Ryan77

I'll be building a big block, but in the mean time I thought about having some head work done to my 350. I ran my combo with the headwork on my Desktop Dyno and it gave me 374hp@6,000rpm and 384ft/lbs@4500rpm. When I changed from hydraulic to roller lifters the power went up to 420hp@6,000rpm and 420ft/lbs@4500 :eek: :eek: :skep: . Do they really make that much a difference? I'll have the top of the motor off anyway so they'll be easy to replace while I'm there. What do you guys think? By the way they are $225 for a complete set from Crane :cheers:

fauxrs

Desktop dyno does a poor job simulating low duration roller cams, it tends to indicate excessive increases with them.. In fact if you read DD's user manual it explains that in some circumstances you should model a hydraulic roller as a flat tappet solid. Unfortunately it doesnt give clear circumstances when you should do that.

I would take anything DD says with a grain of salt - it is at best a tool to compare some modifications with others - I am not certain that roller cams is one of them.

PatsLs1vette

you cant just add roller lifters to a solid or hydrualic cam,you have to use a roller cam also at the same time.

gkull

It's about $1200 to do a roller cammed motor. timing cover plate with cam button. quality chain and gears. Roller cam. roller lifters. quality push rods. Screw in studs and guide plates. Larger springs. roller rockers taller valve covers stud girdles are a good idea.

yes they make more power than a flat cam. But the dollar to hp ratio is really high.

I would never build a flat cammed motor for myself ever again.

Aaron-74

Roller cams are completely different than hydrualic cams and roller lifter are aslo bigger around then hyd. It's not as easy as just swapping parts I'm afraid. Unless you get the retro fit rollers.


Aaron.

bence13_33

I agree with Gkull. You are looking at about $1200 to correctly change your motor over to a roller motor. You also need to watch how big you go with a roller they put a lot more stress on the entire valve train. With a decently radical roller cam Mark (ML67) told me that you should think of roller lifters as disposible items (expensive ones at around $250). The valve springs also fatigue with time and need replaced.

For the biggest bang for your buck a nice solid flat tappet cam is the way to go. Much cheaper, will make nice power and you can rev them to the moon. Also a decently radical solid flat tappet is not as hard on valve train parts. However, with any large cam you will run into valve spring fatigue problems.

Aaron-74

Bence: I've been thinking of a solid cam. I run into lash problems with my hyd. with the nuts backing off just enough to make them tick a little. What do you do on your solid cam to keep them from ticking. Do you have to adjust them all the time??

Aaron

bence13_33

A solid cam doesn't sound like a hydraulic cam...even when both have the correct lash settings. The solid cam has a more "mechanical" sound to it. My exhaust is so loud that you can't notice it on my motor really. The solid cam is a bit noisier than a hydraulic cam which really doesn't bother me.

The cam doesn't really make a ticking sound when the lash is incorrect. More noticeably is the performance loss. The wider the lash, the less effective lift the cam has. So when the lash starts to get loose the motor has more bottom end but struggles to rev.

I rarely have to adjust my valves anymore. I check them once a month just because I am **** about my motor but they are usually just the way I left them. Some times they are maybe .001" out or something minute like that but they stay pretty consistant now. The problem is when you first install the cam. I would suggest this to you. After you do the cam break-in, shut the motor down and adjust the valves. This is where you will find the valves are most out of wack. For the next couple months after the cam break-in you will want to check them maybe 2-3 times a month. You may/may not find they need adjusted. 3 months after the cam break-in (I use 3 months just to be safe) you should be fine. They will then rarely ever need adjusted and they do stay pretty consistant.

Solid flat tappets I think have gotten a bad rap. It takes me all but about 15 minutes to adjust my valves when they need adjusted.

Also, the nice thing about a solid flat tappet cam is that they are "adjustable" (so to speak). Comp Cams recommends setting lash at around .022". You can vary your lash by as much as +.006" / -.006". Running the lash looser (say .026") will give you less effective lift but contributes to the bottom end pull, the downside is that it takes away from your top end. The opposite of that would be adjusting your valves tighter (say .018") will give you more effective lift and contributes to your top end but takes away from your bottom end. Personally I lash my valves to .018".

P.S. I have also revved my motor to 7000RPMs going through the traps at Keystone, I'd like to see you try that with a hydraulic cam :) .


[Modified by bence13_33, 4:04 PM 3/18/2003]

Ryan77

I didn't think they were worth that much power, thanks :thumbs:

Aaron-74

See, I if I change to a solid cam. I would want something that really wouldn't want to rev beyond 6,000. I don't think my bottom end or my heads will withstand the flow and force of 6,500 or above. I don't know if CompCams makes solid cams below .560/.560 lift and 280 adv. deration. I wouldn't have any use for anything much bigger, but I would like to upgrade to a solid cam for more power and the bad-butt sound.

Aaron-74

The Magnum 294 looks decent :.595/.595 doesn't give the duration though...hmm..

gkull

bence13_33 What size cam did you end up with? Are you running a stud girdle or just locking allens. I'm changing cam, lifters, and block. New billet from Comp and Crane Pro lifters. I have nothing to complain about i got nearly 20,000 miles.

An old Crane solid motor i ran had the 238/248 and it ran like a champ. I know of several Vette owners that use it today and put on thousands of miles a year.