[cjoform]

Alright guys I have decided to switch to a hyd roller cam, which I should have went with in the first place. I get confused reading about what I need. I have an 89 350 that I had rebuilt, Dart Iron Eagle Platinum 200 heads, 4vr flat top speed pros. Anyway the block did not have the 3 holes in the lifter valley drilled but the bosses were there so I had my machinist drill and tap them in case I wanted to run a roller set up. Everything else is roller capable. The lifter bores have the flat step for the dog bones. I have a stock set of GM hydraulic roller lifters, spider, and dog bones that I pulled out of a low mile 5.7 vortec. I know I need different pushrods but what else do I need? I hear stuff about buttons, distributor gears. Is the button for the older block? Also from my understanding a little side to side play in the roller is acceptable correct? Thank you for help.

[joelster]

The button is called a "thrust" button. It goes onto the front of the camshaft and butts up against the timing cover. It prevents the cam from walking too far forward out of the block since you don't have a retainer plate like a factory roller block would have. An sbc roller cam also has a slightly smaller bolt pattern for the timing chain. You already have most of the pieces though. Cam, lifters, spider, dogbones, then you need pushrods, timing chain, thrust button, and springs.

[cjoform]

Is the retainer plate attached by 2 bolts? There are one on each side of the camshaft tunnel/bore. They are located right behind the timing gear. I have these, they were drilled and tapped and I wondered if that is what their use was. The springs I have are Howard and they are listed to work for flat tappet/ hyd roller.

This is a photo I found online. This is the retainer plate and where it attaches right?

[chucksrt]

are you sure they need thrust button? I have a factory roller cam and when I removed the plastic timing cover there was no button?

[cjoform]

I think he meant it needs a button if you dont have the retainer.

[joelster]

If you have a retainer plate then you don't need the thrust button.

[ssmonty]

There are at least two different retainer plates. The difference is the center distance between the bolt holes. I forget the specifics as to which is for what year, but you can find the info if you do a search on my posts.
FWIW
ssmonty

[ssmonty]

I searched my own posts for the heck of it.
GMP PN 10088128 retainer for 3.62" bolt centers
GMP PN 10168501 retainer for 3.294" bolt centers
FWIW
ssmonty

[cjoform]

Thanks for the info ssmonty. I have just about everything, just have to get a retainer plate, pushrods after I measure for them. I am pretty sure 7.2 in p rods will work since the stock hyd flat tappet p rods worked for the current cam but I suppose it is better to measure and know for sure. I also need the cam of course. What about the distributor gear? Do I need to get another gear? I have read some roller cams are compatible with the stock gear. I guess I should ask Comp before I order the cam. Again thanks for the help everyone.

[MouseFink]

GM introdouced a case hardened (melonized) iron distributor gear for the austempered ductile iron roller tappet camshafts and OE distributors, part number 10456413. That gear is also compatible with aftermarket austempered ductile iron hydraulic roller and flame hardened flat tappet iron camshafts. You should use a new distributor gear with a new camshaft.

Steel billet camshafts require a sacrificial bronze gear because an iron gear would eat up the steel billet cam gear in a few miles. Steel billet camshafts are only used with mega-lift solid roller and solid flat tappet cams. No hydraulic lifter camshaft is a steel billet.

[ssmonty]

Just thought I'd mention that the GM gear is for a stock distributor shaft diameter of .493" I believe. It won't fit a MSD dizzy(1/2" shaft). They have thier own melonized gear PN MSD-8561. Ask me how I know.
I also thought I'd mention that if you plan on going with a double row timing chain you'll have to do a little grinding.
FWIW
ssmonty

[MouseFink]

When I wrote "OE distributors" I should have wrote, "original equipment distributors."