I am new to the flathead stuff so bare with me. I hear of releaving the block for the valves, My question is if they have a habbit about cracking between the cyl and the valve seat already and then you machine it out and make it thinner does that make it crack easier? how much can you take off the block to releave them? What is a good cam for this engine I hope to put a T-5 behind it and would like a pretty healty sounding cam. Is there any later model valves that will work to make a bigger valve dia? I'm building a big bore engine with a merc crank and I have a set of edmounds heads.
relieving the block is only effective with certain heads, with some aftermarket heads it can make your flow worse. relieving tends to work well with stock heads mainly 8ba or merc heads. Mostly you are not going to buy a new cam but regrind the old one if it is in good shape. Tom Sparks recomends a isky 400 jr grind. also a lot of rebuiders use chevy valves cause they got a little more meat to them. I guess? I do't know if I'd do that, kinda bad karma putt'in chevy valves in a ford. Next thing you know you'll want to put a sbc in a duece Also you can go 3-3/8 bore on a flatty but if you are worried about cracking keep it at 3-5/16
You should get some good answers on this, but arm yourself with some book knowledge first. Nothing beats well-written tech with pretty pictures. A few books I'd recommend are: Tex Simth's The Complete Ford Flathead V8 - Ron Ceridono Flathead Fever & Street Flathead - Mike Davidson Ford Flathead V-8 Builder's Handbook - Frank Oddo Blown Flathead - Joe Abbin (even if not building a blower engine - it's worth it for the flow data) How to Build a Flathead Ford V8 - George McNicholl (relatively new, but good for the beginner) Now for your questions - I don't believe relieving the block makes it any more prone to crack in the valve area. Most reliefs are between .080-.125" depending on your particular head shape & whose theories you subscribe to (lots of variation here). Cams are another personal choice. For readily available, off-the-shelf cams, the Isky 400 Jr is a good street grind. However, excellent grinds can be had from Schnieder, Litterio, and others. You can, and probably should for a big bore/stroker, use 1.6" SBC valves on the intake side at least. You'll be able to use the Ford spring retainers, but you'll probably have to shim the springs. The SBC valves are a bit longer, but you can trim the ends. I suggest****embling it all first & checking if you have enough adjustment on your lifters to allow running them. I've found most reground cams lower the base circle enough it isn't even a factor. I've not heard of a single person unhappy with a T5 conversion. If you use the S10 T5, you'll want to run a high (low numerically) gear ratio as the S10 first gear is quite low (esp 4-cyl models). Otherwise, find a world class Mustang/Camaro T5 & use the S10 tailshaft & top cover for shifter placement. You can adapt an early shift lever to the T5 shifter. Keep the questions coming - there are plenty of folks on here who have forgotten a lot more about flatheads than I know, so you're sure to get some good responses.
Dont foget Ron Hollerman book Nostalga,read them all also Rumbleseats tips on the 32 to 53 message board.
Ernie pretty much hit the high points. In addition to flow data Abbins book goes into how and where to port and relieve. Porting is a very important step especially if running a big engine. My cam choice is Schneider, they have the widest selection; most are not on their web site, call and talk to the tech guys. I hear the Litterio L-100 is a good cam but havent sat behind one. Isky wants you to run their springs and they havent updated anything in decades. Current thinking is that stock springs are plenty for the street; always follow the manufacturers advise. Chevy 1.5" or 1.6" valves (about .1" longer than Ford) are used for cost and they can be used with Johnsons and a smaller base circle cam. Use the 1.6" on the intakes only if you feel the need. The vehicle often prescribes what you want to do to the engine. A light weight AV8 that may see some strip action wants that little bit extra. A fat fendered sled or pickup is more interested in just getting the mass moving and be a respectable performer in modern traffic.
[ QUOTE ] Dont foget Ron Hollerman book Nostalga [/ QUOTE ] Sadly, Ron's book is out of print...anyone got an extra copy?
If your going to use your motor on the street, I would suggest just smoothing out the the beveled edges of the valve pockets that lead toward the cylinder. You may want make a slight radius from the deck into the cylinder, making sure you don't go past the gasket line. I'm using a full relief, but this is for a dragster motor. In racing there are just two speeds....stop and haul****.
Does that info hold true for flatheads other than Fords, ie Hudsons or Studebakers? Will relieving harm flow with an aftermarket head, like a Weiand? What kinda lift #'s would you wanna look for? I am just gathering info for a future project. Jay
[ QUOTE ] Does that info hold true for flatheads other than Fords, ie Hudsons or Studebakers? Jay [/ QUOTE ] I was looking at a friends Hudson 308 cu in flathead yesterday. It has a beautiful factory relief. He's got it in a 1929 Essex roadster highboy. It's going to be a neat rod when it's finsihed.
[ QUOTE ] Does that info hold true for flatheads other than Fords, ie Hudsons or Studebakers? [/ QUOTE ] As a gross generalization, yes. Obviously, each engine varies somewhat & without flow testing, you're really shooting in the dark. There are so many variables - the Flathead Ford intake makes darn near 180* turn from the intake to the cylinder & that affects how the cylinder is relieved & what works where & why. Flathead Harleys like a stepped relief mostly due to the fact their valves are not flat & parallel like a Ford, rather they're angled. The WRs were angled even more than WLs. Additionally, the intake charge makes something more like a 100* turn coming into the cylinder. Cleaning & smoothing are good things, but radical relieving and/or porting is probably best left to someone with a flow bench...unless you've got something to go by, of course (like 72 years of flathead Ford experience written down in books - or Harley Davidson factory racing pamphlets on how to prepare race engines).
Here is a shot of the 308 installed in the Essex mock-up. He found a 2 carb manifold this weekend and is working on splitting the exhaust manifold. Not sure if it's the 7X or not.
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