News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

Advice on Swap of Rocherster for Carter in 57

Started by cwbbear, August 05, 2016, 12:45:17 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

cwbbear

So, I am about done struggling with the Rochester 4G on my 57 deVille.  Before I embark on getting a Carter AFB and the metal shim and all,  I am curious about any other considerations for the swap.  I am curious if anyone can share the work to adapt the distributor advance (all metal tube), the TV and Accelerator linkage, fuel inlet and other vac lines.  How much "plug and play" vs re-engineering? 

Any lessons learned that I could benefit from?


so IF you are curious,  WHY? well sit right down and let me tell you a little story

After a second rebuild, both hired out, I was getting close. Smooth enough idle and ran fine but the hesitation on acceleration I could not sort out. The flat spot was a take off and putting your foot in it at speed.  If I feathered the accelerator I would make the take off smooth enough but at take off the hesitation/Accelerate would make your head kick back a little.

So I was close yesterday by various fine tuning this and that, both fuel and spark.  I took her out for a test run doing fine, flat spot still but all other aspect of running are doing great.... and all of a sudden she kills my enthusiasm by starting to stumble.  Not like dropping a cylinder every time but there was this clear stumble at any speed.  As I quickly bring my test to an end and I get home the idle struggles more and more.  So, I decided I needed a break (it is 105 here) and hit the pool to cool my head. 

Today I go out and there and she starts right up then I see gas bubbling up the accelerator pump and at fast idle she only runs a few minutes and dies (I assume drowning).   May 57 was manufactured in April 57, so just a month or two before GM started using both carbs.
Reading the forum I read phrased like  "Best thing I ever did" when mention of putting in a carter.  I am looking for a best thing experience. 



savemy67

Hello Chris,

I am curious as to your experience with hiring out your carb rebuild twice.  Was it to the same shop?  Have you contacted them as to your problem?  Do you know if the shop(s) were experienced enough to be able to bush throttle shafts (in general)?  How did the shop(s) test the rebuild?

If your car was manufactured with the Rochester, you might try looking for the AFB parts that would be needed to make your swap a plug and play.  I have not done this, but it might be worth the effort instead of trying to re-invent the wheel when adapting the Carter to the made-for-Rochester engine.  If you are going to scrap the Rochester, I'll buy it for shipping costs.

Respectfully submitted,
Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

Bobby B

Quote from: savemy67 on August 05, 2016, 10:04:06 PM
Hello Chris,

I am curious as to your experience with hiring out your carb rebuild twice.  Was it to the same shop?  Have you contacted them as to your problem?  Do you know if the shop(s) were experienced enough to be able to bush throttle shafts (in general)?  How did the shop(s) test the rebuild?
Christopher Winter

Chris,
Hi. Nothing wrong with Carter Carbs, but I'm a big fan of a Rochester Carb. Nothing like a finely tuned Quadrajet if you want performance/economy. I have a guy who is a Master of the Rochester Carburetor. I've done Pontiac stroker motors and they run best when using Quadrajet's that are rebuilt and set-up properly. If it's the same guy, take it back until he gets it right. Rochester's seem to have a little bit of a bad reputation because they are a little tricky to set them up properly. I have them done like new for a little bit more than you can purchase a kit for. Bolt on and go, no issues ever. Maybe you have the wrong person working on it, or something else is going on with your car.
                         Bobby
                                                                                                                                                                             Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

Glen

Does your car have an electric fuel pump?  What is the fuel pressure at the Carb?     
Glen Houlton CLC #727 
CLCMRC benefactor #104

Jon S

Quote from: Bobby B on August 05, 2016, 11:19:02 PM
Chris,
Hi. Nothing wrong with Carter Carbs, but I'm a big fan of a Rochester Carb. Nothing like a finely tuned Quadrajet if you want performance/economy. I have a guy who is a Master of the Rochester Carburetor. I've done Pontiac stroker motors and they run best when using Quadrajet's that are rebuilt and set-up properly. If it's the same guy, take it back until he gets it right. Rochester's seem to have a little bit of a bad reputation because they are a little tricky to set them up properly. I have them done like new for a little bit more than you can purchase a kit for. Bolt on and go, no issues ever. Maybe you have the wrong person working on it, or something else is going on with your car.
                         Bobby
                                                                                                                                                                             Bobby

Bobby -

The 4GC is no Quadrajet!  . . . the Carter is far superior to the 4GC.
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

