Cylinders 1 and 3 not firing at idle when running engle 110 cam in a 1641cc running twin weber 34 ict's and 4-1 single quiet pack exhaust

Cylinders 1 & 3
not firing at idle when running 1641 barrels, stock heads, 4 - 1 quite pack
exhaust, twin ICT weber 34's.....

Some say.......
"The engle 110 has
enough overlap that cylinders 1 and 3 will not fire at idle due to the reversion
pulse pushing air up the intake port. The reversion pulse occurs when the
intake valve opens and the left over combustion pressure pushes spent gases into
the intake. How much depends on the amount of valve overlap, how restrictive the
exhaust system is, and at what RPM you are at."

So what's reversion?......

"when the pressure wave from the exhaust pulse reaches the end
of the pipe, it will be reflected. At certain engine speeds at which the whole
system (exhaust AND induction) are in the proper resonance, this pressure wave
(reflected as a pulse of rarefied air), will reach the head at the precise
moment of overlap in which both the exhaust valve and the intake valve are open,
producing a partial vacuum that helps to draw air into the cylinder. In general,
this will only happen over a narrow rpm range. For a Harley, there will only be
one such range on the safe side of redline. At all other engine speeds, a
compression pulse blows through to the carburettor and is carburetted once on
the way out, and again on the way in, producing a rich stumble and a resultant
loss of power at that rpm range. In general, the "sweet spot" where the
reversion pulse helps will be well over 5000rpm
 
Another issue might be.....

"Unless you are using one carb per cylinder with the dual port the air fuel
is forced to choose between one runner or the other due to the reversion pulse
of the intake valve closing. The farther up the intake it has to choose the
worse the discrepancy in the idle quality gets. "

The long and the short of this is that "The Engine Shop" (TES) who built my short block say that this is not an issue I explained that compression is low at cold on 1 and 3 now between 110-115 but between 120-125 on 2 and 4 they are happy for me to continue to run the engine despite my (and other OCD'ers concerns) with this compression ... basically they (Jim at TES) couldn't explain why 1 and 3 don't run on idle or weren't interested so I will continue to run the engine and if it goes bang I will be calling TES under warranty for a new one : )


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