View Full Version : Roller cam into a non roller block
10-18-2006, 04:34 AM
I found a sweet hydraulic roller cam for my EFI 406 but the block is non roller. I have a couple of questions?
1) Has anyone converted their pre 87' block into a roller cam motor? I know you need the retro roller lifters, dual springs and shorter pushrods for the taller lifters. Do I need a cam button to keep the cam from walking since rollers are machined diffrent?
2)I've seen roller lifters(retro fit) go for $380-$500 for a set of 16. Does anyone know where I can find them cheaper? I saw a guy on ebay who sells his blueprints to convert a pre 87' block into a roller lifter block(using the spyder lifter retainer). Not sure if it's a good idea to drill into the lifter valley to save 200 bucks.
3) Is all this even worth it for a roller cam? any opinions?
10-18-2006, 10:46 AM
I'd stay away from th comp cams lifters. They don't make a Hyd roller lifter that isn't crap. A speed-pro set or lunati is a good choice. A roller cam in a similar profile to a flat hydraulic is going to add approximately 100 lbs of torque to the engine. I'd make sure you use a roller thrust button and a good timing cover, even a fresh gm one if nothing else.
10-18-2006, 02:52 PM
There's alot of horsepowwer in going from a flat tappet cam to roller,you pick up as much 75 horsepower.
Comp cams make a retro fit kit doesn't require any machine work.That will have everything needed to install the cam.
For lifter I would use Comps 853's,they are for a retro fit install and just like the stock roller lifters,it's the Pro Magnum or the "R" lifters poeple call them that they had problems with.
10-18-2006, 03:11 PM
For lifters: The hot ticket right now, bar none, are the Morel lifters. If I were building my engine again I wouldn't even consider anything else. Totally awesome parts. Isky sells them under their name too. I currently use Comp HR lifters with no ill issues up to 6700rpm with beehives and a rev kit but the Morels are simply far better pieces. They're about $500 a set. Lifters are not a place to cheap out!
Pushrod length, like a standard lifter, needs to be tested and determined at the time of assembly using a length checker. HR lifters usally require pushrods that are ~.400" shorter.
You will need a method to set and control cam end play. You'll want a timing gear with a thrust bearing against the block and you will want an aluminum timing cover with either a thrust button or bearing. I really like the Cloyes externally adjustable 2-piece covers. A water pump with a cam stop isn't a bad idea either as even a cast aluminum timing cover will still flex. Shoot for about .005" endplay.
Word of warning about the cam itself, DO NOT BUY A CAST CORE ROLLER. Make sure you get it on a billet core with a pressed on iron distributor gear. Comps HR's are by default a "special cast material" which as far as I can tell is synonomous with "junk." Shredded distributor gears and wiped out lobes are the norm with the Comp cast core rollers. Comp by special order will do any HR on a -9 Billet core and then make sure you ask for the pressed on iron distributor gear. Crane's HRs by default are billet core, iron gear.
Final word of advice going HR, you can disregard the spring rate advice that most of the MFG's provide-- they want stuff that is too soft and can't adequately control the valves and you end up with float at a very low RPM. With standard springs about 150-160# closed / 425-450# open is good, with beehives you can get away with about 150# closed / 350-375# open because of substantially decreased mass in the spring & retainer. I changed to beehives earlier this year and really, really like them, I picked up 300rpm or so with less spring pressure!
10-18-2006, 10:02 PM
Thanks for the advice. I'm still debating if I should go roller or not.
10-19-2006, 05:28 PM
I HIGHLY doubt a roller cam with the same profile as an hydraulic will make 75hp more and 100lb ft. Do you guys have any dyno graphs to back this up? From my understanding a main advantage of going to a roller cam is that the valves can be opened up much faster (steeper lobes).
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