Hot Rods Solid lifters, what causes them to need to be adjusted all the time?

Screw in studs and good locks on the rockers are the key . Our drag cars only get adjusted twice a year and mostly need no change. Thats 7000 plus rpm every run.

 

All old Ford Y-blocks were solid lifters. I think the oiling problem in the rocker shafts were the reason most people had adjust them. I had to adjust my valves on one head a lot with my first car, a 56 in high school. But I found out that rocker shaft mounting bolt was pulling out.

 

That is why I specified pushrod engines. New OHC engines seem to go longer but eventually the lifters get weak in them too.

My point is that a solid lifter engine, with proper valve train and regular adjustments, should be as quiet as a hydraulic lifter engine, and stay quiet for the life of the engine. If your valves need to be adjusted oftener than every 20,000 miles or get noisy there is something wrong. Others have pointed out that old Chevrolet V8s have rocker studs that tend to pull out, and adjusting nuts that won't hold their adjustment when they get a little wear on them. But these defects can be remedied with better hardware.

The OP wondered why his solid lifter cam needs to be adjusted frequently. But he also states the cam has been in 2 or 3 engines and is not worn out and that he always uses new lifters. This suggests to me that the problem is not cam or lifter wear, but somewhere else and the adjusting studs seem like a logical place to look.

The consensus seems to be that if he uses pinned or threaded studs and adjusting nuts with a lock nut or locking screw his problem will be solved.

 

It depends on the use. Old farm tractors have solid lifters and they often run for decades without needin adjusting. but they run at low RPM and low spring pressure. The GMC V6 also have solid lifters and many run over a 100,000 miles without ever being adjusted. Ive run 30-30 cams in chevys. and drove them hard. and they needed adjusting quite often. I drove a semi with over a million miles on it. and that solid lifter 425 cat had never had the valve covers off. Lots of engines came with solids anf never needed constant or even frequent adjustment. Y block fords-^ cyl chev and GMC the flathed ford ect.

 

First off, it is not a good idea to run a used cam in a different engine even with new lifters.
That Engle 95 was an excellent cam for it's day. the reason it worked so well was it had a higher rate of lift than most cams of it's day. That is also why it usually needed more adjusting. It would go a long time if it wasn't run past the valve train. In a high rpm situation it just had to be touched up more often. It has to do with valve float.

 

Hang on Hoss. The cam is in the attic. It's not in an engine. My original question was why does a solid cam require more adjument than a hydraulic lifter? What is wearing in the valve train to cause this? I don't actually have a problem to solve. Make sense? I just wonder about things....

I do have a cam that I have used in several engines with no issues. It was talked about, but is currently residing in a 30 year old box of parts in my attic.

 

Cam/lifter wear or bad adjuster nuts is probably your biggest culprit.

I run poly locks on everything unless I have shaft rockers which have lock nuts. I do not adjust all the time and more often than not I just check them once or twice a year just because I can. I have discovered that more often than not adjustment is more often needed on a new cam and lifter setup. One they finds themselves it is seldom necessary.

Now here is a tid bit that has no bearing on anything but an interesting tid bit. Harley Davidson Motorcycles are roller cam from the factory and have been since the '30s for sure. We discovered way back when that the hydraulic lifer engines needed adjustment more often than the solid lifter engines. Just ass backward to the thinking of most car related hot rodders.

OK rabbit trail. LOL

 

Hydraulic lifters are self-adjusting. Once it's been initially adjusted into it's operating 'range', it will self-adjust to compensate for any wear. That was the whole point of adopting hydraulics, to eliminate adjustment as a maintenance item. The early versions had multiple issues for performance use, so a switch to solids was usually the one of the first things changed in a hop-up. Eventually technology improved them to the point that in all but all-out race use, they could equal the performance of solids.

As to wear in a mechanical valve train, you have multiple wear points but they don't all effect it the same way. Valve/seat wear will tighten clearances, all other wear points will loosen clearances. Stud-mounted rockers are less stable compared to shaft-mounted rockers under high-stress conditions, which is why things like larger screw-in studs, stud girdles, and shaft rocker conversions are popular. Mechanical lifters also 'shock' the valvetrain more.

IMO, the valve/seat wear is what causes most adjustments. All the other wear points will have initial 'break-in' wear but should remain relatively stable after that.

 

In a SBC upgrade to 7/16 studs and use locking nuts, you won’t have to adjust them. There’s a lot of deflection with a 3/8 stud and adding high valve spring pressure, combined with + lash that comes with running solids beats things up the way I see it.

