The Stovebolt Site Forums The Shop Area Engine Shop Hydraulic Lifter with Solid Cam?

An 83 year old neighbor helped me rebuild my 1956 Chevy truck 235. He suggested I swap the solid lifters for the hydraulic lifters I had in a passenger 235, so I did. I've read that using hydraulic lifters require using hydraulic cam. We never swapped cams that I can recall. Do I have a potential engine problem?

Don't worry about it- - - -you'll wear out the cam in a short time, and then you'll be able to swap cam and lifters together. You'll ruin your new lifters in the process. If you've run the new lifters on the solid cam for more than a few minutes, they're not suitable to swap to the correct cam.

A solid-lifter cam has "acceleration ramps" that take up the clearance gradually, then start lifting the valve. By running the hydraulics, you've effectively increased the duration of the cam lobe by lifting the valves on the acceleration ramps, but the lift rate is so gradual there won't be any increase in performance. The idle will be a bit rougher, and the manifold vacuum will drop slightly, which makes it difficult to get the engine to run smooth at low speed.

Hydraulic cams also have acceleration ramps, but they're very short, usually no more than 2 or three thousandths before the quick lift rate begins. Ditto for the closing ramp, there's a very short area of slow-rate movement to prevent the valve from slamming down on the seat. Your solid cam will have a longer deceleration area than the hydraulic cam. Always change a cam and lifters together. If one is worn, the other won't benefit from putting new parts against old ones.

Edit- - - -I just re-read your post, and saw that you put used lifters against a different cam than the one they were used with originally. They won't last more than a few hours until everything is worn out. Tear it down and swap for a new cam and lifters now, before you fill the engine with debris from the cam lobes and lifters as they destroy each other.
Jerry

Hotrod beat me to it, and did a much better job than I would have.

If you have not started the engine, change the cam to match the lifters.

If you have ran the engine, change lifters and cam together.

I goofed many moons ago as a young kid (didn't know anything) and put solid lifters on a hydraulic cam. (Didn't figure that out for years) The engine never did run quite right, and had no power.

Always do cam and lifters together as a set.

Thank you for the replies. I have about an hour on the engine, so I imagine the lifters and cam are shot. I have been having trouble starting it and keeping the idle steady. I will plan on replacing the cam and lifters. Next question ... Should I replace with solid or hydraulic? Is the truck 235 block designed to handle either?

If you had not used used lifters you would have been OK. I have run hydraulic lifters on a solid cam many times with no problems.

A 1956-57 truck 235 was not made to use hydraulic lifters.

1958 and later truck blocks were able to use hydraulic lifters.

All 1956 and later 235 passenger car blocks used hydraulic lifters.

Before 1958 the truck blocks were not drilled for an oil galley/passage to the lifters... How did you initially adjust them? It's no wonder it won't run right.

Hotrod, I don't know about the hydraulic lifters on a solid cam, but I always heard you could use new lifters on an old cam but you couldn't use old lifters on a new cam. I have used new lifters on an old cam several times with no bad results, but maybe I have been lucky.

By the time a set of lifters show enough wear to need replacing- - -flat or concave bottoms on the lifters instead of a slightly convex surface, the cam lobes won't be anywhere near their original contour. Try doing a lift curve graph on a cam with enough miles on it to need a lifter change sometime, then compare it to a new cam's timing and lift specifications.

It might be possible to run new lifters on an old cam, but it certainly doesn't help the engine's overall performance. There will be noticeable differences in timing and lift between cylinders, which seriously impairs power balance between cylinders. That holds true for both solid and hydraulic cams. It's a function of time and mileage, not how the valve lash is handled.
Jerry

Hotrod, what if the lifters weren't worn out? I thought it would be better to replace the lifters just as a precaution on some jobs, but I was talking to my machinist a few days ago and he strongly recommended using the old cam and lifters if they were still good, but mainly I believe because of the new oil with almost no zinc.

