[lucifershammer]

I was taking my old Mark IV 454 that was in my Chevelle and re-gasketing and painting it so I could then drop it in my Z28. It was built by someone else long ago, with completely unknown innards, but I do know it has a hydraulic flat tappet cam and lots of RTV everywhere. And it leaked oil like a sieve.

It ran great, and had absolutely no respect for my rear tires, but had a goofy noise at the front of the engine when cold that would mostly go away (but was still there a little bit) that I could never find (I thought it was piston slap - until now.)

I pulled it apart, and found that someone had put a cam button in it (see pictures.) It feels like it's a button with a bearing in it. It turns freely, but is kinda loose. I'm thinking this was possibly my noise, and is also most likely completely unnecessary. All cam lobes check out just fine, compression is good, oil pressure is great.

Am I correct in that when I put it back together, I should just leave the button out? (Yes, I will be replacing the timing chain with a new double roller and also adding a cam bolt retainer. And yes, I'm 100% sure it is a flat tappet cam. )

 

[dyno jonn]

Cam button is not needed with flat tappet cams.

 

[lucifershammer]

Cam button is not needed with flat tappet cams.

Agreed. Since this is a completely unknown build, I just wasn’t sure if there might have some special magic thing that was once done that I didn’t know about that I needed to be aware of, or if this was someone that just put one in unnecessarily, so I figured it was safer to just ask.

Thanks!

 

[shovelrick]

Do you think it's possible the cam was "Walking" back & forth so the builder put it there to keep it in place? I know the HFT cam lobes lean towards the rear of the engine to prevent that but??

 

[billdini]

Well I had a 70 Vette with a 454/390 and I got a great price on it. Well those engines didn’t have much of an cam so I installed a Comp 280 in it. Well it certainly woke that engine up but after about 5 minutes it started making really bad noise. I tore off the intake only to find that my lifters in the back were hitting the adjacent lobes. Well I laid into Summit that their cam they sold me was defective. They put me on hold and 5 minutes go by and this guy introduces himself as a past GM zone manager and tells me they had machining issues with many Big blocks and actually had a template to measure the lifter bores. Well my number matching low mileage Vette lost a lot of cash that day. In any case I installed a front button and a bearing plate behind the top timing gear to lock it down. It seemed to work but I sold it pretty quick. I suggest you look down all lifter bores and see if the cam lobes line up with All the bores. Mine got a little worse as the bores went back. Hope I am wrong for your sake.

 

[shovelrick]

Bill that would explain it being in there

 

[billdini]

Bill that would explain it being in there

I hope for Steve’s sake I am wrong but this guy said they replaced a lot of engines because of it. Mine had already been apart with all the goop around the gaskets. It’s possible it could have been ok with a true roller cam but the pushrod angles would be off making it need offset bore bushings and blueprinting. Big$

 

[lucifershammer]

Given that horror story Bill - I suppose I could just pick up a new nylon button and put it in. Should not be necessary, but won’t hurt either.

 

[billdini]

Given that horror story Bill - I suppose I could just pick up a new nylon button and put it in. Should not be necessary, but won’t hurt either.

Steve this Vette had 20k miles on it and someone had already got into it. The problem with the lobe and lifter not sitting correctly they may not spin and lifter loss will be pretty quick. The Zone guy said my only option was to install bore bushings and remachine true center. If it is my issue I would see if a roller cam would fix it. However your lift and duration will be different from the front cylinders compared to the rear cylinders because of the angle between the lifter and rocker. Hopefully I am just wrong like my wifes says I am all the time

 

[lucifershammer]

As I mentioned, I had no problems at all with the engine, other than Valdez like leaks and a strange squeaky like noise toward the front of the engine that we could not find, but sounded suspiciously like a tiny bit of piston slap. I’m thinking now that there was a possibility it was the bearing in that button.

I’m not changing the cam or anything, just going to clean it up and drop it in and let it continue to show disrespect to my tires. While I’m here I will put on a new timing chain and I suppose a new nylon button for the “just in case” factor since it had a button there before and it won’t hurt.

If it is unhappy, it comes back out and gets a more serious going through. I need to do it to test fit a big block in the car anyway to get it setup for it, so I was cleaning it up just in case it doesn’t have to come back out anyway.

