Bored out to .040 Question

[ssj7kids]

My engine guy reported that he bored the cylinders to .040 to get them cleaned up nice. It's a 53 F100 V8 Flattie. We are putting a Merc crank in it cause the original one had a crack... which is a good thing, as it gives us a longer stroke. However, he asked me to ask you guys: Got the Ford off the boring bar this morning. It cleaned up at .040. My concern is that the cylinder walls are corroded on the water jacket side more than I like. Can you check on your forumn and find what they feel what is acceptable with the 4 inch stroke crank as it will put more leverage on the cylinder walls. See if anyone of them feels we need to sleeve the block or ??? What do you guys think? I'm thinkin this is just gonna be a daily, not a race car truck.

[petey shoes]

I believe that .060 is the limit. if your not going to over carburate or use blower, and don't spank it too hard, you should be alright. is water jacket still capable of proper cooling? is one cylinder thinner than another? (jacket side). they all look a little knarly on inside water jacket, let worst cylinder be your guide.

[effie_man]

i heard 0.080" was possible but would have cooling issues unless sleaved

[petey shoes]

I suppose with the meat a flatty has, you could, but I wouldn't. just asking for trouble!

[jmadsen]

First off I don't know crap about these engines, (Ok, well I have two now, one is dissasembled but that doesn't mean anything ? LOL) so I couldn't begin to help answer your question but I would maybe ask how much are they corroded, can you determine how much material is gone. and is it in just one small isolated area or a larger area?

Maybe you could find some other engine (flathead) rebuilders or machinest to bounce these questions off as well? I know of two experienced flathead rebuilders here in Salt Lake area.
I am also sure that the first answer you recieve from all of them is "It depends" .......... on this, that, how are you going to drive it, cam upgrade etc ??? Maybe even 3 ring vs 4 ring pistons??
Good luck with it and let us know what you end up doing with it.
Josh

[F6Guy]

the flathead has fairly long rods which the rod ratio is what affects cyclinder side loading. Also a flatttie from 49-53 depending on core shift when the block was cast should be able to take .125 overbore eaisily, .250 over is possible but you will need to have the block sonic tested to make sure the meat is still there after fifty years of having water in it. Three ring pistons are a plus as this will free up some extra HP due to frictional loses an extra ring can cause.

[petey shoes]

i knew they have lots of meat, but i didn't know they had THAT much.

[ssj7kids]

Yeah, I'm not sure they have that much...
My engine guy did do a sonic test but was concerned about pitting.
We are going to go forward with it, and not put sleeves in it. We (mostly he, as I don't have any experience with this) are feeling OK about it.

[effie_man]

i should think its ok, one of my spare motors has a rebuilders tag on it and its says its bored 0.040" over so i wouldnt worry. My rebuild im going 60 if the block turns out ok

[fixnair]

My machine shop just finished my '52 @ .080 over. They said you can go up to .125 over w/o problems. I have just begun a search for engine kits but do not see any with piston sizes over .060. Anyone have any experience here?

[F6Guy]

flathead jack and h&h flathead both sale pistons up to 3 3/8 bore most performance pistons start at 3 5/16 inch. ross pistons even sales 3 11/32 pistons. I was going to put a blower on my truck but have decided to go with a 4 1/4 stroker crank to keep the factory look and have been looking hard at what bore to go with. I really dont want to go more than .060 over myself but that is do to overheating issues when pulling something really heavy. If you wont be pulling anything real heavy .125 shouldnt be a problem but .040 is all the better as it will leave you plenty of room for future rebuilds which will ensure plenty of years of flathead fun!

[petey shoes]

it would appear to me that if you stroke er out as you say, then , wouldn't the torque pull hard enough to get you through any (hard) pulls without overheating?? and wouldn't the horsepower keep you moving once your on the roll without overheating/overworking cooling system?? i agree with your philosophy of .060, it always semed to be the (standard), just wondering if you thought out your hp and torque stats for pulling and working the -beast-? i,m interested in knowing what you produce! pete

[F6Guy]

the more cubes of displacement the more air the engine can take in, in turn making a bigger bang and intraducing more heat into the cooling system from the exhaust. Im trying to get all my parts togeather and if my damn tractor quits giving me fits I might can build my engine next year. All the stroker kits Ive found come with 3 5/16 pistons so I will have to call and see if I can get diff. sized pistons with the kit. plus I have to pull the heads on my spare motor to decide on a bore size. Another thing to consider is i found that speed-o-motive can thermal coat the exhaust ports to decrease the amount of heat intraduced into the cooling system.

[petey shoes]

yup, the weak link in a flatty is the single exhaust port for two cylinders. ever think of putting in a turbo? ceramic coating is a good idea, even on headers.

[havi]

Stock: 3 3/16" I have read that 3 5/16" +.030" is safe. bores out to 3 3/8" provided no core shift during the casting process (would require sonic testing). After cylinder boring the pistons should be .004" piston-to-bore clearance. Ross racing pistons have oversized ones available, atleast for a 4" stroke, not sure about a 4 1/4", though.

edit: after reading all the posts again, I see F6Guy beat me to it, lol.