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Discussion Starter · #1 ·
Looking around for a tunnel ram for my 434, cked on ebay and I think everybody thinks they are worth a mint now. The Wiend Hi Ram is only $375, free shipping from Jegs. Seen some older ones, but you trouble with fuel puddling in those. Found 2 matched Holley, 1850s on ebay that came off a tunnel ram. So far the price is good, that could change. Anyone on here running a T ram on a larger sbc? Just wondering which carb performed good, after performance more than looks. Although they do look cool. Last one I had was on a BBC 482 that ran high 8's in a 67 nava drag car. They were 750 DP, and drove around the pits like a street car.
 

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I'm running 650 double pumps sideways on a 377. Took a little tweaking in the jetting but I got it to behave on the street and wide open is more than generous.
 

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I'm running 650 double pumpers on a Ford tunnel wedge (their version of a tunnel ram) on my 428 with no problems on the street. Like Mario said pay attention to the jetting and your power valves.
 

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I bought a pair of Holley 1850's direct from Holley for $200 ea. with full warranty. Holley gets carbs back that often have no problems, as owners don't know they have other fuel pressure issues, etc. So they go through them, and check them out; then sell them as factory rebuilt, with full warranty. I found Holley selling them on Ebay, but you can also contact them direct. The twin 1850's should be a good choice for your build.
I see used tunnel rams all over the place in pricing. Some higher than new, and others as cheap as $100. Gave $110 for the Weiand on my Falcon, but it was painted silver, and I had to chemically strip it. I check Craigslist, and swap meets, and don't get in a hurry.
 

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Discussion Starter · #6 ·
Bought a tunnel ram, I was thinking 650 DP carbs. That's what Quick Fuel recommended also. I found 2 1850's, but I think they'll fall a little short with this engine. The heads are Pro 1's, ported, 2.08 intakes, with a Bullet 658 lift solid roller. It makes some good steam in my chevelle, the 40 chev will be quite a bit lighter. I'll watch around for carbs, I got time, that's for sure.
 

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The guys on queerbay are nuts for what they want for sbc tunnel rams. All the companies made millions of them. Have to agree with Vall. Go to Holley direct. I'm in the business.
 

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I think the 1850's can work well. I'm using them on my 464 BBC with Edelbrock aluminum heads and Weiand tunnel ram. It's probably closer to your big inch smallblock. With a Holley vacuum secondary spring kit, and quick change vacuum housings you can install the balance tube so they sync with each other and open together. A little work with larger nozzles, (if needed) and they should play well on your big inch engine. Other than the quick change spring kit, and balance tube, mine are bone stock and allow the engine to pull very hard.
 

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I would certainly try the 1850's being you spent the money already. If it works you're done. I tried using them but had great difficulty getting them to work inline and sideways. I also had a solid roller 640 lift with a weiand tunnel ram and the double pumpers seemed to be more manageable for my setup. But it don't mean anything till you try the ones you have. Just my humble opinion.
 

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Another Humble Opinion

Another humble opinion that's pretty much in line with Mario. I originally was running an Offenhauser cross ram on my 428. I had it set up with vacuum secondary 600 cfm Holleys sitting sideways. I had the equalizer tops on the secondary diaphragms for the balance tube, had the spring kits, 50cc pumps, larger squirter nozzles and a good selection of power valves, everything to make the carbs run right, and that motor just didn't run like it should. Enter a pair of 650 double pumpers and that motor came alive. Then when I replaced the cross ram with the tunnel wedge it was like a whole different motor. I've included a photo of the old vacuum secondary set up.
In the end you have to find what works best for your application though. Good luck and keep posting. I'll be real interested in how the carb tweaking goes.
 

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Did anybody check for the idle mixture screw gaskets? Often omitted by the "experts". Creates misfires, rough or no idle and other assorted nonsense.
 