 

[68Chevele]

Do you think it's possible the cam was "Walking" back & forth so the builder put it there to keep it in place? I know the HFT cam lobes lean towards the rear of the engine to prevent that but??

That's why I run them with my flat tappet cams. Never had any noises or problems with them.

 

[Diabel1969]

I've run them in many small blocks, including the one in my Malibu to stop cam walk. May not be needed, but it's cheap insurance and doesn't hurt anything..

 

[billdini]

That's why I run them with my flat tappet cams. Never had any noises or problems with them.

I've run them in many small blocks, including the one in my Malibu to stop cam walk. May not be needed, but it's cheap insurance and doesn't hurt anything..

My machinist is adamant about buying a reinforced timing cover or he wouldn't guarantee the engine build but that is with my new roller. Installing one on a roller cam according to him without a reinforced cover is a waste since the cam will move anyway. On a flat tappet the convex shape on the lifters keeps the cam centered and allows for the lifter to rotate on the lobe. Roller cams have nothing to keep them centered except for the button and sometime the bearing plate behind the top timing gear. Because of the need for the flat cam to center itself IMO you might be doing more damage than good.

 

[68Chevele]

My machinist is adamant about buying a reinforced timing cover or he wouldn't guarantee the engine build but that is with my new roller. Installing one on a roller cam according to him without a reinforced cover is a waste since the cam will move anyway. On a flat tappet the convex shape on the lifters keeps the cam centered and allows for the lifter to rotate on the lobe. Roller cams have nothing to keep them centered except for the button and sometime the bearing plate behind the top timing gear. Because of the need for the flat cam to center itself IMO you might be doing more damage than good.

I use a small piece of angle iron with holes on each side, I weld a thick washer in the middle and adjust it so the cam can only move .005 when testing the cam movement back and forth. Has worked out great so far.

 

[billdini]

I use a small piece of angle iron with holes on each side, I weld a thick washer in the middle and adjust it so the cam can only move .005 when testing the cam movement back and forth. Has worked out great so far.

There is always more than one way to skin a cat. If it works it works...

 

[BillK]

Used to be very common practice to keep the cam from walking back and forth. If it has been working ok why mess with it ? If anything I would switch to a solid teflon one. I have seen the little roller bearings come apart in the type you have now.

 

[lucifershammer]

Used to be very common practice to keep the cam from walking back and forth. If it has been working ok why mess with it ? If anything I would switch to a solid teflon one. I have seen the little roller bearings come apart in the type you have now.

Thanks. That’s exactly my plan. Just waiting for the new button to arrive.

 

[billdini]

Used to be very common practice to keep the cam from walking back and forth. If it has been working ok why mess with it ? If anything I would switch to a solid teflon one. I have seen the little roller bearings come apart in the type you have now.

Sorry Bill and I know you are a machinist but if you have a flat tappet cam walking back and forth there is an underlying issue causing that. How would you know it is walking back and forth and excessive movement could cause a lobe hitting a lifter.

 

[lucifershammer]

Update: Got the new cam button, and got the engine cleaned up, painted, and new timing chain/gears and retainer and button in place. I know it probably wasn't necessary, but it was 5 bucks for peace of mind. Thanks for the input everyone.

I also test fit the new low-rise intake. The carb does indeed sit about 1.75" lower than a Performer RPM does. I'll have to put a 1/4-1/2" spacer under the carb though, or else the transmission TV cable will hit one of the intake bolts. Otherwise the cab fits perfectly with no spacer or anything (so if it were a stick car, I could just cut the kickdown arm off the carb and be done with no spacer.)

And, yes, the engine is red. It is going into a black with red themed car, so the engine & water pump will be red, with black oil pan, balancer and pulleys.

 

[Stickman]

Update: Got the new cam button, and got the engine cleaned up, painted, and new timing chain/gears and retainer and button in place. I know it probably wasn't necessary, but it was 5 bucks for peace of mind.

Did you have to trim the button while checking end play to get your cover to fit properly ?? My machinist said BBC with a roller cam tends to walk backwards, and the SBC tends to walk forward, so he didn't feel a reinforced cover was necessary for my BBC build.