putting a flat tappet cam in a roller cam block?

July 8, 2003

anyone know if I can do this? I would like more choices for cams and they're a lot cheaper. The big issue I can think of may be the oil supply holes in the lifter bores, I don't know if they changed or not. also the cam companies talk about using billet steel instead of castings for roller cams, anyone know why? what is the reason for not running roller lifters on a regular hydraulic cam? presumably the surface finish would be different.

I'm talking about low mileage life expectancy hot street engines.

Perry

July 8, 2003

i may be wrong here, but when i was young, my dad explained to me that you cannot run roller lifters on a hydraulic cam because the hydraulic cams have a slight angle ground in them to cause the lifters to rotate a little every time the bump comes around, whereas on a roller cam, the lobes are ground square to properly make contact with the roller on the lifter. Again, I may be wrong, I would like to hear from grumpyvette on this. that way I'll know if im right or not.

July 8, 2003

Don't all 87-96 chevy v8's have provisions for roller lifter camshafts. But most of them still have flat tappet cams installed. So I would assume a block from those years would be fine. However, I don't know about 96 and up, as all the engines I know of came factory with hydraulic roller camshafts.

Anyone else have any other insight?

baddriver · July 8, 2003

I can't imagine why you would want to do this.

Sure, the cam is cheaper, but if you care at all about performance, the small extra price you pay for roller lifters/cam will make an unbelievable difference in power and mostly low-end torque. I am sure you can get a roller cam with any lift and duration you want.

If you are not interested in performance, why are you doing a hybrid swap?

forgive me if I have misunderstood your intention, but I think most people would be happier with the performance of a roller cam over the flat-tappet cam.

July 9, 2003

The cost of a flat tappet cam might be cheaper but when add the cost of lifters is it really that cheap? I think you can reuse your roller tappets. You should call the tech line of the cam company you plan to use.

Carl

80LS1T · July 9, 2003

i may be wrong here, but when i was young, my dad explained to me that you cannot run roller lifters on a hydraulic cam because the hydraulic cams have a slight angle ground in them to cause the lifters to rotate a little every time the bump comes around, whereas on a roller cam, the lobes are ground square to properly make contact with the roller on the lifter.

I think your right about that. I was thinking the same thing!

Guy

pparaska · July 9, 2003

If you have the OE roller lifters, the difference in camshaft price is worth the advantage of a roller cam. But if you have to buy the entire valvetrain for either, you can save several (3 to 4) hundred bucks running a flat tappet cam. Depending on the roller cam, it may have lazier valve action and less power potential than one of the newer Xtreme or Crane Powermax cams. This is especially true for 270 or less advertised duration, even some 280 adv. duration cams. Don't believe me, read Vizard's book on cams and valvetrains.

July 9, 2003

thanks for replies yall.

I haven't got the cams and valvetrains book yet, but it's on the list.

I think the tapered lobe comment is probably why you shouldn't mix the std cam with roller lifters. every sbc after about 87 that I have torn into (3 or 4) has had a roller cam in it.

I have a few cars around now that I'd like to do minor mods to but don't want to spend the cash on. a hydraulic flat cam and lifters can be had for less than most roller cams without lifters.

Lately I'm getting interested in max performance on old beaters with a couple hundred bucks in them. I've got most of the vizard books (read 'em twice) and a pretty good collection of engines, parts, and tools around.. I built a datalogger for the G-tech that can also log 7 additional channels of O2 or whatever else I wanna hook a sensor to. This way I can compare mods. I'm just starting into the world of grinding on carbs and heads etc.. and picking cams by calculating dynamic compression etc.. to build dirt cheap hot street engines. I guess I've decided for a decent performing engine you shouldn't have to spend so much cash, and I'm willing to try it out at the risk of a few old engines and some lost hours machining on parts. I've got a lot to learn, it should be interesting.

Perry