Hey, i bought a 383 stroker motor from a guy and now im bout ready to drop er in the car. I have a th400 tranny to bolt up to it. My question is, is what do i need for a flexplate? Can i use a sbc 350 one? Or do i need to buy a special plate because the 400 crankshaft in the stroker build?

 

Is the engine internally or externally balanced?

Jake

 

Check the damper on the front of the engine. If it is a weighted 400 damper, then you need a weighted 400 style flexplate.
If it's a neutral balanced 350 damper, then you need a neutral balanced flexplate.
If it's an aftermarket crank and is internally balanced, then you need neutral at both ends of the engine.

 

So long as his new engine is 2 pce seal crank; if it is newer 1 pce seal then he needs the correct ext balance flexplate
And if you have to run a 400 flexplate it will most likely be a 168 tooth so you may have to change your starter if you have one for a 153 tooth now

 

So how can i tell what kind of dampener i have?

 

Still need help!

 

Neutral balancer is perfectly round; front and back

400 balancer is cut away or has weight inside
http://cgi.ebay.com/ebaymotors/Chevy...Q5fAccessories
http://cgi.ebay.com/ebaymotors/New-H...Q5fAccessories

 

Externally balanced harmonic dampers/balancers have a counter-weight on the engine side of the balancer.

I read that at least one company sells a balancer with a removable weight so it can be used on either internally or externally balanced engines.

If you're still in doubt about what you have, stop by a machine shop and show it to one of the guys there. He'll tell you what it is.

Jake

 

They sell bolt-on counterwieghts for the internally balanced 350 flexplates. That is so you can reuse the stock 350 flexplate with a externally balanced 400 crank.

Check Summit, Jegs, Speedway.

 

http://cgi.ebay.com/ebaymotors/Chevy...Q5fAccessories

This is the style balancer i have, so going off of that i need a 400 style flywheel? or a 350 with a weight?

 

I have a flexplate for externally balenced 383, It was bolted up between my 383 and 700r4 .

 

If it is on a '92 1 pce seal engine, then it is only ext balance at rear; still neutral at front
400 is ext balance both ends

 

Cheap fix and keep your stock internal balance 350 flexplate

http://www.summitracing.com/parts/QTI-RM-521/

 

It came off a two piece rms

 

Don't confuse the issue. That has nothing to do with the OP's situation. It is also incorrect to state it as you did (the weights on a one-piece RMS flexplate aren't the same as a two-piece RMS externally balanced flexplate).

 

So i have a factory 350 flexplate layin in the shop, i can buy one of those wieghts and mount the two together behind my stroker motor, retain the starter i have and be done with it?

 

Should be able to, as long as your torque converter bolts to it and starter mates with it. Is it 153 or 168 tooth?

 

I believe it is a 153 tooth, it came on a stock 350 block that i was going to rebuild. I have a starter to match it like i said as well.

 

Trucks typically had 168 tooth flexplates, for what that's worth.

Sorry if I didn't read all your posts thoroughly. Been having to do a lot of speed reading on TGO lately.

 

So is there a difference between the 168 and 153 tooth other than the starter?

I guess im gunna have to go out and start counting

 

Just meaure flexplate
168 is 14" dia ; 153 is 12 1/2"

 

Never said they did.
Just clarifing tyler92's statement that he had a ext balance flexplate because he has a '92 car and it may well have had the 1 pcs RMS balance because he did not state when posting that his 383 was 2 pcs.
Many do not correctly understand the balance setup on the 1pcs RMS engines

 

What year was your block? maybe I missed that.
Is it a one-piece or two-piece rear seal?

 

I dont know the year of the block, I can provide the casting numbers if that helps...
And I also dont know if its a 1 piece rms or 2 piece...

But here is a picture of my harmonic balancer, if this helps any let me know what ill be needing for a flexplate.



Ill run out in the shop and get the casting numbers and post those up asap as well, thanks for the help, and keep it coming :]

 

Somebody out there has to know what ima need?

 

 

I think you need the larger diameter weighted flexplate - flexplate for a stock 400.

You really need to look at the backside of your damper. It should have a section cut out on the backside part-way around the outer ring.
I see the holes drilled on the front side, which is why I assumed it's a 400 damper and why I said I think you need the weighted 400 flexplate.

Your rear crank flange is the older style that used 2-piece rear seal.

A stock 400 damper looks like this on the back:
http://www.partzfinder.com/PhotoDeta...ode=PIO-872004

You can see part of it is cut away.

 

305sbc: I for sure have a 400 balancer if thats one in the picture, mine is exactly the same as that...

Now what do you think i need to get?

 

I don't believe that's a 400 damper. Those holes look like standard balancing drilling, not counterweights.

You definitely have a 2-piece rear main seal block/crank. Since you'll be using a TH400, the standard factory 168-tooth 400 externally balanced flexplate should be fine, as long as the starter doesn't get in the way of your headers (shouldn't).

 

As 305sbc states above , you need a 400 flexplate which will probably only be available as a 168 tooth

 

Well I have 2 flexplates layin in the shop, ill go down and take some pictures of them tonight and maybe someone can identify them for me; hopefully I got one that I can use.

 

Unless they came off of a 400 SBC or 454 BBC, they won't be the right thing. You'll either need to get one (they aren't too expensive), or get one of those weights that bolts between the crank flange and the flexplate.

 

If id get one of those weights that bolts between would I be able to use a stock unweighted 350 flexplate?
Im just wondering if the size of the hole for the crank is any different going from a 350 to a 400.

 

i will take a pic of what i have , and you can see if its what you need

 

That's the idea. And, no, there is no difference in the crank flange or attach bolts between a 2-piece rear main seal 350 and a factory 400 crank.

 

I checked my damper collection last night and my 400 damper has the holes drilled on the front, on the same side that the weight is cut away on the rear.

One of my non-400 dampers had a couple of extra holes drilled in the front, all of the others have no extra (offset) holes drilled.

I know there is an aftermarket weight for the rear crank flange to allow you to use a neutral balance flexplate, but I always just use a 400 flexplate or go internally balanced via crankshaft modification.
I think the 400 flexplates are pretty cheap.
A company called Renegade sells it for $35 through Motorville in Lenexa Kansas.

 

Well I went down in the shop last night and took some pictures of what I got, im not exaclty sure of what they are tho...

This is a weighted flexplate that I got from a buddy. Its 14 inches wide with a 2 inch center hole.


This is a non weighted flexplate that I took off of a project 350 motor I had. It too is 14 inches wide but it has a 2 1/2 inch center hole.

 

The top one is externally balanced and the bottom is neutral balanced.

You have a 69-72 chevy 350 block according to the casting number so you then have a 2 piece rear main seal so you then need a internal balanced (neutral balanced) flywheel/flexplate.

 

The best thing to do is contact the person you bought the motor from and ask if it is internal or external ballance. This is the Only way to know for sure what you need.

 

The top one is off a late model 1 piece RMS engine; ext balance at REAR only / neutral at front .
Note smaller PCD of crank bolt pattern compared to early model 2 pce seal one at bottom

Not if he has a 400 stroker crank as noted above.
Needs correct 400 only flexplate

 

a couple of my damper pics:
http://s702.photobucket.com/albums/w...art%20weights/