Just how far can a Model A motor be bored out? Picked one up a couple weeks ago, 2 pistons stuck. Soaked with WD40 both top & bottom for several days. Tapped with wooden stake a little each day, top & bottom. After about a week they came out, no big problems. Then found several long gouges in nbr 4 cyl, a few less in nbr 3, only 2 short ones ones in nbr 2 and none in nbr 1. Pistons were stuck in cyls 1 & 4. THe gouges had to have been there well before i started, cause it sure looks like there is rust in the bottom of the gouges in nbr 4 cyl and that is the worst one. Best i can measure, or guess, those gouges look to be 40 to 60 thou deep. The pistons i took out were marked 050 on the tops. Am i just screwed here? Mike
.125 over is the farthest I'd go. I think thats around a 4" bore too. Ore you can have the cylinders bored then cold sleeved to std. and bore the sleeves to your liking.
There has been a lot of discussion on Ahooga about this...a search there would lead you to people with the actual experiences. I think general consensus is about so: .080 is almost always fine, .125 (4.00 bore) has been done successfully by many. Obviously, severe rust in water jackets or any number of casting problems can do you in. Apparently at 4.00, many report perfectly fine operation and a few report overheating. If I were heading for 4, i'd research sleeve availability and thickness first just to see if there's a block-saving plan B available if problems occur. A variety of Olds and other pistons have been fitted to these things, Ross and others make custom pistons to suit. I'd consider custom or modern pistons with modern moly rings, since wear in the bore would be a bad thing at this stage and the reduced friction would be real good too.
A variety of Olds and other pistons have been fitted to these things, Ross and others make custom pistons to suit. I'd consider custom or modern pistons with modern moly rings, since wear in the bore would be a bad thing at this stage and the reduced friction would be real good too.[/quote] 283 chevy flat tops baby like a glove tom
As already stated, .125 (1/8" for us fractional sorts) is the traditional max bore on an A block (and yes it is a 4" diameter, stock A's are 3 7/8"). Pretty much all the banger powered cars I've seen in the late '50's early '60's Hot Rod magazines use the .125 bore, making the engine a 213 c.i. mill. You definitely want to make sure there is no 'cylinder drift'- the cylinder is excatly centered, or the cylinder walls could get mighty thin in places. I read that Tom Kelly has built engines using 351 Ford pistons, but it didn't specify Windsor or Cleveland in the article (too modern for me to know the diameter on those).
You're gonna find a LOT of opinions on this subject... One way to resolve the issue is to have the block sonically tested to determine wall thickness. the issue is not whether or not there's material left after a 0.125" cut, but whether or not the remaining material will dissipate heat properly. When you go out a skosh too far, there's not enough meat left in the wall to insure even cooling of the cylinder. Hot/cold spots make for uneven ring sealing - and potential piston scuffing. Model A motors are low-revvin' beasties which don't put a lot of heat into the cylinder walls. Damn if I can't remember the correct min cylinder wall thickness...Must be getting old. Perhaps someone else can chime in with min wall thickness... In any case - less is more here. You're already out 0.050"; a 30 thou cut should get rid of any piston-related scoring. If you hafta go more...I'd recommend sleeving - or find a new block. FWIW, B blocks are still available - I coulda had a decent one last fall for $150. B's have better cranks and pressure oiling, and if you're building a banger - they're the hot ticket! if you're in doubt on this block, I'd say fuggedabou***. It's not worth the heartache of dropping green on it only to have it fail a year after the build. Take the time to do it right, as there are plenty of blocks to choose from out there. Hell, Pop's got spares to last him the rest of his life!
Like all have said .080- all day long, .100- maybe, .125 getting a little shakey! Above .080 I would find a sonic tester and check wall thickness. The B blocks a more prone to core shift than the A's. Good luck!
4" is definetly OK, I'm running my 4-port at 4" now and a Winfield flathead at .100" over. In the old days they used to bore them to 4 1/16" but this required offset boring as they get too thin betrween the siamesed bores. Today the problem is getting head gaskets over 4". Model A pistons are available to 4" or Olds, Chevy, Ford pistons can be made to fit.
