The Stovebolt Site Forums The Shop Area Engine Shop Hydraulic v. Mechanical Lifters

Looking for advice on using hydraulic or mechanical lifters in a 235CI engine in my 55 1st series 3/4 ton. Currently the engine has hydraulic lifters but I have considered swapping them out since they need to be replaced anyway (some are cracked on the top). What are the advantages/disadvantages of each? Also, do I need to change the cam if I change to mechanical lifters? The truck drivetrain is somewhat modified, but not to any extreme. I am putting in a Saginaw 4 speed and swapped the rear gears to 4.10 but not much more. As always, any and all advice is greatly appreciated.

You need to look at the bottom of your old lifters. If they are not perfectly flat then the cam is probably worn to the point where it should be replaced. You can install either solid or hyd. lifters if the cam is good. I like hyd. because they stay in adjustment. If you put new lifters on a worn cam you are wasting your money.

Unless you are going to turn the engine 6000 rpms or above, I would use the hydraulic lifters. Once you adjust them new, you can forget them and also not hear that rocker arm clicking sound. The hydraulic cam is ground different than the solid one, so use a cam to match your lifters.

Go with a new cam and keep the hydraulics. Once you get the cam broke in and the lifters adjusted, you won't have to adjust them again. The hydraulics will run smoother and quieter. Why a new cam? Since the old lifters show damage, the cam is probably damaged or has excessive wear on those lobes. The only way to check it is to degree it and check the lift. By the time you have done that, you could have put in a new cam, which doesn't cost that much.

This is a great quesation. As one who as had problems with hydraulics my next engine is going to have solids. There is a tech tip for noisy hydraulics at Inliners that is credited to me even though it was Tom Langdon's idea, he gave me credit because I'm the one who tried it. The fix worked for the most part but there are still times I get off the highway after towing steep hills in Vt. and I think I hear lifters clacking. I spent too much time replacing colapsed lifters, listening with hoses, dropping the oil pan to look for suction side pump leaks and sealing conections, and grinding flats on the offensive lifter. Yes, I would prefer to use hydraulics, but just wonder if the trouble is worth it.

Yes, you do need to put in a solid cam to use solid lifters. The ramp of a hydraulic cam is steeper than that of a solid, and though some people used solid lifters with hydraulic cam for racing it will shorten the life of your cam and valve train(so I'm told).

Great responses. Thanks for all the input. Gives me a few things to keep thinking about.

Good input, Grant. We tend to forget the technology advances when dealing with these older vehicles. My first experience with hydraulics was in a 63 and many improvements had been made in lifter technology by then. I would hope that the replacement lifters are improvements over the originals, but you can't tell with disassembling one.

Fred, after reading over I realized I was vague and asssumed everyone knows about the 235 hydraulic lifter problems. I don't believe there is a problem with the lifter itself but rather the design of the 235 oil pump. It isn't submersed in oil so any leak on the suction side of the pump results in air in the oil supply. Lifters don't like air. It usually manifests itself a noisy lifters that can be heard right after a highway run. Let it idle a couple minutes and it quiets down. I tried leak checking the pump by pressurising and checking with leak tech or soapy water. I sealed the inlet threads OK but noticed the pressure relief valve leaks. In theory this should not be a problem becuase I would assume the valve will be pushing out excess oil pressure, not drawing in air but 2nd time around I threaded it and ran a tube down to submerse in oil. Still noisy. For some reason the air seems to go two one or two lifters. In my case it was one at # 3 cylinder. This is when I tried Tom's idea of grinding a flat on the top half to let air escape. Seems there is a GM v-6 out there that had this done at the factory to quiet lifters. As I said it seems to work for the most part, but there are still times I think I hear some clacking.

Grant,

This periodic clacking will not hurt the engine will it? If the only benefit to having hydraulics is to quiet the engine then maybe a shift to mechanicals is warranted?? Thanks.

I imagine they are clacking as you go down the highway, just can't hear them until you come to a stop. I did have one completely colapse before I got the situation somewhat under control. As I said, my next engine will have solids.

With Grant's input, I will change my vote and hang a pregnant chad on the use of solids in the 235. Call Patricks and get the M4F cam and a set of solid lifters.

Sad to say, according to Partick the lifter manufacturer went bankrupt and there are no lifters to be had for around 3 months. I just happended to have a set of solids put away that I got when I started having hydraulic problems.

Dang. And he was cheaper than what I could buy locally at jobber prices. Guess now we know why!

AHHHH!!! And I was going to call Patrick this afternoon to order all this stuff. Oh well. I will keep all the comments in mind.

I talked to Bob Langdon of Stovebolt Engine Co. last night. He says he has a good supply of lifters on hand. He also sells a cam that he likes, it's a dual grind with the exhaust a little longer duration than the intake. Anyone try this cam? He says idle is not as smooth as as the M4F cam but he has done some dyno work to develop it. He will be in today but is taking the rest of the week off to go to swap meets. He also has a supply of the powerglide intake valves for anyone who might want to put in bigger valves.

Grant,

THANKS! I appreciate you tracking the info for us all. I will check with them for info.