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Tunnel Ram 4-Speed Bog

General engine tech -- Drag Racing to Circle Track

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62ChevyII
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Re: Tunnel Ram 4-Speed Bog

Post by 62ChevyII »

Do you have any idea what the base pressure is of the clutch and how many turns of pressure he has in it? Sintered iron clutches need very little pressure to work. He shouldn't need a heavy flywheel if the clutch works right. If you can get the clutch to slip like it's supposed to it should help with the bog plus help that Top loader live a little longer. 8) You can keep taking clutch out of it until you hear it slip noticeably going into 4th then add a 1/2 turn of pressure back into it and it should be good to go. Also, does it have any counter weight on the pressure plate fingers? Taking some weight off can soften it up too.

Also I assume you guys made sure the float level is high enough?
n2omike
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Re: Tunnel Ram 4-Speed Bog

Post by n2omike »

62ChevyII wrote: Mon Aug 24, 2020 12:09 am Do you have any idea what the base pressure is of the clutch and how many turns of pressure he has in it? Sintered iron clutches need very little pressure to work. He shouldn't need a heavy flywheel if the clutch works right. If you can get the clutch to slip like it's supposed to it should help with the bog plus help that Top loader live a little longer. 8) You can keep taking clutch out of it until you hear it slip noticeably going into 4th then add a 1/2 turn of pressure back into it and it should be good to go. Also, does it have any counter weight on the pressure plate fingers? Taking some weight off can soften it up too.

Also I assume you guys made sure the float level is high enough?
This is exactly what I have told him regarding the clutch. Not sure where he is on the float levels.

Is there room for jet extensions with side pivot floats? Asking in case he wants to add the QFT plates that allow you to use jets, or wants to turn the carbs around backwards. I've always used center hung floats, and with a quick search, don't see a reference to jet extensions in side hung floats.

Thanks
novafornow
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Re: Tunnel Ram 4-Speed Bog

Post by novafornow »

I agree with the timing idea. They can take quite a bit
n2omike
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Re: Tunnel Ram 4-Speed Bog

Post by n2omike »

novafornow wrote: Mon Aug 24, 2020 11:01 am I agree with the timing idea. They can take quite a bit
I had him lock it out at 36 degrees. Definitely runs better that way.
ClassAct
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Re: Tunnel Ram 4-Speed Bog

Post by ClassAct »

EDC and a couple others nailed it. He has WAY TOO MUCH clutch. That’s always what that is. Don’t use a steel flywheel. You don’t need the hit with all that gear. It certainly is NOT a carb issue. It’s a clutch issue. Until the guy gets that, he’s going to fight the car. Take clutch out of it.
bigfoot584
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Re: Tunnel Ram 4-Speed Bog

Post by bigfoot584 »

n2omike wrote: Sun Aug 23, 2020 11:22 pm
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!
That's my screw up your right the float is still side hung it wouldn't work, sorry about that,
damn senior moments.
F-BIRD'88
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Re: Tunnel Ram 4-Speed Bog

Post by F-BIRD'88 »

Could try adding air pressure to the slicks to get a bit of wheel spin on launch, to keep the rpm up.
n2omike
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Re: Tunnel Ram 4-Speed Bog

Post by n2omike »

Thought I'd post an update:
Turns out he had the secondary floats set too low! I was tempted to backhand him across the forehead, but he had suffered enough. lol
All is good now. He's a beginner. He's also launching it like a little girl, so we're working on that as well! LOL!

Thanks for all the input!
travis
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Re: Tunnel Ram 4-Speed Bog

Post by travis »

I’m curious about the recommendations for adding a bunch of timing. Is this an anomaly with running a TR?
F-BIRD'88
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Re: Tunnel Ram 4-Speed Bog

Post by F-BIRD'88 »

travis wrote: Mon Sep 14, 2020 4:37 pm I’m curious about the recommendations for adding a bunch of timing. Is this an anomaly with running a TR?
No its not an anomaly.. Think about what amount of spark timing is needed for combustion if/when things are not ideal.. Eg: at idle low speed rpm when egr effect is high on a cammed engine.. Port velocity is low so fuel vapourization suffers . Afr is not ideal.. Lean mixtures need more timing Exhaust gas in the mix needs more spark timing, untill the engine gets up in its tuned power band carbs start metering fuel correctly and egr clears.

Aggravated by a cold plenum.

Tunnel Rammed cars very often really respond to locked out timing and can even benefit from a reverse like spark timing curve as the car launches, till it all comes together.
using "high speed retard" but right after initial car launch.
Street Tunnel Rammed cars often really like locked out timing + (combined with) some vacuum advance (10-12° ±)

Yup low secondary fuel float level (especially without jet extensions) will cause a launch bog, with inline mounted holley carbs.
BigBlocksOnTop2
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Re: Tunnel Ram 4-Speed Bog

Post by BigBlocksOnTop2 »

Annular boosters
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