I have been reading info on getting a weiand tunnel to run on a stock 350 chevy. I am wondering at this time if anyone has a answer to the following, I have installed a tunnel on my 38 chevy, because it looks cool. I am not looking for top end performance, just want it to run for cruising[car shows, etc]. the motor is from a 70's to early 80's c-10/c-20 truck. has a 400 tranny. i was told the motor had been built with a mild cam and the tranny had a 2500 stall converter. both of these seem to be not true. seems to have a rear end stock gear ratio. the tunnel has 2- 600 edelbrocks. [cause that's what came with it]. the set up is the back carb is the primary feed. [progressive linkage]. the primary[back one] has been rejetted to primary =.095;;sec=.089 with the meter rods= 73/52. the front carb= .098///.095///70/47. floats are set according to instrutions. with this the motor runs on the rich side [back 4 cylinders and front four look to be in the color range that would be xceptable. I have tried to get to the past threads on the hamb but can' seem to get there. I have thought about running both carbs equally and jetting leaner. any thought on next step would be appreciated.
Hi; Your motor won't be happy with progressive linkage, I have ran a tunnel ram on my Model A for 15 years with no problems.gear ratio is important. Chris
I run an Edelbrock tunnel ram an a 383 SBC. I broke it in on the rear carb and noticed the front 4 were running leaner then the rear. While it drove ok progressive it was much happier running 1 to 1. Two 600's on a SBC is a lot of carb, and while the secondaries have an air valve you may want to try disconnecting them for a while and see how it does. On a side note I used to run a Weiand tunnel with two 600 Edelbrocks. I sold it over the winer to a guy in Iowa, were did you get your setup?
I agree with the above, I would run a 1:1 linkage. Also, you'll probably want to swap the cam and rear end gears to make them more friendly to the tunnel ram.
years ago, a friend with a T-bucket wanted one for looks. Junkyard 350 with 2 390 holley carbs is what he used and worked great!
How would you know if you were running an altered stall converter behind a stick wheezer motor. You stall and or flash point on the converter is in direct relation to the torque output of the engine and the weight if the vehicle. If you are running s low performance engine to start with the converter will act very close to the original or the difference will be negligible. That said your description is a little hard to follow. You said that it is running rich, then said that the back 4 cylinders are the front 4 cylinders look OK when you read the plugs. If it is running fat try jetting it down. Do not run your carbs straight up stay progressive, your stockish smog era GM will not take that much air all at once.
A lot also depends on what your tunnel ram intake is designed as. In other words, how big are the runners, how large is the plenum under the carbs, etc. I am not familiar with the Weiand design, or if they have different models; I assume they do. Generally smaller runners and smaller plenum is better for your application. That helps with response and keeping the velocity a bit higher at the lower speeds you are running. As for setting up the carbs, no matter what you have a lot more carb capacity than the engine will use or need. You might try the idea to keep the secondaries closed off, so in effect you are running two 2 barrel carbs. That would still be plenty for your engine, and at lower speeds to boot.
There is another option, he could completely block off the second carb. Its for show and not for go. No reason to even use it then he will have a carb that he can just swap when the first carb wears out.
As stated above, your setup would probably benefit from a smaller carb as well. Either a 390 or 450 cfm.
Fuel distribution will not be even. The farthest cylinders will likely be lean. Better he disconnect the secondary barrels.
Tunnel rams don't like to work well with progressive linkage. A dual plane 2 four barrel intake is OK that way, but the runners on a tunnel ram wont like it. Same reason you shouldn't block off one carb; it will be lean on one end of the engine. I have tunnel rams on two of my cars, and the SBC with twin 450's is an issue with the Holley carbs not having vacuum secondaries. Someday I'll swap them out to vacuum secondary carbs, as they work so much better in a dual carb setup.
like said above, progressive linkage sucks on a tunnel ram, at least in my experience. I started off similar... mild 350 and a slushbox. put a tunnel ram with 650cfm holleys on it. tried tuning for ages with no great success. switched to a pair of 390cfm holleys and non progressive linkage and it was a night and day difference. the car had deep gears and a cam that matched... scooted along nicely. the key is a combination of gearing/cam/carburetion that all works together
mild mill= smaller vacuum carbs+ square jetting (or close) on a 1:1 linkage and throw a little more gear in it-rick
I have a 31model A coupe with a 454 chevy bored 60 over and an offy 360 powerport tunnel ram. It has two 600 carter afbs on it. has an electric choke on the rear carb. Runs great, idles great, starts great winter or summer. Geared high 275 nine inch ford, 400 turbo and thirty inch tall tires. The carbs are hooked up direct. It could'nt possibly do any better.
