The plan, 93 Roadmaster 350(Chevy)change the cam and intake to carb.The cam I have little information on except it worked well with the intake in my last high milage engine till the crank berrings went.The question we changed the roller lifters to reg chevy style,(hydrolic?)because it was suggested rollers and older cams don't workwell together. Everything did work fine but I was wondering if this is a necessary step.I know that I don't have all the info but I was just wondering if generally if there is a reason for this change. Ed
If I'm reading this correct your using standard hydraulic lifters on a cam profile that was ground for hyralic roller lifters?? It Wont last it will wipe the camshaft out and the lifters..... a regular style hydraulic cam has the lobes ground slighlty on an angle in order to rotate the lifters as the cam spins, a roller cam has a flat surface for the roller to run on....not to mention the ramp profiles are totaly different between the two styles of camshafts......
__________________
You dont like it?? Tough S$#t.... I didnt spend my money to make you happy....
Thanks for the explanation.What I was wondering was why I couldn't use roller lifters on a cam designed for hydraulic lifters as we are using an older style cam in a newer engine. Your answer is very helpful so we will change them again as usual there is a good reason for everything . Ed
as stated the lobes on your hydraulic cam have an angle built into them, and the roller requires a flat surface - if you run a roller on that cam the angle will cause the roller to only bear onto one side of the roller, causing the neede bearings to pinch, wear prematurely and disintegrate - destroying everything in its path
DONT do it unless you have a spare motor ready to replace it with
Sorry, more info to add ... As has been mentioned, a flat tappet cam is designed to spin the lifters in the lifter bore when the engine is running. A roller cam is not designed to spin the lifter (in reality the roller lifters are actually equipped with a device to prevent the lifter from spinning ... in the Roadmasters case the "dogbones and the spider"). Combining the two (whichever two you decide to mix ... roller cam and flat tap lifters or roller lifters and flat tappet cam) will end with camshaft/lifter failure.
One thing I should mention ... you cannot swap used flat tappet lifters from one cam to another. Once a flat tappet cam has been run with lifters, those lifters are mated to that cam AND if you decide to remove the cam and reinstall it (whether in the same engine or not) the flat tappet lifters MUST be reunited with the specific lobe that they were initially mated to. For example ... if you remove the cylinder #1 intake lifter it MUST be returned to the cylinder #1 intake lobe, the flat tappet lifter can not be mixed up. If you have a used flat tappet cam and have mixed up the lifters ... you need to buy new lifters (yes, you can install new flat tappet lifters on a used flat tappet cam).
HOWEVER ... due to the design of roller lifters, you CAN reuse used roller lifters on old or new roller cams and you do not need to reinstall cylinder #1 intake lifter back into the cylinder #1 intake lifter bore. Roller lifters do not mate to roller cams.
What does this mean to you? You can either reuse the factory Roadmaster roller cam and roller lifters or you can replace the factory Roadmaster roller cam with an aftermarket performance cam (that also includes the fuel pump lobe) and reuse the Roadmaster used roller lifters on the new cam.
Personally, in my opinion if the engine has the roller stuff already you'd be taking a step backwards by removing it.
-- Edited by Rusty Nuts on Thursday 26th of July 2012 08:21:09 PM
As has been mentioned, roller cams and flat tappet lifters or flat tappet cams and rollers lifters don't play well together. My question is why convert a roller cam engine to flat tappet? I bought a '95 350 out of pickup truck (flat tappet) and added all the roller stuff from a '92 Buick Roadmaster. The only issue I had is the factory roller cam does not have the lobe for the fuel pump ... I just added an electric pump (for now) rather than change to an aftermarket cam with the pump lobe.
I also installed a 1987 Monte SS carb intake and an early quadrajet and an old style HEI, keep in mind you need to change the dist gear to a "melonized" one (I bought mine from GM) when running an old style HEI with a roller cam. The roller cam stuff is the way to go, less friction and no worries regarding the lack of zinc in oils when running roller stuff.
Apparently you can add something like 50 extra hp by swapping on a set of Vortec (GM 350) heads too although I have heard those heads are prone to cracking.
Thanks again for the input.You have answered a lot of the why can't I just do this questions,Now for the why would he want to do that side.I have a 93 Roadmaster engine,a carb style performance manifold and cam,You can probably see where this is going.Don't want to run the computer stuff or the electric fuel pump unless necessary.The cam and manifold and flat lifters were in the eng(92 Roadmaster,I just love those wagons)that the bottom end went out of at the last Armdrop.So I have to go with the stuff I already have for the next engine and was just looking for the best combo and answers to the why can't I just do this ,and once again you guys came through,thanks. Ed
