I have a rebuilt 460 that I put in a 72 Ford Ranchero GT. This engine has a fairly mild hydraulic cam (218/228 with 505 lift that I installed 4 deg retarded to get a little more rpm from it). New lifters also. The block is a D0VE 4 bolt main block that I rebuilt due to loss of oil pressure resulting in some bad bearings. It has ported/polished DOVE heads with adjustable roller rockers. Also has an Edelbrock Performer Intake ,Edelbrock 750 carb, headers, and electronic ignition.

The problem I am having is noisy valves at low rpms. I initially had the rockers adjusted too tightly, resulting in no compression in any cylinders when trying to start it. I backed off the adjustment and got it started, but with some valve noise. I checked the compression on all cylinders today. I had 1 at 15, 1 at 90, 1 at 120, two at 130, and 3 at 150. I loosened the rocker adjustments on the low compression cylinders slightly, and now all eight are between 150 and 155. The problem is that some of the valves are noisy at low rpms. The noise goes away at about 2000 rpm and the engine is very responsive. Since I only loosened the valves slightly to get the compression up, if I tighten them to try to get the valve noise to go away I am going to lose compression again.

This engine sat for over six months with the lifters adjusted with the overly tight setting prior to starting, and I also cranked it quite a bit on the initial start before figuring out that the valves were too tight. I'm wondering if I may have damaged the lifters during this process (and possibly the cam lobes too), although the engine is very smooth and responsive now at anything above 2000 rpm. The engine has a new high volume oil pump and is showing around 60 psi from idle on up.

Any thoughts or suggestions on what I should do next to address the valve noise? I can change the lifters in an afternoon, but thought I would get some other opinions first. At this point, I have only run the engine for about 25 mins, to break in the cam.

Thanks
Chuck

 

What about oil flow, you getting enough presure to pump the lifters up.
Neil

 

Are you using stock rockers with that .505 lift? My 460 with a hydraulic cam has no adjustment on the rockers. You torque them to specs and that is where thay stay. The hydraulic lifters supply the adjustment. If you lose compression when they are torqued down maybe the lift is actually opening the valves (due to the rockers not being able to handle the lift). Another thing could be the rockers will hit the stock valve covers with too much lift as well, which will be noisy. One more thing that could have something to do with it would be coil bind if you used stock valve springs with that much lift. I have been told before that any more than .50 lift will do these things, with stock springs and rockers. These are just some thoughts I had, thought I would pass em along. Someone will be along soon enough, with much more experience than I have to answer your questions. Good luck.

 

Engine has high plenty of oil pressure; around 60 psi from idle on up, and when I remove valve covers I can see that oil has been flowing.

Engine has adjustable roller rockers and aftermarket aluminum valve covers that have plenty of clearance. Cam specs are not very much different than the previous cam, with which I didn't have any valve noise problems. Cam lift is pretty modest at 505. Heads are also equipped with dual valve springs.

I'm wondering if the problem is just a couple of lifters that are not pumping up at low rpms, but not sure why that would change and eliminate valve noise starting at around 2000 rpm.

Chuck

 

Ok so any of my questions were answered. Hey I tried...lol. I am wondering, (more for my education than anything else) why are you running a hydraulic cam and adjustable rockers. I do not know the advantages or disadvantages to doing this. Can you tell me the benefits of doing this?

 

Adjustable rockers were used in 1970/71 high performance CJ and SCJ 429 versions of the Mustang and Torino engines (maybe other years in that era as well), although I believe the SCJ had solid lifters vs hydraulics in the CJ. The D0VE block I have is a 1970 4 bolt main version of the big block used with those cars (although mine is cast with "460" in the block), and although the heads on my engine are not from a CJ/SCJ, they have been ported/polished and fitted with the larger valves and adjustable rockers used on those engines, but upgraded to steel roller rockers, and also use hardened pushrods, guideplates, and positive lock adjustments in the rockers. Adjustable rockers are generally used in higher performance motors and are a fairly common upgrade for non-adjustable valve trains. The upgraded roller rockers are stronger, more stable, less prone to wear, and the roller tips create less friction than standard rockers. Screw in rocker studs used in adjustable valve trains are also stronger and less prone to being pulled out of the head when used with higher lift cams than the pressed-in studs commonly used with non-adjustable rockers.

I'm only a car hobbyist and amateur engine builder and not an expert by any means on this subject, but my basic understanding is that the primary benefit of adjustable valve trains is to provide a stronger and more flexible base for upgraded cam and lifter combinations.

Chuck

 

Did you check and make sure you didn’t bow those hardened pushrods when you had those valves set up to tight? Just a slight bow could raise havoc.

 

Thanks to all who responded to my "valve noise" post.

I think I have my problems cleared up now. Part of the problem was that I just needed to let the engine run some more. Valve noise has pretty much gone away now, so I think maybe I had a lifter or two not fully pumping up, but appears to be ok now.

The other thing I found is that even though I had backed off on rocker adjustments until I had good compression on all cylinders, I still had them too tight. The engine wasn't idling as well as it should have, and after hooking up a vacuum gauge, I saw that the lower the rpm got, the more erratic the reading was, corresponding to an erratic idle. I readjusted all the valves again, backing off a little more, and everything appears to be good now.

While doing some internet research, I found out that over-tightening valves appears to be a fairly common problem. In my case, when I initially adjusted the valves, I incorrectly interpreted "zero lash" to mean "zero rocker arm wiggle room" and that's where I had the rockers at when I gave them a final half-turn of lifter preload. Obviously, (now I know!) that's too tight, and on that adjustment the engine wouldn't even start due to no compression.

I think everything is good now, but If I have any more questions on the valve adjustments, I'm gonna adjust the valves while the engine is running. I think that's probably the best way anyway for someone not really familiar with the static adjustment procedure, but since I have my engine compartment in pretty much showroom condition, including new jet-hot coating on the headers, I hated to splatter oil all over everything. If I decide to do this, I'll get a spare valve cover from a local junkyard and cut a hole in it so I can reach the adjuster nuts. That should cut down on some of the oil splash and splatter.

One other thing - I used a high zddp diesel oil for cam break-in, along with a bottle of cam break-in lube, so that may have played a part in helping keep my lifters and cam lobes protected better during the time I had the valves too tight.

Again, thanks for the responses.

Chuck