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Tunnel Ram hesitation #2959680
08/31/21 07:30 PM
08/31/21 07:30 PM
Joined: Oct 2015
Posts: 192
Gravataí, RS, Brazil
360tripleblack77 Offline OP
member
360tripleblack77  Offline OP
member

Joined: Oct 2015
Posts: 192
Gravataí, RS, Brazil
Hello guys, long time since last post.

I'm having a bad hesitation from the iddle or footbrake to WOT.

There's a 360" SB Mopar, Edelbrock ported heads, weiand Tunnel Ram, 750 annular booster Mighty Demon Carbs, 11.8:1CR, 24° initial timing, 36° Total timing, 96oct pump gas(30% ethanol) . 904 trans, 4200 9.5" converter.

When I installed tunnel ram, I had no issues. 31 nozzle on Both sides, pink cam, 30cc boosters, 3.5 Power valve, 74 primary jet, 82 secondary jet.

No changes and car starts hesitation. Tries to change for 37 primary nozzle and green cam, little bit better but still problem.

Any tips? Really appreciate.


'77 Brazilian Dodge Charger R/T - Street Car
Footbrake, Pump Gas, SB Mopar 360" N/A
3300lbs, Leaf Spring + Assassin Bars
Best 1/8 mile ET
1.50 60' / 4.31 330' / 6.73@102.54mph
Re: Tunnel Ram hesitation [Re: 360tripleblack77] #2959707
08/31/21 08:11 PM
08/31/21 08:11 PM
Joined: May 2017
Posts: 1,155
Denver, CO
B
BigBlockGTS Offline
super stock
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Denver, CO
Wait for the true experts to weigh in but the first thing I thought was 30% alcohol is pretty high- Have the fuel lines broken down? Were they alcohol compatible? Is there some other corrosion or crap in the carbs? Alcohol doesn't do well sitting a long time which is typical for our hot rods. If the original set up worked well, it still should. I wonder if it is simply time to go through everything.

Re: Tunnel Ram hesitation [Re: 360tripleblack77] #2959725
08/31/21 09:11 PM
08/31/21 09:11 PM
Joined: May 2004
Posts: 12,124
Taxes & Virus's R-US, NY
Dragula Offline
I Live Here
Dragula  Offline
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Taxes & Virus's R-US, NY
I am no expert...I like to tinker .....

Those carbs are not known to be lean, especially considering they are annular. But what always gets a car moving is fuel and timing. More timing always gives you a better 60ft, until you go too far. And the more timing, the more fuel the engine will want.

If you comfortable where timing is at, then I suggest squirters...Get a bunch, and tinker. They also make different squirter cams, get a set...Find the best squirters and then tinker with the cams. That is how I do it. I go up in squirter until its too much...No squirter is too big for me...

PS I am anti power valve, so all my stuff is square jetted and easy to figure out. I would go that way to start with, and then if you really like power vales, take out 7 sizes in jet, and put them back in.I do not like them at all.....

Last edited by Dragula; 08/31/21 09:15 PM.

'70 Cuda,...605 Hemi Street Car (6.20 best pass, 1.33 60ft)
https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car)
https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car)
https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9)

'66 Barracuda AWB Stretched nose Blown 440 Car in build stage

'71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph
https://www.youtube.com/watch?v=Znuo3jMUXTk
Re: Tunnel Ram hesitation [Re: Dragula] #2959732
08/31/21 09:29 PM
08/31/21 09:29 PM
Joined: Mar 2006
Posts: 9,252
MI, usa
dvw Offline
master
dvw  Offline
master

Joined: Mar 2006
Posts: 9,252
MI, usa
My big Indy Manifold runs brown cams and .040" squirters. Turned it from falling on its face to a 200ft long wheelie.
Doug

Re: Tunnel Ram hesitation [Re: dvw] #2959747
08/31/21 10:42 PM
08/31/21 10:42 PM
Joined: Sep 2014
Posts: 3,909
Washington
M
madscientist Offline
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Washington
A 3.5 power valve open way too late. I suspect an 8.5 would be a much better choice.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: Tunnel Ram hesitation [Re: 360tripleblack77] #2959750
08/31/21 10:53 PM
08/31/21 10:53 PM
Joined: May 2019
Posts: 539
Lake Villa Il
INTMD8 Offline
mopar
INTMD8  Offline
mopar

Joined: May 2019
Posts: 539
Lake Villa Il
Originally Posted by 360tripleblack77
H

No changes and car starts hesitation.


