Poly Teardown

TimLG · Post by **TimLG** » Tue Mar 07, 2006 8:00 pm

I finally decided to dig in to figure out rough idle and poor performance. Pulled engine out and disassembled, suprised to find lots of new parts, std pistons, sleeved block and my engine problem: The valve springs are really weak, I can open several of them with my thumb. I see it has dished pistons, can I put flat top pistons in it? I've read here that cars had higher comp ratio, any advice on what to use? The cam looks a little worn so It will probably need replacement. I've got my parts at my favorite "Old Machinist" for measuring and machining. Anything I need to look for in a Poly rebuild? Thanks for the advice...........Tim G

Jeffc · Post by **Jeffc** » Tue Mar 07, 2006 9:30 pm

pistons should be flat topped with valve cuffs on outside edges, dished or with valve cuffs in the center
are LA pistons.
Car or truck pistons should both be like above, flat topped with valve cuffs to the outside; the truck pistons will give lower compression since they are a little shorter in size from the rist pin. Ether will work. Stock car pistons should give you 9 to 1, truck pistons should give around 8 to 1.

If you want just a stock cam, Powerseal makes new poly cams, if you want something more Neilson cams are the way to go. Stay with the solid lifters.

A sleaved block would say that ether it was bored
to the limit and could not be bored again before its last rebuild, or there was
a crack somewere. If it were me I would be looking for a good block. Poly blocks will bore as much as 90 over, but no one make pistons that far over unless there custom.

Poly pistons come up on ebay all the time, might look there. Rebuild the heads and put hardend seats in if it has not been done. A number of LA engine springs will work fine in the poly heads and use the same keepers.

The stock oil pump for the poly is the same pump used as a high preformace pump in LA engines.

TimLG · Post by **TimLG** » Thu Mar 09, 2006 6:59 am

Thanks for the info Jeff.
TimLG

Jeffc · Post by **Jeffc** » Thu Mar 09, 2006 11:29 am

Napa has the full rebuild kits, just be sure to get the right years or you will end up with a LA kit since they often list 318s as 64 up as part of the LA engine group.......so if the kit is for a 64 up 318 it will not have the right stuff (67 is frist year LA318), though the bearings, timing chain ect in the bottem end will work just fine, but not the cam and top end stuff......

TimLG · Post by **TimLG** » Fri Mar 10, 2006 8:59 pm

I'm letting the machine shop get the parts for me, prices didn't sound bad. The shop owner, Jack Grey, has been in business in Indy for a long time and seems to know alot about the poly and earlier engines, used to hotrod flatheads. He is confident that every thing is available for the poly. I saw the block and heads today, work looked nice to me. I'll get everything back Tues or Weds then start assembling. Need to find some turquiose engine paint....Tim G

fosh69 · Post by **fosh69** » Sat Mar 11, 2006 12:36 am

Hey are you going to take pictures as you build it up? That would be neat to see, 'specially for folk like me that never seen one apart.

DUDE! I just remembered reading an article in one of the car mags a couple years ago (maybe more) about a performance poly build. If I remember, they pulled over 400hp out (maybe more)... don't remember which mag, and I can't find it anywhere. I remember it involved some boring and head work... d!@#$! I can't remember.

Jeffc · Post by **Jeffc** » Sat Mar 11, 2006 2:49 am

Mopar Muscle did the spread, Gary Pavlovich did the build, over 400HP over 450FP tork with lots of custom and over the counter parts.......http://www.1962to1965mopar.ornocar.com/poly318.html

TimLG · Post by **TimLG** » Sun Mar 12, 2006 6:06 pm

My crank pulley does not have a dampner (Harmonic Balancer), doesn't look like it ever did, just a pulley. Is this correct? Should I try to find one from a newer engine? Tim G

Jeffc · Post by **Jeffc** » Mon Mar 13, 2006 3:00 am

The poly engine did not have a dampner if they were in front of a manule trans in the trucks, engines in front of the auto trans had the dampners. These engines had fully balanced steel forged cranks and did not need the dampner unless they were in front of a auto trans.
If you wish to install a damper, no problem, any LA 318 dampner should bolt.....but you may have to make mods to your pully system depending on how things line up.......

TimLG · Post by **TimLG** » Mon Mar 13, 2006 5:11 pm

Thanks Jeff. I picked up the machined parts today, left the heads, they forgot to e-z out the studs I broke. They broke my dipstick tube trying to remove it from the JB Weld I used to seal it when it was loose. Will newer LA dipstick/tube work? What years or p/n's?
Thanks,
Tim G

Jeffc · Post by **Jeffc** » Tue Mar 14, 2006 1:58 am

All LA stick tubes should work expt 360, but check against your old one just in case, there maybe some differances in applications that I do not know about.
I do know that the sticks used with the front sump pans are not the same lenght as car (center sump) or rear sump pans.

TimLG · Post by **TimLG** » Mon Apr 03, 2006 8:38 pm

Well, engine is almost all together. Primed the oil pump with my homemade drive and have 75psi, waiting on the transmission shop, they tell me they have found all the needed parts, should get it this week. I found a dipstick tube that looks pretty close and will shorten it to the correct length. One question, how much oil? My shop manual says 5 qts less filter and 1 qt for the filter, I have a spin-on bracket. Is 6 qts correct?

Jeffc · Post by **Jeffc** » Tue Apr 04, 2006 9:31 am

Depends on the pan you have, some 4 qts some 6 qts plus the filter, put in 4 and check add as needed till full....