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Did anybody check for the idle mixture screw gaskets? Often omitted by the "experts". Creates misfires, rough or no idle and other assorted nonsense.
My situation was only wide open throttle. Idle and driving was beautiful. What happened to me was a wide open reverberation with uneven fuel due to my cam lift and duration. Plus my compression was under 10-1 which made it hard to deal with. It did it both inline and sideways. It was so bad due to uneven secondary jetting that I had to try double pumpers. My 1850's were brand new and I ended up selling them to someone who said they work great on his big block setup. So it definitely was my combo. The double pumpers allowed me to control front and rear jetting and nozzles front to back which worked great. Now if I could get me some compression some day I can go racing with the big boys. We don't have anymore raceways on the island so I built her for the street and pump gas.
 

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Ok, obviasly not the problem. The 1850's should have been good. But what ever works is all that counts. So what's the problem cant go racing with a bunch of "street cars" that are married to a barrel of fuel. Them assholes make me sick. So called "street cars" that come in enclosed trailers and have plates. SO WHAT!
 

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I fought the twin 450 Holleys on my Austin. Two issues were sideways only mounting, as the Holley Pro Dominator wont allow end to end mounting. But the biggest problem is the Holley 450's don't have accelerator pumps on their mechanical secondaries! I'm unsure what idiot at Holley ever thought not having a secondary accelerator pump with mechanical linkage could ever work well on a street setup? They actually worked great at wide open throttle, but took me weeks of fiddling with larger 50cc pumps, nozzles, jetting, etc. to make them work well for normal street driving. They had a terrible stumble during gentle acceleration.
 

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i will run a tunnel ram on my sbf. i plan to run a big cam for no reason but sound. i will either run 390's or 600's . because i have them. because of the cam and the intake power valves really come into play . gets tricky when you have little vacuum to deal with. but the car is being built to play with not raced.
 

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Discussion Starter · #16 ·
I didn't get the 600's, just bought the wieand Hi Eam tunnel ram. I think DP carbs work better on a tunnel ram. Ifound out that the newer 3310, 750's can be had for a little of nothing, 650 DP carbs however are pretty scarce. Found out that they are having a gasser meet at Thornhill drag strip tomorrow evening. If the rain holds out, I'll ask around there. Last time I heard they had the Ohio Gassers there, I didn't find out until it was over, this time is going to be different.
 

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I would stay away from the 3310 unless they fit inline which on Chevy small block they will not. They will have to mount sideways. Then you'll have to get secondary metering blocks and long screws so you can jet them properly. They don't use a secondary nozzle without the double pump. After buying all that you would wish you had bought the double pumps instead.
Can you at least try someone's 1850's and see how they work?
I wonder if you can get some 1850 single inlet bowls and make your own 1850's if the 3310 is cheap enough. Somehow you will spend enough money where you may regret piece mealing it.
 

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Not exactly the same as your big inch small block, but I'm running 1850's on mine. Weiand tunnel ram, 522 inch big block. Inline, direct 1:1 linkage. I've modified the carbs by adding secondary metering blocks so I can change secondary jetting.

Also put in the quick change secondary diaphragm covers with the balance tube so the front / rear carbs open secondaries in unison.

So far haven't got too deep into fine tuning them, just set idle mixture and balanced carbs idle speed with a synchrometer. AFR gauge is reading pretty close to where I want to be, probably going to go a step fatter on the secondary jets. Will try a different # power valve as well to match what holley recommends for my idle vac reading.

But as it is, the car runs great with this setup. Idles nice, no stumbles or such on acceleration. Decent street manners and when you put your foot down it pulls like a scalded ape! That's 1200 cfm of carb there should be sufficient.
 

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Discussion Starter · #19 ·
I bought a 650, 4777, and got another 1 I'm bidding on. I'm going to go through them and sell my 750 DP.
 

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Becareful of welded bases that don't show easily on the auction photo. I bought one like that. Ended up replacing the base cause it just didn't sit well with me.
 
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