Piston rings

[pAAt]

Just wondering if I can buy .020 or if I can find .010 rings for a .005 bore + (have the used .005 pistons already) ? I would ask Tom, but I might be doing that to much already Thanks, Pat

[Tom Wesenberg]

Pat, I'd wait until the cylinders are honed, and I take some measurements.

I don't think we'll be cleaning parts with gas in that wood stove heated room. LOL

[pAAt]

I was hoping you'd say that Tom !! I heard if your close to the ignition point you generally come out unscathed Pat

[DaWizard]

Heh, says the guy that was on the other end of the room!

[pAAt]

You still with us Wiz ?!! Tom's a little worried about flames and gas ? Pat

[tbirdtbird]

I am curious how anyone ever found .005 over pistons, that is a new one on me

don't set the top ring too tight....we use .022 here, that ring is exposed to the max heat,
that is another area I differ from the Les book.
I have seen hot motors lock because of rings too tight.
They expand as the motor warms up, so your starting gaps close up a lot

[pAAt]

Thanks for the input Tbird. I'm not sure when this engine was rebuilt or if the factory would use .005 pistons in some instances ?? Truck was purchased from a farm auction in 1961 and sat in a shop the whole time. There is plenty of gunk on the engine, so it would have been an early rebuild I would say. Pat

[SteveE]

How do I select the correct ring set to buy for my Model A with a Model B engine? STD size or is there a way to determine which ones are the best size to replace current rings? Do I have to pull the engine to check the cylinder walls with a bore gauge or just pull the head and measure each with the gauge? I assume I have to pull her anyway to do the work anyway. Lost compression across the cylinders with 3 or 4 low and high differences. I will start with replacing the head gasket and look at lapping valves and seats next but assume rings may be shot too. Still learning. Not a mechanic.

[Jwmckenzie]

SteveE Welcome to VFF. First things first, you should try a leak down test, before you start taking things apart.

Here is a write up, with video's, on the leak down test I found on the interweb…..

https://www.ericthecarguy.com/faq/so...k-down-testing

Pretty easy to do, if you have the tool. There is some info on making your own tester. I tried making one with little success, just buy or rent one. Some of the auto parts stores rent the tool.

This test will let you know if you have a valve problem, rings, or some thing else.

To answer your specific question... If you need to do the rings, I would go to a machine shop that does engines and have the bore measured by them. There is a lot to it, more than just one measurement, plus they will have the right tool to make the measurement. They can also tell you if the thing needs to be re-bored or if a hone will do the job.

Jon.

[Mitch]

Welcome SteveE to the VFF.

What Jon said. (leak down)

Lost compression across the cylinders with 3 or 4 low and high differences

You need to do a proper organized diagnosis, before tearing anything apart. Otherwise, you're just going in blind. You did not mention the actual compression readings. What symptoms were you experiencing?

[Marco Tahtaras]

Those points from Jon and Mitch are right on! I'm also curious about the series of events and their timing as it can often tell us a great deal.

BTW, piston size will be marked on the piston tops. It's way too early to assume you need that information.

[DaWizard]

SteveE WELCOME to the VFF!!

[SteveE]

Thanks for the info on the leak down tester. I will give that a shot. I bought a rebuilt 1932 Zenith Carb and after inspection, found that the upper casting was glued together with JB Weld it appears then painted over but cracked in half. I got taken for a ride on that purchase. Hard to tell these days. I am thinking that that created a major loss of manifold pressure. Replacing with my old Zenith that is missing the Power Jet tube that nobody sells. I'll do the leak test too.

[Bob C]

Vince was selling the power jet tube on Ebay at one time.

http://www.fordgarage.com/pages/powertubeinstructions.htm

[Mitch]

SteveE
Try calling Renners. Nice people and he probably has something laying around there

https://rennerscorner.com/carburetor.html

[SteveE]

Thanks, will do.