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Discussion Starter · #1 ·
Have a question that maybe someone can answer. I tried looking around at Summit or Jegs for a kit, but didn't see anything.
The carbs I have on my tunnel ram are 450cfm Holleys with mechanical secondaries, but not double pumpers. So the problem is when you hit the throttle full on at lower rpm's it stumbles for a second and then goes. I'm sure if the secondaries were not mechanical, or if they had an accelrator pump, it wouldn't do this.
I could go through adding a secondary accelerator pump/metering block kit to convert it to a double pumper, but I'd rather convert it to vacuum secondaries. I was hoping maybe someone might know if Holley or Quick Fuel makes a vacuum secondary retrofit kit?
I disconnected the secondary linkage today to see how it ran, and it ran great, but doesn't come on as well from 3,000 rpm and higher as it did before. Vacuum secondaries would be the best of both worlds, but hate to take carbs off that only have about 8,000 miles and spend more money to swap to different carbs. Also not crazy about swapping to double pumper kits, and dump huge amounts of fuel into the engine to overcome the stumble.
 

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I have the same carbs Vall. I don't think they make a retro fit kit for these since they were designed for tunnel rams. Maybe go to a Edelbrock 600 or a bigger Holley. When I bought my tunnel ram, it came with the 450's. I am probably going to sell them this year at the swapmeet and hopefully make enough to get some 600's.
 

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I've seen those 450's selling on tunnel ram kits but I have yet to ever hear of anyone that likes or can get them to work right. With no secondary fuel enrichment they're going to stumble. I had twin 1850's (600's with vac secondaries ) on my T ram 377 and loved them. Mark L
 

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Have a question that maybe someone can answer. I tried looking around at Summit or Jegs for a kit, but didn't see anything.
The carbs I have on my tunnel ram are 450cfm Holleys with mechanical secondaries, but not double pumpers. So the problem is when you hit the throttle full on at lower rpm's it stumbles for a second and then goes. I'm sure if the secondaries were not mechanical, or if they had an accelrator pump, it wouldn't do this.
I could go through adding a secondary accelerator pump/metering block kit to convert it to a double pumper, but I'd rather convert it to vacuum secondaries. I was hoping maybe someone might know if Holley or Quick Fuel makes a vacuum secondary retrofit kit?
I disconnected the secondary linkage today to see how it ran, and it ran great, but doesn't come on as well from 3,000 rpm and higher as it did before. Vacuum secondaries would be the best of both worlds, but hate to take carbs off that only have about 8,000 miles and spend more money to swap to different carbs. Also not crazy about swapping to double pumper kits, and dump huge amounts of fuel into the engine to overcome the stumble.
Is the car automatic or stick? If automatic, what size converter are you running and what gears in the rear? sometimes its not all carb issues.
 

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Discussion Starter · #5 ·
Is the car automatic or stick? If automatic, what size converter are you running and what gears in the rear? sometimes its not all carb issues.
It's a TH350, with manual shift kit, and 2600 stall converter, and 3.73 gears.
I have found out by looking at an internal diagram that the carbs aren't drilled for the vacuum passages needed to convert them to vacuum secondaries, so that's not an option. Edelbrocks are also not an option as my carbs sit sideways, and wont allow two Edelbrocks to clear.
Looks like I'll start saving my pennies and spring for two new 600cfm Holleys. $538 for the pair, so not huge, but I doubt I'll recoup much of the $500 that I paid for these two 450's. The intake came with two 450's that were well used on it, and I got $100 for them; probably be lucky to get much more for these two.
 

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Discussion Starter · #6 ·
I've seen those 450's selling on tunnel ram kits but I have yet to ever hear of anyone that likes or can get them to work right. With no secondary fuel enrichment they're going to stumble. I had twin 1850's (600's with vac secondaries ) on my T ram 377 and loved them. Mark L

Not familiar with the 1850 Mark. I see the 4160 which is a 600cfm Holley with vacuum secondaries.
 

