So I know Tierod has 1.8 ratio rockers with the Comp Cams 270 cam, but has anyone ran 1.8's with the smaller cams? Specifically if anyone has run the Comp Cams 258 cam with 1.8's. I'm looking at custom cam in between the 258 and 264 and the overall lift with 1.72 rockers is .537". I'm a little hesitant because I know the more advanced the cam is, the tighter the intake valve to piston clearance will be.
mitch184
From the 8.1 knowledge god, no name spoken, I know that .540 is all it can handle and that's cutting it super close.
I had a raylar cam with .540 lift and the spring retainers would hit the tops of the valve stem seals occasionally and break off the rocker studs. I used to carry spare studs and those special little nuts for the roller rockers inside my truck. Changed more than one on the side of the road before I gave up and went back to stock. In hindsight it would have been smarter to just switch to a smaller ratio rocker with the raylar cam. The overall specs on it are much better than the stock cam.
Truthfully though, I have never been happier after I traded that 8.1 for the LBZ. I bought the exact same truck as before except with the turbo diesel. It cost me a good chunk, but after a couple years I can tell you that having a computer-controlled turbo with custom tuning is awesome. It costs more to own and maintain and to fill the tank, but the mileage and power are pretty awesome. Anyway, sorry to derail!
Truthfully though, I have never been happier after I traded that 8.1 for the LBZ. I bought the exact same truck as before except with the turbo diesel. It cost me a good chunk, but after a couple years I can tell you that having a computer-controlled turbo with custom tuning is awesome. It costs more to own and maintain and to fill the tank, but the mileage and power are pretty awesome. Anyway, sorry to derail!
I did do that at the very end but the comp rockers I used were 1.7's and they had the same issues with too much lift.
What I found with the "torqued" Raylar rockers was that the nuts put the rockers at the perfect height and compressed the lifters perfectly, as if I had done it by height and not torque. So that was not an issue for me with that setup. It was just plain too much lift.
raylars roller rocker arm setup is awesome IF you use a smaller cam or his cylinder heads (which allow more lift).
The reason I got so pissed off at him was because he should have known the cam and rockers were too much for my stock heads. He kept assuring me that the clearances were fine and it must be a fluke with my truck and blah blah blah. I went through untold headaches and cashflow before I wised up and took everything apart completely to discover the smashed valve stem seals. I just replaced the seals and put it all back to stock and sold it. Bought a turbo diesel, keep it mostly stock with a few choice mods, never been happier.
ive run +50 locks and a .050 thou shim under the valve spring locator. this mover the hole spring and retainer up .050 thou giveing the extra room for the 1.8 rocker arms.also had to modify the the push rod guide plates for clearance . the exhaust push rods were touching the guide plates when the exhaust valve were fully opened.if they touch they'll snap of the guide plate very quickly. ive run the 502zz cam with 1.8 scorpion rocker arms. it gets close but as long as the valve dosent float its fine.later i built a tool to cut deeper valve relives in the piston with them still in the block.this cleared up all the clearance issues. the 502zz cam has .527 intake and .544 exhaust lift with a 1.7 rocker arm. convertes to .558 intake .576 exhaust lift with a 1.8 rocker arm.the stock 8.1L valve springs are crap for anything but a stock motor.
Found this site that advertises their 8.0 and 10.3 L engines that run on propane and natural gas. Yes they are industrial engines but maybe some day in a motor home or mid duty truck. The 10.3 makes 640 foot pounds of torque at 1800 rpm! The 8.0 makes 480 foot pounds at 1800.
8.0 Liter Industrial Engine « Origin Engines
8.0 Liter Industrial Engine « Origin Engines
Those engines have been going into trucks / boats / rvs for several years now. The HO750 from back in the day is a 10.3L engine with aluminum heads, 213 cam, etc.
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The 10.3L engine is the Dart BigM block bored to a 4.6 with a 4.75 stroker crank, which brings displacement up to 632cid. We just sent one of these out to a guy in Los Angeles for his truck with ported stock heads (by Tom @ Champion) and the 203 cam. Here's a pic:
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The 10.3L engine is the Dart BigM block bored to a 4.6 with a 4.75 stroker crank, which brings displacement up to 632cid. We just sent one of these out to a guy in Los Angeles for his truck with ported stock heads (by Tom @ Champion) and the 203 cam. Here's a pic:
i recall reading a couple years ago dart was makeing two versions of the 8.1L. one simesed and one not.but later on thier web site thier was no mention of the simesed block. when useing the bigM block do you have use a front mount crank sensor? or does it have provisions for a crank sensor?
Not to derail this subject but everyone was talking about how well the ZZ502 worked, doesnt the crank have to be changed to match the firing order of the ZZ502 cam or just the firing order on the ignition coils. Ive wanted to do this for a while but dont have alot of knowledge on the subject! thanks for your input
Thanks for the input, I still have heard you have to run a different crank shaft, do you know what truth there is or can just switch coils for timing and be done? Thanks again!
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