[War eagle]

Strange thing happened while rebuilding a 64 center carb (orig) and trying to fit an aftermarket power piston. The washer that pockets into the air horn is large compared to the one removed. The original measures .402 while the aftermarket is .410. Even if someone has "staked" the original and closed up the pocket, it would never have accepted this .010 over washer when new. I opened up another known tripower carb and it too has the .402 diameter washer. I save everything and in the last 40 years have even kept used power pistons from 283 chevs to everything else Rochester and I don`t seem to have that large washer on any pistons. Any ideas out there carb Guru`s?

[Tom Vaught]

I have cleaned up original power pistons for years with my glass beader and they look like new and work great. I use walnut shell mix and the dimensions never change from oem.

See no point in buying a aftermarket part.

Tom V.

[mgarblik]

Originally Posted by War eagle

Strange thing happened while rebuilding a 64 center carb (orig) and trying to fit an aftermarket power piston. The washer that pockets into the air horn is large compared to the one removed. The original measures .402 while the aftermarket is .410. Even if someone has "staked" the original and closed up the pocket, it would never have accepted this .010 over washer when new. I opened up another known tripower carb and it too has the .402 diameter washer. I save everything and in the last 40 years have even kept used power pistons from 283 chevs to everything else Rochester and I don`t seem to have that large washer on any pistons. Any ideas out there carb Guru`s?

China! The parts are just a "facsimile" of what the OE part looked and functioned like. If you can, clean and reuse the OE part. Run into this all the time on all kinds of parts. 99% of the time, it is a Chinese part incorrectly made.

[War eagle]

Tom I usually never buy a power piston but have been chasing a rich idle fuel problem from the start. I have done everything and even rebuilt another 2GC. I decided to switch the power piston and power valve. Those smoky spark plugs and dirty dark oil just doesn`t get better. I even replaced the Summit 2801 with a Melling 068 which I am just about to try. I am running only the center carb with end carbs blocked off and no fuel source until I sort this out. Back to the aftermarket power piston...... I did call the supplier and they claimed to have several 1966 trips and would see if their aftermarket power piston with the large flatwasher would fit and of course it did. It sure doesn`t fit any of my 64 or 65 center carbs. The aftermarket part is advertised to fit 64-66 so I thought maybe in 66 the piston was different. Still don`t know. I also don`t like the fact that the aftermarket piston is plated steel which can`t be that good on the piston bore like the original brass unit. But regardless the washer on the power piston is too large to fit any carbs I have by .008 to .010 and I have the original back in with a lighter spring installed.

[Dick Boneske]

The large 2GC power valve rod is shorter (yes, shorter, not longer) than the small 2GC as used on the '64 center carb. I'll check tonight to see if they have the larger .410 dimension for the washer that you stake into the airhorn.

If you remove 8 turns from the spring on a stock small 2GC rod, your idle problem should be fixed. Also, it helps with the bucking at low RPM's while driving.