Cam Choice

[Steeveedee]

Looks like I'm going to have to rebuild the 402 in my '70 truck. It needs valve guide work for certain. I haven't checked compression yet, as my hands haven't recovered enough from the surgeries (carpal tunnel) to do it. I'm just doing a little groundwork ahead of the fun. It's been punched out once, but I won't know how much until I pull a head and mike the block. I'm hoping for one more bore.

In any event, I'm thinking roller cam instead of flat tappet, to get away from worrying about oil. So, does a roller cam yield more HP for the same grind? Seems like reduced friction would make some small difference. My application is towing a 6k pound travel trailer, so I don't want anything rumpty, I need low end torque, not high revs. If there is an insignificant gain (for the money), I'll just stick with flat tappet.

Any thoughts?

[trac209]

Roller cams do offer friction benefits as well as they just function better and due to the way they are made and how they work. Engine masters did a test of two cams that were very similar and it was around 40hp just for the cam swap iirc

[Mike C]

Big block Chevy's are notorious for cam lobes going flat anymore. If even one flat tappet cam fails, you would have been better off with the roller.

I just built an L36 427 for my 69 short bed. It has the big oval closed chamber heads, so figure 10:1 compression or just a bit more. I plan on running through iron manifolds and want a hot street truck not a daily. I chose the smallest Comp Nitrous roller. It has 113 deg lobe separation and 224/235 duration at .050. I am hoping the nitrous grind will bring the most out of the motor running through iron manifolds. While I think this will be a great street cam for MY application, I would suggest you stay below 220 degrees .050 duration on the intake for your 402.

Look at the computer controlled retrofit Comp roller. 210/220 at .050 on 113 lsa. Or even same grind on 110 lsa would be great with carburetor. I would call Comp as they have grinds that aren't in the catalog.

[BCOWANWHEELS]

Melling hydraulic towing cam

[weq92f]

You should go out to Comp Cams site and download CamQuest. It's kinda fun to play around with to get ideas on what may/may not be a good choice...

It's free software:

http://www.compcams.com/downloads/register.asp


-klb

[Steeveedee]

Thanks for the replies, folks.

I'll download that comp cams s/w and run it.

[alsriv2]

Take a look at the Lunati cam choices. They offer a good variety of roller and flat tappet cams. I have a semi-radical roller in my professionally built 396, and while the builder didn't select the cam profile I wanted (low rpm torque), the cam he selected turned out very well and will get better when I convert over to Fuel Injection shortly. They selected a cam based on my truck and what I reported to be "fact" on the truck setup. (gear ratio, tire size, transmission, stall converter, etc.) My mistake was not verifying everything and finding out after the fact, the PO info was hugely wrong. My shop did a nice high quality build, so I am not blaming them.
My setup:I have a 3.07 posi, not a 3.73 as I was told, a 1800 stall, not the reported 2500, etc. So my cam is kinda wrong for my use/setup, but I am not going to change just yet.
Make sure you talk with the vendor you choose and give them facts about your setup and intended use. That way they can get you a proper cam setup that will meet your needs and you can have fun instead of having to piecemeal a solution like I am doing now.

[weq92f]

Using the CamQuest...

Right now for my 402, 063 Iron head/700r/3.73 top end build I'm looking at:

Both these are Hydraulic roller cams..

Comp XR 264HR Daily Driver to Mild Performance, Strong Torque, Good Mileage 1200 to 5200 264degree, .51 lift, 112 lsa

and

Comp Magnum
270HR: Daily driven street machines. Works with stock converters. Likes headers. 396 needs 3.55-3.73 gear. Very slight rough idle.1800 to 5000 .56 lift, 110 lsa


-klb

[Mike C]

I think either of those would be good. They should both be OK with stock converter and gears with a big block.

[GASoline71]

Retrofit roller lifters cost a grip of cash. Probably worth it in the long run though.

Gary

[jocko]

Can’t see the links at the moment - it’s worth ensuring you’ll maintain sufficient vac for pwr brakes.

[KQQL IT]

Originally Posted by GASoline71

Retrofit roller lifters cost a grip of cash. Probably worth it in the long run though.

Gary

The retro roller in my 400 sb is on its 3 rd go around.