Bear with me guys I've been away from this stuff over 35 years. You guys have been very helpful.

Jerome. I was only comparing the 270 cam to the Isky RPM300. I wish I could build a 7000 rpm sleeper. The last FE sleeper I built I brought home in a basket. It was fun while it lasted.

Gary. If I read the cam numbers on both of your posts they look like the numbers on the cam card I have here from the CompCam I had to replace. If I go with the lower advertised duration and the duration @50 to around 230 I should either keep what I have or go with the CompCam. The few times it ran decent it did sound good. To this point I've only been looking at the @50 spec. Now I understand all the numbers a whole lot better.

I wish I could get in a time machine, go back 40 years and pick up that Racer Brown cam I had in my 56 Ford.

Dan      Kingman Az.      86409

Dan, the larger rated cams (286-etc) will not help you on the lowend torque. Keep the advertised(rated duration) short to help on the lowend torque. The @ .050 should work well in the .232 to .236 range for the setup you have. Call John M and see what he has that will work with your application or take another look at the one comp cam has I mentioned earlier. I would not go any larger usless you build the engine on up.

-Gary Burnette-

Dan,

Puzzled some on your existing Mummert cam spec. The highest @50 cam Mummert lists is a Y-292S with 240* @50 duration. Your only data match to his Y-270S cam is your 108 LCA. Confused.

That aside, I’d be concerned stock 113 heads have enough static compression to take advantage of cams over 270* advertised duration on pump gas. Maybe these two Vizard articles can help you decide.

http://www.popularhotrodding.com/enginemasters/articles/hardcore/0606em_understanding_compression_ratio/index.html and http://www.popularhotrodding.com/tech/0311_phr_compression_ratio_tech/index.html

I’ve a 56 Fairlane, estimated weight 3750 lbs. My 3.44” stroke, 3.860” bore, 312 (now 322 cid), zero decked forged flat top pistons, ECZ-G heads milled 0.060” (estimate 68cc), standard 0.040” Fel-Pro head gaskets (estimated 0.218” head gasket bore over size) calculates to 9.6 static compression. Back tracking that ratio through Vizard’s example in the second reference using 91 octane pump gas and 170*F coolant, allows an 8.1 dynamic compression. My static minus dynamic correction = 9.6 – 8.1 = 1.5 points. From his advertised duration data points (250, 275 & 300), the largest duration cam my heads support is 275* advertised duration. I consider 5500 rpm a safe redline for stock 312 rods, mains and valve train in good condition (has worked for me over 45 years on this 312 build). Any more cam than a Y-270S would lower dynamic compression and low end torque and ad nothing above (don’t ask how I know). I’ve good flowing exhaust ports and fenderwell exit headers. So split lobes might even hurt my situation. I’ve a manual 3 speed Borg Warner T85 with the R-11 overdrive and 3.89 rear gears. If an auto trans with even lower rear gear ratio, original vacuum wipers and all weather driving needs, I’d consider Mummert’s Y-265S cam.

If you’ve any less compression than my build, I suggest keeping what you’ve got or moving down a notch for even better dynamic compression and street manors - unless you are hatching a 7000 rpm sleeper needing a power band above 3000 rpm and are willing to give up lots of 1500 rpm torque.

Jerome

Getting some good advise here. Nathan mentioned the Isky RPM-300 cam. If I'm reading the numbers right it's just about the same as the 270 cam I'm running now except for the lobe separation angle. I think I've narrowed my choice down to 2. I'm looking for low end performance and the "sound". One is the CompCam I've mentioned here but I'd run it with a 4deg advance. The other is Johns 284 cam that I would also run a 4deg advance (is that too much for that one?). Any ideas guys.

Dan      Kingman Az.      86409

What John said I believe is right on the money. For example the .234@.050 I referred to is a Comp tight lash solid .234@.050  with a rated duration of 264. valve lift with 1.6 rocker ratio is .528 minus lash. This seems to be a excellent street cam and should do well at the strip and a few upgrades on the engine will be even better.

-Gary Burnette-

The f 300 is too big for the street .This cam is a low lift oval track cam,made for"low lift rule" in oval track racing with lots of duration for high revving.TRy the RPM 300,it works well for the street and has a nice sounding idle.It will also have nice low end torque for quicker starts off the line,and it will still scream to 5500-6000 easily.Bigger cams need more compression.

55 fairlane gasser 312 /c4, 57 f100 292/c4, 52 mainline gasser 302/t10 4speed

Rono,



I have two 500 cfm Edelbrocks on my 312. Can you give me the changes you made to jetting and metering rods? It would be a great help, as i am not a tuner.



Also what wheels are you using on your 56? Width Dia, and back spacing.



Thanks

Jim

  Jim Rowe Elkhorn, NE

When I first brought the motor to the dyno shop, the dual Edelbrock carbs did need alot of tweeking. The guy running the dyno (Matt) worked for Edelbrock for many years. We had to change the metering rods and jets quite a bit. I have all that documented somewhere, but we had that motor on the dyno for 4 days. We had other surprises during that time too like the crank pulley dampner seperating at about 4,500 RPM and the dizzy flying apart on another pull. It's all good now, but I know I couldn't have dialed that motor in myself without the help of a dyno.

Rono.

  Ron Lane,  Meridian, ID

I think any cam over 240 @ .050" is a bit much for the street. But so much depends on personal preference, weight of vehicle, gear ratio, transmission and compression ratio that concrete numbers are impossible to provide.

IMO the F300 has too much duration for the amount of valve lift. You should get better performance with a shorter duration-higher lift cam.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

Dan, that .234@.050  110 lobe sep sounds like a good way to go, that's what I'm putting in my merc 312+++++. The .224@.050 is good for a stock engine without having to change the stall on a converter with an automatic tranny.

-Gary Burnette-