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Author
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Topic: Solid roller or flat tappet?
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Clasy66
Journeyman Posts: 59
From: Placerville, CA (near Sacramento)
Registered: May 2003
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posted 08-20-2003 02:33 AM
   
I'm planning on a solid cam for my 331ci street/occasional strip motor but I can't decided between roller or flat tappet. What difference in valvetrain hardware will I need for a roller cam, besides the roller lifters? Would it be as reliable as a flat tappet? I've been thinking either a comp 270s or 282s cam.Thanks
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Brandon
------------------------ '66 Mustang coupe
Fresh but stock 302
Holley 4V/Edelbrock Streetmaster 289 intake
Tri-y Headers/2.5" dual exhaust
C4
Front disk brakes
8" 300 open rear
Stock heads and cam Purchased car 06/2003
Goal: 12 second beautiful but mean daily driver.
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two89w
Gearhead Posts: 316
From: sydney australia
Registered: Sep 2002
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posted 08-20-2003 05:00 AM
I cant answer your question correctly about rocker/valve train hardware but being an owner of a solid flat cam.......go for a roller ! 
The Cost will be more but worth every cent or dime in your case !
I think most replies you will get will say the same as myself
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 08-20-2003 08:21 AM
The hardware will be basically the same. For reliability, I used the Compcams Xtreme 274 street roller ( changed firing order to 351W), matching double springs,retainers and locks that accept lashcaps, hardened lashcaps, TFS roller rockers, .080" wall hardened pushrods, hardened guideplates, 7/16" ARP studs.------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank and girdle, 5.4 H-beams, Forged slugs, TFS alum. heads, ported Stealth 8020 intake, Xtreme 274 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)full street trim!
DanH
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 08-20-2003 09:15 AM
Going from a comparable flat tappet to a solid roller may get you 10-15 hp, at a much bigger price tag. And if you are using a street roller, it may not gain that much.Lash caps aren't needed, but are a nice touch to give the rollertip of the rocker more surface area to contact (we have them on KK's solid flat tappet 351W).
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 08-20-2003 09:31 AM
Kid, the reason I recommend the caps is because SS valves tips just don't wear well on the street with lash.------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank and girdle, 5.4 H-beams, Forged slugs, TFS alum. heads, ported Stealth 8020 intake, Xtreme 274 Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi.
11.86 @ 116 mph (7.62 @ 93 mph)full street trim!
DanH
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 08-20-2003 10:01 AM
I bet the higher spring pressures from the roller would be harder on the stems on the street. I ran a solid flat tappet on the street for a couple of years and had no problems without lash caps. But it only had 130# on the seat as opposed to 170# or so that most street rollers use.
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 08-20-2003 10:48 AM
You're right. .600" lift is a little harder on everything, but it really squeezes the HP and torque out of the heads.
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 08-20-2003 10:55 AM
My last solid flat tappet cam I ran in a "street" motor had .589/.605 lift.
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bluestreek
Gearhead Posts: 1724
From: Athens,GA
Registered: Jul 2001
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posted 08-20-2003 11:12 AM
KV, Do you use caps on your 351C race motor? I started out not using them , but noticed some slight grooves in my tips after about 3000 hard miles.
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 08-20-2003 11:20 AM
No I don't use them. I tried them once years ago and didn't like them. If the lash got excessive (which at the time it tended to do), they were prone to come off (I think I had the wrong locks.) So, my experiance with them wasn't very positive, but, I had a lot of stuff wrong back then so I'm sure it wasn't related to the locks.Now my motor comes apart every winter and the stems get surfaced so I don't know how they would fare if I left them on for say 2 years or more. I do run a relatively high amount of seat pressure (240-250# on the seat), but the lift isn't real high for a race motor (.650).
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Clasy66
Journeyman Posts: 59
From: Placerville, CA (near Sacramento)
Registered: May 2003
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posted 08-21-2003 02:58 AM
Why is it that a roller setup needs more spring pressure? Is it because roller cams run a more aggresive ramp vs a similar duration flat tappet? Also, I'm assuming a lash cap is a small "button" that sits on top of the valve stem to prevent wearing the stem itself. Am I right? Sorry, I'm kinda new to this stuff.For 10-15hp I'm leaning towards flat tappet due to the extra cost and complexity. Brandon
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kid vishus
Gearhead Posts: 6405
From: middle of NC
Registered: Oct 2000
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posted 08-21-2003 07:07 AM
There's a couple of reasons they need more spring pressures, the main one is like you stated, they have much more aggressive ramps than a similar flat tappet cam. The second reason is, they lifters are heavier (at least I feel that is a small reason why.) Street rollers aren't as aggressive as a fullrace roller, but they are still enough so they need more pressure to keep the valve on the seat and to keep the lifter on the cam. The 10-15 hp difference is just my guess. It may be more than that, but I have not seen any "good" dyno tests to verify or falsify it either way. 
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