french block exhaust studs/bolts

[offy19]

I just fired up my 1988 French block flathead (4-71 blower) 3-3/8 x 4-1/4. it sounds wicked (400jr cam). Everything was going good until I noticed water dripping from the header bolts. I probably should have left the studs in the block but I don't like metrics. I forgot that the exhaust bolts enter the water jacket on these blocks. Has anyone found a good way to seal the bolts.

[34PKUP]

Seal them the same way you would seal the studs.

[Mart]

You could use sae studs and seal them in. Saves having to drain the block when changing the exhausts. I kept the metric studs on mine but ran a 3/8 UNF die down them and use 3/8-24 UNF nuts. Not strictly correct, but works well enough, even holding the complete motor on the engine stand. To be honest, I found it difficult to get the original French ones out.

Mart.

[34s4ever]

Seal them,thats what I did..

[Ronnieroadster]

Originally Posted by offy19

I just fired up my 1988 French block flathead (4-71 blower) 3-3/8 x 4-1/4. it sounds wicked (400jr cam). Everything was going good until I noticed water dripping from the header bolts. I probably should have left the studs in the block but I don't like metrics. I forgot that the exhaust bolts enter the water jacket on these blocks. Has anyone found a good way to seal the bolts.

To solve thsi problem I just put allen set screws into the holes placed them way down in the hole used locktiie to seal them. Then I just used bolts to hold the headers now when the bolts are removed theres no water leaks. The French block I worked on diid not have metric threads.

[Mart]

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^^ That's right, the blocks are UNC, the French motors used bastard studs 3/8 UNC one end, 10mm metric fine the other.

Mart.

[offy19]

Great ideas! thanks for the help. I sealed up the bolts since I don't have the right length studs, but the first time I have to remove the headers ill use studs to replace the bolts. (3/8 and 7/16 unc)