Chevy Pistons

I have no problems with pistons. So what if they're not the same as the originals? That probably means they're much better. If they were no good then why do they sell in such quantities without my hearing about mass failures! Materials and manufacturing are now better. The originals had split skirts because they couldn't control expansion and ford then didnt know what piston manufacturers know now? And since the thing will hardly exceed 3500 revs, I don't care how narrow the modern rings are they go just fine. The modern ones don't need to be the same as ford made. It was 80 years ago. We've all passed a lot of water since then!
 
George Miller said:
Just let me add that .1875 is way more than any engine manufacture that I know off uses. With 283 piston when put in back wards if memory is right is about .062 that is .125 difference that is a lot in my book. .062 is about the same as a 283. I know they will work ether way but why not do the best you can. Plus less risk of scoring pistons. It does not cost anything.
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Not so many manufacturers are making Desaxe engines with huge offsets
Volkswagens latest has 12.5 mm Porsche 10mm Audi 10mm ? Honda motorcycle 5mm and the list goes on
note this cylinder or crank offset not piston offset
they do this to gain both power and torque
Henry Ford ahead of his time again
they also use friction reducing materials and very high quality materials due to the high thrust loading as you pointed out
the other thing that must be factored is con rod angularity which is a whole new story
 
I'm not on here to start a fight, a reasoned discussion would be good, but I still haven't read a good reason for using Chevy pistons over the readily available part made for the model A. Ring width is irrelevant unless you want the thing to spin up faster but it's a 90year old side valve design and you can only do so much. I've just Rebuilt a low mileage engine for a customer which had Chevy pistons and appropriate rods so we did the same again and it's no different to any engine with the correct pistons. The only conclusion I can make at the moment is that the Chevy pistons can be as cheap as $6 each while badger etc. are about $25 each so it's down to cost.
It's a lot of messing around to save a few $ when they're cheap enough already.
And no, I've never sold insurance and I live in England so I'm not after any business. I have no agenda and no vested interests. I do have nearly 40 years in engineering and vintage motor racing though so while I know a fair amount, there's always more to know.
Can anyone give me a solid reason not to use pistons made for the Model A engine?
 
tbirdtbird said:
go ahead and rev it to 3500 and then get back to us.
You are on the wrong forum
maybe you'll go away soon
insurance salesman?
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Gee...way to make a new lister and Model A hobbyist feel welcome! What, no comments about his possible heritage or family?

We all have a different take on the hobby and in my humble opinion, anyone that is interested in Model As in any particular way should be welcome here.

I find it interesting that the Chevy pistons are an option. I know they have been used in old Triumph engines before.

If you hate the idea, why even open the post?

Just my opinion... "Can't we all just get along?" r.king
 
"If you hate the idea, why even open the post?"

reading comprehension has always been a problem on this forum.

i assume the comment above should be directed to the gentleman who thinks he can rev an A to 3500.

If you bother to look at my extensive record you will see that I am an advocate of the 350 style pistons.

And surely you would not wish newbies on here thinking it was OK to rev to 3500. I am dead set against erroneous info on this board, which will be searched by newbies for years to come for assistance.
 
There are guys over here who race using an A engine, not necessarily in an A chassis and often with better cranks and breathing but they will see 5000 regularly and theyre on std pistons. One of my friends has revved his so high that he's broken three cranks because his flywheel is mostly made of air. I agree thats extreme but its a very fast car driven by a friendly nutter. If you get the porting right and balance it nicely, yes you can see 3500 with a counterweighted crank. The whole car gets a bit flustered so it's a bit pointless but I was just making a point.

My reading is coming along nicely, as an advocate of 350 pistons tbird, you must have very good reasons for using them, perhaps you could share?

RobertB, thanks.
 
tbirdtbird said:
go ahead and rev it to 3500 and then get back to us.
You are on the wrong forum
maybe you'll go away soon
insurance salesman?
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Sorry, but this was just a poor response. He has his own opinions as you do also, so what it is the big deal. He seems like a decent guy to post and ask questions. Just seems like this site has got a few more experts lately and that the average guy just trying to maintain his Model A are getting fewer. Just my 2 cents. Have a good day.
 
