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Piston Identification

Posted: Wed Apr 03, 2019 6:41 pm
by namdc3
Can anyone identify these aluminum pistons from the photos without me pulling the head? They say "Model T-HC" on the inside of the skirt. Does the HC mean high compression, or is it just a coincidence in model number?

Re: Piston Identification

Posted: Wed Apr 03, 2019 7:32 pm
by Mark Gregush
Put the piston at TDC and look thru the spark plug hole, if the top is domed they are HC, if flat normal. Understanding that T pistons come up out of the hole not even across like others.

Re: Piston Identification

Posted: Wed Apr 03, 2019 7:34 pm
by walber
I expect it stands for high compression but can't tell by these photos. On stock pistons the outer edge for about 5/'8" has an upward bevel and then the rest of the top is flat. Most high compression pistons have an even curved top surface, kind of a low dome.

Re: Piston Identification

Posted: Wed Apr 03, 2019 7:50 pm
by George Andreasen
It's the initials of the manufacturer.......Hang Chow, a well respected recycler of old beer cans in China......... :lol:

Of course I'm kidding. They're almost surely high compression.

Re: Piston Identification

Posted: Wed Apr 03, 2019 8:59 pm
by Humblej
Those wrist pin bolts should be safety wired, the cotter pins will not do anything to keep the bolts from working loose.

Re: Piston Identification

Posted: Wed Apr 03, 2019 9:11 pm
by Mark Gregush

Re: Piston Identification

Posted: Wed Apr 03, 2019 9:34 pm
by Ruxstel24
Yes, cotter pins work, but not bent that way.
Needs turned 90* and only one leg bent.

Re: Piston Identification

Posted: Wed Apr 03, 2019 9:49 pm
by Les Schubert
In regards to cotter pins there;
In my opinion NO!! Remove them and the bolts, apply Loktite and torque the bolts to 30 ft lbs!!

Re: Piston Identification

Posted: Wed Apr 03, 2019 10:24 pm
by namdc3
Thanks to all. Yes, they are domed as verified through the spark plug hole. I know it looks like the cotter pin will clear the rod and allow the bolt to turn in the photo, but it's actually long enough that it won't. I think the builder was of the opinion that using a long enough pin and bending both tails both prevented the bolt from backing out and halved the chances of the pin falling out. Thanks for the heads up, for sure, of course. If I'm reading your posts and the linked posts correctly, it's doing what it's supposed to do.

Re: Piston Identification

Posted: Wed Apr 03, 2019 11:07 pm
by Adam
15,000,000 Model T’s were built with cotter pins in the wrist pin bolts...