I've had Johnson adjustable lifters in my '51 Merc 255 engine since the late sixties, and never had a noise (clatter) problem until now. Since the last time I had the engine rebuilt, the lifter noise has been bad. The hotter the engine gets, the louder the clatter. It's a bit embarrassing! The engine runs well, has plenty of pep, and idles dead smooth. Could the noise be anything other than the lifters? I do have the Johnson wrenches to adjust them, but it is a bit of a project to do, so I'd like to make sure that that's really the problem before I tear off the intake. Any suggestions or ideas would be appreciated.
If they are adjusted to the specified clearence they should not be noisey. I would
take the time to pull the manifold and check the clearance adjust if needed. Then get on the rebuilder about his set up, unless the screws move solid or adjustable tappets
get tighter not looser on running engines as the valves pound in.
You might talk to your engine builder and get some info. Were your original Johnsons re-conditioned and reused, or did they replace them with the new adjustables? There have been lots of problems reported with the new ones loosening up and not holding lash where set.
Thanks for the replies. Problem is, the rebuilder would give me no satisfaction and then went out of business. It's a long story, but the short of it is that I'm on my own now. This has been a problem for quite a while and I did nothing about it. The car has about 20,000 miles on it since the rebuild, and nothing has failed or come apart. The engine uses no oil, no water, doesn't overheat, and has plenty of power. I've rebuilt the entire drivetrain and done a 3 year restoration on the body, chrome, and interior. Bit I'm still facing the problem of "why all the noise".
The old Johnsons were used. When started from cold there is some audible valve noise (soft ticking). The hotter the engine gets, the louder it gets (loud ticking). Accelerating through the gears sound like a thrashing machine. As the engine temp drops (i.e. after coming down a long grade), the noise lessens. Could it be anything else more sinister? Wrist pins? Would anything else, effected by heat, result in this type of light (as opposed to heavy) noise?
Thanks for your suggestions of checking the clearances which I will do. But, considering the racket the valves (lifters) are making, they must be way off. But, if they're way off, would the engine still run well and idle dead smooth!
Actually, I did pull the intake and check the clearances about a year after the rebuild. That was about 10 years ago. It didn't make any difference!
Lifter clatter should be constant, not temp related. Does the noise change with throttle setting, or load vs. no load? Is it a sharp sound, or a duller thump? Pistons chuckle at idle, rods are worst at light load acceleration. Really loose rod bearings on a flattie can cause the pistons to hit the heads, making one hell of a racket.
Thanks for the reply. The noise is temp related. It is more noticeable at normal warm temp (160 - 180) than cold start-up. I would describe the sound as light top end rather than heavy bottom end. It really sounds like a chorus of cicadas on a hot summer day! If you're from east of the Mississippi, you know what I'm talking about. The noise is most noticable when accelerating through the gears (higher revs). I've had this situation for 20,000 miles, and nothing has come apart or failed. Could it be lifters that have lost their radius or slop in the lifter chambers? I do have over 200,000 miles on the same set of lifters.
I've had similar problems to yours but not exactly the same. I've "done" several of these engines over the last 45 years or so. The ones with the adjustable lifters have sometimes been noisy. The quietest engines have been the ones with the original style lifters. I've often questioned whether the solid style adjustables are as good as the hollow type. I especially worry about the weight difference. I've re-surfaced original style lifters completely flat on a valve grinder and have had good results, although technically they are supposed to have a slight radius on the base.
I have had engines with adjustables that were whisper quiet. The last two engines I've done have had mild "clicking" on one or two tappets during the warm up period, and are then very quiet when the engine is completely warmed up. The quietest engines were ones that had reasonably low total mileage on them and the noisy ones were probably very high or unknown mileage blocks. I know that these "symptoms" vary from yours, but here are a few possible clues:
Was the camshaft a replacement? It may have been reground without the correct clearance ramps. Is the camshaft or lifter bases worn excessively? Did the rebuilder return all components to their original positions if the original cam and lifters were reused? Not all flatheads have the same valve clearance specifications, and parts may have been mis-matched. 1951 valves, springs, and retainers are different and may have been replaced with incorrect parts.
A local engine machinist with 40 years experience has told me that the lifer bores and/or valve guide bores are very often out of spec. and out of alignment with each other on these blocks, and it is necessary to resize and align them with each other to gain a perfectly quiet engine. I believe this to be the problem with the 268 cu. in. engine that I have in my F-1 4x4 pickup right now. Just a few things to think about.
I bought a used rebuilt Mercury engine for my Ford several years ago that had all the symptoms that you describe. I changed out the cam and lifters, set the valves to proper specs, and had no further noise problems. At the same time, I re-surfaced the valves and made sure the valve seats were concentric with the valve guide bores. This is very important, and without the proper tools, the valve seats can be "messed" up such that they are not in line with the vavle guides. This is bad news!
I've heard this same noise when hearing expensive show cars start up their engines, and I know the frustration they must feel. Some of the owners may not even know what a flathead is supposed to sound like. There are fewer and fewer of us left that know what these engines sounded like when new. If anything, you might hear the sound of the diapragm moving in the fuel pump, or the "whir" of the geneator brushes!
I have to smile at the description of how a flatmotor should sound. My 262 (.040 overbore 255) has no muffler, all you hear is the belts bending around the pulleys! Even when I punch it, its quieter than most muffled V8s.
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