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It's a TH350, with manual shift kit, and 2600 stall converter, and 3.73 gears.
I have found out by looking at an internal diagram that the carbs aren't drilled for the vacuum passages needed to convert them to vacuum secondaries, so that's not an option. Edelbrocks are also not an option as my carbs sit sideways, and wont allow two Edelbrocks to clear.
Looks like I'll start saving my pennies and spring for two new 600cfm Holleys. $538 for the pair, so not huge, but I doubt I'll recoup much of the $500 that I paid for these two 450's. The intake came with two 450's that were well used on it, and I got $100 for them; probably be lucky to get much more for these two.
I have a pair of 1850S carbs that came on a summit tunnel ram kit. I would take half price for them because their used but almost new, dry and clean inside. I have to be honest with you though, my experience with the tunnel ram is that it needs a good stall speed converter first.
Everyone has different combinations that can affect how your wide open throttle acts at the carbs. I had a terrible time with sideways mounted 1850's which Im sure many will say should run inline. No matter what, the secondaries open over certain cylinders and cause all kinds of issues, especially the wide open hesitation which needs fuel compensation to overcome. I ended up using 2 650 double pumpers sideways and upping my converter from a 3500 to a 4500. This brought the hesitation curve up where the intake can over come the fuel lag and the problem is gone.
Hughes performance guided me and stood behind the converter purchase and did a swap for me. They told me the car would wake up considerably and it did. Im running low compression with my tunnel ram (9.7-1) so it wasn't as responsive as it should have been and needed to be rich to overcome the issues I had. So in short the low rpm range of your tunnel ram needs to be the same rpm as your convertor to overcome the lag. I did well with the 650 double pumpers but my real problem was the converter. Of course I learned the hard way but you can't beat the learning experience. thats what hot rodding is all about.
i can sell you the 1850's but I would start with a better converter. Maybe call Hughes in Arizona and see what they recommend for the street. I spoke to Pete in tech support. Good People.
Hope this helps.
Mario
 

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My son used to work at Hughes up until about 1.5 years ago. But I see you talked to Pete. Pete is very good at pin pointing combinations too. So you were in good hands. The trick to 1850 carbs (vacuum secondary 600's) is getting the accelerator pump cam just right. You want the one that starts out soft so you are not over shooting during normal primary use, then quickens up as the throttle reaches about mid travel. This helps add more fuel when the secondaries start openning. Plus get the secondary pot connecting kit so they react together at the same time. Mark L
 

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Vall, just a suggestion. Find a good tunnel ram at a swap meet or online that someone is not asking an arm and leg for. It can be a small block chevy or a Ford or even a 340 360 LA mopar and buy it. Cleqan it up nice. Then set it up with the twin 450' and sell it as a unit. I bet you could recoup your investment and even maybe make a little on the deal??? Mark L
 

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Discussion Starter · #10 ·
I put the linkage back on today to reconnect the secondaries. I can't believe how sluggish the car became with just the primaries hooked up, and really didn't help smooth things up as I hoped. Amazing how much more power it builds with the secondaries connected! It really did feel like it lost half it's power with them unhooked!
It's not a huge stumble when going from part throttle to full, and I can live with it fine for now. It's just something I'd like to overcome, and get it tuned a little better. I'm not sure I want to go to a 4500 stall converter that will create a lot of excess heat with most of my driving under 3,000 rpm's. That's a huge difference that I've been told will create excess heat in the trans.
I don't have an option on my Pro Dominator tunnel ram to run carbs inline. This intake is only made to run them sideways, so that's not an option.
 

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I put the linkage back on today to reconnect the secondaries. I can't believe how sluggish the car became with just the primaries hooked up, and really didn't help smooth things up as I hoped. Amazing how much more power it builds with the secondaries connected! It really did feel like it lost half it's power with them unhooked!
It's not a huge stumble when going from part throttle to full, and I can live with it fine for now. It's just something I'd like to overcome, and get it tuned a little better. I'm not sure I want to go to a 4500 stall converter that will create a lot of excess heat with most of my driving under 3,000 rpm's. That's a huge difference that I've been told will create excess heat in the trans.
I don't have an option on my Pro Dominator tunnel ram to run carbs inline. This intake is only made to run them sideways, so that's not an option.
you may only need a 3500 stall. What kind of compression are you running?
 

