engine rebuild, piston ring size????

[masterdave]

So i busted the cam shaft rotor on my 31 A engine, i happen to have a spare engine that i am rebuilding, snyders autoparts offers a bunch or piston ring sizes, what is standard size so i know how much bigger i have to order for my engine, also i assume i should measure it with a vernier caliper unless there is a better tool to use.

thanks
dave

[Gary WA]

You have to mike the inside of the piston chambers or if there is pistons in the engine should say on top of the piston.040/.060/ etc.

[Jim Parker Toronto]

Dave, if you have the block out of the car, take it to an engine rebuilder in your area. Have them measure the cylinder walls from the top to the bottom for wear. The rings are sold in many different oversizes. I think the stock bore is around 3.875"

[Gary WA]

std bore is 3.875.

[Ice man]

What the hell is a cam shaft rotor. I have only been doing this for 60 yrs, so maybe I can learn something. Iceman

[Bob A.]

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Originally Posted by Ice man

What the hell is a cam shaft rotor. I have only been doing this for 60 yrs, so maybe I can learn something. Iceman

I'm going out to the garage to see if I have one.

[Gary WA]

Maybe distributor shaft????

[masterdave]

I'm sorry for the confusion by camshaft rotor I mean the gear at the front of the camshaft that drives it, it is the gear that conects it to the crank shaft, and i think the pistons are labled .030 so does that mean they are .030 above stock to begin with?

Thanks
Dave

[George Miller]

It might be wise for you to take your engine to a engine rebuild shop. They have the tools and knowledge to fix it right.
But why not just change the cam gear or is the rest of the engine bad.

[masterdave]

The whole engine is in such bad condition it needed to be all replaced I will try and post pics, I have most of the tools I need I
still in the market for a good caliper any suggestions? I will hunt for a rebuild shop but I'm almost positive there are none. I'm quite determined to do this all my self but i'm open to help anybone live in westcehster ny that's where the car resides. I'll take some more mesurements and see what I need

thanks for all the help
Dave

[Bob A.]

Masterdave, I respect your willingness to rebuild your engine yourself, but
Your going to need a little more than a vernier caliper and help from this site. At some point your going to have do some machine work to the block. So do yourself a favor and send the engine out. By No means I'm not trying to be a smart a**
I'm sure others will give you the same advice.

[masterdave]

Bob, don't worry criticisim is what I was looking for imm still new to this, that's what I was afraid of I do have limited acces to a Machine shop but i I don't have the know how the old rings are still on the cylanders I may just keep them there and forget the rebuild it's turning out to be a buyout of my reach I'll have to see what machining tools I have acces to. Is the .030 on the piston. .030 overstocked?

Thanks for the advice
Dave

[George Miller]

Well give it a try we all had to learn at one time. The worst that can happen is that it will not hold up. Go slow and ask a lot of question , but do not listen to those who know it all, but have never done it. It is not that hard but there are a few things you will need to know.

[deuce295]

Dave

Normally if the piston top is stamped with .030 that means the current pistons are .030 over the stock bore. If you are planning on using new piston and rings make sure the cylinders are not scratched up and will need to be bored several sizes to clean up the cylinders. If your plan is to just put some new rings in then you should at least hone the cylinders to help the new rings seat.
Just my experiences. Good luck with your project.

[Model A]

I took my block to a machine shop just to find out what it needed. Turned out the bearings are cracked and pistons are worn. Mine are .040 over, what diameter over is safe for heating block?

[Tom Wesenberg]

Originally Posted by Model A

I took my block to a machine shop just to find out what it needed. Turned out the bearings are cracked and pistons are worn. Mine are .040 over, what diameter over is safe for heating block?

If the cylinders aren't too rusty in the cooling chambers, you can bore up to .125" over.

[Tom Wesenberg]

Originally Posted by masterdave

Bob, don't worry criticisim is what I was looking for imm still new to this, that's what I was afraid of I do have limited acces to a Machine shop but i I don't have the know how the old rings are still on the cylanders I may just keep them there and forget the rebuild it's turning out to be a buyout of my reach I'll have to see what machining tools I have acces to. Is the .030 on the piston. .030 overstocked?

