I just replaced the stock cam with a ta 212 and am using the stock timing chain cover. Is installing a cam bumper a definite must? I'm not racing this car, just going for ice cream. Its finally coming together Thanks again, john
Only need a cam bumper if using a solid or hydraulic roller cam. A flat tappet cam has a lifter rotating taper ground into it. This also pushes the cam rear ward.
Gary, why did the factory stamp a cam bumper into the timing cover? Why did the V-6 use a spring-loaded cam bumper--the later ones using a roller bearing, the earlier ones using a nylon button? Best, Ranger Aiken, SC
No, Larry, I realize that. I am talking about flat-tappet cams that had them--as many of them did. Ranger Aiken, SC
Car manufacturers don't spend money on something, even little things unless they are needed. Cam bumpers are there to prevent the cam from thrusting forward. Flat tappet lobe taper normally pushes the cam back into the block. Maybe they had it in preparation for roller cams, don't know.
Gary, That's true, they seldom touched. Yet that was the exact point of an article in the GS-Xtra (circa 2001?) where Richard said the factory cast-in bumper was useless. He recommended building up the bumper, by welding on the aluminum, and then grinding it down so you had no more than .010" movement forward (forgot the exact spec he suggested). My dad's odd-fire 3.8 from '76 had a spring-loaded nylon bumper to prevent forward movement. Bad design, as it ground a hole into the inside of the timing cover, and plenty deep! At some point, and certainly for the GN, Buick had a "proper" design of a roller needle bearing instead of the bull-crap (bore drilling!) nylon bumper. Jim Bell, being the marketeer that he was, sold the needle-bearing bumper as a KN design when, in reality, it was just a re-boxed GM factory part. The GN had a flat-tappet cam; not sure when the great 3.8 V-6 went to roller cams, but pretty sure they did at one point. Maybe someone can find the aforementioned article from the GS-Xtra? If not, I prolly can. Best, Ranger Aiken, SC
I think that's the one I was thinking about, Larry. I didn't wanna go thru all that work so I just took my cover to a welding shop, had them build up the factory button, and I ground it down. Kinda does make sense about the excess wear, esp. w/ the hi-volume pump. Thanks for looking! Best, Ranger Aiken, SC
Looks like the author of the article didn't think things through. Both the forces from the oil pump and lifters (flat tappet) act to push the cam rearward into the block when the engine is running. A bumper is not needed.
The V6 has alternating forces imparted on the cam from the lifters (unlike the V8), so they end up being neutral. Only the oil pump drag is forcing the cam back.
Scott, why is that? Are the lobes not tapered and lifters not crowned? The V6 has the front mounted oil pump. What's different about the V6?
Then why was a hole bored in my dad's '76 Regal, about .200" from the nylon bumper pressing against the cover? And why would the factory have put it there, since they don't spend a dime they don't have to? Ranger Aiken, SC
