Have a marine roller 270 cam from comp cams. I have gone through and adjusted all valves to the 1/2 as everyone says. They seem to bleed off after 30 seconds or so and are loose again. Is this normal. Also, now I have what sounds like rockers hitting the valve cover. Doesn't make sense never happend before. Should I just add another gasket and go from there.

Thanks for all info...........

Kirk

Check your rocker arms. If you look at them some are shaped different (if they are orig Merc) Some are grounded off to clear valve covers and must be put back in original location. also make sure the flat part off the shafts going thru the rockers are faceing up. If they are not they will not stay adjusted and will eventually do damage. If this is your problem and the shafts or locknuts are damaged replace them now or replace them along with a lot of other stuff later

typically the end rockers will hit many different types of vavle covers. As mentioned above if they are the Cranes from Merc there will be four of them with the corners ground off slightly for clearance purposes. What kind of lifters did you intall? Also I would pull your valve covers and inspect the under side to see what or if anything is hitting. Also what kind of R/R's and valve covers do you have?

They are comp roller lifters, and proform roller rockers along with aluminum covers. Is it normal for the rockers to bleed alittle after adjustment?? My headers are Gil Marine so they wrap up over my valve covers. I really dont see and scaring from the rockers on the lifters....... It is very frustrating!!!!!!

Thanks for all your help

What procedure are you using to do this? On stock cams you can cheat a little. Bring #1 to TDC on the compression stroke, then adjust both valves. Turn engine 90 degrees and do the next one in the firing order. And keep doing this till your done.

But on bigger cams and the way I like to do it is get a remote starter switch. Bump the engine over till the exhaust valve begins to open, then adjust that cylinders intake rocker arm.

Then bump the engine over and when the intake almost closes adjust the exhaust rocker on that same cylinder. Good Luck.

My morel roller lifters were noisy when I set them to 1/2 turn. I had to go 1 full turn and they are quiet now. In days gone by I always set flat tappets at 1/2 turn with no pnoise. Rollers must have a different travel and need more preload to be quiet.

Slight highjack here, but my question also involves backlash adj, but for a 454, non roller version.. The more I look online, the more opinions people seem to have.. Of course with a marine motor, I really don't want to have to adjust while running, what a mess.. So trying to set them cold and non running..
I just bolted my covers back on after setting valves to zero lash, plus 1/4 turn. Is this too little? I have read that 1/2 turn may be too much as well. Would like opinions here as well. Also, as a side note, only doing this cuz heads were reworked, lower end is fine, with low hours, so lifters are not new. I too experienced some minor loosening ( was able to spin rod again, but no endplay)when looking at them the next day. I am assuming this is normal from some bleed down? I have not re-adjusted, but sure am tempted too. Would like to hear opinions please.
Thanks
Rich

I always do 1/2 turn.

The push rods are supposed to spin.

I have always gone 1/4 to 1/2.