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Cam thrust button info needed

Hotrod46

Hotrod46

Member
I am installing a retro-fit roller cam in an older Chevy 350. I know that I will need a thrust button. The aluminum ones seem to be prone to galling and the roller versions have been known to come apart and send needle bearings through the engine.

What about the nylon buttons? Do they have any drawbacks? If they do, I haven't read of any. Comments or opinions needed since I have little experience with roller cams.

Right now I'm leaning toward the nylon.

Mike
 
HR46, the nylon hold up pretty good and are alot more forgiving than the rest. Alot of folks have trouble with them, (the others, not the nylon), and they can be finnicky as hell. I mostly run them with aftermarket covers that are made to adjust then, like in the Coyles, theres others. One such is the rear cam plug ones that work with the thrust plate at the front of the block. Its a good setup, but is labor intensive....
I like simple and can't go wrong setups....since its easy to replicate results easily....
 
Thanks Screaming. I like simple too.

I would have liked to have used a factory roller engine, but I had this crate motor from another project. Less than 10K miles with great compression. I've heard too many stories lately about people wiping cam lobes. Not from the internet either. These were running engines that had been in use, not new fire ups. Since I don't have any history on this engine, I decided not to take a chance.
 
To be honest, I've never seen a roller button come apart. Which isn't to say they cannot or will not, obviously. As for them coming apart and scattering needle bearings everywhere, I've seen plenty of roller lifters come apart, so there you have it.

If you are running a button, of any design, I recommend using a reinforced timing cover, as some of the <cough> 'less expensive' (<--- was that P.C. enough?) covers will easily deflect.

SM, did you ever use any of Isky's 200-96-ACW anti walk kits? They were a bear to get installed the first time, but with the Torrington thrust bearing behind the gear and the roller button up front, they worked nicely. We ended up moving to the Comp 3100TB, just because they were so much easier to install.
 
SM, did you ever use any of Isky's 200-96-ACW anti walk kits? They were a bear to get installed the first time, but with the Torrington thrust bearing behind the gear and the roller button up front, they worked nicely. We ended up moving to the Comp 3100TB, just because they were so much easier to install.

Yea Mike, those are a bugger bear if you've never ever installed one before! hahaha....measure, disasseamble, remeasure, disassembble.... about the 5th or 6th time....

Alot of folks have trouble, and they mess up by not doing it correctly in the 1st place. The 1st thing is just as you said, a non flexing timing cover. Where alot of them fail, is trying to get the endlash too tight, just gotta control it. And fit the cam, then, get the distri. endlash set, then double check it all again....
People seem not to realize that one affects the other.
 
Thanks Mike. All my experience is with flat tappet cams, except for the engine in my T (factory roller block) so I'm trying to learn all I can. I just don't build enough engines to get even a tiny fraction of the hands-on experience that you and Screaming have.

I figured the cheap covers were not the best. I looked at the Milodon billet cover and a Cloyes that I believe had a button and adjustment built in.

Going roller definitely isn't cheap, but based on what I'm hearing, it looks like it's the best option to avoid the current problems. To be honest, the engines I heard about were limited use cars that spent a lot of time sitting. I'm thinking the oil drained off the cam and every time the engine was started it was pretty much a dry start. Too much to ask of oil with very limited EP additives, but probably OK for a daily driver. Just my opinion, but if that is the case, then most of our hot rods fit the limited use description.

Screaming, I may bother you and Mike for more info when I get around to setting the clearance.

Mike
 
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Simple solution to oil drain off. Replace one quart of regular oil with a full synthetic oil of the same weight.....
This will do the same thing as if all the oil was synthetic. The function of synthetic is to stay on the various moving parts that require lubrication, especially at start up.
Synthetic oil stays put where regular non synthetic will drain off. Some additives such as Lucas also do some of the same....
This helps prevent the lose of oil on the small needle bearings and roller bearings in above mentioned parts.

I have never had a roller cam bushing come apart and I have used them in numerous High RPM Nitro engines as well as other racing engines.

Make sure you have the proper clearance between the button and the back of the cover. Varies so do your research.

