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EFV-8 Club Forum / General Ford Discussion / Maximum Bore Size

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Posted By Discussion Topic: Maximum Bore Size     coupeman 04-06-2010 @ 9:08 PM reply profile send p.m. Member Posts: 62 Joined: Oct 2009 THANKS FOR ALL THE ADVICE, SINCE THIS IS NOT A FREEWAY FLYER I WILL STICK WITH 6 VOLT AND MY CANNISTER OIL FILTER SYSTEM. Stroker 04-03-2010 @ 4:11 PM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 Richard: You are quite right, as the 8BA-style motor first appeared as a truck engine. Except for my comment regarding full-floating bearings, I'll stand by my comments on cylinder bore, electrical systems & oil filters. 51f1 04-03-2010 @ 3:37 PM reply profile send p.m. Senior Posts: 573 Joined: Oct 2009 A '48 car engine or a '48 truck engine? They're different. Richard Stroker 04-03-2010 @ 3:37 PM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 coupeman: By the way, do you pronounce your username as "KOOP-man", or "Koo-PAY-man"? Just kidding, I forgot to address your full-flow filter question. From what I have been able to gather, (mainly from this forum), there are a couple of "full-flow" options. Neither one, IMHO are worth the effort, given the fact that our "motors" (technically engines), are not being run under the same conditions as modern motors are. I believe in filters, but these old Ford motors are pretty tolerant of debris. The whole idea of the "full-floating" rod bearing was to allow for the possibility that one bearing surface might become contaminated enough to prevent rotation, and offered another bearing surface to supplant it in that unlikely case. Similarly, the crank contains "sludge traps", which probably lost some usefulness when dispersant oils (detergent oils) became commonplace. Unless you are planning to install a 3.54:1 axle, reduce all the internal running clearances and cruise across the Nation on Interstates at a constant and mind numbing 75 mph, I don't believe there is any need for full-flow system. If you do opt to go that route, make sure all 3-mains are supplied with filtered oil. As TomO stated; frequent oil changes are probably the best alternative. We used to say that "Oil is cheap; Parts are expensive", but given the current price of good oils, that's probably not as much of a "truism" as it once was. BUT IT'S STILL TRUE! Stroker 04-03-2010 @ 2:22 PM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 coupeman: I think TomO's answer is spot-on in my opinion. I think we tend to think of 12-volts as some better solution to a historical problem. IMHO, the "problem" was the price of copper during the Korean War. 12 volt systems allowed for much lighter wiring, and an exponential decrease in the amount of copper consumed in auto production. This same reasoning is why most general aviation applications are 24 volts, only in this case it is to save weight. I believe that in the future, you will see 36 or 72 volt systems in non-hybrid automotive applications, just because the components can be so much smaller, cheaper and lighter. TomO 04-03-2010 @ 12:25 PM reply profile send p.m. Senior Posts: 7256 Joined: Oct 2009 IMHO 12 volt conversion is a waste of money unless you are adding air conditioning. Your car will start and run fine with a 6 volt system, you can buy a 6-12v converter for your radio / CD player for a lot less than the generator conversion to 12 v will cost and properly aimed 6 v sealed beams with good wiring will light the road just as good as the 12 v sealed beams. A full flow oil filter setup is not necessary with frequent oil changes. If your car is not a daily driver, frequent changes are better for the engine than a better filtering system. Filters only remove the solids, your engine has more blow-by and gas leakage too contaminate the oil than current engines. Tom coupeman 04-03-2010 @ 12:00 PM reply profile send p.m. Member Posts: 62 Joined: Oct 2009 Thanks for the info guys I will procede to the crank inspection. Stroker an additional question for you, what is your advice on converting to 12 volts and adding a full flow oil setup? supereal 04-03-2010 @ 7:27 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Dan is right on. If you bore beyond .060 oversize, you will have to order special (expensive) pistons. The best way to get more power out of a flathead is to increase the stroke with a 4" Mercury crank and associated parts. As you mention a "low end knock", you may need a replacement crank, anyway, if the journals are damaged. Stroker 04-02-2010 @ 2:09 PM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 You should be good for a number of over-bores. Hot Rodders in the 40's, and 50's routinely bored their 59A blocks out to 3.375 inches. This overbore combined with a .375 stroke on a 49-53 crank, would net a 296 inch motor. So, in theory, you have a LOT of room to grow. Occasionally, foundry core shifts would throw a monkey-wrench in this scheme however, so given the growing rarity of usable 59A blocks, I wouldn't consider boring it any larger than was necessary to clean up a bore condition problem. In the "good old days", we simply went back to the junk yard for another block. This is no longer a viable option. Big engines were built to exploit a "competitive advantage" performance-wise. Most of us now days just want a nice turn-key "driver". coupeman 04-02-2010 @ 12:18 PM reply profile send p.m. Member Posts: 62 Joined: Oct 2009 During the teardown of my engine(1948 Flathead V-8) I check the bore size of the pistons at the top of the cylinder( no ridges) with calipers and they all measured between 3.260 and 3.270, it appears the pistons are new and the walls are smooth. I did not pull the pistons yet to check ring wear, may not have to considering the appearance of the bores. My question is "what is the maximum bore size for this engine?". Can it be sleeved if it is maxed out or should it be replaced. The reason for the teardown is because the engine developed a low end knock, I am going to check the crank mains next.

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