Technical Will Offy 400 or 425 heads work for me?

Hi, looking at Offy 400 or 425 heads for an 1950 8BA I'm rebuilding for a future AV8. Engine is bored .060 over with an L-100 cam (.368 lift, 246 duration) and Johnson lifters. Does anyone have experience with either of these heads on a build such as mine? My primary question is will either of these heads work out of the box, with my cam and have enough valve clearance without further machining? I'm planning to use Best graphite head gaskets if that helps.

Anybody with any actual experience with these heads see any potential problems in my plans?

TIA, Tony

 

OK, it looks like no one has used the Offy heads with a L-100 cam. How about the Navarro cylinder heads? Anyone used them on a similar build to mine?

Tony

 

Offenhauser heads are hard to find right now, if you check on Speedway they have a ship date in March. I haven't found anyone with them in stock. I'm using an Offy intake but think I will end up with Eldelbrock heads since I can't find the Offenhauser heads.

 

Post your question over on the Fordbarn. Users such as JWL, Ol'Ron, and others are a wealth of info on combinations like yours, if you dead end here.

 

Thanks hotrodA I did check with the Fordbarn but came up empty. I got several opinions, but no actual experience with either the 400 or 425 heads. I figured for sure someone on this site had put an Offy head on a L-100 equipped motor.

Tony

 

The Offenhauser # (400, 425) indicates valve clearance. So, yeah they'll work right out of the box with your .368 lift. Compression ratio rises as displacement increases. According to their catalog, the listed Compression Ratios are for a non-relieved block. A .060 bore is just about 1/16". taking the compression ratios listed, and doing a little math, the #425 head will give you about 7.75 to 1, and the #400 head will give you about 8.25 to 1. I'd go with the # 400 head...

 

It's a good idea to clay the head/valves to make sure .. Regardless of what they say will work

 

I have the same pieces for one of my flatties on the shelf, so maybe a "I've done that" answer will magically appear.

 

Like they said on the Barn, taking somebodies word that it will work, bolting them on and trying to start the engine is an invitation for bent valves. You have to do some checking yourself or take a big risk in damaging your engine. As Clint Eastwood would say : "Are ya' feelin' lucky, punk? Well are ya?"

Dealing with flatheads does not fall under the "1-800-Credit-Card" philosophy of hotrodding. Sorry to say, if you want it right, you're going to have to put in a little effort.

 

Thanks Sanfordsotherson and Thirtytwo. I'm going to call Offenhauser next week as a last resort and see what advice they can give me. I would definitely clay the piston and valve pocket before calling it done. If I get any information from Offy that is of value I will post a follow-up.

Tony

 

Tubman, I don't have a problem with "putting in a little effort" it's just that I've learned that other peoples experience has saved me a lot of grief in the past. I would never bolt on new heads without claying the piston and valve pockets. I just wanted to know if anyone had done a similar build with this head and had any advice or encountered any problems I might benefit from.

Tony