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Tunnel Ram 4-Speed Bog

General engine tech -- Drag Racing to Circle Track

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n2omike
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Tunnel Ram 4-Speed Bog

Post by n2omike »

I helped my buddy out with an engine for a budget Gasser he built. It's a 1964 Ford Falcon. 306, Toploader 4-speed (2.78 first gear) and 5.67 rear. Car is around 2900 lbs with him in it.

Problem is, it will launch... then bog like hell... then take off again, and run through the gears just fine.

From the top down:
660 Holley center squirter carbs
Weiand Tunnel Ram
Ported Chinese cylinder heads. 200-ish cc
Jones Cam around 242 @ 0.050" with a 106 LSA
Around 10:1 compression. Stock rods/crank with ARP bolts.
Locked out distributor with 36 degrees
Set up for 7k rpm rev limit.

Sintered iron clutch with adjustable pressure plate.
Clutch is adjusted pretty tight.

He was launching it like a little girl. Finally launched it on the limiter, and it spun a little bit, hooked then bogged.

I kept telling him to launch it like a MAN. lol He finally did, and spun the tires a couple turns, but still bogged. Was also telling him to loosen the clutch, which he doesn't want to listen to for some reason.

This is our first time messing with a tunnel ram. Is there anything obvious that we're missing... or does he just need to soften the clutch, and launch it WFO? (that's what I keep telling him to do) lol
bigfoot584
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Re: Tunnel Ram 4-Speed Bog

Post by bigfoot584 »

Are the carbs mounted side ways or regularly, seems to me 660's don't have
secondary metering blocks they have metering plates.
They need to be mounted side ways because of the g force your pulling off
the line, if there mounted regularly your uncovering the metering orifice
or what would be the jet.
n2omike
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Re: Tunnel Ram 4-Speed Bog

Post by n2omike »

bigfoot584 wrote: Sun Aug 23, 2020 2:45 pm Are the carbs mounted side ways or regularly, seems to me 660's don't have
secondary metering blocks they have metering plates.
They need to be mounted side ways because of the g force your pulling off
the line, if there mounted regularly your uncovering the metering orifice
or what would be the jet.
They are mounted conventionally inline. These were designed to be 'tunnel ram' carbs, and are made short to be able to mount inline... Is this really the case with these?
Old School
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Re: Tunnel Ram 4-Speed Bog

Post by Old School »

Put a 40 lb flywheel in it and get a clutch setup that will slip just a little. The slipper clutch will also help keep breakage down.

For that small an engine to leave he has to launch it almost on the mat. You may need more timing. Some of the 283-292's we ran in the 70's needed as much as 52 degrees. Almost all were run at at least 44 degrees.

Move the rev limiter to at least 8000.
Steve K
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Re: Tunnel Ram 4-Speed Bog

Post by Steve K »

Just for the hell of it try a couple of Eddy carbs if you can. 600's would do the trick. I have two cars with tunnel rams (bigger displacement but...) and neither bog and both pull hard through the gears. They are stick shift's as well.
Last edited by Steve K on Sun Aug 23, 2020 4:27 pm, edited 1 time in total.
79 Cmaro, 427 sbc, Tunnel Ram Dual Quad with Eddy carbs, AFR 210 Race Ready heads, 263-272 @.50 Comp solid roller cam, 4.10's and a faceplated Tremec TKO 600.
65 Beaumont 406 tunnel ram faceplated TKO600
bigfoot584
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Re: Tunnel Ram 4-Speed Bog

Post by bigfoot584 »

Steve K wrote: Sun Aug 23, 2020 4:15 pm Just for the hell of it try a couple of Eddy carbs if you can. 600's would do the trick. I have two cars with tunnel rams (bigger displacement but...) and neither bog and both pull hard through the gears. They a stick shift's as well.
If you can find two to try, be worth testing.
bigfoot584
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Re: Tunnel Ram 4-Speed Bog

Post by bigfoot584 »

You have no way to use a jet extension on it now, most of
them are converted to rear metering block and turned
sideways, then there's no need for jet extensions.

