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Old 10-07-2009, 11:48 AM
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hydraulic flat vs mechanical flat

Hey guys got a question here that I need some info on. I am about to rebuild my failed 383sbc project that exploded. It previously had in it a hydraulic flat tappet but it wiped 2 of the lobes off. I need to buy a new cam and lifters regardless now so I am considering going the mechanical flat tappet route instead. This engine will not see over 6000rpm so I do not believe a roller cam would be a must-have. My question is what is the main advantages/disadvantages between running a hydraulic flat tappet opposed to a mechanical flat tappet? I know for a mechanical cam you have to check the clearances at the valve stem every now and then but performance wise is there any differences to be noted between the two? I would be interested in going the mechanical route because I enjoy setting clearances and tuning the valvetrain this way. Any input here would be greatly appreciated.

Thanks,
Keith
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Old 10-07-2009, 12:04 PM
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No advantage to solids at 6000. Normally used for higher revs where hydraulics would pump up and limit r's.

Personally, I think you'll be doing this a third time. Bite the bullet and go with a roller hydraulic. Someone on here recently said Howards has retro-fits for around $500.
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Old 10-07-2009, 02:48 PM
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383 solid / hydraulic

if you enjoy setting clearances,, go ahead and get the solid... the ramp rates are more aggresive than a hydraulic, and will make different power thru the range... plus if you happen to overrev the motor you wont blow a lifter as easy..sounds like you like to beat on your motors so go ahead... plus nothing matches the sound of a solid lifter cam at the stop lights...if you can afford it go for the solid roller... anyway thats my opinion,and am sure you will decide for your self...it'ss up to you... you can set the valves with a remote start button in 10 mins or less when you know what your doing...
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Old 10-07-2009, 05:18 PM
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Quote:
Originally Posted by sexypizzaman
Hey guys got a question here that I need some info on. I am about to rebuild my failed 383sbc project that exploded. It previously had in it a hydraulic flat tappet but it wiped 2 of the lobes off. I need to buy a new cam and lifters regardless now so I am considering going the mechanical flat tappet route instead. This engine will not see over 6000rpm so I do not believe a roller cam would be a must-have. My question is what is the main advantages/disadvantages between running a hydraulic flat tappet opposed to a mechanical flat tappet? I know for a mechanical cam you have to check the clearances at the valve stem every now and then but performance wise is there any differences to be noted between the two? I would be interested in going the mechanical route because I enjoy setting clearances and tuning the valvetrain this way. Any input here would be greatly appreciated.

Thanks,
Keith
Flat tappets make noise and need adjustment, hydraulics are quiet and don't add to your work load.

Roller cams are not just for super duper race cars any more, they have been commonly put in most, to all, production by the former big three for over two decades now. The purpose is to overcome wear on flat tappet lobes and lifters as the amount of ZDDP (a dry high pressure lube) has been removed from oils so as to protect catalytic converters from metallic zinc and phosphorous contamination. As we go forward, flat tappets are having a tougher time surviving in the low to no ZDDP environment. The higher the spring pressures, higher and faster the lifts, the greater the lobe and lifter wipe out rate has become. Manufacturers have turned to better materials and processes but the overall failure trend remains much higher than in the good old days prior to 1985 or there abouts.

I even recommend that when building a flat tappet engine, like the SBC, that you use a cam bumper. While intended to keep aftermarket roller cams from roaming around which wipes them out; for a flat tappet cam, it relieves the lifters from the job of carrying the cam's thrust loading on top of their already rather busy schedule of duties. While not a cure-all, in today's world it's less load on an already overloaded interface.

Bogie
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Old 10-07-2009, 10:55 PM
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Quote:
Originally Posted by techinspector1
No advantage to solids at 6000. Normally used for higher revs where hydraulics would pump up and limit r's.

Personally, I think you'll be doing this a third time. Bite the bullet and go with a roller hydraulic. Someone on here recently said Howards has retro-fits for around $500.
The Howards cams are high quality stuff . Put one in my 406 and can't complain. Runs great, MPGs are good,and power is amazing. If I were to build it again I would have went with 2.02 vortecs instead of the 1.94s,they didnt have them listed when I bought mine ,and possibly a comp cam,shorter duration,but more horsepower,torque stays about the same according to a desktop dyno.
I'm in the 475hp range now, the larger valves and different cam would have brought me up around 510.
I see no reason that the Howards lifters couldnt be used on a Comp cam.
But I know for a fact that the Howards cams are high quality.

