1970valiant
young gun
can i change a 1970 225 to hydraulic lifters? or is it oiled different then the 81 225?
sold to hyd lifters
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.............Yes u can, but y would ya......some guys just change the lifters with out changing the cam.....kim.........
Solid lifter cams utillize a "clearance ramp" that is a long, slow, acceleration ramp that is there to gently close up the 18-thousandths, or so space called "valve clearance" that is necessary to deal with the unequal expansion rates that the different metals that are in the valvetrain, have, as the engine warms up. All solid lifter cams use these clearance ramps.
Hydraulic lifters are designed to take up ALL the slack in the valve train, and operate at "zero lash."
This means that if you install hydraulic lifters in an engine that has a solid lifter cam, that "zero lash" lifter will start trying to open the valve ON THE CLEARANCE RAMP... not a good thing.
Holding the valve open such a small amount can cause a "blowtorch effect," and allow still-burning combustion gasses to damage the valve and valve seat.
There's no way around this, that I know of.
So, it's just not a good idea to run hydraulic lifters on a solid lifter cam.
In addition to possible engine damage, the performance would be less, because you'd have a lot more duration with hardly any more flow... not a good thing, either.
Running solids on a hydraulic cam is possible, but iffy because without clearance ramps to close up the gap, you're hammering the cam lobes pretty hard, when they try to open the valves. That can produce a "flat" cam in short order...
I'm sure there are people who have gotten away with this (running the wrong lifters,) but it's more likely, I think, that problems would occur.
Matt Selwa
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When I rebuilt my '71 Slant six I decided to convert it over to a hydraulic cam. You will need to do the following:
Replace the camshaft with a hydraulic cam.
Replace the cam bearings since the rear bearing is different in order to pump the oil to the head.
Replace the head with a hydraulic version.
Value cover will also need to be replaced (the hydraulic version is wider)
I was able to change mine over pretty cheaply when it was rebuilt since I picked up a complete '82 Super Six engine with hydraulic cam to use the entire top end on my older block.
I was going for quiet and smooth and I have not been disappointed.
-Matt
Replace the camshaft with a hydraulic cam.
Replace the cam bearings since the rear bearing is different in order to pump the oil to the head.
Replace the head with a hydraulic version.
Value cover will also need to be replaced (the hydraulic version is wider)
I was able to change mine over pretty cheaply when it was rebuilt since I picked up a complete '82 Super Six engine with hydraulic cam to use the entire top end on my older block.
I was going for quiet and smooth and I have not been disappointed.
-Matt
1970valiant
young gun
ok thanks everyone. ill be putting in a new valve train. so i cant get away with the original valve cover i have now?
IF you keep the head you now have, it seems to me you should be able to keep the same valve cover.
But then, what do I know???? Not much, unfortunately....
1970valiant
young gun
thanks
Charrlie_S
Well-Known Member
Replace cam with hydraulic cam and lifters.
Do not replace cam bearings. The oil groove is on the cam journal, not the bearing.
Leave the head alone, replace the rocker arms, shaft, and pushrods, with the correct hydraulic parts.
Depending on the year of the head, it might be necessary to change the rear rocker shaft bolt and/or redrill the rear rocker shaft hold down bolt hole.
Use the valve cover that came off the old head.
Matt Selwa
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Charrlie: Do you know what was changed in the head on hydraulic cam cars? The newer head is wider and uses a different valve cover then the older solid lifter version.
-Matt
Charrlie_S
Well-Known Member
I can't tell you exactly what was changed.
But any slant six head will swap onto any slant six engine. Also the COMPLETE valve train will swap to any slant six head, with just a minor tweek (rear rocker shaft holddown bolt). A hydro valve train should only be used with a hydro cam, and a solid valve train should only be used with a solid cam. I do know the hyro head needs the valve cover for that head, but a solid head converted to hydro valve train uses the valve cover for the solid head.
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