Rocker arm setup 94 vs 91

[ericsmith32]

Okay I know this had to be covered but I didn't see anything. Is there a advantage to running the 94 roller rockers over the 91 roller rockers. The only difference to me was that the 94 had crapy plastic spacers that break easy where the 91 had springs to keep them in place. What's the deal? I've thought about putting the rocker setup from the old 94 on the 91's motor that's in the aspire currently, I think a couple hla's are stuck currently.

[mechanicaldj]

i believe the cam is different in composition and i think you still have HLA's in the roller rockers.

[FB71]

91 Festies didn't have roller rockers. 90-93 Festies have hydraulic lash adjusters, but are flat-follower. The 94-97 Aspires had rollor rockers and hla's. 88-89 Festies had flat-follower, mechanical lash adjusters. And in over a decade of working on Fords/Mazdas, I've never seen or broken one of those plastic spacers. In fact, I prefer them on mine. They don't side load the rocker and wear the head or add drag.

you need to use the correct cam for each rocker/follower. Mech vs HLA cams have slightly different lobe profiles, and roller cams are steel instead of iron, because iron will 'mush' out under the roller. Roller cam lobes are about half the width of flat cams, and the roller cams don't have a fuel pump drive lobe.

[ericsmith32]

There were two broken on mine, one I did the other by someone else. If you get them stuck under the shaft and tighten it they will break. On the lobe where the previous broken spacer was the lobe was wore off to one side, including the roller piece on the rocker. I'm wondering if someone did some switching not knowing what they were doing. Does the Aspire cam have a different profile? I guess if I decide to change it out I might as well use a fms cam.. that is if I ever hear from him or receive the part I ordered two weeks ago.

[FB71]

well, yeah, many parts will break if they're mis-assembled. I thought you meant under normal usage. I have never seen one just break during use. And if you had rollers on your 91, then someone did change them. That begs the question.... did they swap in the correct cam?.... It doesn't sound like it. And the FMS cam is designed for flat-follower HLA style rockers.

A flat cam's lobes are ground on a slight taper, so that the follower contacts as little of the lobe as possible. This is done to reduce friction. If you put a roller on that lobe, the taper will force the roller off to one side, sideloading the rocker against the cam tower or the spacer. That could cause the spacer to fail. A roller cam's lobes are ground parallel to the centerline of the cam, preventing any sideloading of the follower.