Need original piston for 1938 248

[JoelsBuicks]

I am looking for one used or NOS original standard size piston for my 1938 248 engine. The original piston is different from replacement pistons in that it has a thicker top ring, 1/8-inch instead of 3/32-inch. You'll see the difference in the picture. My engine is in great shape except for one cylinder that will be sleeved and bored to standard.

I can buy a replacement standard piston but it would probably mean that I'll have to buy an additional set of rings since the top ring will be 3/32". Used condition is fine as long as its normal wear and the lands aren't broken.

Thanks,

Joel

[Guest captbrian38]

if the shop that rebuilt my 248 still has the original pistons you can have one. Will know tomorrow with a phone call.

captbrian38, Brian

[cobravii]

Here you go.....

Old Buick Parts - CARS. Inc.

[JoelsBuicks]

Brian, I very much appreciate you making that phone call. Let's hope that they haven't tossed them yet!

Indeed CARS Inc. will sell a signle standard piston but it will have the thinner ring and force me into a set of newer rings when all I would need is one ring. Called them earlier today.

Thanks,

Joel

[jeff]

Joel,

Here's my 2 cents. On my '38, I had one scored cylinder, which was due to a piston ring gland failure that led to a ring failure and then the scoring. I had the cylinder sleeved and replaced just the one piston. Many years later (but not more than 2,000 additional miles) I decided to upgrade to insert bearings since I found a set from a 1950 engine. When I removed the head and pushed out the pistons, I found two more pistons with failed ring glands and broken rings. It was amazing to me that the engine still ran reasonably well. My only conclusion is that all eight pistons had the seen the same level of stress (time, temp, fatigue) and that they were all getting ready to fail. My final solution was a new set of eight pistons and rings, .030 over (along with the new rods).

Now, if you want to replace just one, I do have the survivors in a box in the garage. Also, if any of your babbitted bearings are looking "thin" (meaning very little shim left), some of mine were pretty nice - I probably have two or three that were probably replaced at some time.

Let me know.

Jeff

[JoelsBuicks]

Jeff, I haven't cleaned up my old pistons yet but I need to look closely at the lands. I did look at land wear (gap) and it appears to be very good - although I need to measure it with the new rings. The shims in my rods and mains were still there and the crank wear shows flat by only .0025" max. I did experience the problem you had on my 36 320 engine and really couldn't explain the broken rings - lands still were good. I enjoy the thought of being able to return the engine to a standard spec if at all possible - not just to save $$ but that certainly is a bonus. It may very well be that you can help with one of your original pistons. I'll let you know.

Thank you,

Joel

[Guest captbrian38]

I thought you removed this thread yesterday when I couldn't find it to tell you I had called the rebuilder and he thought the pistons might still be in his aluminum barrel. I called him back and told him not to bother looking because the thread was gone. Now it's back, do you still need the piston and if so I will go and look myself.

Brian

[JoelsBuicks]

Brian, I don't know what happended to the thread. I still need the piston and very much appreciate the help.

Joel

[Guest captbrian38]

Joel, went to CAMS shop today and went through a 55 gal barrel of pistons he saves for scrap but only found one of the pistons and it had a broked land just below the dome, i think it is useless. Sorry. See if Jeff can help you out.

Brian

[JoelsBuicks]

Brian, thanks for taking the time and effort to look. I see if Jeff can help.

Thanks again,

Joel

[Vette58]

If the '39 piston is the same I can send you one of mine. I rebuild the engine with 0.030 pistons last year and have the old pistons still there. I need to check if there are still standard bore (but I guess they are).

I've no clue how much shipping from Germany will cost.

Uli

[jeff]

OK, I'm back.

Send me a PM with your address, and I will send you a piston. Sounds like you are pretty certain about your remaining shims and the health of your babbitt. Reading between the lines, yours sound pretty consistent. Mine were not - I had one or two with little or no shim left, and some with full shim packs. I took that to mean that some rods had been replaced. So again, if you take a closer look and decide some of yours are a bit thin, I may have some better rods to help as well.

Here's where I could use some help. I will be having some door panels made for my '38 2-door Special. I think the correct material can be sourced from Jenkins. But, I don't have patterns - any chance you could take some photos and add dimensions? I'd need sufficient detail to hand the job to an upholstery shop.

Jeff