I just love tunnel ram discussions! At one time I had two 4 speed cars with the following, 383 Chevy stroker strong build, street car, regular gas. Two 600 Eddies on a TR1Y Eddie intake. 350 Chevy mild cam street car. Two 500 Eddies on a TR1Y Eddie intake. Both cars run strong off idle throughout the rpm range using both carbs at the same time. About 2 years ago I switched to progressive, (front carb idle circuits are off and primaries start to open as soon as the back carb secondaries kick in). Car runs great, better gas mileage too. I must be lucky because both engines run great, super on the street. I have a pic of them in my album. As stated above, not all intake models act the same. Good luck with yours.
the car in my avatar has a offy single 4 tunnel, 750 carb 3.73 gears 355 cu. w/ an old dirt track cam ,jets square 76, squirters 31 still runs a little fat , ran a 12.16 at bowling green last week, and 11.90 in Atlanta I also drive it on the street.......ran like crap at first but these guys on here can help you get it right...
Make sure your distributor vacuum advance and mechanical advance are working properly. full advance around 3000. Run it 1to1. The manifold is designed for two carbs running at the same time. I have setup 600's to work on a mostly stock 327. Power valves and jetting. Keep the power valves from opening too soon and jet accordingly. When you do a plug check make sure you run it without opening the power valves or you will not jet it correctly.
porknbeaner, i didn't no about the stall converter thing, thanks for the info. thanks for all of the other replies. I will look forward to more. any help in getting to the past tech discussions related to this ? also, I did try running on just the back carb[no fuel to the front one] and this seemed to be worse. . with progressive linkage it was suggested[from a car show guy to run primarily off the front not the back. this was on his setup]. I haven't tried that yet. I have ordered smaller jets [.089 primary// secondary will be .095's and I don't no if those are relevant to the low speed operation] and larger meter rods for both carbs. once I get those in I will try the 1 to 1 linkage and if need to go further the other suggestions as well. I don't believe I have used the secondary barrels as I have only run this at what some would reference parade speed with the occasional throttle hit. I will also look at how to do the power valve thing. I started the timing set at 12btc and currently have this at 20ish. seems to be the sweet spot with the current setup. again the plugs in the front four cyl's are colored in the xcepable reading and the rear four are richish[not wet but black] I am not looking for drag performance but a cruising run.
It is high-stall converter, not simply stall converter. Every converter is a "stall converter". Some have higher stall speeds than others.
Because a tunnel ram produces a very strong booster signal they tend to run richer then a single plane would with the same carb and jetting. Best place to start is with stock jetting. what the carb would come with from the manufacturer. On this tunnel ram I run one jet size under stock as delivered specs. If you must run progressive linkage and I would not then you must use the primaries of the rear carb to open first. why because they are of al the barrels most centrally located .In fact that is a good rule of thumb for any inline 2 X 4 set up. Why does a tunnel ram not behave they way we would like on the street? because it is designed for much higher RPM typically 7000+)(runner length is too short) Could it be done ? Yes if you made your own or were creative enough to lengthen the runners in someone elses design. I finished this one over the winter and have been using it in a race situation but on a low RPM motor.. (Slant six 6000RPM and down) I designed it for this application so runner length or I should say length from the back of the intake valve to the plenum is 15 inches. I would guess yours in around 9 or 10 inches at best. There is a formula or rule of thumb. This one runs a pair of 500 Holley 2bbl and motor is 246 cubes. No bogs smooth performance. don
I'm unfamiliar with Edelbrock jets, so not sure what the jet numbers you listed mean. I know you can also raise or lower the rods to tune the flow a bit more. Jet sizes wont mean much for throttle response, as they wont come into play when you give it throttle off idle. You really do need to lock the linkages together for simultaneous opening before you spend any more time trouble shooting the system.
I ran an Edelbrock dual top tunnel ram on a 289 Ford,solid flat tappet cam,11 to 1 compression,ported big valve heads,4-speed and 3:89 rear gear,used two 1850 Holleys[560 CFM,vacuum secondaries],1 to 1 linkage,it worked great on the street or the track. ROY.
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