I read that Tom Kelly has built engines using 351 Ford pistons, but it didn't specify Windsor or Cleveland in the article (too modern for me to know the diameter on those).[/quote] no.... i haven't built them with ford pistons Rich Faluka from antique engine restoration in skokie ill builds his engines with 283 chevy pistons and yes i think they are 3 7/8 dia not unless there is another Tom Kelly( i spell my name kelley) if there is another tom then i would like to meet him tom
No expert here, but I seem to remember at .60 or above you are supposed to sleeve? (prolly wrong) I think if you want to know the gospel on A engines you might consider going to the experts, the Model A Ford Club of America, why not check their web site?
Thanks for all the replys, thoughts, & suggestions. Will be headed to some of the other boards mentioned to ask some questions. After that, will probably do the sonic testing thing. If i get decent results from that, may just bore to what is needed to clean up cyls and then build a mainly stock type of engine. No real go fast stuff on this one. Thanks, Mike
why this block? why not find one that isn't *****ed up i have about 20 heck if if my old man and i are anything like the rest of the banger crew they have to have at least a dozen laying around too i guess my question to you is why not find a new block just a thought tom
I found a well-worn shortblock behind an old Montana Ford dealership a few years ago that miked out at 80 over. I DID any inquiry with the Model A restorers at the time and was told it was safe to go 125 over, so that's what I did during the rebuild. Now I've got the long block ***embled and in storage somewhere, but I still haven't used the engine to see how it does. Guess I'd better put it in something. I'd completely forgotten about that banger engine until I read this thread. Geez! 'Must be getting old.
To answer "tub in da dirt" question about why this block, well, i'm not really attached to THIS specific block, except by money spent. The block was part of a package that included a pristine Model A frame, complete Model A front end, less spring, restored & rebuilt 94 carb with cool aircleaner, and this long block motor. If i tried to break the costs down to specific parts, i would say i'm into the motor somewhere between $75-$125, maybe less. Might use it for mocking up things while going after a better motor. I did manage to pickup a really nice, good condition Van Norman boring bar at a recent swap meet. Just needs new cutting bits. Just might give it a whirl at home. Anyway, one other question, what is a restored & rebuilt 94 carb going for these days? Thanks, Mike
Anyway, one other question, what is a restored & rebuilt 94 carb going for these days? Thanks, Mike[/quote] i bet you can get a few a blocks for that carb.... but i like the fact that you want to bore it yourself. check the babit first though i wasn't trying to be an ***(not that i thought you were pissed or anythig) i just like the easier route sometimes now if it was the original motor and or it had some kind of personal value then by all means keep it tom
Thanks for the reply Tom. The guy said he wasn't going to be using the 94 carb and put it in a pile with some other model a parts and said $50. Sure, why not. Then he tells me later that a guy in his club was a little pissed that the sold ME the carb and says he would have paid $175 for it. I didn't know these carbs were bringing that kind of money. Guess the deal worked out a little better that i originally thought. I got the boring bar and a really cool Souix valve seat grinder for $350 and a swap meet in Jan from a neat guy who used to race sprint cars around here. Still working on getting the valve grinder, but thats another story. Boring bar is really portable and all the parts were there. Even got a operations manual with it. Now all i need to do is get the head studs out of the block and try mounting it up to the block and take a real light skim cut on that really bad nbr 4 cyl. This time, i'm gonna try and remember to take a camera out to the garage and get some pics. Mike
I've used 351W pistons with success. Something to think about, when sleeving the A block, they are bored to 4.060" for the sleeve. I've never seen a block that has holes in it at that size.
I have built several "B" race engines that were bored .156. I have several friends that have done the same. I offset the bar to keep the siamese area as wide as possible. As long as you have no real attachment to your block, you might consider a "B" block. As others have pointed out, they have bigger crank journals and are much easier to convert to full pressure. A BIG plus... I would not put anything but forged pistons in even a stock engine.
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