I recently fitted a Weiand tunnel ram with dual Holley 450cfm carbs to replace the single top and Edelbrock 1406 600cfm carb that was originally on the Willys gasser engine. Engine is a pro built 350 SBC with ca 420hp. Trans is a TCI 350 - don't know torque converter stall but guessing 2400 rpm. Ignition is MSD pro billet distributor running manifold vacuum with MSD 6200AL and MSD coil. The Holleys have been completely rebuilt and baseline settings set as per recommendation with Holley. Fuel pressure is set at 4 psi. The engine fires on contact with one pump of gas pedal and is set to idle at 1300 rpm, however it will stall repeatedly until warm and as soon as a gear is engaged it stalls out - even when the coolant is fully warm showing 180˚. I have to rev it to 2500 rpm to get it to move and if I drop below that it will stall out. Previously with the single Edelbrock 1406 on the same tunnel ram with exactly the same ingnition engine/trans etc. the car ran fine - started right up, ran and did not stall with a 1200 rpm idle speed in neutral - 900 rpm in gear. Visually it looks far better with the dual Holleys and before i revert to the Edsingle edelbrock, is anyone here running dual Edelbrock 1403 - 500 cfm carbs on a tunnel ram on, and if so what are your experiences? I admit to being a mechanical moron but I have never been a fan of Holleys for the street and this saga is only reinforcing my doubts. Any insights or help would be much appreciated....
Not surprising, you're going from a single carb with an air valve in the secondary, to a pair of carbs with what is probably direct acting secondaries, but they are not double pumpers. When you open the throttle, lots of air enters, but it's not moving fast enough to make fuel start flowing. Lean bog. Show us a picture of the other side of the carbs, please.
a fuel problem plates closed to far(might need air holes) er pump nozzle incorrect for application( to small) fiddel with em they can be made to work, but
The problem is the Holley 450's, and it will take a lot of fiddling to get them working because they are mechanical secondary carbs that have no secondary accelerator pumps. A better choice would have been vacuum secondary carbs in either Holley or Edelbrock. I've got two cars with tunnel rams, and my 327 has your setup, while my 464 has twin 600 Holley vacuum secondary carbs. I changed out accelerator pumps to 50cc, nozzles to larger, power valves to smaller, pump cams to faster opening, and timing more advanced. They run pretty well now, but still not perfect. On the 464 I bolted them on and ran. No changes, and they run like a low rise single carb, with absolutely no changes. If you want to play with the 450's, then I'd suggest changes that get more fuel into the carbs off idle. Larger accelerator pumps and nozzles will help. Timing advanced a bit also. But if you want to save some time and fiddling, I'd sell them and buy a pair of vacuum secondary carbs. The twin 600 cfm 4160 would be a better choice, or the Edelbrock 9903. Both are under $300.
I admitted to being a mechanical moron Here's the other side - mechanical fuel pump was spraying fuel out of the base of the carburetors before the fuel pressure regulator went on - never had that problem with the Edelbrock without a regulator though....
Okay, I bit the bullet and followed BB427's advice. Opted to go with a pair of Edelbrock 1404 500 cfm carbs. Pair of fresh rebuilt Holley 450s - fresh rebuilt, cheap - used for 50 ft since rebuild anyone?
Get a pair of Holley 660 center squirters (part# 4224) and be done with it. I try to tell everyone this before they spend their money on Holley 450 and Holley 600 carbs, which are not suited for a tunnel ram, no matter what everyone seems to think. The 660 carbs were designed to be used on tunnel rams. The have 4-corner idle, a 1:1 mechanical linkage, and a 50cc center discharge pump. They cost more than a regular -1850 style carb if you're buying them new, but you can find them used on-line. The difference is night and day. Put on a pair of 660s and that engine will become a whole new animal.
sssssshhh ( were hunting wabits) keep your advice to your self.... ha hah a you Sir are 100% correct.
I've been running 2-450 holley's on my street tunnel ram for a number of years now w/o problems ... if you're eager to get rid of your holley's cheap I'd love to have 'em dave
One other thing to consider is that with 2 carbs you have half the airflow signal to each carb as you would to a single carb. Also your idle screw on each carb is turned out much less than a single carb. I have these on my Roadster. You must adjust the squirter cam so that any movement, no matter how small, will produce some sort of squirt out of the pump. I played with many cams and finally used the second hole so the ramp was very quick and made a large squirt very early. Not good for mileage tho
Do any of you guys know anything about restricting down a couple of 1406 Edelbrock carbs for a 2x4 tunnelram? There is a guy who makes air restrictors for the 600s to make them either 500cfm or 400cfm. I've never done it before but I see the principle behind it. I have a fresh 350 sbc with a rough cam, hei, 2500stall, 700r4, 3.36 gears and 9:1 comp. I have 2 1406 carbs but it's overkill in my opinion and thought restrictors might be an option. Any thoughts?
better to start a new thread instead of digging up this old one that has little (if anything) to do with your question......but you will likely be fine with the 600's - hard to over carb with AFB's......
I would recheck the timing curve, your MSD distributor should have an assortment of springs. On a performance motor with a higher duration cam, use the lightest springs possible to get full centrifugal advance A.S.A.P. I do this before tuning the carbs, try to get the timing all in before the 2400 stall speed. There is a spring chart that comes with the MSD distributor. Note: The springs are too light if they don't return to base advance when engine is shut off and started Hot. Springs loose strength with heat, causing bucking during hot start up. (some times I use one light and one medium) Noticed that your vacuum advance is connected, there might be slightly less vacuum running tunnel ram 2 x 4s because of (2 open idle circuits v/s 1 idle circuit ) this might be enough to return the vacuum advance to baseline when you put it in gear causing the stall. Because of this some guys running a performance high duration cam don't use the vacuum advance. I locked out my distributor (no vacuum or centrical advance) using an MSD 6al starter saver #8984. . Norb
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