Browntudor said:
I have no problems with pistons. So what if they're not the same as the originals? That probably means they're much better. If they were no good then why do they sell in such quantities without my hearing about mass failures! Materials and manufacturing are now better. The originals had split skirts because they couldn't control expansion and ford then didnt know what piston manufacturers know now? And since the thing will hardly exceed 3500 revs, I don't care how narrow the modern rings are they go just fine. The modern ones don't need to be the same as ford made. It was 80 years ago. We've all passed a lot of water since then!
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I've got mixed feelings about this.
I have 80+ year old refrigerators whos compressors are made with unbelievable tolerances even by todays standards and the materials are clearly just as good. GE claimed tolerances of a few ten-thousandths of an inch.

We're talking about pumps that often have over 100,000 hours on them and yet still have close enough tolerances to pump gas under pressure without rings!

My point being I don't know if the new ones are necessarily better than the originals. Seems like an assumption we cannot make based off of what was available in mass production in the 1920s-1930s.

While this is a 1933-34 rotary pump I still feel it gives an example of the close tolerances that were possible in mass production at the time. No cork or copper or rope gaskets needed. Just steel on steel.
http://youtu.be/gn0u7dFBCTk
 
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Thats very impressive that it's still going after all these years, I think it's a different thing though. There wouldn't be much variation in temperature and if the piston and bore are the same material then expansion rates would be the same so clearances would remain constant. An engine has to cope with combustion which creates by-products contaminating the oil, temperature variations and whatever is in the air, all of which are undesirable.
An automotive piston has a shape that is similar to an oval, tapered barrel with the dimensions dictated by the diameter, stroke and material and they're made to micron tolerances. I'm not expert here but I've learned a bit when I've had pistons made for the cars I rebuild and it's a whole discipline in itself, but as they tell me, a piston is just a ring carrier albeit a complex one.

It's very nice to correspond with you guys, I've had my A for 10 years now and I enjoy rebuilding and servicing them, the quality of engineering and materials is very high and the cars are a hoot to drive. It's a fast as a three litre Bentley but you meet a nicer class of person!
 
Browntudor said:
Thats very impressive that it's still going after all these years, I think it's a different thing though. There wouldn't be much variation in temperature and if the piston and bore are the same material then expansion rates would be the same so clearances would remain constant. An engine has to cope with combustion which creates by-products contaminating the oil, temperature variations and whatever is in the air, all of which are undesirable.
An automotive piston has a shape that is similar to an oval, tapered barrel with the dimensions dictated by the diameter, stroke and material and they're made to micron tolerances. I'm not expert here but I've learned a bit when I've had pistons made for the cars I rebuild and it's a whole discipline in itself, but as they tell me, a piston is just a ring carrier albeit a complex one.

It's very nice to correspond with you guys, I've had my A for 10 years now and I enjoy rebuilding and servicing them, the quality of engineering and materials is very high and the cars are a hoot to drive. It's a fast as a three litre Bentley but you meet a nicer class of person!
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Yes,
Huge temperature variations and garbage from combustion are two things a refrigeration compressor luckily doesn't deal with.


Try not to get offended too easily here. Many are very emotional about their cars but I think they mean well in the end.
 
I should add that I've taken original pistons out of ancient A engines and while the cranks can be several grinds undersized and the white metal(Babbitt) is falling apart, the pistons are standard without sleeves in the bores so they can't be bad. The modern ones in engines used by some of us get a lot of use and don't have an easy life because the cars are so usable and durable that we will take the ford out rather than the modern. That's why I asked the question.
 
Hello,
No, I'm not offended, I'm fine. I was slightly surprised by an earlier response but it's obvious it's not the majority. :)
 
Robert it's good that you are not offended. :) I will probably never get around to building an updated "A" engine, but if I did, I would follow all of George Millers post. He seems very knowledgeable on chevy pistons and has a way of explaining there use in a polite manner. He has a lot of good info to share. But you have choices. Just my 2 cents.
 
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zzlegend said:
Robert it's good that you are not offended. :) I will probably never get around to building an updated "A" engine, but if I did, I would follow all of George Millers post. He seems very knowledgeable on chevy pistons and has a way of explaining there use in a polite manner. He has a lot of good info to share. But you have choices. Just my 2 cents.
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Hey zz,
I agree entirely !
Would this gentleman sound like someone that you would like to carry on conversation with, regarding things..Model A !
I re-read his input and my answer would be a resounding ..YES :)
On the other hand, disrespecting another member, be they newbie , or old timer, is to hazard the wrath of the owner of this FREE medium..Ryan. Ryan has stated emphatically that your butt WILL get the boot for disrespectful and/or uncivil behavior...and damn well should,eh !! This forum has become a nice place to visit , as most of the 'drama' creators have gotten Ryans message..but unfortunately not all yet:( !
 
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