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Ok i have a buddy putting together a 500 cubic inch blower motor that had a little mishap 12 #s of boost 671 blower on a k boat,yhe motor had a roller cam and lifters,he was thinking of putting a flat tappet cam and solid lifters in it due to being about a 1000 dollars cheaper we would like to no the ins n out or dues n donts over the two,hp and long jevety thanks
 

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steelcomp was here
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You'll never make the same power with the flat tappet as you will with the roller. Having said that, if you're on a budget you can get some good flat tappet grinds that'll perform very well. A custom grind will be even better. You'll need to change valve springs. The biggest issue with flat tappets today is available engine oil and proper break in. You'll need to run a flat tappet friendly oil, and make sure you'r very diligent about breaking in the cam correctly. Done rignt, a flat tappet should last the life of the engine. Done wrong, it'll be junk in the first ten minutes.
Just to add, for a custom grind roller and a set of standard lifters, you're looking at well under a grand. If you want more info on either the flat tappet or roller, let me know.
 

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mo balls than $cents$
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i wouldn't waste my time building sumthing like that without a roller:D bbc hyd roller lifters are cheap these days and don't require all the high buck springs/retainers:)bulb
 

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just a ski boat with bark
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i wouldn't waste my time building sumthing like that without a roller:D bbc hyd roller lifters are cheap these days and don't require all the high buck springs/retainers:)bulb
That's pretty generalized isn't it Tom? If he wants or needs to turn 7000-7500rpm I don't think cheap hydraulic roller lifters will work. After he steps up to solids then the additional spring pressures required for most lobe profiles that turn higher rpm are no longer "cheap". Now once he gets the springs with the seat pressures needed to turn that higher rpm then you need to start looking at "pressure fed roller lifters" which aren't cheap so the rollers will live with all the off idle low rpm cruise that happens in most of these hotrod boats.

I'd love to step up to a roller but converting isn't "cheap" especially for the rpm range I run in. Yes it would gain me some HP but as usual speed cost money.

Just my .02
 

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Stepping up to a roller from a flat tappet is an expensive endeavour, better valves, better pushrods, springs, retainers&locks, rockers, cam , lifters, preferably a good girdle unless you step up to the shaft mounts then the $ goes through the roof.
Its another one of those things that depends on the intended use, if its a max effort deal, the rollers the only way. Hp costs $$ , how fast do you want to go.
If its just a little lake hot rod that you want to sound good and just run a little better than average, then a flat tappet may be for you.
 

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mo balls than $cents$
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That's pretty generalized isn't it Tom? If he wants or needs to turn 7000-7500rpm I don't think cheap hydraulic roller lifters will work. After he steps up to solids then the additional spring pressures required for most lobe profiles that turn higher rpm are no longer "cheap". Now once he gets the springs with the seat pressures needed to turn that higher rpm then you need to start looking at "pressure fed roller lifters" which aren't cheap so the rollers will live with all the off idle low rpm cruise that happens in most of these hotrod boats.

I'd love to step up to a roller but converting isn't "cheap" especially for the rpm range I run in. Yes it would gain me some HP but as usual speed cost money.

Just my .02
not really loren i've seen some pretty good deals on name brand lifter sets and with the proper beehive single springs, they easily do 7k, but yeah 7500 would be too much i'd think too.i won't be goin back to solid rollers at all anytime soon, hyd is just easier on parts and if i can build all my power before 7k and make a motor take less maintence, i gonna. the hyd roller lifters i'm currently runnin i get free anyways, hard for me to ever think bout solid at this point:p
 

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Ok i have a buddy putting together a 500 cubic inch blower motor that had a little mishap 12 #s of boost 671 blower on a k boat,yhe motor had a roller cam and lifters,he was thinking of putting a flat tappet cam and solid lifters in it due to being about a 1000 dollars cheaper we would like to no the ins n out or dues n donts over the two,hp and long jevety thanks
As soon as I read this, then read Carnivalride's I can see there needs a little clarification. If this a real honest to God APBA, side by side, 120mph on the straights, 80 thru the corners, K boat, you are just kidding yourself with a flat tappet. You will never make enough HP. If on the other hand, if this a blown flat bottom, river racer "k" boat, and I suspect it is, you will probably make more HP than you can deal with by using THE RIGHT flat tappet. Chances are the thing won't be floored for more than 10-12 seconds at a time, on perfect water. I can count on 2 hands the number of people that can drive those things enough to need that HP. I get beat up all the time for saying the terms K and GN get thrown around to loosely by river racers. My recommendation is, follow what Steelcomp said, run good oil like BradPenn, or a good syn, and keep clean underware available in the boat at all times.



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Roller. Bottom line we have limited friendly oil for this stuff anymore and without the OEMs using millions of flat tappet lifters and keeping the QC to less then 1% PPM failure the aftermarket is flooded with junk flat tappet lifters.

Get a good set of springs, very good set of lifters and when you can always go larger diameter, good heavy wall pushrods ( forget what we preached in the '80's and 90's) and the larger the better, and a good billet core camshaft and again if you got the bucks go big here on journal size.
 

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As soon as I read this, then read Carnivalride's I can see there needs a little clarification. If this a real honest to God APBA, side by side, 120mph on the straights, 80 thru the corners, K boat, you are just kidding yourself with a flat tappet. You will never make enough HP. If on the other hand, if this a blown flat bottom, river racer "k" boat, and I suspect it is, you will probably make more HP than you can deal with by using THE RIGHT flat tappet. Chances are the thing won't be floored for more than 10-12 seconds at a time, on perfect water. I can count on 2 hands the number of people that can drive those things enough to need that HP. I get beat up all the time for saying the terms K and GN get thrown around to loosely by river racers. My recommendation is, follow what Steelcomp said, run good oil like BradPenn, or a good syn, and keep clean underware available in the boat at all times.
i agree with steel and gn7.there are some really good grind flat tappets out there and even better you can have one ground custom that will do the job better.

it depends on what you are doing.

use good oil not cheap shit.Valvoline makes racing oil that about 6-7 bucks a quart that has additives in it for flats.also you have alot of choices as to additives to add with it.

flats are not a thing of the past for me and alot of the guys i know.use your head when setting them up and go play.

they generally wont make as much power.

its all about money $$$$$$$$.

good luck Travis
 
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