Scarab ignition issue
 

I have an 85 scarab two with twin 454, about 9.1 stoke 781 oval ports and slight upgrade cam over the 330 piece and still q jet thunderbolt 4.

Problem is the timing jumps around 3 degrees at idle and I set it at 36 total at 3200 rpm, this puts it at 12 at idle. One engine at 3 grand it barely misses like a small puff sound out the exhaust every once in a while. Also, the timing light on that engine at 3 grand misses badly hard to see the mark and does not fire at times. I have never been able to get these motors over 4 grand or 50 MPH, and the motor don't have 150 hours yet.

Is it plugs? coil? the cap and rotors have about a hundred hours on them.

Thanks,
Tim

Just checked cap and rotor look fine, pluge #1 ok but lean.

if it were me I would drop in a pair of aftermarket HEI dists, buy the vac advance block off and the wire ends and give that a try, cheaper than changing parts in the mercs..very reliable, been running one for several years now..works great !

I like the HEI idea, never tried the vac block off, what should total advance be?

Fixx
 

Put hei's in it, then put the timing @ 34* @ 3500 rpm's,this will give you more rpm's in the upper end..a;so sounds like your engine are running lien,try bugger carburetors like halley's 800 or 850 cfm..your probably running out of fuel in the big end of the rpm..