Thanks for the advice
Dave

If you need to have the block bored, most machine shops don't charge too much for that. They can measure the cylinder taper and let you know what size pistons you need. If you take the engine apart yourself, be sure to mark the rods and pistons, so they go back the same way they came out. You may save some money by taking the engine apart the taking the bare block to the shop.

If you keep the same pistons, be sure to check for side clearance, so you don't wind up with piston slap. Also check the side clearance for the rings. A new set of 4 pistons will be about $90 to $100. Rings add another $25

[masterdave]

First thanks for all the advice guys

does any one know a good machine ship in the westchester ny area
the cylander walls seem to be scratch free i found the engine partialy rebuilt it looks like someone started a rebuild never finished it and gave the engine to my grandfater it sat for 20 years untill last weekend when I dissasembled it (made sure to lable e erything) It would seem as if they cylanders were bored to .030 during the unfinished rebuild and it was never completed. I cleaned and reset the valves so all that's left is the piston work, that's where I
stuck now.

Thanks for everything
Dave

[Mikeinnj]

Masterdave;

You sound determined to learn about your engine and you can do some of the work yourself such as assembly, after the machine work has been done by a shop familiar with Model A engines. Take the engine apart yourself and inspect everything that moves and wears. Mark the position of each part and label them accordingly.

You may have to beg, buy or borrow some specialized tools to dissasemble and inspect it properly, such as a head stud removal tool,valve spring compressor,feeler guages, sockets to fit the Crankshaft bolts/nuts etc.

Some of the things you should note are the following:

Is the block cracked anywhere? After cleaning a machinist would magniflux the block and crankshaft for cracks and repair if feasible.

Are the cylinders scored (vertical scratches or scuff marks the length of the cylinder bore) ? Are they worn larger than the piston size ?

Are the crankshaft main and rod journals worn > Measured with a caliper or micrometer ?

How does the babbit material look on the rods and main surfaces. Look for loose,cracked or missing pieces of babbit and measure the fit of all the bearings with plastigauge or tinfoil as described elsewhere on this site.

Check the valve seats for pitting or wear and have new hardened seats installed along with one piece valve guides and modern valves and adjustable lifters if necessary.

Measure the journals on the camshaft and check the lobes for wear and replace if necessary with a regrind or a new one from Bill Stipe.

Many of the above machine work steps could be done at a machine shop in your area. You should look for someone who seems passionate and interested in working on an 80 year old engine.

You can rebuild the oil pump yourself with a kit from suppliers and check the gear that drives the oil pump and distributor shaft and replace it if questionable.

You should buy some of the available books on "how to" regarding this work on the Model A or seek assistance from local Model A club members as there is usually at least one "go to" guy in each club for such advice.

There are several competent Model A engine re-builders within a 2 hour drive from you who could do the babbit work if needed or the whole job should you decide the task is beyond your ambitions.

Good luck !

[Bob A.]

Originally Posted by masterdave

Bob, don't worry criticisim is what I was looking for imm still new to this, that's what I was afraid of I do have limited acces to a Machine shop but i I don't have the know how the old rings are still on the cylanders I may just keep them there and forget the rebuild it's turning out to be a buyout of my reach I'll have to see what machining tools I have acces to. Is the .030 on the piston. .030 overstocked?

Thanks for the advice
Dave

Dave I'm not criticizing you. I don't know your mechanical skills and what tools you have. Most of these fellows that answered you have been in the business for over 40-50 years including myself with a minimum of $50.000-$75.000 worth of tools without counting the roll-aways. . It all comes easy to them and myself and we are still all learning, it never ends including buying tools.
My advice to you was a cost effective way and and a long term enjoyment.
I know we all started somewhere but we most likely had a hands on guy showing us or at least I did. Anybody who tells you they learned strictly from reading a book or learning from this site is full of sh*t it takes more than that. I'm sorry but throwing a set of rings on a piston and lapping valves in my book doesn't constitute rebuilding an engine.
I apologize if I came on too strong .