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mcculloch timing
#2
steve,
i'm posting a total answer for you. you probably know all this but others may profit from one bit or another.

you can run pump gas and alky at same timing.
you could consider advancing the motor on alky as it'll run cooler .
but i wouldn't bother as you also risk killing the motor .
i think my mc10 is at about 25-27 degrees but i've never fussed with it much and you know it's fast.
has the standard mc10 flywheel.

more important to have good port work the mc10 is 9 ported with a opened up exhaust.


also good carb function is huge.
my carbs are at about 8-10# pop off on alky.
i ALWAYS seal test any leaks are bad.

my carbs are usually t-slotted internally if you like i'll send you pix or post here.
typically i use a cr1a cresent but any good alky will do.

i usually replace the shutter and i fuss with it till i see no daylight showing when it's closed.
they are ovalish and almost never go in square first try.
the pressed double dot or the slot indicator goes topside
shave the shaft if it isn't to increase air flow.
check the shaft for wear both through carb body and on the shaft.
toss and loose or worn shaft it makes a difference.
the throttle shaft needs to be totally free it should make a snap sound when released.
i usually replace the return spring and check the clip they are usually used up and about to fail.
if the throttle shaft clip retainer slot is worn out i will replace throttle shaft , otherwise the shutter wears the bore and itself opening up clearances inside.


inspect your reed block remove any casting flashing and check the flats where the reeds contact.
my favorite is a six pedal for the older macs.
i also oval and campher the pulse holes and check the gaskets for perfect alignment.
i like to oval the hole so theres zero chance of blockage.
a tiny blockage here will slow down the pulse ALOT.
check the internal area of manifold to often there's casting flash that is slowing down velocity.

i'm also really anal about flatting the plates on the carb and intake manifolds areas.
also flat the intake area, stuffer and head on motor block.
actually ANYTHING thats supposed to be flat on the motor i check and fix with flatting.

polish the carb air passage too

i'm posting all this in interest of fairness. if your engine runs as good as mine i'll stop hearing about me running a cheater which i don't!!! Tongue
Dave L.
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Messages In This Thread
mcculloch timing - by steve miller - 02-02-2017, 10:25 AM
RE: mcculloch timing - by David Luciani - 02-02-2017, 11:26 AM
RE: mcculloch timing - by steve welte - 02-02-2017, 03:54 PM
RE: mcculloch timing - by Bob Alexander - 02-04-2017, 07:27 PM
RE: mcculloch timing - by steve welte - 02-04-2017, 08:21 PM
RE: mcculloch timing - by steve miller - 02-04-2017, 08:28 PM
RE: mcculloch timing - by john phippen - 02-04-2017, 10:49 PM
RE: mcculloch timing - by steve miller - 02-05-2017, 09:38 AM
RE: mcculloch timing - by Bob LeFevre - 02-05-2017, 01:01 PM
RE: mcculloch timing - by steve miller - 02-05-2017, 01:52 PM
RE: mcculloch timing - by Bob LeFevre - 02-05-2017, 09:28 PM
RE: mcculloch timing - by Scott Kneisel - 02-05-2017, 10:14 PM
RE: mcculloch timing - by Bob LeFevre - 02-05-2017, 10:43 PM
RE: mcculloch timing - by David Luciani - 02-05-2017, 11:09 PM

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