Help selecting a solid roller - Please

Get in touch with Dan Jones. He will tell you what you need. He did it for me. Look under 5481's new heart for specs.

Mark

Have you calculated your compression ratio with the combination of Quench heads & Domed pistons?.
I believe just running flat top pistons with Quench heads gives around a 10 to 1 compression ratio, plus with dome tops & any kind of cam lift you are Definitely needing valve relief cuts in the pistons!...Mark

The actual compression ration is suppose to be 10.63:1

I would like to avoid fly cutting the pistons.

Come on Jones, McCall, George, Jules, Jack, Pantera Doug, and others.

I used to run domed pistons with 4V heads and never had a detonation problem with 93 octane. The pistons also had to have valve relief cuts.

Mark

If I understand your explanation, drivability isn’t an issue for you. You just need some vacuum to operate the power brake booster. For the record, 70° overlap based on seated valve events (advertised duration) is the most overlap I’d use in any 351C 4V engine that fits that description (i.e. occasional street use, some usable vacuum) or even a road race engine that must accelerate out of tight corners.

For your “rough idling – adequate vacuum” application I’d use a single pattern cam employing a Comp Cams “high energy” solid roller lobe, in this case lobe number 1476. Have the camshaft ground with an intake lobe mathematic centerline of 107° ATDC and an exhaust lobe mathematic centerline of 117° BTDC. The lobe lift is 0.3666” and the lash at the valve is 0.020”. The specs end-up looking like this:

Advertised duration - 288°/288° (at 0.015” tappet lift)
Duration at 0.050 - 244°/244°
Net valve lift – 0.614”/0.614” (1.73 rocker ratio & 0.020” valve lash)
LSA - 112°
Overlap based on advertised duration - 64°
Overlap based on “effective” duration at 0.050 - 12°

“Seated” valve events based on advertised duration:
EVO - 81° BBDC
IVO - 37° BTDC
EVC - 27° ATDC
IVC - 71° ABDC

The "duration at 0.050" of all solid tappet cams is over-stated due to the lash adjustment. To compare this camshaft to a hydraulic camshaft you can estimate that this cam’s “effective” duration at 0.050” will be in the ball park of 236° and therefore its “effective” lobe intensity shall be in the ball park of 52°.

Modern mechanical roller tappets seem to be the most troublesome application for the 351C lubrication system. Denny Wydendorf will tell you all mechanical roller tappet applications “must” use tappet bore bushings. However, for the record, and for the benefit of others reading this post, the Lunati mechanical roller tappets (72413-16 or 72459-16) have a reputation for metering oil properly if the block is not equipped with tappet bore bushings.

Since your Pantera’s engine IS equipped with tappet bore bushings you can use Isky’s tappet part number 3972-RHEZ. The roller of that Isky tappet rolls on a bushing rather than needle bearings, and the bushing is lubricated by "force-fed" oil rather than relying upon oil splash, thus resolving the two biggest failure modes of mechanical roller tappets, including street applications.

quote:

Originally posted by captaintobeys:
I would like to avoid fly cutting the pistons.

Come on Jones, McCall, George, Jules, Jack, Pantera Doug, and others.

Me? Really? Huh?

Well what George suggested is very good, but I wanted to match the valve lift to the flow values of my A3 heads, so I went to the CompCams 294 solid lifter profile. It's a .605 lift.

The A3 heads flow 330 @ .600 on the intake. 220 on the exhausts. It's like this cam was made for them. Your iron heads SHOULD show about 300 cfm on the flowbench at .600. All they need is a good valve job.


For what I use the car for, I don't mind the 74 degree overlap this cam has at all.

It DOES have a very interesting idle. Sounds like a marching band, boom, boom bada-bada boom boom.

It idles at 650 rpm with the Webers, and the 180s make it scream through the exhaust at ANY rpm with these headers and mufflers like a F1 car.


I once had my cap knocked off of my head walking about 20 feet behind a GT40 running...by the exhaust pulse of the headers. Guess what? My Pantera did this to me too.


Does it throw fuel vapor back through the carbs? Yup. Do I care? Nope. Ran Webers for 35 years this way. Haven't blown up anything yet...AND I am "como si dice" ...not gentile with the throttle.

Does it make enough vacuum for the brakes? Nope, but that is also a function of independent runner intakes not making enough volume of vacuum.

Very, very, very simple solution...CompCams vacuum pump. With all the engine noise existing, you don't notice the pump. Works great though.

The benefits to all of this? Like a kid riding the roller coaster at "Playland" who won't get off.

Interesting effects? Yup. Ferrari owners behind you turn on their windshield wipers...and use the windshield washers! Corvette owners at red lights who pull up alongside will never say "hey, nice car". They look straight ahead like you don't exist AND you will see them playing with their radio...mostly turning up the volume? GOTTA' LOVE IT!


It is fine on the street. It is what you want on the track at an open track event. The secretion of endorphin's in the brain seem to be stimulated by this entire setup. I just kinda float around, feet never touching the ground with this setup. Weird if you ask me, but I don't do drugs. I do this stuff.

...oh, this ain't none of those roller things, it's a straight up old fashioned solid lifter. You know. What Tyrannosaurus Rex used to kill with? Simpler. Less parts to break.

George - Does your cam reccomendation require cutting the piston tops for clearance?

Jeff its impossible for me to guarantee that. I don't how much the decks or the heads have been milled, what the actual deck clearance is, or exactly which pistons are installed in terms of dome configuration. In all honesty you'll have to check piston to valve clearance no matter what cam you install or who recommends it. Its the only way to have peace of mind. If anyone recommends a cam that is so mild they can guarantee no piston clearance issues, you'd probably be unhappy with it for other reasons ... like low valve lift. And such lobes are hard to find in this day and age.

Stand back and look at the cam specs however, the valve lift isn't all that great, about the same as a Lunati hydraulic roller cam. The duration at 0.050 isn't radical either. Your request to avoid having to fly-cut pistons was taken into consideration when I was considering the options. But please, regardless of whose cam you install, check the piston to valve clearance and make sure the exhaust valve has 0.100" clearance minimum. Its floating exhaust valves that normally kiss the pistons.

I was going to check it no matter what. If I have to cut them, that is just another step in doing this correctly. A buddy recomends the old clay method.

I will probably call Comp today.

All they will tell you is to check it with clay. There WAS a spec being given by at least one of the piston manufacturers back in the day, but many were providing for bigger valves and very high lift cams beyond stock already.

A stock cast piston would likely be the least clearance.

The only safe way is to measure it. You do that with clay.

You could always post your question on speedtalk. There are a bunch of very knowledgeable people on there that just talk engines. The only thing I can say is make sure you get good streetable "bushing" lifters. I just went through this looking for a cam for my 533ci Pantera. I quit and decided pulling the valve covers off every other oil change was not worth a couple hp to me.