Originally Posted by zildjian4life218
Can anyone let me know about the cam thrust button? Will I need one. It looks like the nose of an OE roller and "retro-fit" roller are different so im not sure what problems ill run into here. Also I read that a rather mild hydraulic roller cam will need springs with a spring rate of about 250-325. Can anyone elaborate on this and give me some suggestions on valve springs.. I looked on howards sites and they don't have a recommendation for that cam. Thanks
The OEM roller and aftermarket roller are different at the nose requiring different assembly.
The OEM roller:
The nose of the OEM style roller cam is extended that has a reduced diameter which fits through and uses a thrust plate. That any installation requires that about a quarter inch section be filled between the timing gear and block as a result of the cam nose. The non roller cam timing gear cannot be used as it fits too far forward with this arrangement for the timing case cover to fit and too repeat, it's short to the block by the thickness of the thrust plate.
To make this cam work on a non-roller block you need to buy a thrust-plate, then cut the ears off of it to make it into a round, thick thrust washer to fit between the block and the cam gear. Then the timing gear and chain set needs to be the single row roller for the LT-x roller cam. Then you will have to mock assemble this to see if the timing cover will clear the chain, if it doesn't usually an extra gasket will provide enough shim. Once this is known, then you need to install the thrust button and set its clearance.
The Roller for standard F/T blocks (retrofit):
These pre-roller block cams use the flat tappet cam nose that does not use a seperate thrust plate. These are about a quarter insh shorter than the OEM style roller cam such that the back side boss of the timing gear is the thrust surface against the block. These use standard flat tappet style timing sets. there shouldn't be clearance issues with the timing case cover and a single thickness gasket, but you need to check to be sure. These us a the aftermarket thrust button without any need for a modified thrust plate to function as the thrust washer as this is built into the cam gear unique to the pre OEM roller blocks.
A side note:
Many trucks from 1987 to 1995 use a flat tappet cam in the roller block, these do not need a thrust washer as like earlier blocks. The flat tappet cam in these engines is shorter (same as earlier F/T engines) and mounts the same timing set as earlier flat tappet blocks. These engines are easy to convert to the factory roller cam as all the needed provisions for the thrust plate, spider, and raised tappet blocks are there so they just take the detail cam and tappet parts to modify.