Max timing advance

[Fast Fred]

?, just the way it works, not an engineer my self, but that box of melted pistons
i got is good for me. the more efficient a Moda is the less timmin it will tolerate.

[Roy Hodges]

[QUOTE=Fast Fred;70408]?, just the way it works, not an engineer my self, but that box of melted pistons
i got is good for me. the more efficient a Moda is the less timmin it will tolerate. :cool
.................................................. .................................................. ..................................
.................................................. .................................................. ..................................
I'll drink to THAT . ...Frigid

[50sFlash]

WOW! Fred. TMI I just spent the last three hours going through that thread. I had a 75 Stinger that I was going to put on this boat I'm building, but decided the 2 35s would look cooler (I'm all about looks) but I could have made it fly with all that I read. In my world though if you're melting holes in pistons it's because it's running lean. I saw one place where you said you ran stock jetting which may be great for the carbs CFM at 5 grand, but as the air flow increases at 8 grand you're at max fuel flow in the hi speed tube result is a lean mixture, and a hole in the piston. But what do I know?

[Fast Fred]

when thay go lean it will burn the center of the piston, by the plug, when thay detonate from to much timin it will melt the crown at the exhaust port, stick the ring and then everybody goes right by

ya i know, what you said is true, but not for a outboard looper.

[50sFlash]

Thanks Fred. I know that knowledge didn't come fast or cheap. It's great that you are willing to share it with those of us that are way over our heads. Back to my little drawing board.
Jerry

[john miffco]

timing must be retarded after 6,000 rpm
on any motor 2 or 4 stroke,,,,,,,,
especially 2s cause of the burn on every stroke,,,,
piston does not get a stroke to disapate heat as in a 4 stroke motor

even on drag motors...
yes they shut down with 1 pass,,,
but that pass is very high compression,,very high rpms,,very hot burning fuel and lean for max power

a simple way to run high timing for low end and retard for high

i used a car electric solenoid with a msd timing retard box to retard timing when i ran unlimeted ob
the car solenoid was from old carb cars,,,,,was the air conditioner solenoid to raise idle when ac on,,,,,and was adjustable,,,,,,
mounted to hit the timing arm,,,,to retard when activated by rpm pill on msd

this and indexing the spark plugs stopped my piston burns and hard scuffing on the ex side,,,,,,,,,,,

plus retarding the timing adds rpm,,,,,,,
john

[Fast Fred]

i used a car electric solenoid with a msd timing retard box to retard timing when i ran unlimeted ob
the car solenoid was from old carb cars,,,,,was the air conditioner solenoid to raise idle when ac on,,,,,and was adjustable,,,,,,
mounted to hit the timing arm,,,,to retard when activated by rpm pill on msd

more good stuff,

thanks 50sFlash

[50sFlash]

I'll throw one more little tidbit out there to think about. I think that is happening because the ignition and flame pattern isn't burning until it's ready to leave the cylinder. When I ran S/B chevs in a dragster back in the late 60's we ran over 50 degrees total advance, and if I wanted to run really fast we ran regular gas because the lead in premium retarded the spark too much. One of the problems is it doesn't start with a starter real well, but we push-started the dragster, and you couldn't lug it down, the RPM had to stay above 6 grand, and you had to run very rich.

[OUTBOARDER]

timing must be retarded after 6,000 rpm
on any motor 2 or 4 stroke,,,,,,,,
especially 2s cause of the burn on every stroke,,,,
piston does not get a stroke to disapate heat as in a 4 stroke motor

even on drag motors...
yes they shut down with 1 pass,,,
but that pass is very high compression,,very high rpms,,very hot burning fuel and lean for max power

a simple way to run high timing for low end and retard for high

i used a car electric solenoid with a msd timing retard box to retard timing when i ran unlimeted ob
the car solenoid was from old carb cars,,,,,was the air conditioner solenoid to raise idle when ac on,,,,,and was adjustable,,,,,,
mounted to hit the timing arm,,,,to retard when activated by rpm pill on msd

this and indexing the spark plugs stopped my piston burns and hard scuffing on the ex side,,,,,,,,,,,

plus retarding the timing adds rpm,,,,,,,
john

That is awsome!!! Maybe I wont have to use the MSD after all!!!
I wonder if there is a off the shelf solenoid and controller that could be used?
Need to pull a few degrees out after 6K..............

[john miffco]

the 4 stroke sb chevy can go with more timing advance
its a 4 STROKE
have a full stroke for piston to cool
have valves to close precisely,,,,,
2 strokes are more non efficient
lots of raw wasted fuel runs out of the ex
the port heights regulate the flow,,,,,
the ex is always open and is regulated by the rings
can and does mix a smigin with the intake stroke
the intake has a reed valve,,,and can burn or be blown out
so timing is more critical in a 2 stroke motor
and a flash fuel is needed like unleaded and not a cooler long burning
high octane as for 4 strokes
but with the higher heat from flashier fuels
the timing at high rpms need to be shortened,,,
to have a shorter burn to get out ex before intake charge
then for less heat on the piston top to not burn top
since it does fire on each stroke
when i ran alky mixed with nitro or prope,,,,
i could not go over 18% because of the long burn
it would melt the reeds,,,,,,,,,,,
in a maxed out 2 stroke there is a finer line to deal with than a 4 stroke

also another alternative to the msd controller
is using a shift light,,,,,,,
this connects to tach lead also,,,,,
take the bulb out and use the bulb leads to active the solenoid

just my thoughts
john