Roller cam conversion a different way, is this possible ?

[Rusty67]

Ok, so I'm kind of ignorant as to how much meat is on the internals of engine blocks. I don't really know much about the different castings. What I do know is that the physical size of the cams used did change at some point. Is it possible to machine a block so that it can accept the larger/more modern cam and cam bearings ?

Also, I know that the roller cam motors have bosses cast into the block that are drilled and taped with threads for the "crab tray" or what ever you want to call it to retain the roller lifters. Is it possible to modify a block to make this stuff work ? I figure it might cost more at first but servicing the block with new parts would be a lot cheaper in the long run.

Am I crazy for thinking this could work ?

 

[D.Hearne]

You've been misinformed. The factory 5.0 roller cams fit the earlier blocks fine, the problem is the lifter bore bosses, the flat tappet block bores are shorter than the roller block bore bosses. This is why you must use a reduced base circle cam with a the stock style roller lifters in a flat tappet block, this lets the lifters ride lower into the bore where the oiling bands aren't exposed. Or you can go the other route and use the std base circle cam and Crane's link bar lifters, there's nothing to modify this way, but the lifters cost you over $400. Either way you go, the total cost for a roller cam in a flat tappet block is close to $600. With the reduced base cam, the cam cost's you more, about $200 more than the off the shelf 5.0 cams. Plus the custom length pushrods for this. Crane has a set of off the shelf rods that work with the link bar lifters.

 

[69gmachine]

You didn't mention if you're working with a 302 or 351W. 302 roller blocks are so readily available I wouldn't waste time or money on a conversion. If you have a 351W and want a hydraulic roller, you can use a reduced base cam. The pushrods will be 7.8" for a 9.5" block, and most Windsor style heads. If you use a standard size cam, use 7.7" pushrods for Windsor heads. There is enough meat to drill and tap retainers for the spider, but I would recommend using one of the aftermarket link bar lifters from either Crane, Comp Cams or now Edelbrock. Although I don't have conclusive evidence, when I over revved my engine I bent 6 of the eight intake pushrods using OEM roller lifters and spider. I think the reduced base circle cam may be the culprit. Anyway, I'm not taking any chances this time. I bought a regular off the shelf hyd roller grind and the Comp Cams version of the link bar lifters. The 7.7" pushrods fit perfect (same size as in the FRPP catalog for a hyd roller 351W). BTW, 7.8 is the stock small block Chevy length, and 7.7 is a shelf stock .100 undersize. Also, you can get a reduced base circle hyd roller from Comp Cams for the same price as a shelf stock hyd roller cam. If you decide to go reduced base circle, I have two, one is brand new in the box. You can PM me for the specs if interested.

 

[chromedog]

85 and later 351w blocks are roller cam compatable... the casting number behind the starter is f5te

 

[Rusty67]

You didn't mention if you're working with a 302 or 351W. 302 roller blocks are so readily available I wouldn't waste time or money on a conversion. If you have a 351W and want a hydraulic roller, you can use a reduced base cam.

I'm asking because I'm geting a 351w for free but its a 69 block so obviously I can't just stick a roller cam in it without some special considerations.

I wouldn't use a reduced radius cam simply for the reliability concerns. That much torque going through a physically smaller part scares me. I assume that the difference between the roller and non-roller 351w blocks is the same as the 302 blocks ?

 

[dennis112]

85 and later 351w blocks are roller cam compatable... the casting number behind the starter is f5te

Wrong. 351w roller blocks did not appear until late 93/94. My 89' 351w block is not factory roller compatible. No enlarged lifter bores and no bosses in the valley to bolt the spyder retainer bracket.

The casting # of a factory roller capable 351w block is F4TE. Not all F4Te's left the factory with a roller, but the block still has the taller lifter bores to accept them. Additionally, not all 94+ castings are rollers, but the F4TE is pretty much a sure thing.

Note that any block can use the Crane retro-fit link roller lifters. That is an expensive option, but it is certainly the best overall solution.

 

[mrfomoco]

I did the roller conversion myself. It really isn't that scary, especially for the benefits if you ask me.

 

[351carlo]

Maybe he was confused with the 85/95 or he typo'd? I mean F5TE tells you right away it's a 1995.

Everything has already been said that needs to. I don't like the idea of a reduced base circle, but it could just be me. I've heard some bad stories, but I've also heard some link bar lifter failure stories too. That said, I run a solid flat tappet so I don't have those worries