ricks70Duster340 said
I have a 408 with a 750/3310 carb, HEI style distributor, 727 with 3500 stall converter, 28" tires with 3.23 gearing. Am using MVA as the engine seems to like it. Though I can feel slight vacuum at idle, there is such low vacuum at idle that the vacuum canister does not respond (vacuum gauge at idle jumps all around so useless to tune with). The off-idle transition does not bog, but I think it should be a bit crisper. I tried running without VA but had to advance the timing such that the starter dragged when the engine was hot. The idle screws are both out about 2.5 turns. The engine will not run with them any further in. I changed the PV to a 3.5 and that helped the low speed pep & the plugs no longer run pig rich. At idle/low speed the exhaust smells rich. I've never "tuned" an HEI distributor so wondering if anyone with a BPE setup has done so. Distributor cent. advance is below:

Initial timing=16 @ 650
16 @ 1000
26 @ 1500
31 @ 2000
34 @ 2500
36 @ 3000

Hey Rick, happy to try and help. Looks like you have a bunch going on, and alot of chefs in the kitchen already. Lots to read above, but my biggest observation is you are searching for a sweet spot with ignition timing, but you have some things going on with the carb that tell me that needs addressed also.

Mixture screws at 2.5 seems like more than this engine should want, and the fact it won't run below that is telling me something else is going on. The idle bounching so much you can't get a vac reading is also off. These engines leave BPE with those mixture screws at 1 to 1.5 turns, and the stock equipped power valve. I think asking it to idle at 650 may be why it seems so choppy also. I would try 750-800 for starters. How do the plugs look? I would think it has to be rich at 2.5 turns.

You will have to remind me exactly what distributor this is, (big cap, small cap with external module, or msd clone?)

This is the roller cam 408 correct?

Engine should only want 32 to 34 total mechanical, which should get you a few degrees back for initial mechanical, and the sake of easier starting.

Feel free to email or pm me and we'll see what we can do!