Inliners International Forums General Discussion Engines 2G Rocheser Orientation

I have a 66’ Chevy truck with a stock 250. Recently replaced the old leaky BV with a 2G, I used the 1BBl to 2BBL adapter for now until I upgrade to 4BBl intake. Had to turn the carb 90° to get it installed, no big deal this puts the bores inline with the engine. This is where I am lost, it run’s a heck of a lot better than the 1BBL, but when I make right turns it tries to stall like it isn’t getting any fuel. The problem is compounded when trying to accelerate and make the turn; it will flat out die in the middle of a turn. Any advice on what to do would be awesome, hey maybe its just a carborientationtrundirection phenomenon…

The Rochester 2-GC is an awesome carburetor; but running through a 2 barrel to 1 barrel adapter, you would be lucky to get it to run as well as the 1 barrel it replaced. We did extensive testing on these conversions many years ago, and found to come close to breaking even, the adapter needed to be at least six inches tall, and channeled. We never found any improvement by this type conversion.

To make the best of a very poor situation, make sure the float level is EXACT to specification for the specific carb you are using, by tag number.

If you plan to later install a 4 barrel, I would suggest doing very little to try to make a 2 to 1 work, and simply reinstall the 1 barrel until you are really to do the 4 barrel conversion.

Jon.

Thanks carbking, this is not a permanent setup just wanted to get the 1BBL out of the way. I am getting better mpg than before so I guess the old card was shot. I’ve got an extra stock intake manifold I thought about redoing to accept the 2G and access to all the machining tools to do the job, just didn’t know if it was worth the time and effort or to just get a 4BBL intake like an Offy or Clifford. I was looking at it again today and see the bowl is on the outside, driver’s side of engine, maybe this is the culprit.
How far in MO are you anyway, I’m about 15min south of state line in NWA area.
Thanks
Jason

Eldon, Lake of the Ozarks area.

Jon.

Kansas City,MO here.

Jason, since the carb orientation places the float bowl on the left,or drivers, side of the engine a turn to the right will force fuel away from the jets and cause a lean condition. Turning right and accelerating at the same time will compound the problem. As Carbking stated, make sure the float level is correct.

Thanks Ron, that is what I was thinking about the carb orentation. The float is set at spec, if I were to increase the fuel level in the bowl would that not create other issues like excessive fuel during normal operation. Anyway I apprecitate the feedback and wish you a Happy New Year...
Both you guys are about 3.5 hrs from me maybe sometime next spring we can get together.

Jason

Jet extensions?>

I think since this is a temporary setup and your mpg's are better than with the 1 barrel you might want to look into turning the carb so it mounts as on a V8.
Not sure why you need to turn the carb, linkage?

On a Holley the jet extensions would help, but on the Rochester don't the jets go in at an angle?

Pete,
Your correct, the jets point up at ~45 degrees and jet extensions would compound the problem. The answer would be to mount the carb like you suggested.

Ron

Thanks for the info guys, no one offered their opinion on if it would be worth the time to open up the top of a stock intake for this 2G, so I will and understand I’m no expert by any means. I could have it done within a day at the machine shop. It makes sense to me if I open the intake flange it will allow more air in consequently utilizing the 2G more effectively, but are the intake runner up for it.

Pete,
Which way does the orientaion need to be, bowl in front or bowl in back? Yes it was becuase of the linkage and the way the adapter mounted to the intake.
Thanks

Jason:
If I remember correctly there are carb heat passages that allow exhaust heat to warm the area under the carb mounting surface. Boring this out will break thru this area and ruin the intake manifold. Perhaps someone else here has done this and can add to the caution....

Jason - I think Jeff is correct about the intake, I don't think it is possible.

I personally believe your problem lies in the using a two-barrel on a one-barrel manifold, not in the orientation. We have seen these things mounted correctly, backwards, and to the side on various street applications (and some race applications) with no problems.

However, if you want to change the orientation, the bowl would have been to the front.

As far as linkage is concerned, it is very easy to change linkage motion 90 degrees:

(A) Visualize a capital letter "L" with equal length legs.
(B) Drill 3 holes in the "L"; one at the "heel" of the L, and one at the end of each leg.
(C) Fit the L over a stud using the hole at the heel.
(D) attach a linkage rod to the holes in each leg
(E) when the L rotates on the stud, the linkage motion is now changed by 90 degrees.

Personally believe this will be a waste of time, but it is fairly easy, and if you have the time, it will allow you to correctly orient the carburetor, and prove what happens one way or the other.

Jon.

Thanks for all the info folks, I deffinatly learned a few things. As long as nobody will fall apart , I will play with the extra intake and see what I come up with . I cant just turn the carb because the adapter is what changes the oreintaion. Im not gonna mess with it anymore till I get the correct intake. Thanks again guys.
Jason

DOH!!! My suggestion for jet extensions was made before I thought about the fact that2GC carbs don't have their jet passages drilled horizontally.

But here's some additional food for thought to maybe further muddy the waters:
I own a tub with an '85 mustang 5.0L GT V8 engine.
I built a tri-power intake for it with the end carbs dummies - it just runs off the center carb on a 2V intake. [At my age I need a functional tri-power on my street rod like I need another hole in my head]. With a 4.11 posi in this light car it launches hard enough to rip yer jaw off. Now here's the kicker - because the Ford distributor is in the front there wasn't enough room to mount three 2GCs so I mounted them BACKWARDS! with the fuel bowls facing the rear and it drives great. One would have thought that on hard launches the fuel slosh may have uncovered the jets but this has not been the case.I think the G forces on this setup on a hole shot are probably greater than side Gs on a truck turning so maybe other factors are at play - like fuel level adjustment or the manifolding itself, as carbking and others have stated.