hey guys, long time no post...question on the fly wheel between odd/even fires

i have the 231 odd which is adapted to the sm 420.

i really dont like the rough of the odd and want to go even, but since itll be a rock crawler of sorts, i would like the heavier flywheel.
i just saw a post where someone was asked if they are running the lighter flywheel or the heavier 55#.
it said they always run the heavier flywheel even on even fires...
what???!?! pump dem brakes a second...

my dad (who sold me the jeep) said you cant mix them up. he said an oddfire can be trimmed to an even fire by the right machinist....but then it cant go back.

what i understand about flywheel (not much honestly) is that its heavier because the oddfire runs like a harley and it needs the extra weight to keep the crank/timing chain from jumping with each double firing pulse and then the lul inbetween them. it makes it run semi-smooth but helps in breaking the chain.
so, to me, it seems logical that even though i have a smoother even fire, i should be able to run the odd fire flywheel for rotating mass.

someone please set me strait. i come here to learn and then i read something and it blows me away...right now (when it comes to flywheels), im not even in the ball park, let alone left field...=)
and what i mostly find is that you guys are almost always right and we/he/i was misinformed.

 

If you have an Odd Fire now ( 90-150-90) degree firing order...........the only way you can get to an even fire ( 120 degree firing) is to change motors. The even fire has a different Crank, Cam, Distributor and cylinder heads. except for some even fire heads that with some work may be the only thing that will fit on your old Odd fire. The real issue is water passages matching up between the head and block.

The early odd fire motors benifited by the heavier flywheel in added kenetic motion related torque. They also calmed the odd fires pulse.
THe odd fires were externally balanced and the even fire were internally balanced............I have an odd fire 225 that has had the complete rotating assembly balanced internally.
If you took an old heavy Odd Fire externally balanced flywheel and balanced it to zero "0" there should be no reason it would not work on a later internally balanced motor.

 

ok, balance it to zero...will it be able to go back to the odd fire once i do that if i balance the crank odd crank? i have 4 even fire motors and 1 odd.
i understand about the rotating mass/kinetic energy and stuff between them, i am asking from a dimensional/mechanical stand point...i like the heavier fly wheel idea for crawling. internal balance both crank (odd fire) and zero balance the fly wheel and they will swap in and out...nice.

so are all even fires balanced internally including the 77-78 with the small port heads (i have one of these too). i have a both even fire and odd fire fly wheels, but i want the weight for crawling.

thanx for your reply.

edit-if this swaps back and forth like this, i might just go a new direction with it. ive been at a stand still debating what motor to use.
i have an oddfire 30 over, comp 260h, 9.6 flat tops, hei, even fire heads with a gasket matched dual port offy intake and a holley 470 truck avenger.
i also have an even fire 78 small port with hei, 81 block and a complete 84 engine.
i have a turbo setup from the old t-type regals with the draw through.

and last but not least...an 84 grand national turbo setup (minus the block). this would give me fuel injection and a turbo for playing in the sand/mud or passing folks. i need a wiring harness to make this run and they are $775 new.

i was thinking of running propane for idle quality and angle immunity. if i can switch to the even fire motor and just balance the flywheel, that opens up a whole new can of worms...which way do i go?

i might epoxy the intake on the t-type to match the small port and build an even fire turbo/propane motor with the heavy fly wheel. propane will handle the 9.6:1 even on 8#'s of boost.
hell, it would prolly be cheeper to just build the grand national setup and stick it in, but then i am stuck with gasoline and have to buy new pistons with less compression.

or, build the 78 even fire with propane and channel it through a holley economaster (450 spreadbore) and build monster low end torque coupled with the heavy flywheel. would be great throttle response...

i have all these things except the propane setup...my brain is overloading...
too much turkey...too many buick parts.
what to do????

 

I don't think your question got answered.

Will the heavier odd-fire fly-wheel fit the even-fire engine?

 

The oddfire flywheel can be used on the evenfire engine and vice-verse but the flywheel must be re-balanced.


Sent from my iPhone

 

outstanding!
i discerned that from what tarry wrote.

i think i will do that and ditch the odd fire. the even fire makes MUCH more sense unless one is trying to keep stock. folks say "the crank is stronger"...i havent ever heard of anyone breaking a crank wheeling so i think the point is moot. u-joints, axels, everything else but... =)

thanx guys.
anyone wanna buy some buick parts? =) i might put them up on the parts page...