I'm rebuilding my "51 Flathead 8. I'm not new to engine work, but never this engine. Very tired, nasty sludge in the oil pan, just awful. Anyway, block is good. Small crack between headbolt and water passage at #5-6. Crank is good. As I was tearing down, I measured valve clearance. Ford solid lifters. I found a couple valves with .025 or more clearance. I am guessing the only way clearance could increase is with cam wear. I find .015 difference in cam lobes. Am I correct in this? Replace cam? I don't have a valve stem grinder. Go to adjustable lifters?
Appreciate experienced mechanics's thoughts.

Thanks

 

I've never rebuilt a flathead 8 either, but have done other solid lifter engines. It's most likely cam wear, especially if your oil looks sludgy and lost viscosity and lubrication properties. I read recently that there has been a higher rate of solid lifter camshaft failures in older engines over the last two decades or so, which some attribute to running inferior oil or modern oils with less ZDDP in it. Not sure how much truth there is to it, but if the Flathead is that tired and valve clearance is that far off, I'd assume the cam is due for replacement. If it was me, I wouldn't put an engine back together with that cam, only to have to replace it soon after a rebuild when you can't get the valve clearance to spec.

 

Do you have a machine shop in mind? There's a guy named Phil Miller , north of Montoursville just off of route 87, that does great work. His number is 570-435-5960.

 

Get the entire engine rebuilt, that's a 70 year old motor. Install a new Cam, yes ,.many companies offer adjustable lifters...ie. Speedway . as far as machine work, IF you can find a Flathead Guru left out there, go for it ! A competent machine shop would grind valves for a minimal charge. A motor builder doesn't/shouldn't care whose name is on the Valve Cover, in this case the heads, it's a motor ! So don't get caught up in this nonsense where place want to charge you $8,000.00 for a Flathead build. Any questions, feel free to text me. I rebuilt my '49-53 8BA motor, finned heads, Aluminum Intake, Holley 4v. etc....hooked to Ford AOD trans and ford 8.8 Posi rear. Good luck, do LOTS of research before the build, and have fun !

 

Does your engine have "Rotomatic" spring assemblies, or the 48-50 style? A '51 should have Rotomatics, unless they were changed at some point. If they are Rotomatics, .025" clearance is only about .007" too wide on the exhausts. In a flathead, carbon or lead buildup on the valve heads or block seats will increase the clearance. Have you removed the valve assemblies yet?

Was this engine running recently? or was it locked up? If any of the valves were sticking (varnished in place), and the engine was turned, the tops of the lifters could have been damaged, which also increases the clearance.

While I wouldn't say flathead cams never wear out, they aren't known for doing that. Easy enough to check by measuring across the base circle and the top of the lobe, and subtracting the base circle measurement.

I would also not go strictly by visual examination for cracks. Dye penetrant or mag particle testing is the minimum, pressure checking is the most rigorous (and more $$$).

I wouldn't buy adjustable lifters from Speedway, their quality is very suspect. Sealed Power or Johnson Adjustables from Red's Headers are the originals and still the best. Too many reports of others having inadequately hardened faces and inability for the adjusting screw to hold a setting. https://reds-headers.net/index.php?m...af7e9fb3afc445
That said, if your machine shop is experienced in grinding Flat V8's valves to set clearance, that is ideal. The stock lifters are a beautiful design, very lightweight, and run quietly.

 

Maybe it's just me, but whether they are known for wear or not, I would not spend the time and money rebuilding an engine to reuse a 70 year old cam. Just my 2 cents

 

Lots of good replies.
Albuq, engine hasn't run in over 20 years, maybe 40. I never heard it run. I got the "It was running when we parked it" story. It would turn with a bar. Easily, no hard spots. All the valves seemed to seat on the block with no carbon to hold them off. And, yes, Rotomatic style. The valves looked good, no burnt ones.
I measured the highest point on all the cam lobes. I found the highest was .015 taller than the lowest. I am assuming the exhaust and intake have the same lift. I lost track of which was which, so just measured them all. I am thinking that is too much wear and should be replaced. I don't have a problem with solid lifters, but if the valve stems are somewhat worn, can the train be made right again without replacing all the valves? I guess that is the real question I have.
I do have a budget.. The copilot/treasurer says $2,000 is not out of line. 3 pistons are shot from broken rings. A couple more look to have wear in the ring grooves. If I buy 8 pistons, might as well be .020 over and the heads need to be checked to -.010 And a "modern" cam
If I can reuse the valves, guides, and lifters, I would do that and save a few bucks for the T5 I have planned.
Abe, thanks for the suggestion of the machine shop. The guy near me does $30,000 race engines and I understand he is very good. I just don't think he would do a "repair to serviceable" job. He is used to blueprinting things.