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My son used to work at Hughes up until about 1.5 years ago. But I see you talked to Pete. Pete is very good at pin pointing combinations too. So you were in good hands. The trick to 1850 carbs (vacuum secondary 600's) is getting the accelerator pump cam just right. You want the one that starts out soft so you are not over shooting during normal primary use, then quickens up as the throttle reaches about mid travel. This helps add more fuel when the secondaries start openning. Plus get the secondary pot connecting kit so they react together at the same time. Mark L
When I mounted the carbs sideways , I got a horrible out of balance resonance due to the unbalanced fuel running down into the cylinders under the secondaries. I tried balance tubes but still no good.
My cam and heads just didn't work well with the vacuum secondaries. I had to evenly jet all 4 sides of the carb and set the right nozzles evenly on both sides. Then it ran great without any hesitation.
In fact at the reunion at Beaver Springs the car left like an 11 second car and if I had more motor or less gear I would have gotten High eleven time slips. Shooting from the hip I got a 1.6 sixty foot there. I don't have any strip here on LI to practice my combinations.
 

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Wow that's a travel from Long Island to the Grove ! ! How long dose that take you ? There's a track les then 40 miles from me, called Numidia race way. Have you every been there ?
No never been there. I wanted to try Island Dragway this spring but I heard that they closed. Have you heard that?
 

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Wow that's a travel from Long Island to the Grove ! ! How long dose that take you ? There's a track les then 40 miles from me, called Numidia race way. Have you every been there ?
Wow that's a long ride as well. Lewis burg is the land mark for me which is not far from numidia. I need an enclosed trailer. I can't get caught in another thunderstorm again on the way home. This was not fun. Tornado warning as well in the area.
I was racing the clouds and praying it wouldn't hail on the car. Do you know of any around there that are 24 ft?
 

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There are some dealers local, but I can check our Graigs list to see what in my surrounding area. This is probably a good time to loo were guys are looking to upgrade some. I sold a nice 40 footer here this pasts year. That would have housed your race car and then some. But sold my dually and down sized to a 2500 Dodge, and just stored a few cars in it.

 

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There are some dealers local, but I can check our Graigs list to see what in my surrounding area. This is probably a good time to loo were guys are looking to upgrade some. I sold a nice 40 footer here this pasts year. That would have housed your race car and then some. But sold my dually and down sized to a 2500 Dodge, and just stored a few cars in it.

much appreciated. Im trying to use my 1500 silverado to pull the trailer so I need to stay small. 24 ft is the biggest I can do price and truck wise.
 

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Discussion Starter · #18 ·
you may only need a 3500 stall. What kind of compression are you running?
I'm running around 10:1 CR. I've never run 1/4 mile, but when I ran it this summer in the 1/8 mile my 60' times were in the 1.7-1.8 range, even feathering it to get through the stumble. It does help if I apply the line loc and bring the rpm's up until I feel it starting to pull a little, so maybe a little higher stall speed would help. Just don't want to go too high, as 99% of my driving is on the street, and mostly below 2500, unless I hit the freeway.
 

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I'm running around 10:1 CR. I've never run 1/4 mile, but when I ran it this summer in the 1/8 mile my 60' times were in the 1.7-1.8 range, even feathering it to get through the stumble. It does help if I apply the line loc and bring the rpm's up until I feel it starting to pull a little, so maybe a little higher stall speed would help. Just don't want to go too high, as 99% of my driving is on the street, and mostly below 2500, unless I hit the freeway.
Were you spinning the tires during the 60 ft? I am betting you were even when trying to overcome the stumble. I think the carb swap will get you a 1.6 sixty foot if you have good tires to hook.
You have a nice engine combo.
I guess this is a case of straddling the fence with race and street and getting a happy medium you want to live with. We all go through this. LOL
 

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Discussion Starter · #20 ·
If I was spinning the tires I didn't feel it, and nobody watching saw any tire spin. Since I'm feathering the throttle through the stumble it probably isn't spinning enough to see it easily. No tire smoke with the M&H drag radials, and they really do hook up well!
I've had two different pairs of tires before these that definitely let me know if they were spinning. They would smoke and the 1-2 shift usually resulted in a lot of steering and throttle peddling to try and get it under control. It was pretty scarey driving with tires that didn't hook up well, and a 89" wheelbase car!
 
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