merc crank and other questions

ole39

ole39

Senior Member
i recently scored a merc crank, it has been turned but the seller didn't know how much and it's going to need a cleanup. what is the max a crank can be turned? this is going to be a cruiser, not a race car.
where is a good place to get rings and bearings?
i am going to use a 49 merc cam,used of course. I've been told not to use new lifters, I do have a set of lightly used adjustables, is this ok, if not, what?
good place to get water pumps?
i will leave you with a bit of humor, the greatest torture device known to man is the trouble light. it never shines where you want it, its always in your eyes, and always snags on the tiniest things. just my observations, thanks and have a good day
 
Max undersize on the crankshaft journals will be dictated by the bearings you can find. Both Third Gen Auto and Van Pelt list main and rod bearings from standard to 0.040 undersize. I have heard of no problems with durability going to that undersize (the hot rodders used to grind the rod journals down .140 as part of offseting for more stroke).


Get rings and bearings from your favorite flathead vendor. I currently like Third Gen Auto, Van Pelt, and C&G. Others here have great results with other vendors.


I like new reproduction water pumps with sealed bearings and ceramic seals. The only place I have purchased these from is Speedway Motors, but other vendors sell them too.
 
Find some shop that cam at least bore this type of engine and fit the pistons, also do a valve job. Remember the application of the engine will determine the cam carb and ignition. Keep it simple @!$$$$$$$$
Gramps
 
hi Ron, yup, going to keep it simple. new valve train and seats, its already 3.5/16, 49 merc cam and a regular dual with 94"s. been told not to use new lifters. have a lightly used set of adjustables, your thoughts?
 
You have a used cam . . . it was broke in with its original lifters - which is what it should be ran with. Nobody can claim to know that your used cam will last with whatever used lifters you have - they are not a "matched set". So, it is a crap shoot at best.

If it was mine, I'd have 'Pete1' or Kiwi Tony regrind the camshaft and then run new lifters. The best way to do it is with NOS original lifters (non-adjustable) and have somebody who knows what they are doing setup the valve clearances as such. You can probably get NOS stock lifters from a couple different sources.

You'll have zero issues with stock lifters (when setup correctly) - they will not lose adjustment - which so many of the repop adjustables do today.
 
When I had the 8ba rebuilt that's in my '39 p/u I had a good set of used Johnson adjustable lifters that I wanted to use. The cam that was in the engine was iffy according to the machinist. I had an unknown used cam that I got with some other Merc parts that that was in better shape. Long story short I used the "Merc" cam with the Johnson lifters and everything worked out just fine. Maybe I just got lucky but the rebuild runs like a top. But then its just in an old beater truck. Your results may vary.
 
flatjack9 said:
With the low spring pressure in a flathead, I would not be afraid to do as you are planning.
Click to expand...




Nor would I. In fact, 20,000 miles ago I put a used 8CM Merc cam and stock original tappets in my '41 Merc (with "8BA style" engine). With 40-50 lbs seat pressure and less than 100 lb open these things are very low stress. My 2 cents.


Terry
 
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