Either grind off or shim the button for the proper clearance. Yes reinforcing is highly recommended. Best is a cast cover that has the provisions for a fuel pump drive.
Block off cover makes it easy to check for proper clearance and also provides adequate support.
 
Screaming, I may bother you and Mike for more info when I get around to setting the clearance.

Thats what we're here for, to be of some help to someone....

Like Nitro said, the old Crower, Mickey Thompson, Hilborne covers had the pump attaching to the cam at the cover, which makes them unique for setting up cam buttons. Theres still a ton of those old things around the swap meets, I love the finned alum ones....I grab them for every motor I might even think about messing with.
 
Thanks for the all the replies. I think have enough info now to order everything and get the right stuff.

Nitro - The synthetic mix sounds like a good idea. I think I'll give it a try.
 
In my opinion, and I am wrong a lot of the time, the problem is not with the button or even the cover. When we stopped using the monster high pressure ,high volume battleship pumps that everyone else said was required lots of our problems disappeared. If you don't think your mega oil pump turns hard just listen and watch your drill when you preoil it for the first time.Imagine the pressure on the cam at road ,let alone 6000 rpm, your drill is not even running at idle speed. At every start up and while running, any parasitic drag on that oil pump forces that camshaft towards the front of the engine. Do this long or often enough and you will have problems . Best of luck.
 
joecool said:
In my opinion, and I am wrong a lot of the time, the problem is not with the button or even the cover. When we stopped using the monster high pressure ,high volume battleship pumps that everyone else said was required lots of our problems disappeared. If you don't think your mega oil pump turns hard just listen and watch your drill when you preoil it for the first time.Imagine the pressure on the cam at road ,let alone 6000 rpm, your drill is not even running at idle speed. At every start up and while running, any parasitic drag on that oil pump forces that camshaft towards the front of the engine. Do this long or often enough and you will have problems . Best of luck.
Click to expand...
Yassar !!! My dear ole pa in law [ may he RIP] told us young bloods idiots years ago those HV & HP oil pumps were nothing but a waste of time & money that could be better spend somewhere else to go faster. He said build it right with proper main and rod clearences and NO WORRIES DUDES!!!! It took us idiots awhile but he was right.
 
bigblk1177 said:
He said build it right with proper main and rod clearences
Click to expand...

I read an interview with a NASCAR engine builder several years ago (can't remember who now) about their switch to tighter clearances and thinner oil. They picked up several horses in reduced crank windage, scavenge pump loads and oil drag in the bearings. Bearing life went up too, but that was probably due to better oil technology.
 
Reduced rod journal diameters figure into that equation, too.

It's hard to believe the differences in motor oils, until you actually see it on a dyno. My former employer ran an IHRA Pro Stock car for a few years. He had built a new 800 inch motor and had pretty well squeezed out everything without taking stuff apart and tweaking the heads and intake. He drained the Pennsylvania dino oil and filled it up with a synthetic. No other changes were made. Bang, first pull netted a gain of 13 HP.

We ran some different oils in the Comp car. The car was fast, so we ran it heavy and on dino oil. Once eliminations started, I always knew I could pull weight out, or start changing to the other oils. One of the standard synthetics would net us .07, so you always knew an oil change would bring in another half-tenth, plus.
 
Most of our drag engines we try to keep the oil off the cyl. walls as much as possible. We do this so we can run low tension rings. The hi-pressure /volume pumps push so much oil out of the rod/crank journals and a lot of that ends up on the walls. Low tension rings help h.p. #s a lot. There is a lot of misinformation out there on lube systems. Our race motors run 30 to 40 lbs pressure and idle at 10 lbs or less, but everything has to be right on the inside.
 
I have used several of the Comp cams ones and have never had a problem the first roller cam system I did didn't run very long I did not change the gear over to bronze.
 
I guess I should update this thread. I went with a Cloyes cast aluminum cover that had a roller button built in. It was very easy to setup since a slender dial indicator tip could be inserted through one of the cover bolt holes. The end play adjustment is in the cover, so all you had to do was watch the indicator and set what ever end play you want.

The cam I used is a Howards roller cam that uses a stock distributor gear. I verified this with a call to Howards.

I haven't had a chance to finish getting the engine back in the car, though, so I can't comment on how well it runs.

Mike
 
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