spanks13

iTrader: (5)

Interesting specs I found on speedtalk. This does agree with your ball theory, but the lobe goes close to vertical once you're off the seat. It is increasing the aggressiveness of the lobe by accelerating the lifter harder. Many grind cam profiles specific for the wheel size you're using.

Stock is .700" you're moving up to .850" That is 2.5x larger of a gain than the table listed below (unless the cam you ground used profiles with the larger wheels in mind).

QwkTrip

iTrader: (23)

That's good insight, got me convinced already!

Mickyinks

im sort of getting it , ill do some experimenting on paper with oem lifter size and these jesels and see if tht shows anything

spanks13

iTrader: (5)

Yea. The centerline of the lifter wheel is in the same place, but the diameter is bigger so it contacts the cam lobe sooner, and raises faster. Max lift is the same because the lobe lift is the same.

jayyyw

Who says you can't learn anything on forums anymore, lol. Good info.

I've never had a cam ground for myself, by calling a company to grind specific specs. I have a cam I want to get that was ground for a larger lifter/wheel diameter. So, would I just call them and give them the lobe numbers, durations, LSA, and then tell them I need it ground for a stock diameter lifter/wheel?

Che70velle

iTrader: (6)

Yessir. Anytime you custom grind a camshaft, they always must know the lifter wheel diameter, and will cut the base circle accordingly. So if you’re looking at a camshaft cut for a larger diameter wheel, it will likely have a smaller base circle and won’t end up being what you wanted, when you degree it with a smaller Oem size lifter wheel.

Last 1

iTrader: (2)

I don’t know if it will help you ,but Lake Speed has video on YouTube on ring gap
they are showing they are gaping the top oil ring the same as second ring to help with ring flutter
and making more power

Mickyinks

so if i wanted the same lift using the same cam profile, at max lift the lobe would ground .075 shorter and closed the bottom of the lobe would b .075 shorter so will be gentler over the top and the bottom of the lobe , it would make the entire cam lobe act softer, more rounded
s

Mickyinks

so next question is what does adv duration of a cam tell ? is it how fast it opens and closes ,
example would b a 245-385/ 259-375 to 248-285/262-300

Double06

iTrader: (1)

The advertised duration is the duration a .006 lift or so on hydraulics and solids I think are at like .020. The example above is odd as I have never seen a 100+ degree (259/375 - the 375 is almost like a lobe lift) difference in the advertised and the .050. Solids are usually 30 to 40 degrees and the hydraulics are like 50 to 70 degrees. Now I guess some of the old OEM hydraulics (like 1960s) were close to 100 degrees. The delta I am talking about is the say a 246 at .050 and say 298 degrees at .006 on an aggressive hydraulic roller. I would say the delta does have something to do with the overall ramp but in general I think it is just a way to get the lifter going before the party starts.

QwkTrip

iTrader: (23)

The duration specs are simply how long the valve remains above an associated lift value. It's all written on your cam card. But I think you have to know what lobe profile the cam was made from to figure out the actual shape of the cam lobe. For example, my cam was made from a Comp Cams "LSG" lobe profile. I don't know if actual shape of those profiles is publicly available? (They might guard that info since it is their secret sauce to success.) The things of interest to you can be answered by the cam manufacturer though, you probably don't actually have to figure this out on your own.

Mickyinks

I sent my heads off to Tony Mamo , they got there last week..He will port them to V2 specs, new titanium valves, new guides ,valves seals and springs. Will finally get my block back from machine shop next week, , I got my new cam and piston rings a few weeks ago so should have the short block built by next weekend, Then itll be a wait for the heads to get back here, Looking forward to getting it back on the road

Mickyinks

I finally picked up my engine block from machinist yesterday. He bored the lifter bores . installed lifter bushings and honed to fit new jesel keywaylifters, crack tested crank, light cylinder hone, put new cam bearings in it . Now to build short block, ... For the clearances ill go .0024 mains, .0022 rods, ring gap top .0020 2nd .0024 oil .0015 Its a NA build so i think those clearances are correct Ill get the heads back from Mr Mamo in the new yr, hes done his latest port work , new titanium valves, hes gong to up the seat spring pressures a little. Did some work so i can up compression a little He also specced a new cam , going up in duration a few degrees of what was in it, Im going to try 1 of Tonys ported oil pumps Was thinking of getting a new timing chain but it didnt have an slack and look like new so the old double chain will go back in.... 3 weeks and itll be up and running... Should bump up horsepower.. a little, itll be rite on the verge of cracking 700rwhp, my guess is 697rwhp

jayyyw

When you get your cam in, make sure the oil orifice hole on the lifters reaches the oil galley in the block/lifter bushings before assembly. There's been a lot of talk of that lately. Albeit, on Dart block stuff but definitely won't hurt to check. It might hurt if you don't check, lol.

Mickyinks

Thanx for the heads up, will keep an eye on tht. Im confident the machinist has installed correctly, , theres only 2 in australia who are set up to do the job so youd hope they know what there doing. Will i hv to measure the bottom of lifter wheel to oil hole then from what position of cam lobe to oil gallery?? or can i visually see its correct??

jayyyw

That I do not know. I've never done it myself.

Mickyinks

While the blocks bare ill try get some measurements in relation to lifter oil hole , grooves to oil gallery, .... I should be able to get a couple of reference points to cross check once cams installed