Oversize 318 poly pistons?

Posted By: polkat

Oversize 318 poly pistons? - 09/09/10 06:16 AM

My '64 318 Poly in my Fury needs boring. it smokes and some of the upper cylinder measurements go out to about 3.925" Can oversize pistons still be found for this engine? If not, considering the ususual piston valve notching, what pistons can be substituted?

Also, I have heard that the poly can be bored as much as .100". If so, what pistons are commonly used for this? I'm trying to keep costs to a minimum since I've been one of the nations unemployed for a while now.

Thanks for suggestions!

Posted By: dOc !

Re: Oversize 318 poly pistons? - 09/09/10 06:58 AM

I have seen ads on eBay for the 30 and 60 over pistons ..... TRY a WANTED ad here !

Posted By: Dodgem

Re: Oversize 318 poly pistons? - 09/09/10 01:46 PM

When My buddy did his the machine shop he used just got them through regular piston suppliers
Summit has them
http://www.summitracing.com/search/Depar...63/?Ns=Rank|Asc

federal mogal so you can get them anywhere and the use standard LA rings

Posted By: patrick

Re: Oversize 318 poly pistons? - 09/09/10 03:22 PM

depending on how much lift/duration you have, you can probably use LA flat top pistons an not have an issue with piston to valve clearance...

what is the cc's of the poly heads?

http://www.summitracing.com/parts/STL-H814CP30/
http://www.summitracing.com/parts/STL-526P30/

Posted By: Dodgem

Re: Oversize 318 poly pistons? - 09/09/10 03:37 PM

Quote:

depending on how much lift/duration you have, you can probably use LA flat top pistons an not have an issue with piston to valve clearance...

Valves are real close on the poly pretty much need the poly piston they all have notches

Posted By: Anonymous

Re: Oversize 318 poly pistons? - 09/09/10 04:08 PM

Quote:

Valves are real close on the poly pretty much need the poly piston they all have notches

I looked at the Summit pistons you linked to above, and they don't have notches.

Also dished. Kinda look like low CR truck pistons to me. But

Posted By: Dodgem

Re: Oversize 318 poly pistons? - 09/09/10 05:19 PM

does say that but the ones my buddy used were stock and had valve reliefs??
discription of one on Fleabay

These pistons are flat top pistons with two eyebrows along the piston edge. When listed, we have +.020", +.030", +.040", and +.060" pistons available. Please contact us for other sizes. We ask that you specify piston/bore size and bearing sizes with payment. Image is for illustrative purposes only. Buyer will receive correct part(s) for application described within listing.

http://cgi.ebay.com/ebaymotors/Dodge-Ply...=item2ea38cb8ac

Posted By: Anonymous

Re: Oversize 318 poly pistons? - 09/09/10 05:39 PM

Quote:

description of one on Fleabay

These pistons are flat top pistons with two eyebrows along the piston edge. When listed, we have +.020", +.030", +.040", and +.060" pistons available. Please contact us for other sizes. We ask that you specify piston/bore size and bearing sizes with payment. Image is for illustrative purposes only. Buyer will receive correct part(s) for application described within listing.

http://cgi.ebay.com/ebaymotors/Dodge-Ply...=item2ea38cb8ac

I'd bet money those are Egge pistons. Never used them myself, but have read that they don't have the metal anti-expansion inserts like the factory and that they are OK for a parade car, but not for any performance use.

As for the ones Summit offers, maybe they've changed since you bought them, don't know. I'm curious myself because I have an early 318 poly I'm thinking about swapping for the 277 that's in my 56 Plymouth.

Older NOS or NORS 318 poly pistons do show up on ebay now and then. I'm thinking I'll either go that way or, in my case, just hone the cylinders, re-ring and re-use the original pistons. I realize the last is not an option for the OP, given the amount of bore wear he has.

Posted By: patrick

Re: Oversize 318 poly pistons? - 09/09/10 06:10 PM

Quote:

Quote:

depending on how much lift/duration you have, you can probably use LA flat top pistons an not have an issue with piston to valve clearance...

Valves are real close on the poly pretty much need the poly piston they all have notches

best way to truly check that is to pull a head, put clay on top of the piston, rotate it around a few times assembled, then take out and cut the clay with a razor blade to check actual clearance....

both gross lift and duration (timing events) play into v-p clearance...you could have plenty of clearance with .5" lift but short duration, and not enough with .450" lift and long duration.

the F-M poly ones are listed at 1.79" comp height with a .090" deep, 3" dish. the LA/magnum replacements I listed are spec'd at 1.745/1.755" CH flat tops/no valve reliefs. even if you had to add eyebrows into them, they're $80-150 cheaper than the poly replacements, and should give more compression...

Posted By: BobK

Re: Oversize 318 poly pistons? - 09/11/10 02:11 AM

Contact Gary Pavlovich. glpavlovich@cox.net He is a Poly guru. Got me 40 over pistons, and a wicked grind cam. He is a good person to know!!!!!