Motorized Wheel Chair Source

chevyraceman_383 says:

Well it would really help to know what pistons your running. This sounds like detonation caused by too much compression/cyl pressure, too low of octane fuel, too much timing

Std. 4 vr flat top pistons will range from 5 to 9cc
With 58cc that would give you 9.9:1 to 10.4:1 compression

That would be a combo that needs 93 octane fuel, limited timing, rich carb, etc etc.

Now if you have 2vr flat tops, no way its gonna run on pump fuel with 58cc heads. You will need race fuel

I think your prob is timing more so than carb jetting.

On a higher compression engine like this, you really have to watch your timing. 32-34* total. If you don't have a dail back type timing light, then that would be around 10-14* BTDC at idle with std timing light)

I ran a 1405 carb on my 10.18:1 355 but wilder combo, better heads, etc. I had to limit timing to 34* total, use an adjustable vac advance can and set it for only 8* of advance.

On my carb I set floats to 7/16" rest, 15/16" drop, pump arm in top hole, .100" prim jets, .104" sec jets, .068x.042 rods and the pink step up springs

Fuel pressure set with reg to 5.25 psi

I also couldnt run any lower than 93 octane fuel