More questions about solid rollers, and going back to hyd rollers...

[vector1]

320 lbs on the seat......

[DAVID GAGNARD]

On a solid roller, I would never go under 250lbs seat and 500 lbs open and I wouldn't care to run a lot more than that on a billet core.

Brent:

Just asking, on my race car (331 stroker) I was running a solid roller Comp camshaft, 586 lift and 288 duration, on the cam card they recommended 215 lbs. on the seat, mine were set at 225 on the seat, don't remmeber off hand what the open pressure is...I have a 7,000 rpm chip in it and do run it up to the chip on track....on the dyno we did do a few pulls in the 7500 to 7700 rpm range....the actual hp peaked at 6400 rpms, so no need to rev it much more than that.....

Building a new engine as we speak, same 331 stroker, going with another solid roller, of 624 lift, can't remember the exact duration (haven't got the cam in yet), wanna say around 285 duration.....don't know what they recommend for seat pressure yet, but I'd think anything in the 200 to 225 range would suffice.....

Your thoughts???????

Thanks;
David

[blykins]

David,

Can you post all the cam specs?

I say you're on the right track with the spring pressures. If it's a race car, you're already of the mindset that you'll be doing maintenance. If it's a billet camshaft, I'd run some good pressure on it. It won't hurt it.

I just did a 347 for a 7.50 1/8th mile car. It peaked at 6500 as well with a solid roller...236/242 @ .050", .600" lift. I installed 250 seat and 600 open pressure on those heads and used the lightened steel retainers.

Of course the lighter the valvetrain, the more you can get away with on spring pressures. But I have minimums that I use with different cams.

Valve float is not your friend....and if you decide to stay in the gas a little longer before going through the lights, or before braking in a straight, I'd rather not worry about losing control of the valvetrain. It's not fun when that exhaust valve hangs open longer than it should.

[DAVID GAGNARD]

Brent;

The cam card for the Comp cam is the one I've been using for 4 years now...very pleased with it, peak hp was 472 @ 6400prms and torque was around 420 @ 5700 rpms, idles nicely at 900 rpms and if I remember correctly pulled about 12 to 14 inches of vacum @1000 rpms....

I'm building a "new" motor, using the new BOSS 302 block with t he same heads and rotating assy., was planning to go to a more aggresive camshaft, been looking at other solid rollers in the 600 to 625 lift range.....

This is the Lunati Voodo cam I'm currently looking at, not 100% sure I'll get this one, but the specs are in the ballpark for what I want...

I'd have to check my notes, but I think with the setup I have I have enough piston to valve clearance for a max lift of around 675, my springs are good for 725 lift.....I was gonna go with no more than 625 lift just to give some added clearance.......

not having any luck posting cam cards, but here is where you can veiw them........

http://www.lunatipower.com/CamSpecCa...rtNumber=63032

http://www.compcams.com/Cam_Specs/Ca...?csid=830&sb=2

David

[blykins]

David,

My little 347 that I did made 482hp @6500 and 430lb-ft with 10.3:1. The restriction was that the customer couldn't afford a new carb at the time, so we ended up using an old Demon 650 that he had. It wasn't a max effort as he didn't need that much horsepower to run the class he had, but he thought that at some point he would want to run a faster class. I used out of the box AFR 185cc heads and a Super Victor intake. It was a nice little motor.

If you don't have a cam yet, I can help you pick lobes. I rarely order off the shelf cams. But based on where you want the power to be and how often you want to do maintenance, I can help out.

There are some good lobes that make real good power, but they're harder on springs. I like the TK lobes for a solid roller, but they're pretty radical. However, if you want to make the power, they do a good job.

If you're planning on going a little wilder on the cam, I would go with a billet cam and up the spring pressure. If you think you have room, you can shim the spring up a little more, as long as you have good retainer/valve seal clearance and coil bind clearance.

Also, sometimes valve lift will fool you. You may have good piston/valve clearance with this cam, but a larger cam with different valve events may hold the valve open longer in a certain spot and it may get close.

When I assemble, I clay the piston up just to check radial clearances. For depth clearances, I use a dial indicator with checking springs and check it every 5 degrees.

[DAVID GAGNARD]

Brent;

I too clay up the pistons on assy. to check for clearances, and so far, I've be good to go....running a very old "slightly re-worked" set of Edlebrock Performer RPM heads and a 650 Demon on my setup. Victor Jr. intake.

My rpm range on track is normaly from about 3000 to 6500 with the occasional spurt to 7000 depending on the track, races last form 15 to 25 minutes.....

I like the characteristics of the Comp cam I have, good idle, real good torque and not a loopy a$$ed cam, I hate those loopy cams, they may make good power, I just don't like them....I'd like to keep the duration at or under 288 like the comp cam has...my ideal cam would be the same thing I have with the Comp cam, but more lift, anything in the 615 to 625 range....this should get me at or near 500hp which is all I actually need for my use........and still have an engine that is not too radical and will give me the service life of the present one....

The setup I have now has been super good and dependable with very little mantinence. Once a year I pull the valve covers and check/set the valves and that's about it.

I may give you a shout in the next day or two and maybe we can discuss a cam..........236/242@ .050 duration should equate to 27? to mid 280's total duration???? if so, I'd be reallllllllllll interested in a similar cam..........

If you're planning on going a little wilder on the cam, I would go with a billet cam and up the spring pressure. If you think you have room, you can shim the spring up a little more, as long as you have good retainer/valve seal clearance and coil bind clearance.

Plenty room to get my spring pressure up another 25 to 40 psi, and I have real good retainers/locks and should have enough spring coil bind clearance for up to 715 lift area.

Thanks;

David

[blykins]

David, we can talk about it further, but that 236/242 cam on your engine wouldn't make the power with the Performer RPM heads as they would with the AFR heads that I used on the 347.

With a lower flowing head, you have to make up the power with the camshaft. That's why you were having to get up into the mid 240's duration to make the power you were making.

If I were to spec you a camshaft, we'd discuss where you wanted peak hp to be. I always cam to make the most for the rpm range that you're running and then the horsepower kinda falls where it falls. The reason being, if you're reaching for a certain hp number, then essentially you're overcamming to make a number and then you deal with hp rpm peaks at slightly unusable levels, plus a finicky bottom end, more maintenance, etc.

I put quite a bit of emphasis on .050" duration and LSA. Then I look at advertised durations to determine how wild I want the cam lobe ramps to be and to check dynamic compression ratios. The closer the .050" and advertised durations are, the steeper the ramps are, and the rougher it will be on valvetrain components.

If you keep the same heads, same compression, and same displacement, then a smaller cam is going to make more torque, but lower the horsepower and the peak hp rpms from where you were before.

I can make more power than you were making and still keep the level of driveability and maintenance that you were getting before.