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+--- Thread: RP Tappet noise (/showthread.php?tid=9177)
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RP Tappet noise - Graham O - 16-02-2024
Having done 100 plus miles on my re-build car all is relatively well except for the engine noise. I am used to my (now sold) 31 A12/6 which would run quietly with just the slightest hint of tappet noise.
Tappets were set at 6thou inlet and 7thou exhaust when cold.
However, my motor is very noisy and it seems to come from the tappet domain. I would normally think that tappet noise comes from wide tappet spacings, but my thinking leads to a reduction in spacing as the motor and gaskets etc. settle in.
So what I have not yet done: Reset the tappets. Sorry but other priorities have kept me away from the car.
What I have done: Following advice from a well respected A7 racing enthusiast, I flattened the cam follower profiles. Your next question will be - by how much. I'm sorry to say I don't know and I will have to find my jig I made to sit over my belt sander to answer, but you can safely assume that the profile is flatter.
So my question is this: Should I expect loud tappets because of the flatter cam followers, or is it a common settling in result and I should just get on and fix the tappet settings.
I promise to post the results of the tappet setting exercise when it comes soon.
Graham
RE: RP Tappet noise - John Cornforth - 16-02-2024
Hi Graham
The head gasket won't affect the tappet clearance with a sidevalve design, though the valves may settle a bit into their seats.
Were the heads of the tappet screws re-faced during the rebuild ? They tend to acquire a wear dimple which makes using a feeler gauge problematic.
RE: RP Tappet noise - Parazine - 16-02-2024
I have flattened cam followers in my Chummy engine and it is generally pretty noisy, although not specifically "tappety" if you understand.
RE: RP Tappet noise - David Stepney - 16-02-2024
I run my RP with tappets set to 6thou inlet and eight thou exhaust. Yes, the tappets can be heard, but it goes well. I have always preferred to have the tappets generous rather than too tight.
I recall, in my rallying youth, that the works Ford Kent engines always sounded positively clattery, as the exhaust tappets were set to give a constant vacuum reading for each cylinder, and i understand that they could be as wide as 25 thou, but they didn't half go well!
RE: RP Tappet noise - Chris KC - 16-02-2024
Graham, under what running conditions are you noticing the noise?
RE: RP Tappet noise - Graham O - 17-02-2024
Thanks for the comments.
I did not explain that the reason for the larger radius on the cam followers was to give a faster lift to the valves to give a better intake and exhaust passage.
I have also fitted a silicon gasket between the cylinder block and the crankcase. That may have compressed and reduced the valve clearances a little.
The noise is consistent across the motor (i.e. all tappets) and is there at all speeds.
I don't remember refacing the tappet screw heads so I may have had a setting problem, but that would probably lead to some tappets being louder than others.
Graham
RE: RP Tappet noise - Chris KC - 17-02-2024
If you've replaced the block base gasket, check the tappet clearances. I wouldn't waste effort considering other possibilities till you've done so.
RE: RP Tappet noise - Malcolm Parker - 17-02-2024
If you flatten the cam followers, you generally need to reduce the height of the guides in the block. If you don't, the tappets foul at the top of the guide and the base of the cam follower will not seat on the camshaft. Could this be your problem?
RE: RP Tappet noise - Steve Jones - 17-02-2024
(17-02-2024, 10:16 AM)Malcolm Parker Wrote: If you flatten the cam followers, you generally need to reduce the height of the guides in the block. If you don't, the tappets foul at the top of the guide and the base of the cam follower will not seat on the camshaft. Could this be your problem?
That was my thought as well. Only has to foul slightly and the tappets will never adjust correctly.
In the manner of Blue Peter, here's one I did earlier
Steve
RE: RP Tappet noise - John Mason - 17-02-2024
I second Chris. Check the tappet clearance first before you do anything else. It’s easy and simple although can be fiddly. Unless it’s obvious where the problem is start with the easiest things first in your attempts to fix things.
John Mason.