Tunnel ram or no tunnel ram...

68 HEMI GTS

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I’ll be curious to see your results, gonna get any track data this year? I have an low deck Indy tunnel ram floating around but wasn’t sure if the gains are with the hassle.
 
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younggun2.0

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I’ll be curious to see your results, gonna get any track data this year? I have an low deck Indy tunnel ram floating around but wasn’t sure if the gains are with the hassle.
Wanna sell it? I just ordered TF 270’s and need max wedge tunnel ram for low deck
 

Miszny

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I’ll be curious to see your results, gonna get any track data this year? I have an low deck Indy tunnel ram floating around but wasn’t sure if the gains are with the hassle.
I will only have some street foot brake numbers, next season I will put it on the dyno. I need some time to get these carbs working well. I already see that I need to do some air bleeds and jets shopping. I have jets in pairs and air bleeds x4 only.
 

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absolutely awesome looking. I hope it is all it should be!
Thanks, it actually started right up. I went thru the carbs and already know why previous owner had problems getting acceptable idle speed. Secondaries were open so much that you could shut the primaries completely and it still ran at 1000 rpm!
Gas pedal reaction is savage, this is 1st improvement I can instantly see.
 

Miszny

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I’ll be curious to see your results, gonna get any track data this year? I have an low deck Indy tunnel ram floating around but wasn’t sure if the gains are with the hassle.
Lots of work is needed to make it look and fit nice but looks alone make the time spent rewarding :)
Mine had significant core shift, but no welding was needed.
 

68 HEMI GTS

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Any 230 heavy blocks that you want to part with? I plan on builing my new 500ci short block...

I don’t, while I think it would be nice to have one I think these people are nuts that try to sell them for the price of an aftermarket block. Biggest thing if you’re going to make a ton of power is just find a block with good thick cylinder walls and add caps. Preferably alum if you’re really going to get after it (big compression or N2O).
 

Miszny

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I don’t, while I think it would be nice to have one I think these people are nuts that try to sell them for the price of an aftermarket block. Biggest thing if you’re going to make a ton of power is just find a block with good thick cylinder walls and add caps. Preferably alum if you’re really going to get after it (big compression or N2O).
These blocks are available between 900 and 1400$ depending on shape and if there are caps or not. I will not use factory caps anyway so i could just but a bare block that can be bored to 4.375 hole.
Aftermarhet block is wayyy more from what i have seen?
I dont really want a ton, I plan to make over 800 n/a and over 1100 with nitrous. Its a street car mostly :)
I was thinkimg to use milodon steel x bolted caps and some hardblock as dampening material. I use halp filled block on the street without any issues.
 

Miszny

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OK I drove the car today all I can say is: if you are thinking about getting tunnel ram, GET IT!
The difference is big, throttle response is much better, revs up faster and the torque is very surprising. I still have some tuning to do, its too rich at wot, lambda shows low 11s, but I have absolutely no doubt that its an improvement when it comes to power and torque.
The only donwside is tuning of all that stuff, takes time and access to idle screws is not ideal.

I have a question about jetting. Do I need to square jet or can I just drop few jet sizes on primary side of both carbs?
There are 82 jets square in both carbs now. I was thinking about 78 on primary side and 80 on secondary side. Unfortunately I dont have many jets x4 and nothing x8.

How do you post movies here?
 
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68 HEMI GTS

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You can just drop the primary’s. Take it or doesn’t have PV’s. Might be something to consider depending on your high speed cruise A/F.

You have to upload to YouTube then post a link for video’s.
 

Miszny

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You can just drop the primary’s. Take it or doesn’t have PV’s. Might be something to consider depending on your high speed cruise A/F.

You have to upload to YouTube then post a link for video’s.
No PVs in carbs. I have a bit lean cruise at mid to high 14 but no surging or anything. Seems happy, goes richer when secondaries kick in and they do kick in quite fast. There is linkage progression but very small comparing to my previous carb. I will play with jetting today and see where I end up.
 

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No PVs in carbs. I have a bit lean cruise at mid to high 14 but no surging or anything. Seems happy, goes richer when secondaries kick in and they do kick in quite fast. There is linkage progression but very small comparing to my previous carb. I will play with jetting today and see where I end up.

IMO, if you are going to drive this on the street it NEEDS power valves on the primary side. Those who say otherwise do not grasp what that valve does.

Install power valves and you can drop the primary main jets at least 6-8 numbers. Then tune from there. You‘ll never get your cruise A/F ratio close without power valves.

I swear that Holley has done more damage to that carb and how it works and tunes than anyone else. They STILL have videos, books, YouTube advice on how to incorrectly time the power valve circuit. It’s idiotic.
 

71GSSDemon

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Power valves are great for tuning street driving. I am running 660s and they never came with them. I am very happy so far. I wonder about changing the front blocks and jetting down. Hard to change what is working well though
 

Miszny

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IMO, if you are going to drive this on the street it NEEDS power valves on the primary side. Those who say otherwise do not grasp what that valve does.

Install power valves and you can drop the primary main jets at least 6-8 numbers. Then tune from there. You‘ll never get your cruise A/F ratio close without power valves.

I swear that Holley has done more damage to that carb and how it works and tunes than anyone else. They STILL have videos, books, YouTube advice on how to incorrectly time the power valve circuit. It’s idiotic.
I will see how it behaves, I did some miles today and I am very surprised how civilized this is. It was on the rich side but I will play with it a little tomorrow and see where I end up. I have no problems playing with carbs.
What in gear afr should I target with this setup?
 

