can we use a cam button?

[ed hess]

This motor came without a cam in it when i bought it so i never saw how it would look if it was installed. The thrust plate was there.

Looking at the pics in the service manual i dont see any cam button.

This cover i bought came with a cam buttton.

Do we need one?

Would we benefit from its use?

ed

 

[dgoodhue]

Re: can we use a cam button?

As far as I know, cam buttons are for using a roller cams in a non roller
block.

 

[jwaller]

if it has a thrust plate then it doesnt use a button. but you can leave out the thrust plate and use a button...but....I would use the thrust plate.

 

[Christian Dionne]

Cam buttons are for Solid Roller cams with no taper on the lobes to keep them from moving forward. Stock Hydraulic Rollers have this minor taper, and do not have the tendacy to walk to the front. As for using one, I'm not sure if its ok or not, might call Comp or Crane and ask. I'm sure some people here might know better.

 

[myclone]

wallyworld is right.. If you use the cam retaining plate that comes stock you dont need the button. If you ditch the retaining plate you will need the button.

Using the stock retaining plate is easier/more simple and works fine.

 

[Lynn D. Brown]

Cam Buttons

Cam Buttons

While we R talking about Cam buttons, the Regals, GN's - G bodies - come stock w a Cam button on a Hydraulic flat Cam. Unfortunately it rubs against the Al Front cover and tries to wear a hole in it. Another F'up by GM.

I was surprised to find nothing when I took the Ty block apart.

 

[myclone]

Re: Cam Buttons

Re: Cam Buttons

While we R talking about Cam buttons, the Regals, GN's - G bodies - come stock w a Cam button on a Hydraulic flat Cam. Unfortunately it rubs against the Al Front cover and tries to wear a hole in it. Another F'up by GM.

I was surprised to find nothing when I took the Ty block apart.

The buick uses a hyd flat tappet cam which has a taper on the lobes to spin the lifters in their bores but this taper also tries to force the cam out of the front of the block due to the pressure from the valve springs. This necessitates(sp?) the cam button to keep the cam in place to properly spin the lifters and not wear out the timing chain from being ran while out of alignment with the crank. Sytys have a roller cam which the lobes have no taper and roller lifters do not spin in the bores (if they did it would be VERY bad). All the stock roller cam retaining plate does is keep the cam in proper orientation for the lifter/lobe interface and keep the cam gear/dist gear in the proper relation.

A cam button and cam retaining plate do the exact same thing only they go about it in diff ways.

 

[ed hess]

myclone
very good explaination
thanks
ed

 

[Lynn D. Brown]

Cam Buttons

Cam Buttons

Very interesting info background on Roller vs Flat Cams.

So, does the Ty Roller Cam rub against this front retainer plate ? I just looked at my plate and don't see any wear after 100 K. Surely the cam is held tight so it does not move around ?

This brings up another interesting point. I put an ATR Roller Cam in my GN, and I guess U still need to use the button to keep the Cam from moving. The stock button has no bearings in it, so it wears on the Al front cover - one of the design flaws in the 3.8 L engine. There is an aftermarket button that rides on bearings, but it is a teensy bit longer (~¼" or less) than the stocker. Well when I tried to use it, I guess the Roller cam must be a teensy bit longer than the Flat one, because when I cranked down on the Al cover, I cracked it - Was I pissed !!

 

[myclone]

Re: Cam Buttons

Re: Cam Buttons

So, does the Ty Roller Cam rub against this front retainer plate ? I just looked at my plate and don't see any wear after 100 K. Surely the cam is held tight so it does not move around ?

Not really per se. The mesh of the dist gear and the cam gear actually try to push the cam out the back of the block but the timing chain gear on the cam keep that from happening. IMO the retaining plate is there to keep the cam from walking forward should something out of the ordinary take place during the life of the engine. Also once the cam gear/dist gear get a bunch of miles on them they will develope enough wear which may allow the cam to move forward at times.

So, IMO the retaining plate for the roller cam in a stock application is more for piece of mind for the manugacturer. A .75 part will keep them from a barrage of warranty claims to replace timing chains, cam shafts, lifters, etc.

This brings up another interesting point. I put an ATR Roller Cam in my GN, and I guess U still need to use the button to keep the Cam from moving. The stock button has no bearings in it, so it wears on the Al front cover - one of the design flaws in the 3.8 L engine. There is an aftermarket button that rides on bearings, but it is a teensy bit longer (~¼" or less) than the stocker. Well when I tried to use it, I guess the Roller cam must be a teensy bit longer than the Flat one, because when I cranked down on the Al cover, I cracked it - Was I pissed !!

Not to sound like a wise ass but in the world of internal engine clearances a 1/4" is equal to a mile. Engines are set up with internal clearances in thousands of an inch so "a 1/4inch too long" is WAY too long. You coulda prolly had the cam button shortened easily by a machine shop and been fine. Its not a high stress component so just chucking it in a lathe and turning some material off would prolly have saved you a cracked front cover. Dont dispair though... If I had all the parts that Ive scrapped due to minor "hiccups" then Id need another house to store em all in. LOL