Langdon HEI timing & vacuum

[Sharps40]

18 initial is way too much advance for any inline 6 in stock or near stock form.   I know.....broke two pistons that way due to pinging/detonation.

 

Call Tom, but I'll suspect your mechanical advance is bringing in 20 degrees or so plus another 10 on the can.  Easy enough to check by simply measuring and marking your harmonic balancer.

 

With a flattie, set your initial 0 to 6 and maybe up to 8 degrees (conservative) advance, check for pinging and kick back on the hot restarts (from your post you still have ping and kickback at start up even at 12 initial.)  and if all is well, go enjoy the smoother operation and greater power an HEI provides.   but stay outta the Big Fat double digit initial advance numbers. 

 

You should not need more than 8 initial on a stockish flattie (not race prepped) and will live long and prosper staying in the single diget initial advance.

Edited February 17, 2019 by Sharps40

[martybose]

Amusing to see this thread come back to life 12 years after I started it.  I'm not going to try to justify it, but I eventually backed the initial timing down to about 4 degrees with the vacuum connection to manifold vacuum.  It was that way for several years with no issues.

 

Marty

[Sharps40]

See......told ya 18 was too much!