I recently bought a Model A coupe from an elderly gent who had obviously put a lot of effort into the build. Its very well done. It has a 1966 327 with 461 fuelie heads and a Comp 268 hydraulic cam. He claims he rebuilt the motor and it has about 1300 miles on it. I found receipts in the paperwork I got with the car that indicate it was probably rebuilt 20 years ago. He finished the car about 10 years ago but rarely drove it and eventually heath issues forced him to sell it. It had always been kept in a insulated garage in a mild climate. He struck me as a good, honest guy who was just happy it was going to someone who really appreciated it. I did the usual change the oil and filter, new fuel and filters, etc. It runs well but the lifters are pretty noisy. I adjusted the lifters by going through the firing order on each cylinder at TDC and adjusted to zero lash plus 1/2 turn. All lifters were found to be at zero lash initially. It is quieter, but still pretty noisy. My question is - do you suppose the Comp lifters bleed off more quickly than stock and are therefore noisier? I have run numerous hyd. cams and lifters over the years and this is by far the noisiest. I don't want to just throw parts at it but I do want a solution. I have/and have had other sbc motors and never experienced this. I was going to try adjusting them while it's running, but the previous owner put roller-tip rockers on it and they are cast instead of stamped, so they are thicker and the clearance by the adjuster nuts is so close that you can get a socket in to adjust them statically, but while it's running and the rockers are moving, it just about yanks the ratchet out of your hands. Would you replace the lifters? With stock ones? Replace cam and lifters? Adjust them down a bit more? (I don't want to take a chance on bending the pushrods). Any other ideas? All insight is appreciated!!
I think you may have identified the problem. If I was going to change anything it would be those roller rockers. There's other possibilities too. Contact the previous owner and ask him if he used Rhodes Lifters. Another thing to check...Make sure the rocker studs are not pulling out.
F-One, Good insights! It has screw in studs that all look snug. I also wondered about Rhoads lifters. I had a set years ago and never again. If I replaced the lifters - what are your suggestions? Never thought of the rockers being the culprit. Are roller rockers typically noisy? Thanks in advance
My first thought was Rhoads lifters, they do sound a bit like a solid lifter. They were a big deal 20 years ago, at least in some circles and by the way, that Comp 268 cam is a sweet street cam, I had one in my 350 before I upgraded it.
I'm real conservative and I don't go past 1968 much. Those rockers are unknown. What ratio are they? I don't like the fact that you have trouble setting a hot lash with them. I fool with SBFs and Fords are nutty concerning rockers. What I would do is contact Comp Cams or you may can find it online. Comp Cams should have the card on the cam and be ready to give you all the recommendations concerning that cam. I would find out what ratio rocker they recommend and buy a set of their OEM style rockers. Maybe the roller rockers are OK, but again I don't like that you are having trouble with them. Another thing too, OEM style rockers just go with the 327. Ask Comp Cams about their lifters. Ask if this is a common issue. Does this engine have forged pistons? Forged pistons will slap until they get hot. They have their own unique sound. Could it be something else? Torque converter.. Fuel pump..something around the water pump and belts. Those may be longshots but you need to isolate where the sound is coming from and confirm it's not something off the wall.. Check the oil. Look for metal. You can change lifters but it is a risk. Never mix your old lifters and the new lifters...need to be new. I have had luck reusing a cam with new lifters, others have not. It worked out fine for me.
Make sure all of the rockers are getting enough oil. A friend of mine had a 64 Impala with a 327 . he did a stock rebuild and when he started it the rockers were all noisy .He called me over to look at it and it turned out that the cam bearings were not installed properly. I tried Rhoads lifters Once ! Never again. Not only are they noisy, but I had one pump up solid with no cushion from the hydraulic function of the lifter. It was like adjusting a solid lifter to zero lash. Cost me a Comp 280 Cam and a lot of work to pull the motor and get all of the debris out.
I don't have anything positive to say about Comp , the roller tip rockers are noisy . Some older valve covers don't have enough room to clear the larger rocker body ( pushrod end).
I've dealt with chasing valve train noises and after changing cams, lifters, rockers, etc. it ended up being loose guides. I'd get one of these https://www.napaonline.com/en/p/BK_...MI4_LP2ry76wIVlxatBh39RQfIEAYYAiABEgJdNPD_BwE and probe around the head while idling to see if you can isolate the noise. If its one or two valves, grab the retainer while the rocker is up and see if you have a lot of play in the guide.
Borrow or buy a push rod length checker and verify correct length is installed, I use Proform 66789 with the 3/8 rocker arm studs. A lot can change on a old 327 block & heads in 50 years, decked block, shaved heads after market rocker arms, ect. I also had this problem on a 350 when I tried an unknown brand of roller tip rockers that I picked up at a swap meet. Put the stock rocker arms on and it all went away, later put Comp cams magnum roller rockers in and it is quiet as a mouse motor should be
Man, Thanks guys for all your responses! Since posting I have identified the rockers as Comp Magnum Rollers. I didn't realize there was such a debate about the pros and cons of roller tip rockers. I think I will go the easy route at first and swap out the rockers for stock. I mean it's a street motor pushing a Model A. No need for overkill here. And Tikety Boo brings up a very valid point about all that can change on a 50 year old motor after it's been in the hands of numerous hooligans like myself! We'll see how the stock rockers do.
Years ago. I ordered Rhodes lifters to go with the new cam going in my OT Pontiac. The vendor said to not use them as the cam was not radical enough to justify the Rhodes lifters. The 268 is not that aggressive a cam. If indeed you have those lifters installed. Sent from my SM-G965U using The H.A.M.B. mobile app
Thought of some thing else that might be the cause, it was covered in a different hamb post (rocker stud flex) . If I can find it again, will edit it in here Got the same cam as yours in my 64 Chevelle and added a stud girdle because of rocker stud flex. If you can borrow a stud girdle nut (they are longer) it will show you how much the stock rocker arm stud bends @ .480 lift when turning it over with the starter, you will be amazed. Norb
Found It: Hydraulic roller lifter recommendation- USA made preferred, posted by flatoz After post #37, hamb member Montanal measured and found .013 flex on 3/8 studs, thought the flex was opening up the preload so he installed a girdle and ticking went away.
You might try running a thicker oil especially if you are using a synthetic. Sometimes a normal oil will tend to bleed off too quickly and the thicker oil film can prevent it. I have to wonder if the lifters made today have the same internal clearances as those made years ago.
Solved! It was the Comp roller rockers. I replaced with original style rockers and all the racket went away. Thanks F-ONE for being the first to suggest that. For once - an easy fix. Course now I see that the back of the intake gasket is leaking.....it's always something. Which brings me to my next subject for debate: Given that you can often buy a car for cheaper than you can build it, which is worse - sorting out the previous owners poor decisions or spending the time necessary to build it yourself the way you want it. I've done both. When I'm in the middle of one path I usually wish I picked the other!
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