Questions on Cam & Springs...

[GordSipko]

And they are only good for .487. Ill call Crane and see what they can do.

Check your math! The 99848's coil bind @ 1.153". With the recommended 1.7" installed height, this would give max lift of 0.547".

[RacerX11]

Check YOUR math again. You forgot to take into account one critical measurement. The bind height for a spring is the point where the coils go solid. You can't run a cam with lift right up to the bind point. You need to leave about 0.060" between cam max lift and bind height. This is where they come up with the 0.487" max lift.

Marty

[RacerX11]

It does mean something. It means it'll work,lol. My pistons are dished so i have a little more room than you do. Only other thing i could think of are the heads being different between your Gen1 and the Gen3 id be using. Which springs are you using on yours?

It doesn't mean anything at all....the gen1 valves are straight up and down, and are recessed almost 0.500" into the head, so there really isn't any issue with clearance. On the Gen2/3 heads, the splayed valves puts the outer edge of the valves very close to the piston tops even when closed. The piston dish doesn't gain you anything, since it is at the outside of the piston, where there is no dish, that the valve will contact first.

I tried running a Crane H272 cam with 1.5 liters on my 3400, and I had piston and valves touching. I don't know if it was due to an out of tolerence timing set, or what. I know other people have run the 272 with no problems.

My advice: clay the engine and check for clearance before you put it all together. It is an expensive problem to fix if you find it out later.

Marty

[Corpse]

I think it should just be common knowledge though. that, when you install a cam and, are unsure of clearance, make sure to not just turn the key.

Take out the plugs and hand rotate it a few rounds. Make sure there is no severe issue. Then, from there if the valves hit due to float or something, at least you will know that they were not touching normally.

Cause if you hand rotate it and they touch, imagine if yuo were to start her up.

-Dave

[Jon89LE]

Thats why i had mentioned IF there was a change in the heads, which obviously now i see there was. Id really rather not spend the time and money and THEN find out it doesnt work. Id rather be 110% sure before i do anything that there will be enough room in there even with a little float taken into account. Anyone know how much clearance there is from TDC and the valve?

[GordSipko]

Check YOUR math again.

Ok, I checked my math and Crane's web-site. Crane spec the 99848's for use with the H-272 cam, so apparently they aren't subscribing to your coil bind calculations either. Personally, I wouldn't run the springs that tight + Crane do show valve float @ 6500 with this spring - it's not quite enough spring.

Be aware that there are a number of tolerances that do come into play - lobe lift might not be exactly as advertised (and it's never greater), installed height (close to but not exactly 1.7"), rocker ratio (1.5 is nominal and rockers vary) and very slight compression of the hydraulic lifter under operating conditions. So, real world valve lift only approximates theoretical lift.

A better spring to use might be the 99846. It is spec'd for .570 gross lift, but requires 1.75" installed height which will require offset retainers and/or keepers or possibly some machine work. Seat load is 10% higher and with a much higher spring rate, increased lobe/lifter wear might be an issue.