VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1928 head on a 1926 block.

Hey chipper, chevybill and ChevyGuru,

Starting the new thread as mentioned in my last reply from Danskers posting "Do I really have a 23 Sedan". Appreciate your thoughts.
As mentioned sometime in the 30's before Dad bought this car the original owner had replaced the original head with a 28 head. Now from talking to a great many folks, I got the feeling this was quite common. Fast forward to 1951, original carb stops working (don't really have the details there but it could not be fixed).
Dad bought a new carb but for a car and model that I believe was probably closer to 30's era. I know the bolts lined up but it was not at the right angle, he had to cut the intake manifold and rotate the neck about 30 degrees or so, welded it back on. This allowed the linkages to be at the correct angle for the throttle, choke etc. What can I say, he was a poor farmer and did what he could on a budget.
Anyway, everything worked (with the vacuum tank) for another 50 years.
Enter year 2000, car started having fuel issues, noticed the vacuum tank had developed a crack, since the rest of the car had also started to deteriate and I had always wanted it restored we started a restore in 2001.
Since I wanted it as much back to original as possible, I bought another unmodified intake manifold and a rebuilt Carter Carb spec was consistent with a 26 model and had the vacuum tank repaired. After the restore and this new set up the problems mentioned in Danskers thread began.
I will go into more detail on those issues after you get a chance to digest this. Most likely it will be Monday before I can look at the posts again. But, is it possible that the 28 head with this setup was causing any issues. I know it has bigger valves and more compression, or at least thats what I have read. But I can't see why it would make that much difference, and don't think it does. But was never 100% sure.
Thanks again, Brett

The vacuum tank does not care where the vacuum comes from just the amount and pressure differential to atmospheric. If the intake manifold has the insert used in '28 Chevys the hole in the end can be partially plugged if not completely. It would be a great idea to check the inches of vacuum and approximate flow rate produced at the tank fitting. That is in addition to the tests to be done on the vacuum tank written in the other post.

An intake manifold leak, plug in the vacuum line can affect the performance of the vacuum fuel pump.

What about the carb? I put a Carter RX-0 back on it after the restore. With the 28 head should I have used RAKX? I have heard differnet answers from just about everyone. Most of them saying the RX-0 would still work fine.

bmelia the RX-O will run on it, but the RAKX has a larger throttle plate. The valves are 1 21/32" dia. on a '28. The RXO was used on engines with 1 1/2" valves.

The RAKX-0 will run better but RX-0 okay (particularly if you don't push it hard).

Thanks, that's what I thought as well, of course the RAKX-0 is almost impossible to find in working condition and if you do find one it costs more than I am willing to pay at this point.