If I'm reading this right it ran well and then had a problem with no changes?

To me that means, fix the problem not change the tune-up.


69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 595rwhp 475rwtq.
Re: Tunnel Ram hesitation [Re: 360tripleblack77] #2959782
09/01/21 04:59 AM
09/01/21 04:59 AM
Joined: Jan 2003
Posts: 2,709
A shed in England
Tig Offline
master
Tig  Offline
master

Joined: Jan 2003
Posts: 2,709
A shed in England
We chased a similar problem for months, tried every thing, squirter's, timing, wedge floats, j tubes etc. We knew it was a fuel control issue as the problem never appeared on the dyno and if we induced tyre spin into the chassis it cleared. The O2 data said it was going lean then a rich spike. Turned out it was fuel just sloshing out of the vent tubes, we had to lower the fuel level in the bowls (below recommended) and all was well. This was on 2 x 1150 Dominator's BTW.


'74 Challenger..9.46 and 145.9 so far. 4023lb!!!# N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @142.4 with our old mule 580 wedge
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
Re: Tunnel Ram hesitation [Re: Tig] #2959949
09/01/21 02:43 PM
09/01/21 02:43 PM
Joined: Sep 2003
Posts: 1,041
San Jose Ca.
boatracer572 Offline
super stock
boatracer572  Offline
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Joined: Sep 2003
Posts: 1,041
San Jose Ca.
all great comments above... this is a common occurrence in my world (boat drag racing) the first problem i see with your combo is the staggered jetting ,that in its self will cause erratic afr and rich and lean conditions. tunnel rams have equal length runners.. IE jetting should be square to start. the power valves need to be plugged as well.. i have found on 4150 style carbs turning the accelerator cams up side down works great and will save money on cams. squirter wise, i drill out the squirters with a .040" size drill to start out with,.but dont be surprised if you end up going much larger.... try this odds are your problem will be fixed worst case scenario you will need to increase the accelerator size to 50cc twocents

Re: Tunnel Ram hesitation [Re: boatracer572] #2959963
09/01/21 03:11 PM
09/01/21 03:11 PM
Joined: Jan 2003
Posts: 2,709
A shed in England
Tig Offline
master
Tig  Offline
master

Joined: Jan 2003
Posts: 2,709
A shed in England
Originally Posted by boatracer572
all great comments above... this is a common occurrence in my world (boat drag racing) the first problem i see with your combo is the staggered jetting ,that in its self will cause erratic afr and rich and lean conditions. tunnel rams have equal length runners.. IE jetting should be square to start. the power valves need to be plugged as well.. i have found on 4150 style carbs turning the accelerator cams up side down works great and will save money on cams. squirter wise, i drill out the squirters with a .040" size drill to start out with,.but dont be surprised if you end up going much larger.... try this odds are your problem will be fixed worst case scenario you will need to increase the accelerator size to 50cc twocents


Yep It seems entirely feasible that all square jetting and 1 to 1 linkages are the way too go with a TR and that is the way we have it at the moment.
But... I'm soon to fit EGT's and a Racepak. It will be interesting to see if we need to treat each cylinder as individual.