Turn the carbs around and use jet extensions on the primary,
you'll need to revise the throttle linkage.
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Re: Tunnel Ram 4-Speed Bog

Post by F-BIRD'88 »

Install fuel bowl vent extensions.
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Re: Tunnel Ram 4-Speed Bog

Post by rebelrouser »

What weight flywheel is he using? Years ago I had an Anglia with a 4 speed and tunnel ram car weighed 2200 with me in it. The standard 30 lb wheel, was so heavy it just burned the tires, but no bog, only other available wheel at the time was an aluminum flywheel, 12 lbs I think, and it was so light the car bogged no matter what you would do.
I fixed it my installing 50 cc accelerator pumps on all corners and making the squirters really big, from my memory. I know that when I sold it to a guy, first thing he did was buy an brand new shiny Holley and guess what, it bogged.
n2omike
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Re: Tunnel Ram 4-Speed Bog

Post by n2omike »

bigfoot584 wrote: Sun Aug 23, 2020 4:29 pm You have no way to use a jet extension on it now, most of
them are converted to rear metering block and turned
sideways, then there's no need for jet extensions.

Turn the carbs around and use jet extensions on the primary,
you'll need to revise the throttle linkage.
He's not allowed to run sideways carbs.

You know... turning them around backwards is VERY CLEVER! I like it!
Thanks!
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Re: Tunnel Ram 4-Speed Bog

Post by EDC »

Take some clutch out of it.
"Quality" is like buying oats. You can pay a fair price for it and get some good quality oats,
or you can get it a hell of a lot cheaper, when it's already been through the horse.

Nil Satis Nisi Optimum

Ed Curtis - www.FlowTechInduction.com
nabx22
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Re: Tunnel Ram 4-Speed Bog

Post by nabx22 »

Has this car got a fuel pressure gauge the driver can watch?I just went through pretty much the same thing as you are describing on a bbc camaro.The car was momentarily dropping fuel pressure at launch.We found the return on the stock sump tank had come loose and it was allowing air to be pulled into the supply line.
n2omike
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Re: Tunnel Ram 4-Speed Bog

Post by n2omike »

nabx22 wrote: Sun Aug 23, 2020 6:20 pm Has this car got a fuel pressure gauge the driver can watch?I just went through pretty much the same thing as you are describing on a bbc camaro.The car was momentarily dropping fuel pressure at launch.We found the return on the stock sump tank had come loose and it was allowing air to be pulled into the supply line.
Very simple fuel system. Has a tiny tank that holds maybe 1.5 to 2 gallons that hangs on the front of the car. Looks like a small beer keg or something. It's an old school nostalgia thing. Has a single fuel pump that goes from there to the engine.

I did see where Quick Fuel makes a billet aluminum metering plate that accepts jets. They sell it in a kit with a notched float for around $55 at Summit. Thought that might be worth looking into.

https://www.summitracing.com/parts/qft-34-2qft
bigfoot584
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Re: Tunnel Ram 4-Speed Bog

Post by bigfoot584 »

n2omike wrote: Sun Aug 23, 2020 6:22 pm
nabx22 wrote: Sun Aug 23, 2020 6:20 pm Has this car got a fuel pressure gauge the driver can watch?I just went through pretty much the same thing as you are describing on a bbc camaro.The car was momentarily dropping fuel pressure at launch.We found the return on the stock sump tank had come loose and it was allowing air to be pulled into the supply line.
Very simple fuel system. Has a tiny tank that holds maybe 1.5 to 2 gallons that hangs on the front of the car. Looks like a small beer keg or something. It's an old school nostalgia thing. Has a single fuel pump that goes from there to the engine.

I did see where Quick Fuel makes a billet aluminum metering plate that accepts jets. They sell it in a kit with a notched float for around $55 at Summit. Thought that might be worth looking into.

https://www.summitracing.com/parts/qft-34-2qft
Careful with that it allows use of a standard jet, but not a jet extension
the notch only clear the jet itself.
n2omike
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Re: Tunnel Ram 4-Speed Bog

Post by n2omike »

bigfoot584 wrote: Sun Aug 23, 2020 7:45 pm Careful with that it allows use of a standard jet, but not a jet extension
the notch only clear the jet itself.
I liked the idea of turning the carbs around backwards and adding jet extensions to the front (now rear)...
I've only dealt with jet extensions on center hung bowls. I use the screw in types with the notched floats.
Will jet extensions even work with the center hung floats?

Have you... or anyone else... had experience with doing this?

Ed, Definitely going to try and get him to take a lot of clutch out of it!

Thanks!
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