 

huh, seems I haven't seen that problem with modern pushrod engines. only have experience with a few of them (chevy trucks) but they stay quiet well after 100k miles.

 

One cause I haven't seem mentioned. Rocker tip wear. It used to be common the regrind the rockers at valve job time, back when that was fairly common at 50-70k. The first past across the grinding stone was eye-opening as there was usually a sizeable 'dish' in the tip. Not only does that create added lash, it also makes an accurate adjustment impossible. I thing those adjustments could account for a lot of readjustments, they just weren't right the first time.

Hollow pushrods also tend to wear at the rocker end with high spring pressures.

If you add the tip, pushrod, rocker ball/shaft all up you could need an adjustment, especially in an engine with marginal top end oiling. Like a gunky 272 or 292.

As far as hydraulics go: IMO, modern oils have just about eliminated that longevity issue. I have personal experience with several engines with 200K +, still a quiet as new.

 

If I were to use solid lifters I think I would go with direct lube lifters.

 

'Poly-Locks'. Are these (by name) the 'tall' nuts with the set screw in the center?
If so, as no one has mentioned it, the end of each Chev rocker stud has a 'concave center', which occurred when the threads were rolled.
Reason for Poly Locks to loosen the set screw. ('Experts' have argued that the poly set screw is serrated, and "can't come loose."...These experts were also serrated.)
The studs must be faced flat, (I made a recip bracket for facing them on a stone, one at a time)
Joe Mondello was very distinct on this.

 

Actually yes they are the tall ones with the set screw in the center. I did mention them. and yes the guy who said that the set screw is serrated is serrated. LOL

 

My old Tahoe had 180,000 miles when I sold it. A Mexican gentleman the next town over bought it six years ago and he has taken numerous trips to Texas to visit family. Still a strong runner and quiet too. Regular maintenance pays dividends.

 

Then there's girdles...... Stabilizing the geometry of such studs........Which connects the ankle to the leg to the.....
Nothing is perfect= period. So band aid's, or adder's to increase maintenance, is up in the air..........
Super Stockers come to mind here- Ever see what they do with what they have to work with?
maintenance is still required= results may vary on operator......
I would run any cam, as long as being known good, regardless of age, if all was good with the rest of my valvetrain. Root knows wazzzzuup.

 

7/16" is a little overkill for a flat tappet cam...Just for the sake of conversation ..anyone remember the chevy 5754 ? mushroom tappet cam? Think it was called off road # 2 cam.

 

The 754 cam was the 2nd design off-road cam. But, I think the 140 was the mushroom tappet cam, but that might be the Captain Morgan thinking for me!

 

I remember it, and the lifters. The reason for mushroom lifters is the greater diameter allows a more aggressive camshaft. The lifter bore remains the same but the foot of the lifter is bigger. The block had to be spot-faced at the underside of the lifter bore for clearance.

 

Nope I got the 7140 in my Stude it's the #1 cam Love it! Never tried the mushroom cam would like to hear from someone who has.

 

My bad, the mushroom tappet cam was 366293.

 

Some interesting stuff here.

 

I only use 7/16" studs regardless of what type of cam or lifter. One of those things I was steered to many years ago, the same with connecting rods.

 

Thanks for al the replies. It has been educational, to say the least.

 

Yep, we use one in our dirt track car back in 79. You had to put the lifters in from the bottom. Real hot cam for the time. Not sure of the number, but we got it from the Chevy place.





Bones

 

I have been following this thread and enjoying it. I need to give my 2 Cents. When we were young we had no money to race so buying a set of used 202 heads was a big deal. Running solids was preferred. Adjusting the valves was a night mare to keep in adjustment. Some of it was ( imagination! ) But, Most was worn valve guides/valves. Every time we would adjust the valve they were good. 10 minutes later they were all over the place. I believe our oil was not good in those days so wear was quick and adjusting was frequent. The valve train needs to be "Excellent " to keep tolerance!

 

2 data points that are kinda OT. Rocker arms on street cars - I used to hand file them to match the wear pattern from the valve stem, they were then easy to adjust with feeler gages and the engines ran great. Engines with a lot of miles often had significant wear in the rocker arm socket from the pushrod, those had to be replaced.

I remember watching the guys running stock cars at Cajon Speedway - they would change the lash up or down between heats as a way to modify the cam timing on their sbc 350s.