I posted a few months back about valve train noise after my 475c cam install with S&S lifters and fuel moto adjustable pushrods. I’ve since put over 500 miles on the bike. It runs great but has always had valve train noise once the motor is heat soaked.(really only noticeable at idle) It’s super quiet when cold. I’ve recently learned Harley makes adjustable rockers for the M8 but I’ve not seen much feedback. Has anyone here had any luck with these? I’ve heard the videos on YouTube of M8s with bad lifters and mine certainly is nowhere near that bad, mine almost reminds me of any modern car engine running when you take the plastic insulation cover off the engine and you hear all the valves and injectors clicking. I’ve also seen numerous videos with my cam and there is 0 valve train noise. I also talked to S&S and they told me this cam should be very quiet as far as valve train noise goes. So after replacing my lifters twice and trying different pushrod adjustments with no difference in noise I feel like these adjustable rockers may be the answer…

 

Did your engine make noise like this before the cam change?

 

no I never noticed it before the cam swap

 

Adjustable rockers are for reducing rocker to valve stem lash. If your rocker to valve stem lash was OK before the cam change, it's not likely the cam change would create more lash.

 

i guess my thinking is the variance in valve lash isn’t enough with a stock cam to be noticed, unless that variance becomes excessive. But now add the increased ramp rates of an aftermarket cam and now the slight variance may be more noticeable? S&S and fuel
moto both brought up the inability to be able to individually adjust valve lash as a possible reason for the noise.

 

To review, the rocker arm to valve stem clearance is a set measurable amount that has nothing to do with what cam is installed. If the rocker arm is touching one of the valve and not the other, this is the clearance that can be taken up with an adjustable rocker arm. On an M8 engine, rocker clearance, according to the manual, of up to .008" is OK. I checked my clearances when I built my engine and came up with zero clearance on two arms and .0015 on two on the arms.
If an aggressive cam ramp is making a stock, quiet valve train noisy then the rockers on your engine might worth measuring for clearance. But, you checked with S&S and elsewhere and said this is a quiet cam, so, I suppose it's your call now.

 

In case you don't have them, the part numbers are: 17300069, 17300070. I would check availability before I started tearing the rocker boxes off. Surdyke had a price of less than $100 for both.

So, if you want find out if the adjustable rocker arms will solve the problem, you can pull the rocker boxes and release the tension on the valve train and measure with a feeler gauge the valve to rocker clearance. There should be zero clearance on all valves. If there isn't then the adjustable rockers should solve that problem. If you had your head refreshed when you did the cam, then it is possible the technician didn't set the valves up correctly. The other things that could happen would be a faulty rocker arm or just wear. I've included a link that gives some insight into this.
https://www.fixmyhog.com/video/m8-ad...r-arms-017915/

 

wow I didn’t realize they were that cheap. I thought I was going to have over $500 in doing adjustable rockers. Thanks. I’ll definitely pull the rocker boxes and check mine for sure now.

 

Well it's going to be $200 because its $48.08 for each rocker.

 

I imagine it’s like everything else; you need two of each part number to do both cylinders?

My front cylinder has had a little more singing than the rear since new. Makes since seeing as how the stock rockers work.
Good info!