Piston options for the 200

[fordconvert]

What pistons are out there for the 200's now days?

The reason I am asking (incase you have not been able to make sense of the rest of my posts the last few weeks) is I want to keep my bottom end as is for now because of time and money issues. Its already 60 over on pistons and who knows about the crank but it is still servicable as is so I dont want to touch it. My orignal head has been partially reworked in the past and needs work again. It is the smaller chamber and log version. With my current bottom end I get around 8.5:1. I picked up another motor that has a newer head and has not been worked on before but also needs work. With my bottom I would end up at 7.25:1. My machine shop cleaned up a couple of holes on each and cc'd them to be sure and I measured my block. At this stage I am willing to spend the money and get the smaller head done because it will work with my existing bottom.

My question is will I be able to build up another bottom that will get me into that 8.5:1 range again with those smaller chamber heads or are those parts hard to come by these days? My current pistons seem to have a 9cc dish and are down 0.046".

 

[addo]

I can't remember the current block's amount of bore ridging, but it has excessive deck height. I would suggest make fit whichever head will give the best compression for least cost, in the meantime.

Should the block later require replacement, shoot for zero to plus five thou deck and your ideal CR by choosing piston dish and relieving the combustion chambers as needed.

 

[CZLN6]

Howdy Again:

I'm waiting on casting codes to get an idea of what heads you're working with- from your other post.

As Addo said, Either head will work for now just mill it to achieve your desired CR with your existing block.

When you do build a short block, go for zero deck height, again as Addo said, but Id reccommedn a stock type dished piston of 6.5 to 7 CCs- and last of all, mill the head to the desired CR. The current crop of composite head gaskets will assure you of enough deck clearance.

Last time we checked, the only typical piston that seems to have disappeared is the Calif. Emmissions 13 cc dish pistons originally for 66 & 67 calif. Emmissions equiped engines. So that leaves the stock type dish & flat-topped HSCs. Of course you can get anything custom made, but bring your PHAT wallet.

Adios, David

 

[fordconvert]

Thanks for all the info so far.

Any ideas on what combo I could have now that is giving me that .046 deck height? Is/was there some other motor that had the same piston with a slightly differnt pin height? Could I have a mix of 170 or 250 parts? I used a dial indicator to find TDC and a straight edge and feeler gauges to come up with the height.

 

[CZLN6]

Howdy Back TJ:

I can tell you that 170 pistons are flat-top and have a bore of 3.5"- so that's not it. The 200 and 250 engines use the same pistons.

Since you have oversize pistons my guess is that the piston manufacture dropped the pistons pin height. This is not uncommon. It helps the builder to compensate for machining and Compression increases due to boring.

The dish could have possibly grown due to degradation over time and wear. If the dish is rough and irregular that may be it.

The only realistic solution to this much deck height is to have the block decked to zero when you rebuild the bottom end.

Adios, David

 

[MustangSix]

I think David nailed it. A lot of piston manufacturers "destroke" the CD to allow for decking the block.

If you're willing to change the pistons, you could go to a flattop Tempo 2.3 piston.

 

[wsa111]

Go one better, install the flat top HSC pistons & offset grind the rod journal to at least .030-.040 under & pickup .025" to .030 in stroke, then you will be closer to the desired 0 deck height.

 

[rbohm]

8) if you want original style pistons, or other engine parts, try this website

www.egge.com

they have a bunch of original style engine parts that they reproduce, including the original style steel shim head gasket for our sixes.