On the engine I am working on now, I had a heck of a thing happen. I took it into the machinist to get it honed rather than just use a glaze breaker and left the lifters in the bores so as to keep the honing dust out. I lifted the engine from the oil pan side and took it into town. When I picked it up he had a chain attached to the head side and we set it in the pickup. When I got home, I noticed a piece of wood in the back cam bore. I wondered how the heck it got in there and pulled it out. Immediately after I pulled it out, I knew what it was for. About 2/3 of the lifters fell out. I thought I would still be OK if I were careful and turned the block over. At the last second I lost control of it, the block bounced on the picked bed and lifters started rolling every direction. Of course I had to then buy a new cam and lifters, $164. I wish I had done a little more thinking before I pulled the stick out.

Your machinist is definitely on the right track. If a lifter doesn't show signs of wear, I have no problem with re-using it as long as the lobes and lifters stay matched up. That avoids another break-in procedure for new lifters, which accelerates the cam lobe wear. I take a different approach, though- - - -removing the lifters and wrapping a piece of masking tape around each one, then marking the position with a felt tip marker so I can replace it in the right position. Then the cam comes out. I quit trying to fib to myself that ANY machine work can be done without a total cleanup, including pulling oil gallery plugs and cleaning every oil passage with rifle brushes and a pressure washer. There's just too much risk of a tiny piece of debris ruining the whole job without a detailed cleaning. How did your machinist get the hone grit out of the cylinders without a hot water and detergent scrubdown followed by a boiling-water rinse?
Jerry

That is an excellent idea on the masking tape and numbering them. I usually just arrange them in a row in a place where there is no danger of them being somehow disturbed, but your way is definitely better.

He didn't do any cleaning and I didn't have it hot tanked either. Would have had to buy new cam bearings and labor for installation in addition to the $50 for the hot tanking. I will scrub it down with detergent then pressure wash it. The bores will then be wiped with a white rag soaked in diesel oil and repeat this process until I get a clean rag. That is very time consuming, but it is necessary. Some say automatic transmission fluid is better than diesel oil. I may try that this time.

Hotrod, another question. This engine is a propane irrigation engine. My cousin recommends assembling the rings with no oil at all, just put some lube on the piston skirts. I just don't feel comfortable doing it this way, but he is the best mechanic I know. I have always lubed the piston rings in the past and can't say that I have ever had a problem with getting the rings to seal, even on propane engines.

I'll have to disagree with him there. The only lube the rings get on startup is what you put there, until the splash off the rod bearings starts wetting the cylinders. I'd be reluctant to subject them to a dry start- - - -too much of a possibility of getting scuff damage. I drip a pretty good quantity of oil onto the rings, and also give the cylinder walls a good rubdown with an oil-soaked clean rag. It won't stay there more than a few up/down strokes of the rings, but those first few revolutions until the oil pressure builds up can be critical.

I thought up the tape and sharpie method of keeping track of parts through many years of working with high school auto mechanics students. I defy anyone to keep a set of engine or transmission parts laid out in an orderly fashion anywhere in a high school shop that doesn't get scrambled by some kid playing grab-azz with his buddy at least once a day!
Jerry

I have a reprint of California Bill's book from the early 50's on hopping up 6-cylinder Chevys. It's packed in a box somewhere and I'm going on memory. But he said to always use old (used) lifters on new camshafts... Part of the book describes his dyno testing of various carburetor, head, cam and crank combinations in 216 (and 235) Chevys. Anybody else have that book and remember that?

I think Forrest Gump's Mama had something to say about advice like that!
Jerry

California Bill (1954 edition of the book) refers to late '30s to early '40s used original tappets (in good condition) being superior to later tappets and to replacement tappets (late 40s - early 50s).

Thanks Tim. It's been a few years since I read that book, and another one by Roger Huntington (?). Maybe that's not the correct name. His book was more professional, more technical... You know the one? (Sorry to hi-jack the thread.)