im pricing out parts for the 351 project i'm starting and it has come to my attention that converting it to roller lifters is WAY more expensive then keeping it flat tappet. i dont have much expirience with flat tappet lifters, what makes rollers so much more desirable? are flat tappets more noisy? dramatic power difference? way more wear on the cam? i realize rollers are better, but are they really $300 better? i got a feeling im gonna go oldschool tech on this project.
the main difference is less friction and a more aggressive ramp.
Spend the extra and go roller, other than the reasons stated above, you'll never have to worry about wear on the camshaft as there isn't any with rollers
If you can find a '94 or newer block (F4 casting) it'll already be roller
I would go roller. The biggest difference is of course friction that is only oudone by the fact of the valves open nd close much faster. That allows the valve to be open longer during the stroke. Huge difference.
If it helps, I'm building a flat tappet motor right now. It's not fancy but it'll be a stout 302. It's the best I can do for my budget. Cams are alot cheaper for a flat tappet motor.
^ I'm getting ready to do the same. It all depends on how much money you want to spend IMHO. I'd love a roller block, but I have flat tappet. Hence.... a new flat tappet cam
well, obviously the less money spent is better. any ideas whats the biggest lift and duration i can go in a 351w with flat tappet? i realize with roller its almost the sky's the limit. but if i can still run a pretty radical cam with flat, maybe i'll just do that. cus not only do i have to get conversion lifters, which are alot more, but i also gotta get a roller cam, which is a little more expencive but not bad. the conversion lifters worry me the most.
Don't forget about springs!
Flat tappet cams were only used for 75+ years prior to the rollers, not a big deal... We ain't talking wild RACE ONLY cams here, valve opening/closing events are going to similar on flat & roller street cams...
If you had the block that's another story, but converting one ain't worth the money IMO...
Tom
X1+ Flat's are fine ,sometimes safer.
+2
If it's a flat tappet block keep it. You really won't notice a huge gain by going to a roller if both cams have the same specs.
thanks guys, that mostly what i was wondering, if there were any huge dissadvantages. seems like flats are the way to go. there was good bit of sticker shock when i saw the price of conversion kits. thanks again
-keith
sticker shock aint the words for it, its highway robbery. They have roller anything for just about any older blocks / heads. you just gotta pay.
Serriously why the hell are the retro-fit lifter kits sooooo expensive? All the lifter has extra is a tie bar:hick: