VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 help with 48 chevy

I don't have any issues with his instructions.

I consider my method as just as good and may be quicker. When you get to the step where he has you adjusting the valves with specific figures, it is quicker to just adjust all valves to .010. Now turn then engine as he specified and set everything to .010. You need not spend a long time in getting the setting of .010 to all valves. All we wanted to do was make the engine runnable.

Now start the engine. Set the idle speed as low as you can without stalling. Now you can accurately adjust each valve as directed by the Internet mechanic. For more accuracy it is advised that after starting the engine you can go down the line and adjust every valve until it is quite. Then come back and set them correctly and you will be able to hear the improvement in the running and the noise.

Let's put the horse back in front of the wagon. Before the valve adjustment insure your points are set correctly and the timing is right on the mark. When you finish the final valve adjustment go back and set the correct idle speed. And the last step is to adjust the air mixture screw for maximum speed.

There are other ways to accomplish this chore. A good solution is the use of a vacuum gage. For this procedure you need a Motors Auto Repair Manual (the blue book) and follow the instructions.

i will recheck timing, point gap and dwell and then pull valve cover and see what is there this weekend. thanks again for the hands on instructions. david

today i worked on 48 all day. i rechecked timing, point gap, pulled valve covers oiled all valves and reset on which was real loose. it ran better for a while then it started backfiring again. i am thinking it may be carburetor. i am sending it to chipper to try on his test engine. i am about out of ideas. i am about to give up. david

Check the one valve that you adjusted to see if it came loose again.

i did check #2 intake valve again and it was still set at 8. would a blown head gasket cause this type of problem? should i run compression test and if so what should i look for? dd

A backfire can be caused by several things. A fuel mixture in the carburetor that is too lean, leak in the manifold gasket, leak in carburetor gasket, timing, sticking valve, burnt valve.

A compression check is easy to perform and may indicate the reason for the back fire or other maladies.

today i blew out all gas lines, cleaned fuel pump, put on new fuel filter, and installed carburetor that skip cleaned up for me. i rechecked timing, adjusted valves, put in new plugs. it seems now to be running fine however i couldnt test drive it since it had two flat tires. thanks for all your help. i will keep you posted. david

I suspect that the major problem was a failure in the accelerator pump circuit. I was told that there was no squirt of gas into the throat when the accelerator arm was advanced. That will cause a hesitation or even backfire if the extra gas is not present to overcome the instant lean condition.

correction chipper was the one who fixed the carburetor. i am really pleased to solve the problem since i was very frustrated.