piston help 196

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grendel_cave

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It looks like I'll be needing some new pistons for my 196. ...long story. They'll need to be 30 over, but aside from that I'm not sure what to look for: forged pistons or cast ones. I'm also not sure of what options, companies I have to choose from or which are best for my application. Without somewhere to start, I can't ask Jeff what to look for. This is going to be a fairly spirited 196, decked, milled, camed, balaced, etc. Any help as to what pistons are available would be appreciated. Thanks.
 
Here are some pictures for the "destroking question." I think what people are referring to as "destroking" means bleeding off compression. Which piston bleeds off more compression? I'm guess the d shaped recessed head bleeds off less than the other. Am I correct in this?

Who makes a better piston: federal mogul, zollner, or silvolite?
 

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De stroking is in reference to the ch compression height on a piston. The ch of a given piston is the distance from the center of the piston pin hole to the top of the piston. On a domed or contoured piston the top from which the measurement is taken some times a reference point and not the true top.

When a piston is "de stroked" the ch is reduced so that after re machining the block and head the compression will remain basically stock.. A common amount to de stroke is .020-.030".

With an engine that originally was manufactured with the thin steel head gaskets(.020 thick) and a modern head gasket (.040 thick) is used to rebuild the engine a destroked piston will significantly lower the compression ratio. Not what you want.

I truly feel that with todays fuel an IH can have its compression ratio raised .5-1 and suffer no problems and easily use low test regular.

Silv-o lite pistons would be a great piston and they are not destroked.

As for you pictures the piston style is not a issue in de stroking only that you reinstall the same/correct style. The first picture is a non emmissions "contoured) style and the second is an emmissions 392/196 pistone. He notch comprissing 10cc is used to make the compression ration what the IH engineers desired.
 
The piston dome profile must match the head you are going to use. The domed piston is the "pre-emissions" design, the flat top with eyebrow is the emissions motor.

Silvolite pistons in both cast and hyper-eutectic are readily available in the "flat top" design for this application in any oversize. However, any piston of the proper dome design is more than adequate for any "built" 152/196 motor.

You must look at these engines as a "system", selecting the wrong piston design for the head profile will result in valve collisions. Simply mixing and matching parts in an indiscriminate manner will only lead to an uncompleted motor once the money pit runs empty. This one got real close to becoming a "project" instead of a viable dd motor, take a badly trashed 152, swap in a badly trashed 196 that had mucho casho dumped into a non-oiler from the git-go, then try and marry an early 196 with a late 196 that had been cleaned but also had the block and crank trashed, and whadda ya git??:

http://www.forums.IHPartsAmerica.com/I-h-s-t-o/1786-michaels-62-Scout-restoration-thread-2-a.html
 
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Yeah, I definitely did go about it the hard way... But I did learn a whole hell of a lot! If you end up gettin the pistons I have a set of 4 .030 rings that I would sell you. I had to buy a whole v8 set, so I still have 4 left over. Good luck on your build.
 
Will the box note if a piston is destroked? I know a guy who has a got a set of 4 federal mogul, hyper-eutectic pistons with the teflon coated skirt. Would federal mogul denote if any "destroking" has occured?
 
grendel_cave said:
will the box note if a piston is destroked? I know a guy who has a got a set of 4 federal mogul, hyper-eutectic pistons with the teflon coated skirt. Would federal mogul denote if any "destroking" has occured?
Click to expand...

Some mfg's do some don't. See if they list a compression height on the box.
I have the ch of a set of silv-o lite flat tops for a 196/392 at home. I'll see what it is and post.

Iirc a decompressed piston will be 1.876 ch. Ans a non is 1.904.
 
So I called silvolite and spoke to them at length. According to their math, it looks like the my compression ratio would run about 8.15 with their pistons (keeping in mind my 196 has been decked 10 and the head 7). If I went with federal mogol, my ratio would go down to 7.98. The silvolite's are only offered in eutectic not hypereutectic. So the question is:

would I notice a difference between 7.98 and 8.15? Is the sacrifice of .17 in compression worth gaining the extra durability of a hypereutectic piston?
 
I am not a proponent of hyper eutectic pistons. I either go cast like s-l standard or forged.

Seen to many crack because people believed they were hi performance pistons. The s-l pistons will take all of the punishment you can through at them in an normaly asperated IH.

I don't agree with the comp numbers s-l gave you. With .010 off the deck and .007 off the heads you should be close to 8.25-8.3. Yes you will feel the differance between that and 7.9-1 esp low end throttle responce and torque.

Just built a 0 decked 392/396 using the s-l piston with the 10cc dish and yeilded 8.8-1 cr with slightly enlarged combustion chambers@ 85cc. The heads were not machined at the sealing surfaces. A few deetails in link below.

http://www.forums.IHPartsAmerica.co...IH-sv-4-popper-combustion-chamber-volume.html
 
I found a set of oem perfect circle pistons that are .30 over and the the correct compression distance. I've never heard of perfect circle, but my research reveals that they were produced by Dana. Have you ever run perfect circle pistons? How is the quality?
Thanks, aaron
 
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