Flathead Question

I recently bought a 59ab flathead, came with a complete frame to a 48 Merc. To my surprise the engine has adjustable lifters and appears to have an aggressive cam. I have done a search but cannot find the info, what does the valve lash need to be set at with adjsutable lifters? They are the johnson adjustables as far as I can tell. Not sure what the cam is. I really don't want to take the motor down as it still has the cross hatch in the cylinder walls! I could check the lift of the cam if that would be of any help.
Thanks in advance.

 

I'm pretty sure it depends on the cam, my isky 400 is .018" for both intake and exhaust.

 

Frizi
Pull the distributor and look at the front of the cam. Good chance that there will be numbers/letters, etc. on the front of the cam. With that info, someone will be able to tell you about the cam and the clearance specs.
Jim

 

Sounded like a reasonable decision, but there are no markings on the face of the cam. Any other ideas?

 

I worked for a flathead guru last summer. He said he ran .014" intake and .012" exhaust on everything. Had something to do with air flow regulation.

 

Mine are lashed at .016 for both. It's a 59AB also and has a plate with the lash specs rivited to the block along with the bore and crank journal sizes.

Cliff Ramsdell

 

Many of the engines were factory authorized rebuilds in which case they always used adjustable lifters. Does it have a tag fastened to the bell area? Most stock cams use .012" and .014" or there-abouts. I use .016 on my L-100 You can use a dail indicator to measure valve lift and add lash. That will give you an idea of what you have.

 

I am pretty sure that it is not a factory rebuild as it has a 4" crank and has also been ported and polished. There is also no tag on the bell. I can check what the valves are currently set at, maybe I will get lucky and have a couple of cylinders which the valves are set to the same lash.

 

Measuring the current lash is a great start. I would go with the most common intake and exhaust setting and use that. Unless you want to pull the cam and have it profiled to determine the make and grind to be sure of the lash specs, what your doing should get it running fine.

A lot of the aftermarket cams have different lash settings. These play into the actual curve of the cam, so unless you have it exact it will run good, but not perfect.