Author Topic: 496ci Tunnel ram  (Read 6054 times)

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blykins

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Re: 496ci Tunnel ram
« Reply #45 on: March 12, 2022, 01:15:52 PM »


Those are Comp "CR" lobes.  Middle of the road as far as aggression. 

Advertised durations are 305/311.  That would put your overlap at 94°. 

If you ever get the hunger for another cam, I'd be at 270/282 @ .050", 113 LSA, 108 ICL, with .677"/.695" gross lift.


I think you mentioned it earlier .... What would you like to see for  overlap for this combination ?

I'd be aiming for 80-82 degrees of advertised overlap.   As a comparison, my 496's with TFS heads (10.5:1, Performer RPM intake, etc.) and a little port work will make about 645 hp @ 6000 with 72 degrees of overlap on a hydraulic roller. 

The better the head, the less you need to hang the valves open at the same time.  The factory headed engines I build generally like to see more in the overlap area.  My little 352 mule lost a good bit of horsepower when I closed it up on a cam swap. 
Brent Lykins
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JC-427Stroker

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Re: 496ci Tunnel ram
« Reply #46 on: March 12, 2022, 01:26:00 PM »
 Thanks ....

BattlestarGalactic

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Re: 496ci Tunnel ram
« Reply #47 on: March 12, 2022, 02:10:18 PM »
Larry, I know there are a ton of variables like air, traction, temp etc etc, but I hope you update this with some track numbers when you take it out. Just curious what difference it makes in the real world, with no other changes.

I know you said a buddy was making a scoop, which is probably the best performance route, but I'm curious what changes it may make between running with the stacks vs without, or with the scoop, IF you happen to try that. Certainly not trying to push you into doing changes for me though. IF there's any difference at all, my guess would be, in order of best to worst: scoop, then stacks, then open.

Another good thing about the swap....you don't have to bend over as far to do jetting changes..lol

Heck, I never change jets.  LOL!!   Since they are side saddle, you don't have to pull the carbs to change jets.  Though it was mentioned on the dyno that I may need to throw 1-2 in it due to air speed on the track compared to sitting in the dyno room.  At least for spring/fall weather.  I am going to try to remember to call my data logger supplier and see about adding an O2 sensor into that.  I had a wide band on the car for a few years but removed it and put it on the black car for better tuning on it.

As far as induction changes we were talking about that at lunch today with the shop.  They wondered what I was going to do with the hood and I told them I had a flat hood on order.   The discussion came up about needing a scoop as the velocity stacks may be in a vacuum situation at near 130 mph and may cause a lean out?   With the TW under the hood, I'm not sure what kind of turbulence was going on under the hood?  I have no core support to speak of, it's all open and then the grilles in the back of the teardrop.  So, what is all going on?  The world may never know.   Time will tell.

Larry

JC-427Stroker

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Re: 496ci Tunnel ram
« Reply #48 on: March 12, 2022, 02:29:32 PM »


Heck, I never change jets.  LOL!!   

.  They wondered what I was going to do with the hood and I told them I had a flat hood on order.   The discussion came up about needing a scoop as the velocity stacks may be in a vacuum situation at near 130 mph and may cause a lean out?   With the TW under the hood, I'm not sure what kind of turbulence was going on under the hood?  I have no core support to speak of, it's all open and then the grilles in the back of the teardrop.  So, what is all going on?  The world may never know.   Time will tell.

What type of clearance between the hood and the top of carbs will you have ?

In the boat I'm running the dual flame arrestors. On the dyno the K&N velocity stacks were worth 5 hp over open carbs. They really smoothed out the air flow.



cjshaker

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Re: 496ci Tunnel ram
« Reply #49 on: March 12, 2022, 05:56:59 PM »
What type of clearance between the hood and the top of carbs will you have ?

It's a tunnel ram. Unless he raises the hood a foot, there is no clearance, Clarence. ;)
Doug Smith


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JC-427Stroker

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Re: 496ci Tunnel ram
« Reply #50 on: March 12, 2022, 07:01:48 PM »
:)

jayb

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Re: 496ci Tunnel ram
« Reply #51 on: March 12, 2022, 08:41:26 PM »

  The discussion came up about needing a scoop as the velocity stacks may be in a vacuum situation at near 130 mph and may cause a lean out?   

Larry, I was worried about that too with the Hilborn stacks coming out of the hood with my 64 Gal; you probably remember seeing that the time we met up at the track.  That car went 143 MPH, and the A/F numbers and manifold vacuum never changed at speed.  Of course, that setup was EFI, not carbs, but at least based on my experience I don't think you will have to worry about a lean-out.
Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

BattlestarGalactic

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Re: 496ci Tunnel ram
« Reply #52 on: March 13, 2022, 06:25:28 PM »
What type of clearance between the hood and the top of carbs will you have ?

It's a tunnel ram. Unless he raises the hood a foot, there is no clearance, Clarence. ;)

Roger, Roger..... I mean Doug.....LOL.

Jay,. I remember the day well.  Had a blast and have pictures to prove it.  I don't see a major issue but it was a conversation we had over lunch.
Larry