Oldsragger

The engine have been stored inside a garage on some wood planks 3-4 yrs, but it seems to the flexplate have take some weight on it, and i see its not rigth.. On the pic below u can see the starter ring is nearer to the engine block on right than the left side, i twist the engine around on the flexplate and see its not 100% with diffrent distance.

I can use a big flat screwdriver or a bigger tool to bend it out, so im woundering, should i bend it out and check the clearens all around with distance to the block, or do i need to buy a new? If i need to buy a new one, is it bolt on, is it done balanced? OR can i Just swap over the old flexplate from my old engine? The thing is, the crank have been balanced with the flexplate, and i dont want to dissaseble the crankshaft cause of a new flexplate install for a new balance prossedure,,:/ the flexplatw i see have a welden on weight on it.

Ideas?

oldcutlass

To be honest, flex plates flex. You won't know for sure until you bolt the torque converter on and it will straighten it out somewhat.

Oldsragger

Ok, but im thinking about the engine,or bad balance to the transmission/converter, if it will damage something inside if its not in balance, but yeah, the converter may be stable it up i guess,maybe it dosent matter then.

oldcutlass

Won't effect balance, The main thing is if its true enough for the starter to spin the engine 360 degrees with the torque converter bolted up.

Oldsmaniac

I would replace it as its easy to do now and not so easy in the car with trans attached.

Oldsragger

Ok i see,,

ok, Well if i should replace it, i can Just buy a random flexplate for olds engine? Or does i need a special one? Im thinking on the weight that is welded on. Or maybe all have this welded weight on, maybe only the place when install does matter?

I can take a pic of it to show better

pogo69

I dont think it will be a problem ...as said once it pulled onto the torque converted and bolted to it, it should be just fine. you could remove it from the crankshaft and lay it flat and measure it with some feeler gauges and see where it creased....the plate or the welded gear ring

Oldsragger

Ok, yeah i can take it off and check, do i need to replace the bolts with new when install it again?, im thinking if its stretched tread type bolts, and how many lb-ft should i torque the bolts again? Maybe i should have some tread lock on them too.

Well i had a little plan to fire up the engine on thw engine stand with the time, but i see i cant do it now when the flexplate are like this i guess, i Will Just fire it up in the car then when all things are installed

Oldsmaniac

The flexplates have 2 different bolt patterns for crankshaft, 64 to 67 330, 400 and 425 are different than the 68 up 350, 455, 400 403, 307. You can reuse bolts.

pogo69

i agree you can reuse the bolts if the threads are good and I have always used a threadlocker on those bolts and the torque converter bolts ...thats my preference.... 60lbs go to the 30 on all then to 60

Oldsragger

Ok thanks, this is a flexplate on a 400 G block btw, here is a pic of it, it standas numbers all away around, i dont know why,

Another question, what is the tread size on the bolts that going in the holes when install the tranny? Got some bolts today from work but they are to big. Need to have them to install the engine on enginestand.

Oldsmaniac

The bolts to attach trans to engine are 3/8 16 thread. The bolt heads use a 9/16 socket to tighten.

Oldsragger

Thanks a lot, at least i know what to search for about these bolts.

Octania

The bolts to the converter are an oddball special length too, and should be identical for a balanced set. They are usually flange head also.

USUALLY 3/8-16 but some converters are metric threaded. If it goes about 1 turn and gets tight, that's a metric/US mismatch.

Oldsragger

Ok, Well im thinking to Just swap all the parts and bolts from old engine 307 to the new engine so i dont to search for new bolts. When assemble

steverw

Between being bolted to the crank in the middle, and the torque converter on the outside, I think it will allign up ok. If you have to change it then you would need to have the new flex plate neutrally balanced, since the motor has been balanced.

Oldsragger

i found this on ebay now guys, it looks same as me and have same weight welded on, so i guess this is ready to run include balanced? its for 260 - 350 - 403 - 455ci it says..



Found same on summit racing, so i will ask the local amcar store here if they have or can order for me, so i guess i just buy a new one to be sure. thanks for answers until now.



well maybe i can ask in the same time, is it some torque specs for the flexplate bolts to the converter?

steverw

If this is an Olds flex plate, and it does look the same to me as the on pictured above, it will need to be neutrally balanced. You did say in your first post that the rotating assembly had been balanced... right? If so an unbalanced flex plate will throw it out of balance. Maybe a little, maybe alot. First i would check the one on the motor and see if its true, and go from there.

Oldsragger

Im not sure to be honest, maybe i remember wrong,maybe it was only the rods and piston that was balanced or made as same weight, i Will check the building papers again to be sure. Well the flexplate should be same, but i will check the weights on both if it matters, this flexplate is just a replacement opinion i read.

My flexplate and the new flexplate have same numbers and holes and possision of that welding part too i see,but i will study my flexplate more tomorrow, right now i cant see it have nothing more weight or balance parts on it, if it not are on the inside on the plate then. But it looks stock to me.

joe_padavano

All stock 1968-1990 RWD flexplates are balanced the same and interchange (some FWD flexplates used with the TH325L4 transmission are smaller in diameter). If your flexplate has the stock balance, just replace it now. If your flexplate was custom balanced with the rest of the engine, you can have a machine shop match the balance of the new flexplate to that one.

Oldsragger

Sorry My bad, the crankshaft was only polished and not balanced, but the pistons and rods was balanced on some way,it stands in papers. Ok so i will just replace it.

Oldsragger

Hi again, i have Just install new flexplate and i have new bolts, should i torq the bolts with oil on or locktite? How much ft lbs should i torq the bolts? Thanks!

Oh, i found it, 60ft lbs if its right.. But stands nothing to add Oil on the bolts or locktite

pogo69

yes loctite is a good idea...ive always used it on flywheel/flexplate bolts and torque converter bolts

Oldsragger

To late now, now all bolts is torqued to 60ft lbs,, but the new bolts have lock-washers anyway, i guess it will be fine :) didnt use Oil on treads either.

I will use some locktight on the converter bolts, cause i Will use them up again.

Oldsragger

Maybe made a clock of the old one, hmm, anyway nice to have on the garage wall.