'47 V8 radiator cap replacement?

topchop

topchop

Senior Member
Just got the new motor and repaired radiator installed in the '47 sedan, and ready to go. Forgot to order a proper radiator cap from MACs.

Anyone know if a radiator cap (4lbs, preferably) is available at NAPA or other outlets locally?

If so, part number?

Thanks.
 
The last one I ordered for my '48 came through in a very fresh modern box and was by a big name company, which I cannot remember...so there is an excellent chance it is available through regular parts stores. Just try to find a clerk old enough to know how to log onto a "catalog". NAPA's online search just does not cover everything they have.
NAPA 703-1419 is probably it...whether it is or not should be obvious when seen, since it is bigger than normal later size. Pretty sure this one is it.
I think 703-1020 is your gas cap...again, big, so it will be easy to reject if wrong.
 
Last edited:
topchop said:
Just got the new motor and repaired radiator installed in the '47 sedan, and ready to go. Forgot to order a proper radiator cap from MACs.

Anyone know if a radiator cap (4lbs, preferably) is available at NAPA or other outlets locally?

If so, part number?

Thanks.
Click to expand...

You want a 4 lb cap BUT there seems to be a problem with the lengths from
under the top of the cap from where it seats on the top of the filler neck to
the very bottom of the bottom rubber seal. The problem is the top of the cap
seats and the bottom is short not hitting on the brass washer like seat down
in the bottom of the filler neck. If this don't seal you only have a regular cap
not a pressure cap. Like this coolant escapes out the overflow. When you put
the cap on LIGHTLY you should feel the spring action down on the bottom
seat before the underside of the top hits, this is the pressure part of the cap
starting to seat. Napa should have the correct cap. G.M.
 
Bruce Lancaster said:
The last one I ordered for my '48 came through in a very fresh modern box and was by a big name company, which I cannot remember...so there is an excellent chance it is available through regular parts stores. Just try to find a clerk old enough to know how to log onto a "catalog". NAPA's online search just does not cover everything they have.
NAPA 703-1419 is probably it...whether it is or not should be obvious when seen, since it is bigger than normal later size. Pretty sure this one is it.
I think 703-1020 is your gas cap...again, big, so it will be easy to reject if wrong.
Click to expand...

Bruce, you are right on with that part number.
NAPA guy was helpful in finding one at the next NAPA store down the road.
Only problem, being a "Made in MEXICO" part, one of the locking tabs was not formed 90 degrees. Easy fix.

Don't need a gas cap at the moment, but will definitely file the part number for future reference.

Thanks.
 
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