Piston identification help

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Dusterdude72

Dusterdude72

IN MOPAR MUSCLE MAGAZINE
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I know they are 318, I know they are 30 oversize.....what i do not know is what brand and the specs on them.

I have no part numbers to cross reference....but I have seen alot of guys on here Identify a piston just from looking at it so I was hoping that maybe someone could do that in this case.

picture below and thank you in advance

DSCI0686-1.jpg
 
I had the engine apart and I could see any numbers just looking down the cylinder from the bottom side....cant say for sure if there was any or not.

But I "think" I seen a raised stamping on the bottom side of the piston that either said USA with a shield behind it or a flag that said USA but I wouldnt swear to it.

I was hoping maybe someone could identify it from the style of the piston and the style of the valve reliefs.
 
anyone have a clue? I figured this is prime time for everyone to be on fabo....was hoping for a few more responses lol.

any help on figuring this out would be appreciated ,thanks all
 
Judging from the valve reliefs, I would say early Hemi. Measure them and see what the diameter is. The 354 had a standard bore of 3.94". Dodge and Desoto both had Hemis with bore sizes in the same range as the 318.
 
its a 318 block that had been bored out

and the pistons a .030 over pistons.

I "think" that a stock 318 bore was 3.91 inch's and with the current .030 over bore it would be 3.94 inch's of bore.

hope this helps
 
grumpuscreature said:
Judging from the valve reliefs, I would say early Hemi. Measure them and see what the diameter is. The 354 had a standard bore of 3.94". Dodge and Desoto both had Hemis with bore sizes in the same range as the 318.
Click to expand...

I would have to agree, they look like Hemi, they're definitely not LA small block with those valve reliefs.
 
Poly Pistons. Al;though my attachment isn't a photo of the pistons, the valve angles are the same as the valve reliefs in the piston photo from DusterDude.

valves.gif
 
They are poly 318 pistons.
You have a early 318 motor.
Hemi pistons are shaped like a up side down v.

If you have the oil pan off, you might be able to read a part # and a compression ratio on the inside of the piston.
That is were part numbers are cast.(inside skirt)
They look pretty new.
It's a dish piston.
 
I know they are pretty new being that there not factory size.....so they must be aftermarket ......so I am not sure why you guys are refering to them as factory pistons? and I am confused on rather they are hemi pistons or?

sorry just confused here lol.

what would be the purpose of having these pistons? larger valves? I ran the part number on the head and they are the factory matching heads to this block.....the valves appeared to be factory valves "to my eyes anyhow".

The picture I gave everyone to look at is a few weeks old....I have since built the engine and assembled it and I am not going to rip it apart to find some numbers which is why I was hoping someone could identify it by looking at it.

the "usa" logo I mentioned was what I could see on the skirt of the piston but i had trouble seeing if there was any part numbers.

all help is appreciated ,thank you everyone
 
the are my head casting numbers if this helps any One heads numbers are 07296 2658920-3
and the other head was 07296 2658920-4

From what I gather the 318 a "poly block" was nick named the semi hemi .....such a cool name lol.

I have a 66 LA 318 with matching heads ( I was told they were the smallest chambered LA head produced by some members here on fabo ....meaning higher compression ratio.....plus being .030 over pistons (also adding to compretion) plus....I am not positive here but judging by the surface of the heads it appeared that the heads may have been milled before...I could see Identical "milling" lines across the entire surface of both heads....if thats the case, that would also add to the compression.

so am I right in thinking this is why they went with a dished piston?

and could it be that at the time the only pistons they had available to them were a set of .030 over poly pistons which is why these pistons have the valve reliefs where they are?

is there anything to gain from these pistons? or no?

does it sound like a good setup so far?

what kind of numbers do you think I will be pushing HP and torque wise with this block and the over bore and the pistons and milled heads,long tube headers,mild cam,edlbrock performer rpm intake manifold and a 4 barrel 650 cfm edelbrock carb?

Thank you everyone in advance for any help....sorry for all the questions and the long messages, I am just trying to give as much detail as possible so I can get the most detailed of an answer.

THANK YOU
 
DusterDude72 said:
the are my head casting numbers if this helps any One heads numbers are 07296 2658920-3
and the other head was 07296 2658920-4

From what I gather the 318 a "poly block" was nick named the semi hemi .....such a cool name lol.

I have a 66 LA 318 with matching heads ( I was told they were the smallest chambered LA head produced by some members here on fabo ....meaning higher compression ratio.....plus being .030 over pistons (also adding to compretion) plus....I am not positive here but judging by the surface of the heads it appeared that the heads may have been milled before...I could see Identical "milling" lines across the entire surface of both heads....if thats the case, that would also add to the compression.

so am I right in thinking this is why they went with a dished piston?

and could it be that at the time the only pistons they had available to them were a set of .030 over poly pistons which is why these pistons have the valve reliefs where they are?

is there anything to gain from these pistons? or no?

does it sound like a good setup so far?

what kind of numbers do you think I will be pushing HP and torque wise with this block and the over bore and the pistons and milled heads,long tube headers,mild cam,edlbrock performer rpm intake manifold and a 4 barrel 650 cfm edelbrock carb?

