496 coming together
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Instructor
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Thread Starter
Instructor
Joined: Dec 2017
Posts: 239
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A 247/256* cam is pretty big for a hyd roller....and along the lines of what I think Chris would have spec'd for you..... A comparable cam in a solid roller would likely be 257/268* or so..... usually its roughly 10* more for a solid roller for comparable specs, this is due to the .02x" you lose from valve lash in a solid, vs. 0 lash in a hyd roller.
A 247 hyd roller will work pretty well for your combo, I'd run it for sure....
Since your receipt says "solid roller"./....I'd say its a solid roller.
A 247 hyd roller will work pretty well for your combo, I'd run it for sure....
Since your receipt says "solid roller"./....I'd say its a solid roller.
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do you have the l88 or the tall l88 hood? Wondering because I’m wondering now if I should put a Vic jr on there or if the rpm is the best way to go. Combo was designed for Airgap rpm so I don’t know if I’d be messing it up by switching.
Last edited by Muzzyzx7rr; May 11, 2018 at 04:29 PM.
Le Mans Master
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From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
What you need to watch with the Vic Jr is it does not have the factory rake on the manifold. The A and B numbers are the same 5.9". The RPM air gap has the rake A is 4.45", B is 6.0", and the carb pad is 5.22".
Race Director
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From: Napa Valley California
It will help with vapor lock and add some additional low end torque.
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
What does the paper work say for the valve lash? Modern solid roller still have to allow for some expansion, but not so loose to beat the push rods and the top of the valve stems up. .012 intake and .018 are now the common idea.
So they have near parity with the duration of a H-roller lifter. AJ posted that a solid roller of over .020 needs like 10 more degrees. That was very true in the past. When the H- roller valve springs are in the mid 300# pounds at max lift it causes some plunger compression for loss of lift and duration. It is a real problem for H-rollers when they are trying to do higher lift numbers approaching .700 with heavy valves.
The total flow of a solid roller cam with steep lobe ramps and far exceeds the flow of an equal duration H-roller today.
So they have near parity with the duration of a H-roller lifter. AJ posted that a solid roller of over .020 needs like 10 more degrees. That was very true in the past. When the H- roller valve springs are in the mid 300# pounds at max lift it causes some plunger compression for loss of lift and duration. It is a real problem for H-rollers when they are trying to do higher lift numbers approaching .700 with heavy valves.
The total flow of a solid roller cam with steep lobe ramps and far exceeds the flow of an equal duration H-roller today.
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Instructor
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What does the paper work say for the valve lash? Modern solid roller still have to allow for some expansion, but not so loose to beat the push rods and the top of the valve stems up. .012 intake and .018 are now the common idea.
So they have near parity with the duration of a H-roller lifter. AJ posted that a solid roller of over .020 needs like 10 more degrees. That was very true in the past. When the H- roller valve springs are in the mid 300# pounds at max lift it causes some plunger compression for loss of lift and duration. It is a real problem for H-rollers when they are trying to do higher lift numbers approaching .700 with heavy valves.
The total flow of a solid roller cam with steep lobe ramps and far exceeds the flow of an equal duration H-roller today.
So they have near parity with the duration of a H-roller lifter. AJ posted that a solid roller of over .020 needs like 10 more degrees. That was very true in the past. When the H- roller valve springs are in the mid 300# pounds at max lift it causes some plunger compression for loss of lift and duration. It is a real problem for H-rollers when they are trying to do higher lift numbers approaching .700 with heavy valves.
The total flow of a solid roller cam with steep lobe ramps and far exceeds the flow of an equal duration H-roller today.
.020 hot for valve lash. And I don’t get what you are trying to say.
Le Mans Master
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From: League City Tx
Air gap and a 1" open spacer is ideal, but won't fit under a regular L88 hood.(with the air cleaner on anyway)
I have a 4" L88 hood that is unavailable now.
