whats the largest valve lift with j heads and kb piston

I have a .592/.610 lift solid cam with same pistons, and i am maxed out on valve lift, my piston sits .005 out to the hole. 360 with J heads

65 are you happy with the performance of your cam?
i have a .040 over 360 with kb 107s . my heads still flow air at .577 with out turbulence .. so i am thinking of going a little bigger just past max flow. and running a solid roller. it has 4600rpm converter and 4.56 gear its pretty heavy at 3310 lbs. but i need or can use more cam...lift at the valve is .488 (Old class rules) car runs great but i know more cam will improve it..based on heads flow...i want to take advantage of it.
im ready to pull the trigger...just dont want to buy the wrong cam.
or more than one cam at this stage...

I don't know why guys think if the head gets turbulent you should stop lifting the valve. Just because it went turbulent at say .550 lift @28 inches don't mean that at 32, or 42 or 60 inches it won't get turbulent even sooner.

With a head like you have, it's tough to get much more than .600 NET lift, but if you could do more,I would say do it. If you have to notch the piston for P/V then so be it. If you wanted to mill the stand down and all that you can NET about .700 and still get HP.

More lift is almost always better.

just not on this motor..
i have a short block and a set of 245 heads..just not looking to do the hard work with the valve train on that motor right now..

i am not taking this one apart right now..unless it blows up. still got kids to pay for..but its time to get the car back out some this yr.
i know looking at my notes...the heads still worked at the .577 lift. it was done at that number..not much more gains after that..but turbulence came in.(i cant read the smudge...)around .620 ..i just want to put in a a little more cam than its has now.. the cam is tiney.
the motor was built in 04 so my memory of the flow bench and notes arent good enough...and my page is smudged pretty good fubaring my notes..
i am going mostly off memory..
what i really want to do is avoid piston to valve interference with the roller...i can get pretty aggressive early...thats what iam shooting for.
it makes real good numbers from .300" on.
just want to pick a cam... been kicking it around in my head..i could fire the car and go run it right now..but since its cold out...i want to pull the cam and stick in something to wake it up.
not go too technical...just avoid a mistake.
i am looking at a .590 lobe.. but have to have a custom cam ground because i have non conventional rocker ratios

is scott brown still around..?
he did all my last cams...but i have no contact for him anymore?

It is fairly simple, you just measure how much space you have at TDC and then use that number when you pick the camshaft. Typically you need to pull the valve springs on #1 cylinder and then use a dial indicator to tell you the space that you have for the valve with the piston at TDC. Look in the lobe spec part of the cam catalog and it will tell you the lobe lift at TDC. Multiply by the rocker arm ratio and that will tell you the valve lift at TDC.

Lobe lift at TDC depends a lot on duration rather than lobe lift. A cam with a lot of duration has to get the lifter moving up sooner than a cam with less duration. And rocker arm ratio is critical to this measurement since a high ratio rocker arm gets the valve moving a lot faster than a low ratio arm.

I use the valves that I will run and put tester
springs on then use the dial indicator to measure
from 10* before to 10* after TDC so I can see if
I can move the cam around for the installed.. I
do every degree and measure to when it touches the
piston and I do both the intake and exhaust... thats
just how I do it

That seems to me to be a sensible method. If the valve has enough clearance at 10BTDC it MUST have enough clearance at 24BTDC unless the camshaft has a hump in its curve (joke).

Isky used to post VOTDC figures but I wasn't aware the others did that, too.

R.

Comp has the info in the master lobe listings. Usually tappet lift at 106 and 110 ICL's IIRC.

Right, you have to look in the lobe catalog. Comp publishes a separate lobe catalog as does Crane. Some of the "less mainstream" cam companies do not publish a lobe catalog so you're out of luck. In that case you buy the cam and measure it yourself using the Mr P. method.

My method of measuring the valve drop at TDC works when you have a lobe catalog. It allows you to design a new cam knowing that it will drop in and have plenty of clearance.

Keep an eye on clearance between bottom of retainer & stem seal at maximum lift on a J head, at .600 it's pretty tight

I have only made a mild attempt to try and get more clearance between my guide seals and retainers on my J heads.
With +.075" retainers, mine show a minimum of .570" clearance and the taller retainer is not the issue, my issue is that the locks stick down about .06" lower than the retainer. So my minimum clearance is between the top of the seal to the bottom of the locks.
With lower guide seals or taller valves, I can see getting into the .600" lift range.

EDIT: Since the fourth lock groove is sticking down past the retainer by .06", I trimmed off the last groove off of my locks. The three remaining grooves are in full contact inside of the +.075" retainers. This gave me an additional .06" clearance from the top of the guide seal to the bottom of the +.075" retainer. I now show .61" to .63" clearance after this modification.
Note: My spring pressures are only #310 at max lift.

Even with the above modifications, this just gets enough clearance for lifts in the .530"-.550" range pending how much clearance you use. Much more lift on my setup would require longer valves.

Ran .623 lift. I did some piston notching for additional clearance.

thats what i did the last time i was diving into this. i have to check my notes.but the 10* btc and atdc is really the answer to my question. if thats adequate to use to pic a cam

i have bronze guides installed. ill have to pull I/E springs to see what i got going on.
thanks guys ill post when i get going on this. to bring this post to a conclusion.
Jim

Can you tell me what head gasket thickness is?