Hydraulic Flat Tappet or Retro-Fit Hydraulic Roller Cam? And which one?

[67rally]

I'm looking for a little camshaft advice for my '67 Camaro. It's a 4spd with 3:31's, headers and 2 1/2" dual exhaust.

I pulled the intake and heads off my 350 today and it has no provisions for a roller cam. The block number is 10054727, which is an '87-95 block, but it is a truck motor, so it does not have the bosses in the valley for a spider.

I will be installing a set of Vortec heads. I have already swapped out the valve springs for a set of LS6 beehive springs, which in theory should bring the max lift up from .480 to .550. I also have an Edelbrock Performer RPM Vortec intake for it, and will be re-using my Edelbrock 600cfm carb. I have an electric fuel pump FWIW.

I'm going to be using a Comp Cam, along with their lifters and pushrods, but would welcome everyone's input on which cam I should run. Should I look at the Retro-Fit roller cams, or just go with a flat tappet?

This isn't going to be a daily driver, but it will see mostly street duty so it still needs to be driveable. I do want an agressive idle, and would like to make some very good power. Any recommendations? XE line? Thumpr line? Thanks.

[TheJDMan]

I would recommend the Edelbrock 22015 roller cam kit. It has a lopy idle but is very street drivable and a power range from 1500 to 6500rpm. This is a complete kit which includes the cam, lifters and push rods. It requires no block modification to install.

http://www.summitracing.com/parts/EDL-22015/

[67rally]

I would recommend the Edelbrock 22015 roller cam kit. It has a lopy idle but is very street drivable and a power range from 1500 to 6500rpm. This is a complete kit which includes the cam, lifters and push rods. It requires no block modification to install.

http://www.summitracing.com/parts/EDL-22015/

I can't use a roller cam.

[TheJDMan]

Yes you can! You don't need a roller block for this cam. I installed it in an early 60's block.

[Chevelle598bb]

Yep. Retrofit lifters and a cam button to install a hydraulic roller in your block. Then you can use conventional oil and not have to go thought the butt puckering (is my cam going to go flat) break in.

As for cams, the comp xe make great power and are street able. The xe268hr would be great as long as you have at least 9 to 1 compression. I would step above that if not.

Have the top of the valve guide been cut down on your heads. From the factory the vortecs can only handle about .470-.480 lift due to retainer to seal (top of valve guide) clearance reguardless of the spring used. Also the ls6 springs are a little light for a small block Chevy with a retrofit hydraulic roller. Comps 918 spring would fit the bill better due to more seat an open pressure. Your motor would valve float about 5000-5500 with the ls6 springs.

[67rally]

Alright, cool. I'll look into those.

I was under the impression that the LS6 springs would allow you to run more lift. This round of engine upgrades is just a quick fix to hold me over until I do an LS swap in a year or two. With that said, I'm not going to have any work done to the heads, or swap out the springs again.

Based on that info, I'm open to new suggestions that would work with the current combo.

[67rally]

As for cams, the comp xe make great power and are street able. The xe268hr would be great as long as you have at least 9 to 1 compression. I would step above that if not.

Have the top of the valve guide been cut down on your heads. From the factory the vortecs can only handle about .470-.480 lift due to retainer to seal (top of valve guide) clearance reguardless of the spring used.

Not sure about the compression, but this was a low compression engine originally. What do you mean by "step above that if not"?

Valve guides have not been cut down(at least not by me).

[Chevelle598bb]

If you want to stick with what you have you will have to use a flat tappet cam. The xe268 in the hydraulic flat tappet form will work for your application. It is right at .480 lift. Do you know what installed height your ls6 springs were installed at? At 1.800 they have 90lbs of pressure and at 1.700 which is the standard sbc installed height I am not sure as I don't know the spring rate off the top of my head. With the xe comp cams (hydraulic flat tappet) I like to see 100-110 lbs on the seat and 300-325 lbs open. Also retainer to seal clearance will need to be checked with any cam over .460 lift. It is easy to check.

With a stock short block with dish pistons and vortec (64cc) heads you should be around 9 to 1 or so. The xe268 is the biggest I would go if not stepping down to the xe262. If you had more than 9 to 1 compression you could step up to the xe274. With low compression and too much cam the motor will run like a dog.

If you want the sound more than the performance then the mutha thumper line is something you may want to look at. You will get that rumpity idle that you are looking for at the cost of a few horsepower. The xe262-xe268 will have a little bump but not near as much as the smallest mutha thumper.

[skigoose]

just my two cents, I had a 427 in my 68 Camaro, behind a 4spd M22, the cam was from Comp and I went with solid lifters (kinda like back in the day) well the cam went flat, and after some investigation Comp admitted to a faulty cam blank, and I also learned a new term.... Consequential damages, meaning that they are responsible for the cam and lifters, but nothing else, none of the engine damage for all the metal going through it, that was my expense, the next cam was Nitrited and Hyd.

[Chevelle598bb]

Nitriting the cam is a great idea with a flat tappet. It is costly but does help with wear resistance. Also an oil additive such as gm break in zddp additive is a must since there is no zinc phosphorus or other high pressure additives in conventional oil anymore. Comp cams has had many flat tappet cam failures in the past and I'm sure there will be more. Although there is a lot more to the cam failures then just comp having a bad cam core. There is also the issue of some people breaking the cam in with too much spring pressure, too tight lifter to bore clearance (cheap overseas lifters), inferior lifter materials (cheap overseas lifters), coil bind, improper retainer to seal clearance, improper breakin procedure, improper oil. Many other cam manufactures have many flat tappet failures also. Plus when you look at the sales ratio of comp to other cam manufactures and comps failures to other cam manufactures they equal out. The key is proper valve train set up and break in procedure. After that just turn the key and hit the gas.

[67rally]

Thanks guys, keep the suggestions coming. I just finished pulling the lifters, timing chain and cam this morning and would like to order new stuff so it's here by next weekend. I'm doing a ton of research, and your input is appreciated.