Stovebolt.com Forums The Shop Area The Engine Shop Straightening the Rochester B and BC castings

Using two gaskets will simply cause the castings to warp much worse.

Jon.

Thanks Jon and Carbking. I’ll not use 2 gaskets to solve my problem. I’ll build Jon’s jig and do it right.

Question...... why do these Rochester carbs warp anyhow??

The potmetal used is part of the problem. It behaves differently under heat than other metals. The largest problem I think is over-tightening of the screws and the fact the Rochester B and BC models only have 4 screws in the first place. I've been told the Rochester boys knew this was a problem right away. Why they continued with the design from 1950 until 1967 is a real puzzle.

Do you want to borrow the jig I made? Please let me know.

They only expected vehicles to last 5 years or 50,000 miles. Planned obsolescence. Boy, are we messing with them or what!

Some say they would not have made it 5 years before that carburetor started dribbling but yes...they never counted on this, did they? You may recall in October I mentioned I was up in Arkansas and saw many inline 6 engines still powering irrigation pumps. I'm pretty certain one of them was a 235. Could have been a 261 I suppose, but most of the pump engines were 235s because they were less expensive. You can still buy a brand new GM 250 six long block for $2300 (non-hardened valve seats) or $2500 (hardened valve seats). Comes with HEI and water pump. Manifold is for a 1bbl. Great for cotton field, corn, soybean, etc irrigation.

Jon, thanks for offering to let me borrow your jig. Wish I would have thought to try and meet up with you last week while was in Dallas visiting my mother for Christmas. Could’ve brought the old carb with me and we could have straightened it right then and there. I’ll let you know next time I’m headed your way and I’ll borrow your jig. Thanks again.

Thank you Jon, I was unaware they could be straightened. I have tossed many in the past. Next one I get one I will give it a try. Ed

Reviving this thread with a probably stupid question:

On a Rochester carburetor that has been rebuilt at least once (by me), and is now leaking gas anew, what are the most likely sources of the leak(s)?

I'm asking because a neighbor is working on my truck (long story) and says the carb is leaking to the point of smoking with the engine running. We're out of town and I'm trying to decide whether to just buy a new Rochester or Carter carb vs rebuild again or try another maneuver such as the one in this thread. The goal is to drive the truck from our current house to our new house. I hate to throw money/parts at a problem and hate to throw rebuildable parts away.

Any links to other relevant threads are also appreciated, thanks.

I suspect the metal to be a zinc-aluminum alloy ("Zamak" is an example).
Yes, it's heavy, but the zinc adds a useful characteristic: it holds fine casting details and threads better than aluminum.
400° F is safe because it melts above 700°; this saves energy in manufacture ($$) compared to aluminum which melts above 1200° F.
It can be soldered.

I sent you a message to your web mail address. We live in the same state. I may have something I can lend you.