68 HEMI GTS

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I will see how it behaves, I did some miles today and I am very surprised how civilized this is. It was on the rich side but I will play with it a little tomorrow and see where I end up. I have no problems playing with carbs.
What in gear afr should I target with this setup?

Generally if you have enough initial you can get them to idle around 13.5 range in neutral. It’ll put it around 14.0 in gear. If the idle circuit is set up right should only drop around 200 rpm. I target cruise ratio’s of mid to high 13’s low 14’s. They will cruise leaner but this seems to work real well IMO. Then you have to work on all the transition points. I personally would run PV’s as well. It’s a great tool to tune for street use. Not knowing what all your carb set up is I would recommend pulling them down and getting a baseline of all the orifice and bleed sizes. Also check to see if they have a transfer slot restriction installed. I write all that stuff down and keep track as I make changes. Gives you a baseline and a road map of where you’ve been and helps with deciding where you need to go. Others may or may not agree.
 

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I will see how it behaves, I did some miles today and I am very surprised how civilized this is. It was on the rich side but I will play with it a little tomorrow and see where I end up. I have no problems playing with carbs.
What in gear afr should I target with this setup?

Never target a specific A/F ratio. Pump gas varies widely, as do different race fuels. No two O2 sensors read exactly the same either.

Tune the engine so it’s “happy” and use those numbers. Then you can tune from there to get your tune up down to the gnats behind.
 

Miszny

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Generally if you have enough initial you can get them to idle around 13.5 range in neutral. It’ll put it around 14.0 in gear. If the idle circuit is set up right should only drop around 200 rpm. I target cruise ratio’s of mid to high 13’s low 14’s. They will cruise leaner but this seems to work real well IMO. Then you have to work on all the transition points. I personally would run PV’s as well. It’s a great tool to tune for street use. Not knowing what all your carb set up is I would recommend pulling them down and getting a baseline of all the orifice and bleed sizes. Also check to see if they have a transfer slot restriction installed. I write all that stuff down and keep track as I make changes. Gives you a baseline and a road map of where you’ve been and helps with deciding where you need to go. Others may or may not agree.
I have all the specs from Gary Williams. Just gave him stamped number and he told me all about them. They were built for smaller engine with more compression so they are pretty close. When I drove the car yesterday wot was about 11.5, cruise was too lean but after I shut the secondary throttle blades I had it at between 13.8 and 14.2 which is what I had with single dominator so really can’t complain. I know the values I had well.
I went down to 78 primary and left 82 in secondary but it was raining today so I could not test it.
These carbs have 76iab which I don’t like. I want to try smaller to increase the signal on idle circuits, this way I will have better primary throttle blade position I hope.
Now I have to wait 2 weeks for air bleeds…
Weather is going to be nice tomorrow so I will see what primary jets change did.
 

Miszny

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Never target a specific A/F ratio. Pump gas varies widely, as do different race fuels. No two O2 sensors read exactly the same either.

Tune the engine so it’s “happy” and use those numbers. Then you can tune from there to get your tune up down to the gnats behind.
I remember at what values my car ran well with single dominator so I guess I need to target similar values. I will try to tune it better before I put the car into storage for winter.
 

68 HEMI GTS

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I have all the specs from Gary Williams. Just gave him stamped number and he told me all about them. They were built for smaller engine with more compression so they are pretty close. When I drove the car yesterday wot was about 11.5, cruise was too lean but after I shut the secondary throttle blades I had it at between 13.8 and 14.2 which is what I had with single dominator so really can’t complain. I know the values I had well.
I went down to 78 primary and left 82 in secondary but it was raining today so I could not test it.
These carbs have 76iab which I don’t like. I want to try smaller to increase the signal on idle circuits, this way I will have better primary throttle blade position I hope.
Now I have to wait 2 weeks for air bleeds…
Weather is going to be nice tomorrow so I will see what primary jets change did.

Agree, that’s a lot of IAB for dual carbs. Sounds like it’s pretty good on cruise. what’s the MAB size? O2 meters are pretty accurate when calibrated. OEM wouldn’t use them if they were that bad. Pump premium and 110 are usually pretty good in the ranges I listed. When you get into oxygenated fuels and such things change. I do agree though you have to tune the engine for what it likes. I still read plugs and jet for MPH but, I find the 02 meter puts me right about where I need to be on most applications I work on. I have a pretty good feel for it, I play with it enough.
 

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I have all the specs from Gary Williams. Just gave him stamped number and he told me all about them. They were built for smaller engine with more compression so they are pretty close. When I drove the car yesterday wot was about 11.5, cruise was too lean but after I shut the secondary throttle blades I had it at between 13.8 and 14.2 which is what I had with single dominator so really can’t complain. I know the values I had well.
I went down to 78 primary and left 82 in secondary but it was raining today so I could not test it.
These carbs have 76iab which I don’t like. I want to try smaller to increase the signal on idle circuits, this way I will have better primary throttle blade position I hope.
Now I have to wait 2 weeks for air bleeds…
Weather is going to be nice tomorrow so I will see what primary jets change did.

Did you post the specs? If so I didn’t see them. Did Williams tell you to leave the power valves out??
 

Miszny

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Did you post the specs? If so I didn’t see them. Did Williams tell you to leave the power valves out??
He never put pv in them. I didnt ask him about that but I will. I didn’t post the specs. I want to see where I am with this before I start changing stuff.
Frankly I’m surprised how well it drives and how easy it lights the tires in 3rd gear when cruising at 30-40mph

I’d prefer to drive like this!

93DB1F2E-548C-49D4-8726-01CBB9304A8D.jpeg
 
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