cam shaft???...

[wedgee]

Its been 40+ years since I rebuilt a big block and from here to back then, I've completed a couple of small blocks (318,340)... I'm sure I'm over thinking this but,in the "A" blocks, they have a "thrust plate" to hold the cam shaft back into its home...What does the "B" block have to accomplish this, I can't get my head around this....Help...

 

[RemCharger]

The cam gear doesn't allow it to go backwards. The lobe tapers don't allow it to go fwd. There has been some posts about this. But that's the nutshell

 

[wedgee]

The cam gear doesn't allow it to go backwards. The lobe tapers don't allow it to go fwd. There has been some posts about this. But that's the nutshell

so..the lifters after being worn alittle, wont even turn in their own holes I'm assuming...interesting. didn't realize the cam was tapered. so the "plug" at the back end is just there, plugging but not touching..

 

[wedgee]

DING!! yep, it all came back. Thanks

 

[bigbluedodge]

I think the taper on the camshaft keeps the lifters turning in the block their whole life.

 

[440Coronet500]

B/RB engines have the distributor in the front of the engine. Due to the rotating cam/intermediate shaft the cam is thrust rearward hence, no need for a cam thrust plate. 440'

 

[HawkRod]

so..the lifters after being worn alittle, wont even turn in their own holes I'm assuming...interesting. didn't realize the cam was tapered. so the "plug" at the back end is just there, plugging but not touching..

As @bigbluedodge stated, the taper in the camshaft keeps the lifters rotating. Any flat tappet cam has this. It also puts a force on the cam backwards that helps keep it in place

B/RB engines have the distributor in the front of the engine. Due to the rotating cam/intermediate shaft the cam is thrust rearward hence, no need for a cam thrust plate. 440'

Agreed - until you go to a roller cam. A roller cam has flat lobes, so the cam CAN move forward. When adding a roller cam to a big block you need to add a cam button that contacts the timing chain cover and give it about .010" clearance.

 

[TorRed]

Agreed - until you go to a roller cam. A roller cam has flat lobes, so the cam CAN move forward. When adding a roller cam to a big block you need to add a cam button that contacts the timing chain cover and give it about .010" clearance.

I'm going with a Lunati roller in my 383, can I go ahead and buy a cam button that will work or do I have to wait and measure something? If I can go ahead, can you tell me what's the best cam button for my application is?

Thanks,
Jim

 

[HawkRod]

I'm going with a Lunati roller in my 383, can I go ahead and buy a cam button that will work or do I have to wait and measure something? If I can go ahead, can you tell me what's the best cam button for my application is?

Thanks,
Jim

You have to measure, and then shim the cam button behind it to get the spec (about .010") you need. But you need the cam button to start with.

The cam button contacts the timing chain cover, so you should really add extra support to be sure it doesn't flex. Some guys may say that is not needed, but I would rather be SURE it doesn't flex. Here is a recent one I did by simply welding a washer to the cover. Don't go crazy with thickness, as there still needs to be room for your water pump housing!

Good luck!

 

[TorRed]

Awesome, thanks for the info!

 

[RemCharger]

As mentioned, test the waterpump fitment and clearance after the endplay is set and cover fully installed. I have done slight grinding on back of w/p to just barely touch. Gives it some strength