I know Tunnel rams have been talk to death but I've seen no real hard numbers on setups. I'm having troubles with mine so I'll give you all the numbers first and I would like to here from some of you with the same. My mill: 355 cu, 9.75:1 comp,305 heads with 2.02 intake/1.60 exh(bowl work done to unshroud the valves),external coil HEI to clear the tunnel ram,R44ts gapped .045,Flowtech afterburners to an H-pipe to 2 turbo mufflers(from collector to mufflertip 40" in length)a weiand 1984 hi ram and 2 1850-3 Holley 600's(65 jets,.021 squirters,2.5 or 3.5 pv,30 mm accelerator pumps,regular spring in the pod and vacuum balanced). The timing is 36 or 38 degrees all in.Cant remember off hand. Idle mixture is rich as hell until you turn the screw in so its only a 1/4 turn out and its still rich. It also bogs off the line and I cant tell if its a lean bog or not. Understand that I'm about out of cash so I need to make this better sano cashola. Oh and a 3000rpm stal with unknown rear gears
Smaller carb's will help a lot. There are plenty of threads that give a good base to work from regarding your combination.
definitely two smaller carbs or get a single 4 bbl top and run 1 of yours . tunnels don't like a lot of fuel!!
Knew a guy with a 350 and a t-ram and he removed the tubes on his 600's and only ran off the front bowls. Now my 289 had a Offy 360 with a pair of 660's and it ran GREAT, but was in a drag car. 3000# car, 5.67 gears, 9x30 slicks, Jerico, ran a fastest of 11.08 @ 119mph in the 1/4 at FFW Ennis in '94. '69 351w heads and a '65 289 block, N/A.
Forgot the cam specs Cam Style Hydraulic flat tappet Basic Operating RPM Range 2,800-6,300 Intake Duration at 050 inch Lift 234 Exhaust Duration at 050 inch Lift 234 Duration at 050 inch Lift 234 int./234 exh. Advertised Intake Duration 292 Advertised Exhaust Duration 292 Advertised Duration 292 int./292 exh. Intake Valve Lift with Factory Rocker Arm Ratio 0.488 in. Exhaust Valve Lift with Factory Rocker Arm Ratio 0.488 in. Valve Lift with Factory Rocker Arm Ratio 0.488 int./0.488 exh. Lobe Separation (degrees) 114 Computer-Controlled Compatible No Valve Springs Required Yes Camshaft Manufacturers Description Fair-lopey idle, mid-upper rpm power. Requires 9.5:1 and higher compression, 2,800+ stall, and gearing. Quantity Sold individually.
And theres still the no money problem. So no smaller carbs. I may be able to whittle out a single carb top but the twin carbs just makes the look. As for removing the tubes it shouldnt matter as the Idle mixture seems to be the biggest problem. And Hollywood I just moved out of Schroeppel not to long ago,been in and around the Syracuse-Oswego area for an inordinate amount of my life. Long Live the Dino!
David Vizard published a book a while ago with dual carb tunnel ram tuning issues, those 600 carbs should work, there would be a better choice with a smaller carb to have a sharper stronger signal. Your cam will make all the difference in that setup. Gears, cam and intended RPM usage all have to work together. If you know any respected drag race engine builders in your area it may be worth talking to them. Your setup should NOT be miserable to drive, if you are going out on the tunnel ram, dual carb limb, you need to be prepared to tune. I think Car Craft or Hot Rod magazine had some good tech articles also, do a Google search.
pull a plug and see what it looks like. As others have mentioned 2-600's on a SBC might be a little to much for a mild street motor but a bog out of the hole is an indication that it might need to be fattened up. Tunnel Rams can be finicky on a street driven car. After pulling the plugs you will know more.
. Idle mixture is rich as hell until you turn the screw in so its only a 1/4 turn out and its still rich. It also bogs off the line and I cant tell if its a lean bog or not. 1/4 turn out is a problem Give it a small vacuum leak, if it boggs less then you have a rich bogg, more you're lean. Choke it a little bit, if it boggs less then you have lean bogg, more you're rich. Have someone watch for a puff of black smoke at the end of the bogg, when it catches = rich. At least that should get you into knowing rich or lean. Plugs will tell you too, but if you are idling" rich as hell" it will be of little help because they will be black. With that set up you are running, it should perform best if you brake and come up on the converter to 3000 and hammer it . Does it do that well at least? My first guess is there's low vacuum and that's letting the power valve give too much fuel.
You need to know what your rear gear is to set this up. Tall gears will help cause the bogging. I'd start with a low ratio and dial the engine to it. You need a plan. Goodluck.
Rear end ratio is ? Keep meaning to determine it but other things keep drawing my attention away. I do know its not tall. If I had to guess from the way it moves its probably somewhere around 3:73ish. Will be spending most of this sat tuning so I'll have to get some more solid info
I'd put 31 squirters in the carbs and try it. 21s sound REAL small to me. If it's rich at idle, I'd check the power valves. I've never had to run anything smaller than a 4.5. You might also check and make sure you don't have gas tipping in out of the boosters at idle.
I've seen it done before, seems to work. Bend the wire in an L and put it in the idle fuel feed in the metering block.
That's the exact cam I just tossed in the scrap heap! It was way too "pipey" to work well on the street. Felt like a two stroke motor that ran ok to around 3000rpm, then jumped when it hit the power band, just before I shifted. That cam makes almost no vacuum, and your power valves are opening too soon, which makes the rich idle. I replaced that cam with a Isky 270 Mega cam, but you can save a few bucks by getting the Summit/Crane #SUM-K00172. It's a 274/274 with .450" lift, and 106 LSA. It's a little lopier, but comes on right off idle, and really pulls hard all the way to around 6500. My little gasser is running a 327 bored .040", with twin 450 carbs and old camel hump 2.02 heads. I changed accelerator pumps to 50cc, and nozzles to 34, then changed the power valves to 3.5 to help with the rich idle. All that made it run better, with no stumble, but still couldn't really pull well. After changing the cam the tunnel ram works way better, and the car will pull the front wheels at launch.
No kidding with the lack of vac. Changed over to a Wilwood dual master cylinder manual brake set up. Had a friend drive it who has no exp with manual brakes nearly pissed myself laughing at his white face when he came back from a power pull. I told him"bro when you hit the end of the street,grab the bottom of the steering wheel and be prepared to smash the brake pedal as hard as you can" He musta thought I was kidding. He was like how the hell did you drive these things on a daily basis. I told him that you actually had to pay attention when you drive these or they'd kill ya. and the pv's in this are either 2.5 or 3.5 cant remember which
I had a power booster on mine, but when I put that same cam in I had to remove it, as I had no vacuum to run it. With the new cam I have enough vacuum and I'm considering replacing the booster again so I have the great stopping power.
Little late for me as I had to change the firewall. This cars one big abomination. I kinda like it like that.
Roughly 1500 ish need to pull the plugs and clean them. Actually need to strip every thing down and clean it out as the fire extinguisher powder is everywhere and I'm certain its not helping. ps with this crappy ethanol check your floats for sticking just saying prettyy close to your area now got a place in Lima out on 5 and 20
It should be closer to 1000rpm, you could be uncovering the transfer slot with your throttle blades open to far. Those 600's should be fine since they are vacuum operated secondaries and certainly shouldn't come into play at idle. The stock squirters for a 1850 600cfm should be a 28 I believe, I know I was going to rob those to go into my 450's but those had a 31 stock.
I pull the stock ones for smaller cuz I knew I'd have idle issues with this set up. Guess I'll put em back and see what happens
So you probably saw the stude pickup in my profile albums I ran with a single 600 on a tunnel with very good results . Where are you living now ??
Two idea's for you block off the power valves . See what rpm your advance comes in at if your timming falls back at a rpm that's too high it can cause a secere stumble.
I wonder if your high idle has something to do with your mixture screw settings ? I would back the idle down and open your mixture screws up. Mine idles just fine but stumbles under quick full throttle opening, so I can't cure your stumble. Wish I could cure mine...lol
Mine has no stumble at all with the larger nozzles and the 50cc pumps. It idles at 850 rpm, and works well with my TH350 and 2200 stall converter. Are you saying your's wont run if the idle is below 1500 rpm, or that you can't get it to idle lower with the idle scres backed all the way out?
I can back idle screws to where Holley recommends 1 1/4 to 1 1/2 turns out but its like driving a mosquito spraying truck. It will idle at that point but you've got only a couple of min. before the oil is more like kero
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