Me again with the 38 Master Sedan. I finally got the 38 started after a year or so passing and she ran better than ever until gas started leaking out of the Rochester. I decided to replace the Rochester with a Carter W1 which seems straight forward enough but no so. The vacuum line didnt fit so I modified the Rochester fitting to connect the vacuum line. I also removed the cable clamp from the Rochester to connect my throttle and choke cables. All seemed well, starting was a bit of a challenge but she finally started but running poorly. The vacuum fitting has a small orifice in the fitting which seemed to work well on the Rochester, but maybe not on the Carter -The W1 is from a 42 Chevy, but i hoped it would not make that much of a difference. -Any suggestions on how I can smoothen my idle because it is running pretty rough, especially compared to when the Rochester was on there. Thanks for the help Michael PS. So close but it seems like small things keep popping up. I attached some pics
It is going to take some organized troubleshooting to resolve this.
Is the problem only at idle?
One quick test is to disconnect the vacuum line to the distributor and just plug that hole. That should not make a difference because there should not be a vacuum signal at that port when the engine is at idle.
One other “Gene” trick is to swap the #3 and #4 spark plug wires. That should make the engine fire back through the carb idle passages. Those passages are very small and tend to easily plug.
Another trick is to rev the engine with your hand over the intake. Wear a glove or wrap a rag around your hand. As you rev the engine close off the intake. The should pull gasoline through the main passages and main jet to clear out any dirt.
I just went through a similar scenario with a W1 on a ‘49 3100. Just go to my profile and check my posts.
Thank you for th advice, I know little about carbs and less about Carters. The gent who rebuilt the carb is going to give me a call and coach me through troubleshooting too
I am watching this post with interest as I am also planning on changing back to a Carter W-1 from the Rochester on my 37 Chevy Master Sedan. I believe the Carter I have is from a 1937 based on the 838526 tag attached. VCCA member Dean Echols is currently rebuilding my crusty Carter as we speak. May I ask who rebuilt yours? I was hopeful that switching from Rochester to Carter carburetor might have been just a matter of bolting it on but that doesn't appear to be the case.
Hate to partially disagree with Rusty, all Carter W-1 up to and including '37 have split choke plates. '32-'36 have straight throttle arms. 1937 starts the dogleg throttle arms. '37 & '38 have the 90 deg. horizontal part with a hole in it for the throttle cable (retained by cable clamp) to fit through.
I didn't think I had a picture down the throat and the carbs is being rebuilt but looks like I do. In my mind's eye, I had thought there were two pieces with a spring in between but hadn't thought any more about it at the time.
Good to know when looking at carbs as they sort of all look alike.
I believe my W1 is from a 42 Chevy, I didnt think it would make a difference but maybe i'm wrong. I bought mine from a gent on ebay who is out of Northern Ca. The Rochester actually worked well until gas started leaking our of the throttle side
The W-1 has a very small connector passage in the idle circuit. Virtually all W-1's that have been sitting idle for years will require removing the passage access plug, and removing the clog in the cross passage. The passage can be tested while the carburetor is apart to determine if this step is necessary.
Also, removal of the idle jet REQUIRES either a new jet, or the end of the jet that seals in a tapered passage to be expanded.
Either of the above will cause a very poor to no idle.
Hopefully, the gentleman who rebuilt your carb was aware of these possible issues.
As far as the interchange, other than the throttle arm connection, the '42 carb will work fine on the '37.
Ok, my newly rebuilt W-1 arrived without the fitting for the vacuum line. I could not attach the vacuum line so i robbed the fitting from the Rochester, ground it down, threaded it and installed on Carter. The Rochester vacuum fitting has a very small orifice leading me to wonder if it is correct for the Carter as i have no sample. I cannot find a fitting to mate the vacuum line and W-1 carb. -Would someone please show me the correct connection from the distributor to the W-1? -Can someone provide me a source for the proper fittings for the vacuum line and Carter? Thank you as always
PS. Last image is a Carter with a fitting installed, but looks too large for mine, my vacuum fitting is 5/16"
My W-1 on my "40 has that same restricted fitting. Not sure but I think the restriction is to keep the distributor vacuum advance from increasing and decreasing too rapidly as the vacuum increases and decreases. If your ground down fitting works I wouldn't worry about it unless it looks boogered up.
I will let you know as soon as I can, have a small coolant leak from the temp probe housing. I have to drain some coolant before adding some Teflon tape to fitting. I just received my correct choke/throttle bracket too. It’s the little things that are tripping me up but failure is not an option
Ok, started her and ran her til warmed up, idling terribly with or without vacuum line connected and I did plug carb as suggested. I installed new fuel filter too. She runs worse when she is warmed up and I have to have the choke engaged or she will die
First, The vacuum line fitting you used from the Rochester... You ground it down to fit ?? (appears that way in the picture) That WILL NOT WORK, and if this is what you have done, YOU NOW HAVE A VACUUM LEAK at that point. Find the right fitting for the job and hope you haven't ruined the threads in the carburetor.
Second, Does turning the idle screw in and out make little or no difference in the way the engine idles? If so, Jon has given you the answer above. You will need to find someone who can remove the plugs from the idle passage(s) and clean the passages, and especially the economizer jet, properly. Nothing else will work.
I ground and tapped the thread. Where can I find the correct fitting, I tried Autozone, Napa, oreilly, ace, Home Depot and Lowe’s. What is the idle screw? The screw with the spring does nothing, i thought it was the fuel/air mixture screw. I am waiting for the seller to call, I sent him a copy of the carbking post asking if this might be the case.
I should have been more clear. Sorry about that. When I said idle screw, I was referring to the "idle mixture" screw.
Most old carburetor cores will still have the vacuum fitting in them. (the ones I have do) Possibly you could contact one of the members nearer to you than I who rebuild Carter carburetors and ask if they will sell you one?
Otherwise, it's been a while since I had mine off, but isn't this the fitting you are looking for:
