The Stovebolt Site Forums The Shop Area Engine Shop replacing hydraulic lifters with solids

I can't find a definitive response to this question on previous postings, but in brief, can you replace new SOLID lifters in a 235, in place of the current HYDRAULIC lifters and still use the same original(hydraulic)camshaft?
If so, are different pushrods also required.

NO!

The grind is different on solid lifter and hydraulic camshafts, specifically the "acceleration ramp" that establishes the clearance. For instance, if a solid cam has a .012" specified clearance, there will be an area of slow, gradual lift ground into the lobe, 12 thousandths high, to gently take up the slack before the valve actually starts opening. Hydraulic cams generally have only 3 or 4 thousandths of accel ramp, so if you put solids on a hydraulic shaft, the clearance would have to be set about .005" or less, and adjusted weekly, at least. More clearance than that would result in slam-bang valve opening, with lots of noise and wear.

Putting hydraulics on a solid shaft will noticeably increase the duration of the valve opening, sort of a "poor man's race cam". In practice, that's not a good idea, either!
Jerry

In the day if we replaced hydraulics with solids the cam and valve train would not last long.

A few years ago there was a guy that posted here,the father of a guy call Racecarl,who doesn't appear to post here anymore.
Racecarl's dad was a lifelong retired Chevy dealer mechanic.He stated several times that back when 235's were still in production,hydraulic lifter noise and malfunctions were a constant problem.He and others would replace the hydraulics with solids,never changing the cam.He said the engines suffered no cam or lifter related problems for years.
He had no reason to lie,he was a genuine dealer mechanic,he was very versed on these engine working on them for years,try it and see what happens.

I have a 62 1/2 ton chevy truck with a 235 c.i. engine that I am running solid lifters on a hydraulic cam. I could not keep the hydraulic lifters from leaking down so did the swap and adjusted the solids . Have had no problems. Did the same swap on the previous engine and ran over 100 k miles with no problem. I haterd to hear the terrible missing and clattering on the old hydraulics until they pumped up every cold morning. I have been running the present engine 30 k miles so far and she runs fine-just a little noiser than the hydraulics...so I agree with Fast truck and his friend.

Keep in mind that not all solid lifters will work in blocks drilled for hydrolic lifters.
Before hydrolic lifters became available the soid lifters had straight sides.
Once all blocks were drilled for hydrolics many still came with solid lifters but these lifters differed from the earlier type in that they have a channel around them to allow oil to run down the galley and around each lifter and on to the next.
If you put earlier lifters in the later block you will restrict oil flow, that will definitely cause problems.

Are you planning to run new lifters against a used cam? If so, it won't really matter what you use, as the cam will wear out pretty quickly. Go ahead and take whatever advice floats your boat, but I would encourage you to change both cam and lifters as a set, and use the correct cam for the lifters you plan to install. There is absolutely no reason I can think of to run solid lifters, unless you've got an early block that does not have the passages drilled to supply oil to hydraulics.

I'm basing my opinion on 45 years in the auto repair trade, including blueprinting and cam-degreeing about 300 roundtrack race engines, but I probably don't know what I'm talking about. Adjust the hydraulic lifters once, on original assembly, and forget them!
Jerry

The old mechanic suggested using solids on a hydraulic cam as a repair for an engine allready in use,usually one with many miles on it.It was never his intention to use this approach with a new cam or on a rebuild.
235's have very mild cam lift and duration,less than 60 lbs of spring pressure on a seated valve,nothing at all in common with high reving race engines.You can get away stuff that wouldn't last 10 minutes on higher output engine.And the statement from the guy above proves it.I'm far from a professional mechanic,but running a bunch of these engine over the years has taught me a few things about them.
For your information,235 cams have small casting lumps on the rear of the cam between the 3rd and 2nd to the rearmost cam lobes,2 or 4 raised "lumps" identify it as a hydraulic cam,1 or 3 lumps,a mechanical lifter cam.This is somthing often ignored by guys rebuilding these engines.I bet half the guys here got cams and lifters mixed up and don't know it,but the engine runs just fine except for maybe a complaint about slightly noisy valves despite proper adjustment.
The cam casting lumps can be seen from below if the oil pan is off.

Hotrod Lincoln,
Where do you get suitable hydraulic lifters for 235/261 motors?
A few years ago when I was buying rebuild parts for mine I was told by several sources that there were no longer decent ones available for these motors?

Thanks for the great tip on easily identifying an already installed solid or hydraulic cam.
I asked this question many times over the years, and you are right - very few are aware of this apparently.
Just checked my mechanical 261 cam and indeed it has one casting lump.

Just from reading on this board for many years, it appears there are many Frankenstein 235s on the road running pieced together with mismatched parts.
Amazing what these engines can take and still keep running for years.

I replaced all hydraulic lifters with new ones on my late 235 daily driver last winter.
- The engine never ran better in the previous 11 years.
I believe the later 235 cams are harder. Both solid and hydraulic lifters are also different from the earlier years and look almost identical.

I think the trick with hydraulics is to not overtighten the rocker arms.
I only tighten the rockers 1/8 turn after clicking stops with the lifters and pushrods spinning freely.
The manual suggests turning 1-1/2 turns after clicking stops.
But I drive often on freeways for hours and prefer this method .

I can only speak from personal experience and observations.
It seems save to suggest, if you got collapsed hydraulics on a late 235 and always stay under 3000rpm - get a new set of OEM hydraulic lifters and enjoy a quieter ride.