Carb. info. wanted.

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Apr 18, 2021 | 06:45 PM

ThePabst

Thread Starter

Instructor

Joined: May 2011

Posts: 197

Likes: 4

From: Rochester New York

Carb. info. wanted.

I have a Rochester Products 4 banger on my 78 L82 w/Mild cam, its had its share of Ethanol and is real hurt. Tryed a rebuild kit, it got better but its not where I feel she should be. I want to move to a 'Better set up'. Keep in mind that I now have access to non ethanol gas. My car is NOT a trailer queen and I drive it very hard all the time.

I have lags and stumbles in hard corners. Intake gaskets are excellent and I am running a very good MSD distributor that I have proven to be on the money,,, Ideas?

PS
FYI, I'm a Rochester NY Guy,,, Rochester Products will be toast come August of 2022. A sad end of an era.

Apr 19, 2021 | 06:54 AM

BKarol

Melting Slicks

Joined: Sep 2004

Posts: 3,227

Likes: 670

From: Northeast

I also have a 4spd 78 L82 w/Mild cam with an original Rochester #17058211. I am not the original owner so do not know what was done to the carb but last summer I decided it was time for a rebuild after experiencing some problems and sent it to Lars and couldn't be happier. It came back perfect. He provided numbers while on his test engine and has worked great ever since. If I run into problems now I can rule out a carb problem.

Just a few of the items he found ):
Ruptured choke pulloff - choke cold-start function inoperative, and carb has significant vacuum leak

Sticking secondary airvalve - improper windup setting
Incorrect idle mixture screws installed
Very low (lean) APT setting
Extreme low float level (extreme lean)
Float needle clip installed sideways, jamming float

If for some reason Lars was not doing rebuilds I was going to go with a Holley 4175 0-9895. Another forum member who has a rebuilt block, 78 L82 4spd, has been using this and has worked great. There might be better Holley out there but this is proven it would work for me. They are getting expensive $650.

Apr 19, 2021 | 07:40 AM

leadfoot4

Team Owner

Joined: May 2001

Posts: 87,375

Likes: 1,593

From: Western NY

Quote:

Originally Posted by ThePabst

Growing up, I had a couple of neighbors who worked at RP. One was just a "worker", however the other was a real "gearhead", as well as an employee, and he taught me a lot about carburetors. Unfortunately, I haven't worked on a carb since the mid 90s. I used to go by the RP facility, on occasion, and it truly was saddening, to see the number of employee cars dwindle in number, over the years. In recent times, there are more cars being stored by the Chevrolet dealer, in the RP parking lot, that there are employee cars.

With respect to your carb, when you last worked on it, did you happen to install the gaskets that are "ethanol resistant"? I know that there was a site on the 'net, that listed them, at least the last time I looked, which was a couple of years ago.

Apr 19, 2021 | 01:22 PM

Jebbysan

Dr. Detroit

Joined: Mar 2012

Posts: 10,097

Likes: 4,027

From: New Braunfels Texas

Check your float level......

Don't freak out about non-ethanol gas......it is not the problem.

Jebby

Apr 19, 2021 | 04:01 PM

lars

Tech Contributor

Joined: Aug 1999

Posts: 14,380

Likes: 6,391

From: At my Bar drinking and wrenching in Lafayette Colorado

Quote:

Originally Posted by ThePabst

If the carb is the original carb, it is the 800 cfm high performance carb, and you won't find a better setup for your mild L82. Unless it is corrosion-eroded and badly pitted inside the float bowl and in the pump bore area, the carb can be rebuilt and set up to run very well (assuming it has not been hacked and destroyed by a commercial rebuilder).

Lars

Last edited by lars; Apr 19, 2021 at 04:01 PM.

Apr 20, 2021 | 10:53 AM

ThePabst

Thread Starter

Instructor

Joined: May 2011

Posts: 197

Likes: 4

From: Rochester New York

I did install Ethanol resistant gaskets.I'd like something that I can tune easier and tolerates cornering, I get rich stumble on cornering and can smell gas, also, in colder weather I get stumble on occasion in transition to secondaries. Jebby, the first thing I checked was float height, seems to be dead on.

I'm no expert, but I have done several rebuilds on other stuff with plenty of success. I'd 'plan' on installing O2 sensors (You all know how that goes) and would like something I can tune easier than the stock unit. Even if your a pimp for the RPC, you have to admit that they don't tune easily.

PS
I installed a 'life altering' tremec 5 speed kit (Find the triligy on YouTube here: