Since Im running a late model EFI system, I have to have a crank trigger wheel, which requires a bit of effort to get to work with a double roller.

I thought of using an 87+ cam and timing set, which would leave enough space for a thrust bearing, but to my knowledge, nobody makes a cam button small enough to fit.

I can use my single roller, but it only has a standard thrust face. To my knowledge, there shouldnt be much difference between the roller and the flat tappet as far as load on that face goes. The majority of the load is from the thrust generated by the cam gear turning the oil pump, no? Obviously there will be a cam button, but that will be installed with clearance, and will add no load.

 

Hmmm. It looks like crower has a thrust plug for "late model" SBCs with a roller cam. I wonder if they fit the 87+ timing sets? That would dramatically increase the choice of cams, and solve the thrust bearing issue.

 

If you have an early NON roller block and are swapping to a roller cam, you must install a method to control the forward movement of the cam. As you probabl know the way to address this is to install a thrust button to the nose of the cam.

The forward thrust button can be ground to achieve the clearance you need.

in addition to that, a 3-piece Torrington bearing is often used to control rearward cam movement. Some timing chain sets come modified for the Torrington bearing clearance and are a true bolt on.

Not sure if this addresses your issue but I hope it helps.

Jake

 

Im aware of teh need for a cam button at teh front to limit forward motion, as there may be situations that could cause teh cam to move forward, and the wider lobes on the roller could spell disaster if the cam where to walk, and I do have a button and shim pack for installation.

My question is if the torrington bearing at the rear is really necessary? When in operatin, the act of turning the dist. gear to drive the oil pump pulls teh cam back with both flat tappets and rollers. This is why there is a machined thrust face on all timing sets. Even flat tappet cams do not move in operation as the force on teh cam gear keeps the timing gear pressed firmly on the block.

Ive heard most people say that a torrington bearing at the rear of the timing set is a must. But, to me, that doesnt really make sense as a roller should not change the loads on the front timing chain gear. Its certainly a nice feature, but in this case, it will be prohibitive to implement.

 

as I recall Im not too sure about the subject but any cam movement will alter your timing and thats why they used the button up front and the bearing in the back if im not mistaken.

 

I'll be watching this thread, I've had the same question for building up my motor. I don't get why the rollers are more prone to movement than a hydro flat tappet...

My build sheet for my 383 rotating assembly block says one piece rear main roller cam, but the guy I bought it from said that a rear bearing has to be put in if I wanted ot run a hydro roller cam but, I don't see what is different...

 

If its a roller block, and you have a roller cam, then you have a thrust plate behind the timing set, which limits the forward motion. The rear motion is controlled by the machined thrust surface on the cam timing gear, just like a flat tappet.

At the very least, it should have provisions for the roller stuff.

 

With flat tappets the lifters have 1 side just a tad taller so the lifter will spin in place. With all of them rotating like that it holds the cam in place. With roller cams the have flat even rollers that will allow the cam to walk. The problem is even a flat tappet cam will walk that's why Ford's engines have always had the thrust plate.

 

I think when teh engine is running, the cams in GM engines are almost always pulled to the rear of teh engine. The slight ramp on a flat tappet lobe along with the gear forces generated at teh cam gear are what hold it in place. The cam gear is likely what generates most of the force due to the torque needed to turn the oil pump.

Im probably going to just use the stock timing set with a thrust button if I cant get by double roller to work with the trigger wheel.

 

Gotchya, mind if I have a slight hijack? This is a good thread and think its still a relative question.

Is the rear torrington bearing you speak of only for those 86 and prior blocks trying to run a roller cam? Or is it something I should have in my 90 block? If it's needed, how can I tell if I need it?

And as long as I buy the thrust plate and install it, there should be no differences between running a non roller and a roller cam in a 86-92 block?

 

I dont see why anyone would consider it necessary. The small block Ford has been using a plate for an extremely long time, both with flat tappet and roller applications. GM only switched to a plate when they went to a roller cam. None of those have a bearing on the thrust face. So adding a cam button requires a torrington is a silly requirement if you ask me.

 

That was my thought, too. Ive heard the torrington bearing requirement parroted again and again, and I just wanted to make sure there wasn't something I was missing.

 

You will need the thrust plate and a factory roller timing set, if you dont already have it (gmpartsdirect has them, among others). The factory setups did not have any torrington bearings. Its something included with some of the aftermarket double rollers. Its a nice implement, as it limits wear. I know my last block actually accumulated a fair ammount of wear from the timing set over 100k, even with modified oil galley plugs that directly oiled the cam gear.

Off the top of my head, I think there are backspacing differences between non-roller and roller timing sets, but its been so long since I had a roller block... I cant really remember how much of a difference having the thrust plate made on the installation.

 

You need something to fill the recess on factory roller cam previously filled by the cam retainer plate.Some have just cut a stock retainer down or you can use this

http://www.lingenfelter.com/mm5/merc...egory_Code=C30