Mark Jones has made 690 hp with an Air Gap and 1" spacer.
Last edited by ajrothm; May 12, 2018 at 07:56 AM.
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well you’re right in the fact that there is no reason to set up everything right from the heads to headers and restrict all from the heads up. I agree it defeats the purpose.
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I would stick with the Air Gap unless you are planning on spinning it over 6500 rpms often....
Air gap and a 1" open spacer is ideal, but won't fit under a regular L88 hood.(with the air cleaner on anyway)
I have a 4" L88 hood that is unavailable now.
Mark Jones has made 690 hp with an Air Gap and 1" spacer.
Air gap and a 1" open spacer is ideal, but won't fit under a regular L88 hood.(with the air cleaner on anyway)
I have a 4" L88 hood that is unavailable now.
Mark Jones has made 690 hp with an Air Gap and 1" spacer.
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
A 247/256* cam is pretty big for a hyd roller....and along the lines of what I think Chris would have spec'd for you..... A comparable cam in a solid roller would likely be 257/268* or so..... usually its roughly 10* more for a solid roller for comparable specs, this is due to the .02x" you lose from valve lash in a solid, vs. 0 lash in a hyd roller.
Lets say that you have a cam lobe with .640 lift when using 1.7 rocker ratio. You set the hot lash to .020 gap between the rocker tip and the valve stem tip. Your cam rotates around and has to take up the .020 gap before it even begins to lift the valve. (Decreasing duration and total lift) Your actual lift is only .620 and you might be loosing a few points of duration.
An H-roller cam is set to Zero lash and a .640 lobe lift is .640 because of zero lash.
what I was saying about low lash solid rollers and the fact that you do get some compression of the H-roller lifter that they are nearly equal today if they are the same cam and just change the lifter type.
Solid lifter cams are ground more aggressively with faster ramps and higher lift. So they have more total flow than their H roller counter part.
Le Mans Master
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From: Watkinsville, GA and Glen Cove, NY
Holley Strip Dominator. Small single plane and fits perfectly with L88 hood with or without the air box. I am making 653hp with one on my 502 and a bigger solid roller. Horsepower peak is 6500 rpm.
Bill
Bill
Last edited by 69ttop502; May 13, 2018 at 07:23 PM.
Le Mans Master
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From: League City Tx
Yeah the Strip Dominators are bad *** for sure..... IF you can find one....LOL..
Melting Slicks
Joined: Oct 2008
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From: Regina Sk Canada
My 427 BBC ran 11.25-1 compression Eddy rpm Oval ports, hydraulic roller, .585/.585 with .245/.255@.050 Holley strip dominator intake 850 dbl. Made 550 hp and 513 tq had decent street maners, still in my buddies GTO.
My 468, 12.0-1 compression, AFR 305 rec ports, Eddy vic JR, cam motion custom solid billet roller cam. .691/.684 with .262/.272@.050 made 708 hp and 622 tq 1006hp on the bottle.
My 468, 12.0-1 compression, AFR 305 rec ports, Eddy vic JR, cam motion custom solid billet roller cam. .691/.684 with .262/.272@.050 made 708 hp and 622 tq 1006hp on the bottle.
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From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
My 427 BBC ran 11.25-1 compression Eddy rpm Oval ports, hydraulic roller, .585/.585 with .245/.255@.050 Holley strip dominator intake 850 dbl. Made 550 hp and 513 tq had decent street maners, still in my buddies GTO.
My 468, 12.0-1 compression, AFR 305 rec ports, Eddy vic JR, cam motion custom solid billet roller cam. .691/.684 with .262/.272@.050 made 708 hp and 622 tq 1006hp on the bottle.
My 468, 12.0-1 compression, AFR 305 rec ports, Eddy vic JR, cam motion custom solid billet roller cam. .691/.684 with .262/.272@.050 made 708 hp and 622 tq 1006hp on the bottle.
JIM
Race Director
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From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
