Mercury Block - Is it Too Far Gone?

Low-Blow

Low-Blow

Senior Member
I acquired this block from an older gentleman just down the road from me. It had a stuck piston, which I was able to get out. He had left it out under a shed, and it was rained in no telling how many times. The cam is stuck, the lifters look like they are now part of the block, and it has several stuck valves. Before I invest any more time in it, I wanted to know if it is even worth messing with. Your input is greatly appreciated. Thank you!!
 

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anything is savable, but putting too much energy/time in this block in my opion would be a waste of these. Make a nice grill/planter/boat anchor
 
alanwoodieman said:
anything is savable, but putting too much energy/time in this block in my opion would be a waste of these. Make a nice grill/planter/boat anchor
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Thanks! A big plus out of the deal is that the gentleman thought enough about the crankshaft to put it inside his garage. It now resides in my freshly built 8BA!!
 
Man, this part of it is only about two short steps shy of completing the full cycle back to pure dirt. DD


434533
 
even seeing the lifter picture (the remains of the lifter most likely protect the lifter bore in the block)it still looks salvageable, perhaps a little bit of a problem to take apart--I would start by looking for valve seat cracks --though since the crankshaft is out if the inserts are also out the main bearing bores would probably be damaged, but even that could be fixed with oversized bore inserts
 
My experiences with weathered engines have all ended with water jacket cracks. The rain enters through the head gasket holes, collects in the water jacket then freezes. Does it ever get below freezing where you are? Check inside and outside the oil pan rail before you put a lot of effort into more disassembly.
 
Below zero?
Where I have lived blocks with water in them freeze at anything from 32f and colder.
The last 3 8ba blocks I bought had foot long cracks in the water jacket.
The one I got for free was left outside at Santa Cruise, CA.
 
Oops, sorry Yo-yo.
I thought I read “does it ever get below zero?” When you correctly said “below freezing.”
You know how those old guys are. Sorry.
 
7QERWRP.jpg


It feels good not to be alone ...Im fabbing pressure test plates,its the first move I'll make to be sure its worth the effort.Ill write off the labor to tear it down.
 
The only true Mercury blocks were the ones made from 1939 up into the war years. The post war blocks of the 59 family and the 8BA family all use the same block. I'd pitch that turd. Just getting the cam out is going to be a major undertaking so any signs of cracks or corrosion through water jackets will kill that one. There are still a lot better blocks out there.
 
rotorwrench said:
The only true Mercury blocks were the ones made from 1939 up into the war years. The post war blocks of the 59 family and the 8BA family all use the same block. I'd pitch that turd. Just getting the cam out is going to be a major undertaking so any signs of cracks or corrosion through water jackets will kill that one. There are still a lot better blocks out there.
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And, would a "true" (pre-war) Mercury block be any better than a 59 series block? I believe all dimensions are the same between the two except for the valve angle difference.
 
rotorwrench said:
The only true Mercury blocks were the ones made from 1939 up into the war years. The post war blocks of the 59 family and the 8BA family all use the same block. I'd pitch that turd. Just getting the cam out is going to be a major undertaking so any signs of cracks or corrosion through water jackets will kill that one. There are still a lot better blocks out there.
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39 was the "war years" where I come from. I have a relieved 99A block which I believe is Canadian I filled with grease many years ago which is sitting under a tarp at my sisters place - retirement project is to rebuild it.

GB
 
There is a block in the sea not far from my house, it’s 1000 times worse than anything that wou would find on land
 
The early mercury blocks (99A and USA made) had thicker cylinder walls than the later 239 blocks so a lot of folks used them for big bore & stroker hot rod engines. After they changed the blocks in 1941 (largely due to the war effort), they were likely similar in thickness to the later 59 series. I wouldn't say the early ones were much better due to that but they were different and safer to bore large. The post war blocks likely cooled better if they had the 59AB heads. The 8BA block cools a lot better due to the later deck configuration.

When the Mercury 255 crank came out in 1949, then that was a change worth mentioning. More cubes always relates to more power and that allowed for a lot of changes in all the flathead engines that the crank could be made to fit into.

The Canadian 99A engines may be different than the USA ones. I don't have any info on them other than they actually had a 99 casting mark. Canada did a lot of things a little different than the guys across the Detroit River did. The engines that were relieved were generally truck engines since the 95 HP engine was an option in larger trucks.
 
Yes the "99" marking is there near the front of the block, I forget what side but it is just down from the intake plane. Could the Canadian ones have been used in Bren gun carriers, we had a few of these military vehicle here in NZ?

Gb
 
Most Universal carriers had the 221 engines. The longer T-16 version had the 239 block but I'm not sure if any were manufactured in Canada or not. Most were made at the Rouge plant in the US.
 
To the OP, I'd think if a guy really wanted to he could cut, chip, dissolve all the crud and internal parts out of this block in prep for lots of crack testing and probable sleeves. But, the killer is the central oil tube. Is it rusted through? Don't know how to fix those.
 
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