VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Single port exhaust head

Did Cehvy produce replacement single port exhaust heads? I just picked one up, but it does not have the bow tie in the casting. The casting number is 344128 underneath that 6 on the other side a J 8 5. It looks pretty much identical to my 37 head.
Thanks
Woodbutcher

Typo supposed to be 27 head

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Yes, heads for the Chev 4-cylinder were made up to 1942.

The head you have was made on October 8, 1925.

Thanks Ray,
This head looks to be in good shape. I took it all apart and wire wheeled it.
Woodbutcher

While you have the head apart I would take it to a machine shop and have it magnafluxed.

A good glass beading would be a good idea also.

With due respect to Ray, we have found those heads often crack in the exhaust or intake passages which magnifuxing will not detect. It is far better to pressure check them with air. Plug the holes in the head with rubber stoppers and then put a hose on outlet with large stopper and hole for tubing to air supply. Apply a several lbs of air (does not need to be high pressure), immerse in water and look for bubbles. Alternate is to put soapy water in exhaust and intake passages and look for bubbles or even listen for air leakage. That will find more of the cracks than magnifluxing. If the head passes the crack test then you can magniflux to checkf for cracks in the valve seats or combustion areas.

Hi Ray and Chipper,
This is what I did with it. I plugged the water intake, turned the head upside down and filled the water jacket with water and let sit. I found no water coming out any where. It only takes about 2 hours to pull off the 28 head that is on there now, and install this head. None of the valves were seized. They even looked good, but I took the valves that where new from the blown head, and lapped them with valve grinding compound into the new head. They seated real well. I will be switching out heads next week. I will let you know what happens.
Thanks
Woodbutcher

if you dont put the pressure to them it probably wont show to be leaking . i had one i had to put about 18 lbs on to leak . i have 5 out in the shop if some one wants them . one i did not have to put water in it could hear it like chipper said .one i had to warm before it leaked . i have had the best luck with the aftermarket heads it has no numbers no bowtie no nothing . hope this helps

I put the head on my truck Monday night, and filled radiator. Let it sit till last night. No Leaks. Started engine last night. The only leak is a pin hole on the top of head. When I first started and got a little warm it started to leak at the pin hole. as it got warmer it stopped leaking. Overall it leaked about a 1/2 ounce. No other leakes. Engine ran real cool, some where aound 150 deg. F at top of radiator. I still have timing isuues as it still wants to throw some flames out of exhaust port at higher RPM's. But other than that in looks good. Should I try JB Weld on the hole or stop leak in the radiator? This is a completly overhauled engine and a modern rad core.
Thanks
Woodbutcher

JB Weld will probably work fine since it isn't a pressurized cooling system. If it blows a lot of flame out at high speed it is slightly retarded, but It may blow out some flame and be timed right. Best to just recheck it so it doesn't overheat the head while on a drive. Be sure to retorque the head though after getting it hot. The type of gaskets these engines use MUST be retorqued at least twice or they can leak. You don't want water getting into cylinders on a rebuilt and tight engine. Rebuilt engines that are stuck are a nightmare to get loose again. Also when retorqueing the last time, readjust the valves. Also watch it to make sure no water is getting into the inside of the ports. A spark plug removal and cranking will blow out water if it is leaking inside.