Although off-topic, this may be an interesting post/question for some of the "elder statesman" on the Forum (who, oddly enough, seem to have the most wisdom. Coincidence?? I think not!!!!) Many of you have seen my dad's "Coupe" before. We are going to drag race it this summer, and have been wrestling with the idea of getting a proper "tune" on the engine. We are not concerned about getting the optimum power (it's E.T. racing), but want to make sure we have a tune on it that runs good, and will not hurt the engine with a poor tune.

Many of you are familiar with dual quad set-ups. There is probably no question this 350 c.i. is over carbed with two 600 cfm Edelbrock carbs, but I've been told we should be able to get a decent tune on it. I was doing some research on the topic on the web, and came accross someone who had a tunnel ram dual quad setup and was only running one carb!!! This seemed weird to me, but if you think about it, you just tune one carb, but get the unbeatable :cool: looks of dual quads.

As usual, it takes me awhile to get to my actual question, but here it is. With this "cross ram" type dual quad setup like you see pictured below, can we run just one carb?? Someone told me a long time ago the left carb "crosses over" and feeds the right four cylinders, and the right carb vice versa. It's been 10 years since we've had the intake off the car for me to look up inside the intake to see exactly what is going on up in there. I have no idea if this is true, or if each carb actually feeds the entire engine. Seems pretty risky to me to have an intake designed like that where one carb runs one side of the engine. Is anyone familiar with this intake and how it works?? It's an old Edelbrock piece. I think the number on it is "X something". Here's a picture of it.

The body is currently off the frame. I "boxed" in the frame rails last weekend to gain some strength in the frame. A 60 year old Model A frame wasn't designed to hold 350 horsepower!!!

Any advice would be really appreciated. It would make my job of getting a good tune on the car for the strip much, much, easier if I can run just one carb. We have the engine out, and I could post a close-up picture of the intake/carb setup if it helps. Thanks, Brian




[Modified by Brian Matheis, 8:46 AM 1/23/2003]

 

Neat hot rod!!! I don't have any experience with this setup, but I suspect the information you heard was correct, and that each carb supplies one cylinder head. You should be able to simply pull a carb and use a small mirror and a flashlight to look into the intake to verify that.

If so, and I suspect it is, you will probably need to tune the carbs exactly the same. If you are having difficulty tuning, I'd suggest you rebuild both carbs, ensuring that the same size jets, same adjustments on the butterflies, etc are used. Start off with the idle screws backed out the same amount (say, 1 turn), and after installing them and warming up the engine, make all adjustments equally to both carbs, ie, each time you tweak an adjustment on one carb, make the exact same adjustment to the other before deciding whether to make another (pair of) adjustment(s).

 

If I recall correctly, that manifold (which is still available) has an open common plenum, just like the Chevy 302 Z/28 cross-ram, so the individual carbs are not "dedicated" to just the opposite bank. It's WAY over-carbureted in terms of tuning it, and the huge ports/common plenum result in very low air velocity under "street" driving conditions, which gives poor booster signals. These are not easy to tune - maybe Clem has some wisdom on the subject; they ran like gangbusters on the '69 Trans-Am Z/28's, but only at WOT from 4500-8500 rpm (which is all they were designed for).
:cheers:

 

I can't help you with the carb question, but what I think the key to bracket racing is "consistancy". I think it's fun to get out an bracket race too. I really enjoyed my day last year at the corvette drags. For me it's hard to be more consistant than the guys who make it their hobby. My car with a 4 speed and street tires is hard to stay with in a tenth, any slip and your time is gone. Sure you can soft dial a bit and might get a few rounds but it's hard to beat a guy who can run his number. :yesnod: I've even considered borrowing my dads hard top and buying some drag radials and playing with the car more but who know's besides I'm cheep and drag radials cost money. :lol: Maybe I'll race the wifes car a few weekends :eek: eek heaven forbid I brake something on it. Note to self bad idea. Anyway I think her car has more of a traction problem than mine. Have fun and keep us bench racers informed on how you do.


[Modified by INMYBLOOD, 1:08 PM 1/23/2003]

 

....ooh, man that is 'way over carbed for the street....i would think that you would do better by jetting down as far as you can go on both carbs but that is not a street manifold...i'd also run nothing lower (numerically) than a 4.11


[Modified by Kid_Again, 3:47 PM 1/23/2003]

 

Thanks for the compliments on the car guys :D :D My dad has owned it for 20 yrs or so, and it maybe got driven 50 miles a year on a good year. Until his son (me) talked him into bracket racing it :D

Wayne, The carbs are brand new Edelbrock. For tuning purposes we would have rather gone with Holleys, but we would have had to "engineer" a whole new linkage setup.

John, I suspect you are right about each carb feeding the entire engine. It'll be pretty easy to figure out once we plop the engine back in. I'll just unhook the linkage from one of the carbs for a minute and see if the thing acts like it
s running on 4 cylinders!!

The key to bracket racing is consistency on your time, and cutting a good light. It's not like we're going racing every single weekend and trying to vie for the points championship at the track or anything, but I do want to get a good tune. That's why the "only running on one carb" idea sounded pretty good to me. Seems like it could be more cosistent that way too.

David, I remember that article now that you mention it. I subscribe to Hot Rod, and I'm pretty sure it was in there. You jogged my memory on it. In fact, I think I remember telling Dad about it. When I get home I'll dig through my stack of old magazines and see if I can find it.

Thanks again guys, Brian

 

I've got an update on the manifold for anyone interested. I emailed Edelbrock, and they sent me a message back saying the intake indeed does feed one side of the engine per carb. He also said that intake is no longer produced, and was produced in '60s and '70s.

I guess I trust this guy?? I may still try to run the engine on one carb when we get to that point. Thanks again, Brian

 

Maybe I was thinking of the Offenhauser version of the cross-ram when I mentioned the open/common plenum - Edelbrock and Offy both made versions of this (with the bolt-on top plate for both 1x4 and 2x4 carbs), and I know that one of them had the same open plenum design as the Chevy cross-ram. Does yours have the removable top plate, or is the whole thing a single casting?
:cheers:

 

The whole thing is just a single casting with no "bolt-on" top plate. I'm still not sure I believe the guy at Edelbrock. In his message to me, he just didn't confince me he knew for sure.