A good friend has a like new set of uncut offy 375 flathead heads. I can get them for a really good price. Does anyone know what those heads put on a .060 over ford 239 flathead would yield compression wise? I can also get a good used 400 jr cam from him too. Would this cam or heads be too much for an otherwise stock rebuilt flathead in a fatfender car? I really like the looks of the heads, but think the cam may sound too racy and lose that great low lope of a flathead. I am considering gegrinding my original cam to 3/4 specs if it would be better suited. I already have a set of Johnson hollow adjustables and would just need valve springs to install a bigger cam. Any ideas? Thx Matt
You will probably end up with a little over 9:1 c. r. The 400 jr is definetly too much for that engine and the valves would never clear the head.
The lift on the 400jr is 0.400". The heads are clearanced @ 0.375". As flatjack says the only way these heads will work with the 400 jr. is if you relieve the valve pockets in the heads. Releiving them will also lower the compression ratio a bit. Jim
Can I use the heads w/ out a cam change and be ok? I am already putting on a 2 or 3 carb intake and probably headers. Will this be too much compression for a mild flathead? Do they make thicker head gaskets for flatheads like they do for sbc's to lower the compression any? Matt
You can use them with the stock cam with little problem. Dual 97's or 94's would probably be better than triples without a cam change. Headers will also help. Don't know why you'd want to lower the compession anyway. Jim
Wasn't sure if it would be too high with stock style pistons/ rings. Also it is still using a draft tube, so I was concerned about blowby. I figured the big cam would bleed off some compression. Is a super dual intake going to make a drastic improvement over a regular dual in terms of performance? I'm looking at either a offy regular dual or a sharp super. Matt
46 Stright out of the Offy catalog (curtesy of Exeter Auto Supply CA. web site), the 375's on a stock bore are at 7.9:1 cr. Quick calc's based on this number make the 0.060 over bore come out at 8.16:1 cr. Just remember factory cr is around 6.8:1. Regards
Can I use the offy 375 heads if I use a milder cam? Also what comp ratio would I have with EAB heads that were milled? Could I then use the 400 jr cam? I'm going with a regular offy dual w/ 2 94's and a set of red's headers too. the engine in question is in a 46 business coupe with stock 3spd and 3:78 gearing. would the 400 jr move the rpm's up too high? Basically what I'm saying is smaller cam and more compression or bigger cam and a little lower compression. which is going to be better in this car? I really like the sound of a flatty w/ a little lope, but want to be able to enjoy it. Any ideas? Thanks Matt
I'm leaning towards milled EAB heads and a Schneider 3/4 grind. will this combination be good in my otherwise stock 248 w/ 2 carbs and headers? Thanks Matt
Yes, the engine is in my 46 coupe. It just looks like a 42, because of the old aftermarket grill. thx Matt
EAB heads on 060. over ford 239 = what comp ratio? Would like to get around 8-8.5 :1 ratio. Will this ratio be obtainable with these heads? How much milling? Can I use a 400 jr cam with these heads? Is higher compression, less cam lift/duration better for this combo? Or is lower comp with more lift/duration better. Engine is a .060 over ford w/ 2x2's and headers,otherwise stock in a 46 ford coupe w/ 3spd and 3:78 gears. thx Matt
The Jalopy Journal
