flat tappet. vs. roller. lifters

[drem312]

My mechanic is putting in a new jasper reman 350
5.7 Gm motor in my boat . I noticed the old motor had the roller type lifters but the one he ordered and the one going back in has the flat tappet type .will they work fine and last and will I noticed any HP lost ? Read so many different write ups. Thanks

 

[Howard Sterndrive]

Re: flat tappet. vs. roller. lifters

type of lifter, roller vs. flat hydraulic does not affect HP in any noticeable way, assuming everything else is equal in the motor.

some will cry about the horrors of modern zinc free oils and suggest you pour zinc additives in a flat lifter motor, but better to just spend $20 to sample the oil you will be using for zinc. Some marketing companies have a lot of people pouring stuff in their motors without sampling to see where they are to begin with. = bad idea
If it has more than 600 ppm, don't clog it up with additives. If it has less than 300, you might want to consider an additive.
I sampled the department store brand I use - 850 ppm zinc.

 

[Idlespeedonly]

Re: flat tappet. vs. roller. lifters

Like he said if everything else is the same. But most of the time the cam profiles will be quite different. Roller lifters are able to run on steeper lobes. If it were mine I wouldn't go back to a flat tappet. You could possibly use your old cam and lifters, but there goes the warranty. I had a lifter fail on an engine, pretty much destroyed everything. Imho the flat lifters they market now are junk. The correct jasper motor probably isn't a couple hundred dollars more. Just make sure whoever does the breaking does it right.

 

[Bamaman1]

Re: flat tappet. vs. roller. lifters

My question: If the mechanic ordered the wrong motor, is he an experienced marine mechanic?

You didn't say if your previous motor was a 305 engine or a 350 engine. Many 305/228 hp motors have been replaced with larger 350 cu. in. motors--with many satisfied owners.

Boats require so much more torque--and internal engine components are heavily stressed at redline rpms on marine engines. Truck engines won't always hold up under such stress.

The performance difference is that roller tappets have less friction, hold the valves open longer, and the valves open/close quicker. Just make sure it's a marine engine--not a truck engine.

And, make sure the mechanic knows marine replacement procedures.

 

[drem312]

Re: flat tappet. vs. roller. lifters

The previous motor was a 350 and it had been bored .30 over and rebuilt but with like 8 hours on it the cam shaft bearing went and I lost oil pressure.That was a different mechanic who said water intrusion was the problem and not the way he built it.I had two other mechanics inspect it and could not find any evidence of that. They suggested to get a long block instead of building the old one again.So I did. I plan on using a straight SAE 30 weight like the manual says. But have heard of break in oil like the Royal Purple stuff is this what Im suppose to use?

 

[Howard Sterndrive]

Re: flat tappet. vs. roller. lifters

Long Blocks come with plenty of hang tags and paperwork telling you what oil to use and how to break it in.
It depends on the honing process whether you need break in oil or not. Don't put break in oil in the thing if the literature doesn't say so. If the paperwork wasn't there, call where you bought it and ask.

 

[jeromeb]

Re: flat tappet. vs. roller. lifters

"Break in" oil is a lower viscosity than that normally recommended. The theory is the lighter oil gets into and around the initial oil pump and bearing/ring clearances. If the engine was assembled correctly, you shouldn't have to concern yourself with that. No extensive idling and take it easy with the throttle for the 10 or so hours of operation. Give it an oil/filter change while the engine is still warm. This flushes any residue associated with break in. This would be for "break in" or recommended use oil.

Flat tappet engines have been around for years with little or no problems. Rollers are more expensive to build and more efficient performance wise. I don't think that difference would be noticeable to the everyday boater.

PS: You were right to go to another technician. "Water intruding causing the cam bearing to wipe out". A whole lot more would've happened before that.

 

[Jason89sunbird]

Re: flat tappet. vs. roller. lifters

Distributor gear??? You need the right gear for the cam, hate to see you in the middle of a lake stranded.

 

[drem312]

Re: flat tappet. vs. roller. lifters

Distributor gear? Are you saying the old prestolite distributor from the other roller lifter motor will not work with the new reman flat tappet jasper engine ? It should or will be different? I will be starting it tonight and timing it .The distributor fit in nicely. It was all assembled yesterday and put in the boat.

 

[Idlespeedonly]

Re: flat tappet. vs. roller. lifters

If you have a steel cam you need a melonized gear. If your new cam is cast iron you can use a standard gear or melonized. Roller cams can be steel or cast. Some are even steel with a pressed on iron gear. You need to call the supplier of the engine for their reccomendation. Cause your warranty depends on it. They look for any little error on your part to void the warranty.

 

[RogersJetboat454]

Re: flat tappet. vs. roller. lifters

Should work just fine. The only reason I would check it is to make sure it doesn't look worn out.

With some of the aftermarket roller cams, you need to use a bronze distributor gear. The material the aftermarket cams are made out of will eat up the old style iron gears. This is not the case with factory style roller cams though.