Just a update guys and a few Qs.Just received the dual quad intake from states and stoked.A bit of a hot dip and a couple of carb kits and it should be rocken. Need some +40 thou pistons and std valve set for the rebuild and has anybody out there milled valve reliefs in some LA or flat top pistons to suit a poly???Just wondering.....Pics attached.Thanks
You can mill the top of the LA pistons to match the poly valve reliefs however before doing that work out how far down the bore the pistons will be. Ma Mopar played with compression through piston height and a LA engine is not a high compression engine. If the piston is not reaching the top of the block take this difference into consideration. I'm in Auckland so PM me and i can expand further. We have built polys with LA pistons before and did not have to mill them - they were street engines and ran on 91 so nothing exotic. Have you got the pistons already as i have some poly pistons
Yeah thought it would be possible at a possible sacrifice of hp.Thanks for the responce though guys.Have sent a pm 35desoto.Cheers
Another Poly/Dodge!!........these are getting almost common...lol.........nah, good to see, I've had an Oz 62 Chrysler Royal 313 poly/cast iron torqueflite in my 1940 Oz Dodge since 1973, it uses 318 +40thou pistons with a Weiand single 4 intake, originally I had a 57 factory twin 4 intake with Offy cross ram adaptors & a pair of 600 Holleys above each rocker cover, but with a big cam, hi stall converter,etc it was a pig to drive so the single 4 weiand intake has been there since the late 70's, have just recently got hold of another cast iron intake and a pair of Edelbrock carbys so that will be the next job.......anyway heres couple of pics......regards, andyd
Is that where the difference is between the poly 313 and 318 ?......piston height? I have a complete 313 in a very confused 57 Desoto (with a 57 plymouth rear half, and Diplomat badgeing) that I dragged out of Mangere, South Auckland. It runs but I was thinking of freshening it up for another project.
The difference in displacement is a factor of bore diameter, in this example 0.040". Piston height will affect compression. .
If you measure the width and height of the cast iron manifold ports you will find they are smaller than the actual heads. In my experience the weiand 7503 manifold has port openings the same size as the heads and this allows the engine to breathe(amongst several other advantages). The cast Iron ones are great yet seem as though they were engineered to keep RPM down by restrictiing the air flow. The weiand manifold always allowed my motors to reach higher RPM. the fact that in my earlier days I did not allow for deeper sumps and better oil contriol probably added up why we ran a couple of cranks whilst revving to 6500 on a regular basis - nowadays we build motors with several alterations to allow them to live!!! Ah such enthusiasm in those days - so little insight
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