Oops, if I still had those things from my old engine, I would send them to you.
Worn in lifters = cam death if placed on another cam, or even out of order on the original cam due to how they individually wear in on the lobe they ride on.
On that note, I did manage to scramble the lifters in my 3.4 DOHC once or twice to no ill effect (still running strong), but I believe the lobes and lifters are flat ground, and have cutouts on the base circle to cause the lifter to spin. And the contact surface is huge. But yeah.
Blue Shift wrote:Worn in lifters = cam death if placed on another cam, or even out of order on the original cam due to how they individually wear in on the lobe they ride on.
On that note, I did manage to scramble the lifters in my 3.4 DOHC once or twice to no ill effect (still running strong), but I believe the lobes and lifters are flat ground, and have cutouts on the base circle to cause the lifter to spin. And the contact surface is huge. But yeah.
I never understood why people said that about lifters... In a flat tappet pushrod engine, the cam lobes are ground just a weee bit tapered to spin the lifters. The lifter face is not flat but actually gound on something like a 90" radius, so it's an itty-bitty section of a sphere. When you combine these two items, there shouldn't be any "wear pattern" that's different enough from one lobe to the next to cause failure.
Blue Shift wrote:Worn in lifters = cam death if placed on another cam, or even out of order on the original cam due to how they individually wear in on the lobe they ride on.
On that note, I did manage to scramble the lifters in my 3.4 DOHC once or twice to no ill effect (still running strong), but I believe the lobes and lifters are flat ground, and have cutouts on the base circle to cause the lifter to spin. And the contact surface is huge. But yeah.
I never understood why people said that about lifters... In a flat tappet pushrod engine, the cam lobes are ground just a weee bit tapered to spin the lifters. The lifter face is not flat but actually gound on something like a 90" radius, so it's an itty-bitty section of a sphere. When you combine these two items, there shouldn't be any "wear pattern" that's different enough from one lobe to the next to cause failure.
I see where you're coming from, and wouldn't be entirely surprised if it could be done, textbook ASE answers be damned. I think it'd be interesting to get precision measurements of a used cam and lifters with like a CMM machine or something.
I'm definitely not the only one to have mixed 3.4L DOHC lifters (followers?) and dropped them in at random with success. But I think that between not having to move a pushrod, work a rocker arm the mechanically disadvantageous direction against the full strength of the spring, lighter springs and valves, and the flat ground lobe and lifter with ridiculous contact area, it makes a big difference?
Going flat-tappet in an LS1 that was built to turn 7200 as a hyd. roller wouldn't inherently gain or lose you anything except cam/lifter life. Rocker arms are not your enemy in streetable rpm ranges. Rocker ratios are your enemy with flat tappet setups.
About the 3.4 dohc lifters... both the engines that I installed aftermarket cams in are still running strong. One of them was a crate engine... so I would expect it to have been fine, but the other on had 100,000 miles on it before the cam was installed. The lifters were installed back into the same cam carrier spot that they were in before for good practice, but the cam of course was way different. Haven't seen any ill effects yet...
p8ntman442 wrote:A lift and a dirt floor? thats a new combo.
Bleeding edge technology :thumbleft:
Cam is in, new timing sprockets and chain are on, water pump is on.
And my springs arrived today from the FieroStore, true to form, its a loose pile of springs in a box. No Specs or anything.
For doing the springs, the plan was to use compressed air in the cylinders to keep the valves up. Is this a decent plan or is there a better method?
I've never been a fan of the compressed air. I run a pice of rope through the sparkplug hole and spin the crank till it won't go any further. I've never dropped a valve.
This is what I use too, at least on aircaft. It's more positive than air....of course it's horizontal.