'74 Challenger..9.46 and 145.9 so far. 4023lb!!!# N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @142.4 with our old mule 580 wedge
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
Re: Tunnel Ram hesitation [Re: Tig] #2960057
09/01/21 05:53 PM
09/01/21 05:53 PM
Joined: Dec 2012
Posts: 1,823
Wind Gap,Pa.
S
Sammy Offline
top fuel
Sammy  Offline
top fuel
S

Joined: Dec 2012
Posts: 1,823
Wind Gap,Pa.
Originally Posted by Tig
Originally Posted by boatracer572
all great comments above... this is a common occurrence in my world (boat drag racing) the first problem i see with your combo is the staggered jetting ,that in its self will cause erratic afr and rich and lean conditions. tunnel rams have equal length runners.. IE jetting should be square to start. the power valves need to be plugged as well.. i have found on 4150 style carbs turning the accelerator cams up side down works great and will save money on cams. squirter wise, i drill out the squirters with a .040" size drill to start out with,.but dont be surprised if you end up going much larger.... try this odds are your problem will be fixed worst case scenario you will need to increase the accelerator size to 50cc twocents


Yep It seems entirely feasible that all square jetting and 1 to 1 linkages are the way too go with a TR and that is the way we have it at the moment.
But... I'm soon to fit EGT's and a Racepak. It will be interesting to see if we need to treat each cylinder as individual.




Tig....in all my years running a tunnelram I've never, ever seen a square jetting.

Re: Tunnel Ram hesitation [Re: 360tripleblack77] #2960087
09/01/21 07:12 PM
09/01/21 07:12 PM
Joined: Jan 2011
Posts: 75
KY
9
95Kota408 Offline
member
95Kota408  Offline
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9

Joined: Jan 2011
Posts: 75
KY
Great dual quad video for tunnel rams.

https://m.youtube.com/watch?v=IOdcJ1KG3yI

Re: Tunnel Ram hesitation [Re: 360tripleblack77] #2960174
09/01/21 10:51 PM
09/01/21 10:51 PM
Joined: Jan 2007
Posts: 7,793
Mt Morris Michigan
mopar dave Offline
master
mopar dave  Offline
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Joined: Jan 2007
Posts: 7,793
Mt Morris Michigan
First, I would double check your ignition system right down to the spark plugs. Something has degraded. Power valves really dont need to be used with tunnel rams IMO. I pissed away 2 months of tuning mine on the street to find square jetting was the answer. Mine ran ok with 6.5 pv's, but the engine woke up a bit accelerating much faster square jetted. If your stuck on pv's, then 6.5-8.5 like madscientist suggested. Tuning a tunnel ram is different than tuning a single carb. Mine starts right up and idles immediately a bit on the lean side and then richens up as the engine gets warm and i am only 1 1/4 turns on the screws. I use #35 squirters and have tried #37 with no change in responsiveness. My carbs have 1.320 venturi if i remember correctly. small 750's was how they were described to me. Soon to get to the track, will see how it performs there. I really suggest square jetting weather racing or street, it just works. The T ram has individual runners and each runner should have the same amount of fuel feeding each individual cylinder. Good luck with your tuning.

Re: Tunnel Ram hesitation [Re: mopar dave] #2960184
09/01/21 11:36 PM
09/01/21 11:36 PM
Joined: Sep 2014
Posts: 3,909
Washington
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madscientist Offline
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madscientist  Offline
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Posts: 3,909
Washington
Originally Posted by mopar dave
First, I would double check your ignition system right down to the spark plugs. Something has degraded. Power valves really dont need to be used with tunnel rams IMO. I pissed away 2 months of tuning mine on the street to find square jetting was the answer. Mine ran ok with 6.5 pv's, but the engine woke up a bit accelerating much faster square jetted. If your stuck on pv's, then 6.5-8.5 like madscientist suggested. Tuning a tunnel ram is different than tuning a single carb. Mine starts right up and idles immediately a bit on the lean side and then richens up as the engine gets warm and i am only 1 1/4 turns on the screws. I use #35 squirters and have tried #37 with no change in responsiveness. My carbs have 1.320 venturi if i remember correctly. small 750's was how they were described to me. Soon to get to the track, will see how it performs there. I really suggest square jetting weather racing or street, it just works. The T ram has individual runners and each runner should have the same amount of fuel feeding each individual cylinder. Good luck with your tuning.



I’m curious how you keep the cruise AF ratio clean without using a power valve on the primary side? It would seem to me it would be pretty fat if you have enough jet to keep it from going lean at WOT. I forget...did Dom use annular boosters in your carbs or down legs?