Thank you everyone in advance for any help....sorry for all the questions and the long messages, I am just trying to give as much detail as possible so I can get the most detailed of an answer.

THANK YOU
Click to expand...


Post a photo of the engine, if it is a 66? it would be a Poly. The LA 318 wasn't available in 66, If it is an LA engine then you will have big issues trying to use those pistons, the LA valves are side by side, not vertical from each other like the relief cuts in the photo.

If your heads are set up like the photo toolmanmike posted, then it is a Poly, if not then those pistons need to come out.
 

If it's a '66, it's a Poly. LA 318s didn't come out until '67 in the US and '68 in Canada. Post a picture of the assembled engine and we can tell you for sure.
 
Also, the LA engines have the date it was cast on the side of the block. What is that date? It may be dated 66 but it can still be a 67 LA and if someone ordered pistons for a 66 they would have received Poly pistons.
 
I am sorry I got everyone tripped up.....I said 66 because the block is dated a 66, what I forgot to mention was that it was manufactured late in the 66 year so it would technically be a 67 and it is an LA it has regular old heads on it.

as for these pistons causing problems ....I can garuntee that you are wrong as these pistons were ALREADY in this engine when I bought it and it was a running driving car in my neighborhood so I know there was no clearance issues.

I think you are all under the impression that I had the machine work done which is not the case....I pulled the engine apart to inspect it and toss a few new parts in there and gasketed it up and tossed some bolt ons on it.

PICTURES ON THE WAY

Thanks for the help so far
 
DSCI0705.jpg


DSCI0709.jpg


DSCI0712.jpg


DSCI0713.jpg


DSCI0726.jpg


I would have pulled the rods and pistons while I had the crank out but some how I am missing my ring compressor and I knew the engine only had 12,000 miles on it since it had been built and everything looked good so i didnt feel the need to pop them out.....this is when I looked down the cylinders and seen the USA logo on the skirts of the pistons
DSCI0692.jpg


DSCI0696.jpg


DSCI0703.jpg


DSCI0680.jpg


All the pistons are at the same height because the crank was out in this picture
DSCI0681-1.jpg

Hope this gives you want you guys wanted to see
 
Not sure why my pictures are loading funny......I have done it the same way forever now.....I guess if the pictures are not showing up on everyone elses screens aswell,you will need to click the top bar of the picture box where it says photobucket and it should redirect you to the pictures link.
 
Photobucket is having issues, you need to remove the at the beginning and end of the li...considering the dish and relief cuts in them.
 
I dont see why it wouldnt run again? I have done nothing different machining wise from what it already was. and it ran before.

and I agree that it may have low compression but I wouldnt think that it would be as low as one would think when taking into account the milled heads and 30 over bore size and that these heads are the smallest combustion chamber LA heads that were made (so I hear)....so I would think that it would all even itself out pretty decent.

This engine was in a 66 coronet (original car the engine was in) and it moved that car into the 13's in the 1/4 from what the guy was telling me.

So they must have did something right lol.

I agree its not the ideal setup and if I had the extra money I would switch pistons but it has already been done and was a good running engine to begin with and this is not the final engine that will be in my duster, its just the engine I will be using until I can save up and snag a 340.

the only think I can think of is that....they had the heads milled at some point bringing the valves closer to the pistons.....and then bored the cylinders and they wanted to run dished pistons for clearance and for there goal in the set up they wanted maybe? and maybe at the time the only .030 over dished piston available was for a poly style piston?

who knows lol
 
P.S. I tried removing the URL's in the photos and it is still doing the same thing, first time I have had that happen before...hopefully it fix's itself soon.

Also I wanted to say thank you to everyone for there input so far and sorry if it comes off as me telling you that you are wrong when you say what you say I just wanted to point out that it was in fact a good running engine that made good power and that I have done nothing machine wise to change that,the only thing I have done is replace a few parts back to the specs they were prior to rebuilding it and added a couple of bolt on parts.

I just don't get why they ran things the way they did? maybe they were running NOS at one point and wanted a lower compression piston?
 
Ok I figured out the pictures but I had to seriously overhaul the IMG code to get it to work....I really hope that photobucket will fix that problem soon or FABO if its a compatibility issue with Fabo's new software
 
The engine is a LA but the pistons are poly pistons. As long as the bore and the compression height is the same as a LA piston the poly pistons should work like flat tops without valve reliefs. No harm/ no foul! If it ran before it will run again.
 
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