 

The cam can be reground. There are a few members of the Ford Barn forum that do just that. It can be used as a core so even if you don't want it, other Flathead guys can use it. Check out the Ford Barn. Lots of info there. Many members of this forum over there as well. I'm not saying you can't get it here. But, there is a TON of experience and info there. Worth a look.


Getting rid of the stock Loadamatic distributor is a good idea unless you are staying completely stock. It only works with the stock carburetor. Even then, you will be better off with another distributor. Rebuilding your stock oil pump is better than some of the new replacements. Assuming your pump can be rebuilt. Do some searching about the best gaskets and parts to get and what to avoid. The Flathead experts will save you time and money.

 

Most likely you can reuse the same valves, get a valve job done just like any other motor, bore it, REPLACE guides, most Flatheads I've ever seen, the guides are worn beyond repair. $2,000.00 for machine work, sounds good, does that include Pistons and Rings and assembly, hot tanking block, milling heads ???? As mentioned earlier, MAKE SURE the block is usable b4 spending any $$$$$$$. Best of luck.

 

I agree with Scotty, the Ford Barn is an excellent source for in-depth flathead knowledge, do some reading on there.

If you replace or grind your cam, don't go too far from stock. Trucks need torque (Model A's that weigh 2500#, not so much), a wild cam can kill torque down low. My local shop will regrind stock cams to the Isky MAX profile, others can grind it to the '51-'52 Merc specs (a very good torque profile), or as Scotty mentioned the L-100 profile by "Kiwi" on Ford Barn.

Almost everyone goes straight to +.030" on bores, or even +.060". The cylinder walls should be checked for thickness before boring, but bigger bore = more c.i. + higher compression, and most blocks have plenty of meat. Cost is the same, so why not?

I don't see $2k covering even a budget rebuild plus a T5 conversion, to be honest. All said and done, a T5 setup will come in close to a grand, depending how much the trans costs you and how much of the fab work you do.

What truck do you have, an F-1 or larger?

 

Just an FYI, if you replace or regrind the cam, you must install new lifters. Old lifters on a new or reground cam will ruin the cam lobes. When regrinding, there are only a few things that can be modified. Things like intake centerline and lobe separation angle cannot be changed. Basically, there are many limitations when regrinding a cam to create something different.

 

I checked with the machine shop Abe recommended. They are finishing up the circle track racers' work, but will slow down in a month or so. He will hot tank, magnaflux, bore, grind valves and fit my valves to my new camshaft. Also mill the heads for $750. Sounds like a deal to me. I will send him the cam and a sample piston. Or maybe all the pistons and rods. Then it is all done at once.
I hope to have $2,000 in the engine. The trans is the next step, when this is done.
Scotty, good information on the distributor. That is the kind of thing I need to hear. Might as well put in a good one from the start, not have to change later. Why do you say the original works with the original carb, even if only poorly?
I intend to update the cam, but not for high revs where the book says the power is. I'm a low end driver, not a high revver. Near to stock is what I will want.
I'm putting this in my 51 F1 as a driver. I want it reliable, but realistically, not a lot of miles.

 

Phil does good work and is reasonable. He planed one of the heads I bought from Dennis, Pinto Plumber. It was leaking at the rear. He also later planed my left side exhaust manifold because I had an exhaust leak I couldn't stop.

 

That place. About 10 mins from my house specializes in flatheads.....in strasburg pa.......schwans...a lot of people use him.....

 

What book says flathead power is at high revs? Unless they are drastically ported, they are out of breath by 4000 RPM or less. A stock EAB Ford or 1CM Merc cam was the best the factory could do

This is the dyno of a stock 8BA