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: Tunnel Ram hesitation [Re: madscientist] #2960218
09/02/21 07:12 AM
09/02/21 07:12 AM
Joined: Jan 2007
Posts: 7,793
Mt Morris Michigan
mopar dave Offline
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Mt Morris Michigan
Its a BLP down leg that as i recall is a bit different than your tipical downleg. I will have to ask Dom about that to be sure. Mine are jetted 83 square using BLP jets. That would be a 78 holley jet. Cruises lean if any thing, high 14's to low 15's now with the screws at 1 1/4 turns.

Re: Tunnel Ram hesitation [Re: mopar dave] #2960321
09/02/21 01:48 PM
09/02/21 01:48 PM
Joined: Aug 2003
Posts: 40,855
Bend,OR USA
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Cab_Burge Offline
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Posts: 40,855
Bend,OR USA
Originally Posted by mopar dave
I Cruises lean if any thing, high 14's to low 15's now with the screws at 1 1/4 turns.
Those numbers worked well on my old Duster with the six pack and 440 heads and all three of single dominator carbs I ran on it with the max wedge heads up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Tunnel Ram hesitation [Re: madscientist] #2960571
09/03/21 09:40 AM
09/03/21 09:40 AM
Joined: Jul 2004
Posts: 19,313
State of confusion
T
Thumperdart Offline
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Thumperdart  Offline
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Joined: Jul 2004
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State of confusion
It's all in the calibration and my 650ish carbs are awesome square jetted as well with no p/v's but the idle and transition circuits need to be tailored to your combo and I'm not a big annular fan either at least with those small venturi's.....


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: Tunnel Ram hesitation [Re: Tig] #2961654
09/06/21 05:30 PM
09/06/21 05:30 PM
Joined: Sep 2003
Posts: 1,041
San Jose Ca.
boatracer572 Offline
super stock
boatracer572  Offline
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Joined: Sep 2003
Posts: 1,041
San Jose Ca.
Originally Posted by Tig
Originally Posted by boatracer572
all great comments above... this is a common occurrence in my world (boat drag racing) the first problem i see with your combo is the staggered jetting ,that in its self will cause erratic afr and rich and lean conditions. tunnel rams have equal length runners.. IE jetting should be square to start. the power valves need to be plugged as well.. i have found on 4150 style carbs turning the accelerator cams up side down works great and will save money on cams. squirter wise, i drill out the squirters with a .040" size drill to start out with,.but dont be surprised if you end up going much larger.... try this odds are your problem will be fixed worst case scenario you will need to increase the accelerator size to 50cc twocents


Yep It seems entirely feasible that all square jetting and 1 to 1 linkages are the way too go with a TR and that is the way we have it at the moment.
But... I'm soon to fit EGT's and a Racepak. It will be interesting to see if we need to treat each cylinder as individual.

I have found EGT’s to give you mixed results ,what has worked best for me has been O2 sensors and every cylinder, If you try biger squirters and Accelerater pump cams and that doesn’t work, you may need to richen up the intermediate circuit with a smaller air bleed.

Last edited by boatracer572; 09/06/21 10:43 PM.
Re: Tunnel Ram hesitation [Re: boatracer572] #2961827
09/07/21 10:45 AM
09/07/21 10:45 AM
Joined: Jan 2017
Posts: 275
Nevada
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merpar Offline
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Nevada
Seems very simple to me. You need bigger squirt, shooters what ever. I would start with a .037.

Re: Tunnel Ram hesitation [Re: 360tripleblack77] #2961844
09/07/21 11:42 AM
09/07/21 11:42 AM
Joined: Aug 2003
Posts: 40,855
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
Fatten up the idle mixture to cure that twocents scope wrench


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Tunnel Ram hesitation [Re: merpar] #2962202
09/08/21 02:01 PM
09/08/21 02:01 PM
Joined: Jul 2004
Posts: 19,313
State of confusion
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Thumperdart Offline
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Not necessarily, I run pink cams in the # 1 position with .033 shooters and zero bogs or hesitation anywhere.....


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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