Hi guys, just like everybody else before me, I am doing a flat tappet to hyd. roller retrofit on my MAF EFI 327. I know I need a thrust bearing and a thrust button. I have a custom grind 0.495/0.530 220/230 hyd roller cam that was intended to go into an L98 TPI car.

Do I use my double roller timing set from my flat tappet cam (I think I have to grind the dowel shorter?) or must I upgrade to a timing set designed for a roller cam?

Thankjs

 

Anybody? I need to know so I can make sure I have all the parts ordered this week, so I can do the head and cam swap next weekend.

 

You DO need a cam button; you DO NOT need a thrust bearing.

If this is a pre-87 block, then you don't need any kind of special timing set. Any good-quality one will do.

 

Thank you very much for the info. I already bought the thrust bearing - it was inexpensive and I figure it's worth the insurance not to ruin the front of the block. I have a nice double roller timing set on the engine and it's great to know I don't have to replace it. The block is a '67.

 

A thrust bearing won't work unless you have the right timing set for it. Just sticking a thrust bearing behind an unmodified cam sprocket will make it misalign to the crank sprocket. Meaning, if you have a timing set now and it works, then you would HAVE TO replace it in order to use the thrust bearing.

You don't need it anyway.

It's not "cheap insurance" against anything. What do you think a flat tappet setup uses? How many blocks have you ever seen "ruined" by the same kind of timing set setup that you have RIGHT NOW? The design of the lifters doesn't somehow make the front of the block more fragile. In fact, since roller lifters don't add to the force tending to pull the cam into the block (loading the thrust surface) as much as flat lifters do, a roller setup will produce LESS tendency to damage the block, if anything, compared to what you have now.

 

As I understand it, flat tappet cams are cast, so the hardness of a flat tappet cam is more comparable to the hardness of the block. Yes a roller cam will exert less pressure on the block, but the billet roller cam has a higher surface hardness than the cast steel block and can therefore eat through the block with less effort. I know I am splitting hairs here but that makes sense to me.

LOL thanks for pointing out I can't use the bearing. I just bought it too, it's in the mail.

 

What does the hardness of the cam have to do with anything? At no point anywhere in the engine does the metal of the cam touch the metal of the block. It's the thrust face of the timing gear that rides on the thrust face of the block.

 

Hmmm, good point. Then why are companies trying to sell me a thrust washer?

 

Iunno.... to get your money maybe? Just a thought, I could be wrong though.

Although, if you DO go through the necessary machining for it, it would be a good idea. But if you have to pay somebody to machine the cam sprocket, then the cost of the regular timing set, plus the bearing, plus the machine work, will almost certainly exceed the cost of just buying a set already made that way.

Such as http://store.summitracing.com/partde...RN%2D11992%2D1 for example

See the thread also going on right now where I posted a pic of a sprocket purchased with the bearing provisions, and the bearing already installed from the factory.