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CRACKED FLATHEAD BLOCK (2)

Started by tozerco, June 23, 2010, 01:45:30 AM

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tozerco

Thanks to the very helpful advice on this Forum, everything is back on track again with my cracked block.

Yesterday I collected my '37 75 series block from the re-builder ("Pressure tested it, Mate, and the air p----- out of it!") and took it to Metalock. Five minutes, a spray paint/magnaflux test of all cylinders/valve chambers and firm assurances that all can be fixed for about $275!

The crack runs about 3/4 inch down into the exhaust valve chamber, about 1/2 inch across the top of the block between the valve chamber and the cylinder, and down about 1 inch in the wall of the cylinder. The Metalock will attend to the valve chamber and the top of the block and a sleeve will attend to the cylinder liner. The criteria seems to be that the crack is accessible to a drill bit which, in the valve chambers, means that anything more than about 3/4 of an inch to an inch is out of the question.

I would have loved to have taken some photos of the magnaflux process because it was quite extraordinary to see how much it highlighted the crack. I might get the man to repeat the process for me when I collect the block and post them here for everyone's edification!

Likewise, it was very reassuring to see that the same treatment over the rest of the block showed up nothing at all!

While I was there I received another piece of free advice (even though the Metalock guy is also the local Time Sert insert distributor) - drill out those "weathered" head bolt threads and insert new 7/16 Coarse thread Time Serts or you cannot guarantee you will not pull a thread out when the head bolts are torqued up to their final tensions. On close inspection, because the head bolts penetrate the water jacket, over time the water gets into the threads of both the bolts and the block and erodes them. New bolts in eroded threads isn't such a good idea so Time Serts it is. The advice was also not to use helicoils as they are not as good in situations where the bolt will penetrate the water jacket. If you replace one thread on one side of the block, replace all 21 on that side, and use some Loctite on the Time Serts when they are installed to stop the water from entering the thread between the Time Sert and the re-threaded block.

I think there is another post on here somewhere about also applying a non-setting sealant to the ends of the head bolts so they don't rust (and "grow" as a consequence) so that they break off when you next try to remove them.

Finally, and to open another line of discussion, we discussed the installation of stainless steel valves and valve seats to overcome the effects of using unleaded petrol (we are about to go to mandatory unleaded 10% ethanol petrol here next month).

My new "expert's" advice is that it is more important to attend to the treatment of wear surfaces in the valve area than the valve seats. In this regard there is a bronze/copper valve guide "liner" that is pressed into the valve guide before the valve is installed that he claims is the "bee's knees". Anybody have any experience with this?

Finally, having seen the repairs carried out to a huge diesel truck engine block that had blown both faces out of one cylinder (the holes were about 6 inches high and 4 inches wide) and that he has to warrant will handle the extraordinarily high interstate transport mileages these trucks run each year, I am starting to believe that we can repair pretty well anything we can build!


Regards and stay tuned!



John Tozer
#7946

John Tozer
#7946

'37 7513
'37 7533

Steve Lachowetz (No. 25332)

Good for you, I knew that it was going to be repairable.  I was told the same thing about the valves when rebuilding a couple months back, we have been no-lead here for a long time.  Not sure about the sleeve thing, but the next time I am in the shop I'll ask them.

Steve
My58Caddy.com

Steve Lachowetz (25332)

The Tassie Devil(le)

Way to go John,

I had faith in your ability to get it done.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Beege

Hi John

Now you can sell me the tank engine  :)


Beege

tozerco

Beege,

Since I have already got some quotes for the work to the '37, just bring your cheque book! Charmaine doesn't have to know.....

John T
John Tozer
#7946

'37 7513
'37 7533

Beege

Dunlop issues my cheques  ;) I'll be over this weekend...

btw - we should catch up soon.

Beege