Bobby B

Jon,
   I never stated that the 4GC is even close to a Quadrajet. I was making a statement that there's nothing wrong with the Rochester, in general, if set up correctly. 4GC is nothing but two 2GC's put together. Selecting the proper Power Valve Spring, Increasing the Primary/Secondary Jets in small increments, and most important with the 4GC is the setting of the Auxiliary Throttle Valve. If the spring wrap is not set correctly the car will have a flat spot or "Bog" no matter what you do. My point was to have someone who really knows these carbs to have a go at it before giving up on it. Not much choice in a square bore pattern carb for that car.
                                                                                                                         Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

wbdeford

Except for some wear that makes it impossible to get my idle speed down to spec, my 58 4GC works perfectly.  The car runs very smoothly and quietly and can do 0-60 as originally advertised--at least as of 2 years ago, the last time I tried it.  Not saying don't switch to Carter--just that it being a Rochester is not the problem.
1958 Sedan de Ville

Past:
1956 Fleetwood 75 Sedan
1957 Fleetwood 60 Special
1958 Miller-Meteor Futura Landau Duplex
1960 Coupe de Ville
1966 De Ville Convertible
1970 De Ville Convertible
1971 Eldorado Convertible
1979 Sedan de Ville
1980 Seville

cwbbear

I knew I could rely on this group for answers.  Just what is coming to light is my newly developing lack of tenacity.  I had a 1947 Chevy in high school and I worked for a year adjusting the vacuum shift, and that was without the internet and forums for help.  Now I let a little challenge with a carb bet me?

I am back to making that Rochester work, and maybe some anti-wimp counseling. 

There are many good questions asked in this thread because there might be jewels in those,
I have a recently replaced Stock fuel pump - volume of gas seems correct when pumping into a jar. I been considering an electronic for priming because the fuel bowl will drain down to save the starter from cranking fuel to refill system but until then I just do some manual priming after a long time without running.  Living in the desert these unsealed systems have a bit of evaporation in a garage over time.  (hummm new fuels evaporating and mucking up works, in a short time.  maybe)

I will be talking with the last rebuilder about some deal to "try again" with some additional research and discussion on all the service bulletins.   I have used two different rebuilders,  one in Northern CA 10+ years ago (they did JUST OK and I lived with it) and then one here in Southern CA 2 years ago. 


Bobby B

1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

D.Yaros

Quote from: cwbbear on August 06, 2016, 02:20:01 PM
I am back to making that Rochester work, and maybe some anti-wimp counseling. 

I will be talking with the last rebuilder about some deal to "try again" with some additional research and discussion on all the service bulletins.   I have used two different rebuilders,  one in Northern CA 10+ years ago (they did JUST OK and I lived with it) and then one here in Southern CA 2 years ago.

Why not just take the carb off and send it to Booby B's rebuilder?  Just a thought?
Dave Yaros
CLC #25195
55 Coupe de Ville
92 Allante
62 Olds  

You will find me on the web @:
http://GDYNets.atwebpages.com  -Dave's Den
http://graylady.atwebpages.com -'55 CDV site
http://www.freewebs.com/jeandaveyaros  -Saved 62 (Oldsmobile) Web Site
The home of Car Collector Chronicles.  A  monthly GDYNets newsletter focusing on classic car collecting.
http://www.scribd.com/D_Yaros/

fishnjim

These era carbs are not the best in design.   I suspect you have other issues with your motor as well.   I went through this (58) and ended up rebuilding the motor after 2 carbs.  Fuel system has to be attended to first.   The vacuum has to be right for these carbs to work properly and that usually isn't the case on a high mileage motor.   There's problems with the brake booster and wipers on the vacuum system that can also interfere.   Best to separate the intake manifold vacuum from the rest.   If the vacuum isn't stable, the idle will never be.

cwbbear

Quote from: D.Yaros on August 07, 2016, 02:44:49 PM
Why not just take the carb off and send it to Booby B's rebuilder?  Just a thought?

That is on the list after I chat with the one who did mine and see if their specs match the latest in the Serviceman bulletins (aka did they have a clue in the end) and likely after talking with his guy it will be shipped off.

Surprise I also found I am getting a vapor lock now.  It is true I usually do not drive the car in 105 degree weather. I now suspect the stuck float (causing gas to bubble out of the accelerator pump and vent) was actually boiling gas.  more research needed,  used a laser temp test the fuel bowl was 168 degrees F - 

Next is verify the fuel pump can make vacuum at temp and then either decide to only drive the car more than a block in summer or electric fuel pump with temp switch to prime & push vapor lock out so it is drivable. 

cwbbear

Quote from: fishnjim on August 08, 2016, 10:19:06 AM
These era carbs are not the best in design.   I suspect you have other issues with your motor as well.   I went through this (58) and ended up rebuilding the motor after 2 carbs.  Fuel system has to be attended to first.   The vacuum has to be right for these carbs to work properly and that usually isn't the case on a high mileage motor.   There's problems with the brake booster and wipers on the vacuum system that can also interfere.   Best to separate the intake manifold vacuum from the rest.   If the vacuum isn't stable, the idle will never be.

Thank you!  I feel that my testing the oil pump vacuum and wiper system that it works but removing it from the system for this effort - but I forgot in all in the frustration.  Appreciate the level thinking to remove them from the equation