Shane
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Old 10-08-2009, 07:04 AM
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There is still a considerable price difference between roller and flat tappet cams. If you can afford the roller cam- then run it. If you can go that route though going with a mechanical roller would be the absolute best- but a good solid roller cam, lifters, and valvespring set up will cost you right under a grand. A good mechanical flat tappet set up comes in a hair over $200.
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Old 10-08-2009, 07:15 AM
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The thing I have against mechanical cams is that most of my street motor customers have no clue on how to lash them correctly. Back in the day "solids" were the only way to go. Today with computer profiles, there is no reason to use solid lifters on a hot "street" motor.
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Old 10-08-2009, 12:58 PM
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One plus to solid lifters that many have overlooked is the fact that you can get them with a tiny oiling hole lasered right thru the face for lobe-to-lifter face direct oiling. Most all the major cam companies have them, call them "direct lube", or "cool face", or "face oiling" lifters.

On a direct comparison, a solid will usually out power a hydraulic acrossed the power range.
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Old 10-08-2009, 01:06 PM
How fast is fast enough?
 
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with the word "usually" meaning in all cases- unless you screwed up somewhere else.
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Old 10-08-2009, 01:18 PM
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i like solid cams myself. i love the sound they make. like an old singer sowing machine. i would strongly suggest a stud girdle for the rocker studs. you can get them for about $80 bucks now & it will keep you from adjusting every week. after i started using a stud girdle on my 327 i only had to check the valve adjustment every other month, & rarely did any need adjusted. i spun it to 7,000 every day! i would also suggest going about 5-10 deg. bigger when going to a solid flat tappet. the valve lash will eat about 5-10 deg. of cam duration on a solid lift cam.

one more thing, it doesn't matter what type or name brand you buy, add the oil aditive in your oil that's made for flat tappet cams. oil these days suck for flat tappet cams.
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Old 10-13-2009, 05:28 PM
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Thanks for all the info guys, I have a better understanding now. I am planning on taking my time with this engine build and buying quality parts so that the engine will live a healthy life. If I were to go the mechanical roller set-up I don't understand why I would need stronger valve springs if I were to run a fairly mild cam that only has 0.500" of lift. These are the exact heads I have now with those exact springs, http://www.jegs.com/webapp/wcs/store...-1&showValue=1 . If the engine isn't going to see over 6000rpm and I were to run a roller cam, would I need to replace those springs for bigger ones? If so please clear this up because it has always been my understanding that large springs were intended for engines pushing over 6000rpm.

Thanks,
Keith
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Old 10-13-2009, 05:51 PM
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roller

roller lifters require special spring ratings over flat tappet for the reason of steeper ramp rates,,, and quicker opening/closing rates,,,,,just simply replace the springs with the ones the cam manufactuer reccomends,,,, then you will have no problems.... "just do it"
the cam manufactuers wouldnt waste there time matching springs for cams for no reason,,,,simple?,,,
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Old 10-13-2009, 06:02 PM
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Quote:
Originally Posted by 489600
roller lifters require special spring ratings over flat tappet for the reason of steeper ramp rates,,, and quicker opening/closing rates,,,,,just simply replace the springs with the ones the cam manufactuer reccomends,,,, then you will have no problems.... "just do it"
the cam manufactuers wouldnt waste there time matching springs for cams for no reason,,,,simple?,,,
And they are often heavier than a flat tappet, so when you wrap it all up a different spring is required to keep all the subtle changes under control. A floating roller lifter does really ugly things to a cam, and itself, a lot faster than a flat tappet will in the same situation.

Bogie
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Old 10-13-2009, 07:55 PM
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When looking at cams on jegs or summit though i can't see anywhere that lists the recommended springs for any particular cam The springs I have on my heads (look at the link in my previous post) are 1.25O.D. duals. Are these intended for flat tappets only??
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Old 10-13-2009, 09:08 PM
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Quote:
Originally Posted by sexypizzaman
When looking at cams on jegs or summit though i can't see anywhere that lists the recommended springs for any particular cam The springs I have on my heads (look at the link in my previous post) are 1.25O.D. duals. Are these intended for flat tappets only??

for those recommendations ya have to check the manufacturers website (edelbrock,comp, etc) edelbrock is especially good about that sorta thing. hope this helps
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