Temptation to do a swap

Topic: Temptation to do a swap (Read 5170 times) previous topic - next topic

Temptation to do a swap

Reply #15 – September 06, 2011, 11:39:29 PM

Flat tappets are better for the short runs. If you want a 1/4 car or something you can take around a track a few times a year, go Slider cam all the way. For a daily driver you can stomp in to when you get that wild hair to do so, go with a roller. If I recall, you can use roller rockers with slider cam, I could be wrong, but who knows. I also know they make roller rockers for the 351C and 351W as well as the ever so rare 351 Jasper. Just sayin, the engine and head doesn't limit you. Just because it was stock slider doesn't mean you can't make it a roller motor. On top of that, buy that stock roller motor, keep those xx year old roller rockers in it and see how well that works out for you when you put those 7 - 8k rpms of stress on those 130k mile roller rockers. That's a conservative 130k mileage. If you're going to replace the roller rockers in a 351 Roller motor, you're doing the same thing you would have done with your 351C.

Temptation to do a swap

Reply #16 – September 07, 2011, 06:29:39 PM

What are you talking about? How do roller rockers have anything to do with the cam? Also, how did a Cleveland get brought up in this?

Temptation to do a swap

Reply #17 – September 07, 2011, 06:32:43 PM

I don't understand what's going on in this thread. What's wrong with hydraulic flat tappet lifters? This whole "flat tappets suck" thing makes no sense.

Temptation to do a swap

Reply #18 – September 09, 2011, 06:46:28 PM

Flat tappets are metal on metal grinding. They sling little shreds of metal in your engine. If that's your thing, have at it. For a DD I wouldn't have them. They don't suck, they just have a use they're better for and they have a use they're not. That's just my opinion.

Temptation to do a swap

Reply #19 – September 09, 2011, 07:57:20 PM

Quote from: cougarman;366776

Nascar uses flat tappets still, in a block based off the 351 and they turn upwards of 9000+ for hours on end.

Not since last year, they now run the racing specific FR9 that was developed for NASCAR... It's similar to the racing engines developed by Chevy, Chrysler and 'Yota...

Quote from: Mischief;367183

Flat tappets are metal on metal grinding. They sling little shreds of metal in your engine. If that's your thing, have at it. For a DD I wouldn't have them. They don't suck, they just have a use they're better for and they have a use they're not. That's just my opinion.

Not really, the base of a flat tappet lifter is slightly convex, so spins on the lifter lobe... The 2.3 slider cam is basically a disaster waiting to happen, but in all fairness we ran a '87 4cyl Stang to 192K mi and never had the cam cover off of it...

Temptation to do a swap

Reply #20 – September 09, 2011, 11:27:13 PM

Quote from: Mischief;367183

Flat tappets are metal on metal grinding. They sling little shreds of metal in your engine. If that's your thing, have at it. For a DD I wouldn't have them. They don't suck, they just have a use they're better for and they have a use they're not. That's just my opinion.

This post is complete BS. Not a single thing you just said is correct. No, it's not metal on metal grinding. Guess you missed out on something they just came out with called oil. No, they don't sling little shreds of metal into your engine. TurboCoupe50 is 100% correct. The lifters spin in their bores because the lifter faces are convex and the cam lobes are slightly angled. This is done so they wear evenly and INCREASES longevity. The only disadvantage to flat tappets is increased friction compared to rollers. As far as reusing roller lifters, tons of us have done it and spun our motors up to 7000 on a regular basis without ever having a failure. As long as the lifter is in good working order, there's no reason not to use them. Also, why would you run a flat tappet in a race car but not a daily driver? This is such backwards thinking.

I understand that you feel this way about flat tappets for whatever reason but there could be people out there reading this that are taking what you're saying for fact and being turned off to flat tappets for no reason. It's one thing to have an opinion but giving out information that is completely wrong isn't helping anyone.

Temptation to do a swap

Reply #21 – September 11, 2011, 09:42:02 PM

If I may add to this discussion.

Roller lifters do two things - reduce friction and allow for steeper profile ramping (valves can be open longer).

Regarding the use of flat tappets vs rollers in a 5.8, who cares? Isn't the point of a "big" displacement engine to avoid the need for high revs? A 5.8 and numerically low gears sounds like a good compromise for relatively good fuel consumption and drivability. If you want to really go after it, go with a 5 sp auto or 6 sp manual trans, and don't forget to match the axle ratio to the trans gears and intended use. Then you might start worrying about roller tappets.

Ford used rollers in the later 5.0s because they were looking for ways to make power while reducing fuel consumption. In those motors, roller cams reduced internal losses and allowed shorter duration cams with lots of lift.