Technical 239 flathead aluminum heads question

does any one know what size bolts i need to use on these aluminum heads factory ones not long enough. i dont want to use studs. I know studs are 3'' an 3.25" long but not sure if thats to long of a bolt. Please help Thanks

 

What kind of heads and what engine block do you have? 49 to 53 8-BA or 48 and back.

 

Well, you know how thick your heads are. And you can easily determine the depth of threads in your block, or how far do the stock bolts thread in with the stock heads. Common rule is 1 and 1/2 times the diameter of the bolt for threads. Or maybe a little more for good luck. So you put those numbers together and round off to some normal size and you should be good to go. By using common sense.

 

Flathed Fords have a specific "class of fit". You can't just put any bolt in there and not have them leak. Who made the head? They should know the length required. Then go to Mac VanPelt, Joblot, ARP etc for the specific part. Oh and don't use a tap to clean the threads in the block, they will leak for sure.

 

They are offenhauser heads an I called the place where I got them with no help. Richfox I was going to do that but just wanted some other opinions, good minds think alike thanks

 

Oh its a 239 51 block v8 8ba

 

There are a few places on that block where just a bit to long will bottom out and not hold the head down.

 

I don't know why you wouldn't want to use studs, far superior clamping force on a bi metal engine setup that will have the head walking around as it settles. They're also easier on the block threads which are easy to pull right out of the casting with bolts.

 

Be prepared to torque & retorque & retorque your heads over initial couple hundred miles.......as mentioned, these will walk around on you and need to take a good set........pay attention to correct sequence & settings for torquing .......