What should I do to verify Flathead rebuild

What’s the minimum amount of inspection you would do to tell whether a motor has been rebuilt or not?

I’m going to look a flathead this weekend that was supposedly rebuilt a few years ago but was never started. What’s the quickest or easiest way to tell if the motor was actually rebuilt or not? I would think the best way to tell would be to pull a head or the pan but than can be a PITA. The engine is sitting on the pan and the owner doesn’t have a lift. Would you go ahead and pull a head or can I get a good idea from just removing the intake and inspecting the lifter valley?


Thanks<O</O

 

Well if your spending a few bucks on the motor it wouldn't hurt to spend a few more on the head gaskets and intake gasket, I would defintley pull a head and look at the top of the cylinder to see if there's much of an edge and also see if the cylinder walls look like they were honed by the cross hatch, if you remove the intake see if it has adjustable lifters and or if the block has been drilled for lifter adjustment.....that would just be an added bonus. Lastly just ask lots of questions.....oil pump, new or rebuilt, bearings new ? how far was it bored? how far was the crank cut? Good luck with it.

 

After verifying clean, verify that it turns and that you feel regular episodes of compression resistance while wrenching it over...if no plugs, put tape over holes and it will blow off the tape "Phffft!" as each piston comes up on comp. It is common for valves to rust open and bearing journals to rust if engine was not adequately slathered with thick assembly goo. These problems will quite possibly be MUCH less serious than needing a real re-rebuild, but for bargaining purposes the rebuild should be considered kaput if crank won't rotate. Stuck valves should be considered "needs another valve job $$$" until inspection reveals easier fix. If you can read the rod forging numbers without removing pan, this is generally a BAD sign...

 

I would pull one head for sure, cylinder walls should be clean and smooth, pistons and valves should looks new, check pistons for size stamped on top, i.e. .040 over.

Good luck,
Rich

 

if its not bolted in something see if the seller is willing to have a local machine shop take a peak. in the 80's i worked for a engine remanufacturing co. and we were rebuilding 128 motors a day. they were going to outsource the 4 cyl line because we were so busy anyway the supplier sent a sample rebuilt motor, first time i had ever seen a "glass beaded camshaft" reciepts and being able to talk to the rebuilder helps. even newly rebuilt motors can have problems and i learned from getting burned on "good deals" quickly. do you know anyone with flathead knowledge you can take with? good luck

 

It kind of comes down to what are they representing the motor as . . . and what you're paying for it. If you're paying a serious price (as far as I'm concerned, anything over $500), then do your homework and propose the following:

a) I'd like to pull the heads and inspect the pistons and bores. If they are willing to pull them before you get there . . . all the better.

Take some lacquer thinner and a rag and clean the areas between the valves and the bore. Bring a magnifying glass and inspect to see if you see any cracks in this area. Cracks are bad - and sometimes "good motors" have them.​

b) I'd pull at least one rod cap and a main bearing cap -- to see what shape the crank is in.

c) Inspect the valley area -- is pretty obvious if it has been run.

You can always offer to bring another set of head gaskets or maybe pay $100 to inspect and have the option to turn the deal down.

Last year I bought a motor that was supposed to be recently rebuilt and the guy had his Grandfather (flathead expert) check it out before he sold it. It was pronounced a great engine. Now I only spent $400 on it, but when I got it home and pulled the heads -- two BIG cracks between the valves and cylinders. I asked the guy for 1/2 my money back - he agreed . . . never saw the money. It wasn't a lot of money, but the point is that I should have done what I recommended you do -- would have never bought the motor if I had. I knew better than to not check it out . . . was just lazy and I burned myself.

Hope this helps . . . Dale

 

If the guy won't let you take a head off, get a hold of one of those fiber optic bore scope to look in a spark plug hole.

 

Thanks for all the advice.

The heads are coming off or no deal sounds like the smart thing to do here. If it's really been rebuilt and not run, they shouldn't be stuck on the block too bad.

 

"If the guy won't let you take a head off..." Well, depending on what I could see and feel I might or might not want to pull a head...but if he won't LET you, the engine is officially cracked and not rebuilt and and barely worth $50 for the visible parts...
A rebuilt engine that has been sitting and is of course no longer guaranteed by a rebuilder is a pig in a poke...if it can't be examined, it isn't even a pig!

 

Yeah, a lot depends on how well oiled it was during assembly,and the moisture level where it was stored. Nothing seizes up tighter than a brand new engine left to the elements.

 

That's funny. Now that you mention it, I can't think of many flatheads for sale that haven't been claimed to be rebuilt. One that really sticks out in my mind had sunk into the dirt floor of an old guy's garage. Most of the pan wasn't even visible and one water pump was completely buried. But he told me he wanted $500 for it because it was rebuilt. Good luck with yours.

 

Would you believe i visited an army dump store where the guy had six "rebuilt flatheads" laying under a tarp and next to a small creek . The cast iron headers had just about rotted off. These engines had been laying there for at least 20 years.

 

You can do that when they are rebuilt though,you know.They'll be perpetually frozen in time.....and internally.

 

The obvious external tell-tales are soot/carbon in the exhaust, possible burnt paint near exhaust. Look in the plug holes - if it ever ran, it will have carbon on the valves & deck that you'll be able to see.

Pull the intake - may/may not be able to tell anything useful here, but odds are that w/o adjustable lifters, it probably hasn't been rebuilt. Now, a few folks do rebuild with OE lifters & the ancient, but acceptable, weld, grind, test valve adjustment technique with OE non-adjustable lifters.

Those just give you a clue if it's been not-started since rebuilt - many rebuilt engines are rebuilt with cracks out of ignorance alone. If you're paying anything for it, I'd pull a head.

 

If I were selling a rebuilt Flattie I would pull the heads as a matter of course to show prospective buyers.
Bieng able to show the clean bores no cracks is the best way to get good money.
If he doesn't want to pull the heads assume something to hide. Could be expensive scrap.
Rich

 

Another good tip.....does he have receipts from the machine shop? I saved the entire bill on my last motor and asked the shop to detail the work on the bill, just in case I did decide to sell the finished motor. Plus, it's a good way to remember all the pertinent details (is: bore oversize, crank journal undersize, etc). If the motor was "rebuilt" by a friend or the guy himself, you should assume that it probably received nothing more than a set of rings, bearings, and a valve job. There is SO much more to a proper rebuild that most average mechanics don't bother with.

The BEST advice you received was to pull the heads....BOTH, and have a good look. The possibility of cracks between a water jacket hole and a head bolt/stud hole is common and not to worry. The cracks that run into valve seats or cylinders are the expensive kind. Rotate the crank and have a look at the cylinders for a nice shiny cross hatch hone. Check the top of each cylinder with your fingernail for a lip. There should be NO lip or edge there if properly rebuilt. All valves should open and close when the crank is rotated. With the manifold off you can look for evidence of previous running. A rebuilt motor should be clean as a whistle in this area....aside from clean oil of course. The rest of the motor is more or less a crap-shoot, unless he has receipts showing a block mag test for other cracks. New pistons will be clean on top and should have the oversize stamped into the top (ie 30...or 030 which indicates .030" oversize).

If you have any doubts after checking for these things....walk away...or make an offer that reflects the purchase of a motor THAT NEEDS TO BE REBUILT! Good luck..... Mac VP