Stovebolt.com Forums The Shop Area The HiPo Shop Dual Carb Issues

Tom - first, happy you now have it running to your satisfaction.

Instead of posting the base numbers, look at the center sections of the carburetors for identification numbers. The identification numbers will be STAMPED, not raised, and may be in two different areas.

The older YF carburetors had the identification number stamped on the edge of the flange of the center casting (bowl) where the bowl meets the lower casting (throttle body).

After a couple of years, Carter changed the identification stamp location to a vertical flat section on the bowl on the end of the casting opposite the fuel tank.

Carter numbers on the YF units will be either 3 or 4 digits followed by the letter "S", POSSIBLY followed by a second letter.

Examples:

788s
788sa
966s
2100s

There were TWO different throttle bodies cast with the 788. The later one superseded the earlier (but Carter wasn't planning on multiple carbs using these). I probably have the drawings for each, but they are on microfilm, and no offense, I don't wish to spend the time looking. Microfilm is a great archive, but a lousy useable format!

Two questions that I would ask, the answers MAY (or may not) improve the current state of tune.

(1) Have you synchronized the two carburetors (absolutely required for best results)?
(2) When you rebuilt the two carbs, were the internal vacuum springs replaced (NEW) with identical springs?

One reason I preach W-1's in a multi-carb environment is the fact that the W-1 has a mechanical power system. The YF has a vacuum power system. Different springs, fatigued springs, or the lack of synchronization can cause the YF's to meter at different calibrations, even if all else is the same. Also true of the Rochester B's.

I understand your concern for reliability. Some company (and I don't remember which one) has the motto "do it once, do it right".

Get your carbs set up correctly, and then FORGET ABOUT THEM!

The Carters on my truck (a non-Chevy V-8) performed flawlessly and were not touched for 18 years! Only after the truck sat in a shop installing factory A/C and upholstery keeping the truck inoperative for 18 months did the carbs require attention.

Again, congratulations on getting the driveability to your satisfaction.

Jon

Kevin

I thought of the potential for a vacuum leak when I was running through the problem last week. I checked the throttle shaft during that investigation. Actually, the throttle shaft on the base section that I removed was slightly tighter than the replacement. This is why I believe there was some defect or damage internally, within the original carb base section (letter C). Either that or, the carb base that is lettered with a C, is not intended for the 235 with manual trans.

I have a good carb vacuum balancer, and the throats were perfectly balanced when this problem began. I checked them again during my troubleshooting and they were still balanced. My suspicion is that some passageway was either blocked or, was open when not needed for this application. As I do not know what the differences are between the base that is lettered with an A, versus the base that is lettered with a C, I can't be sure that they are interchangeable, or of the same design.

I plan to do some research on this issue today, if time allows. I'll report back on what I find.

Tom

https://public.fotki.com/Chevelle350/stovebolt-reading/chevrolet/soup-that-chev-hot.html

Click the image to go on to the next page.


I've collected a bunch of cool old Stovebolt and GMC inline related stuff, shared here: https://public.fotki.com/Chevelle350/stovebolt-reading/

Jon

Appreciate your help and advice with this problem. I'll check the stamped numbers on the carb bodies for a match. I'll also double check the balance and linkage, to make sure there are no issues. I did not replace springs when I went through these carbs. I'll look into that issue as well.

I agree with your opinion concerning W1 vs. YF. I'd make this change if the W1s were more readily available. I probably should remove both carbs and double check the jetting as well. If they are jetted differently, that would also be an area for concern.

I'll post again when I've had time to complete these inspections. Have a great day.

Tom

Chevy could have saved themselves a lot of time and effort if they had just made a better copy of the inline six truck engine Austin-Healey used for a couple of decades in their sporty cars. They even managed to design two and three carburetor systems that worked, and used a 4 speed transmission with overdrive on 3rd. and 4th. gear instead of dropping an ugly fiberglass body on a 53 Bel-Air sedan frame and suspension and calling it a "sports car"!
Jerry

Tom - I don't understand why you are having a problem finding these?????

The primary reason I started looking at the 483s/574s as aftermarket units 50 years ago is the fact they were, and still are, as common as dirt!!! (or course, dirt is more expensive than it used to be ).

At any given time, there are several cores on Ebay, I probably have 50 cores myself, as in a different lifetime, I had time to rebuild them.

As well as the carbs being common, so are parts; ever single component of the 483s/574s (with the exception of the choke cable bracket) is readily available. The brackets can be found with some looking. I cannot think of a SINGLE one-barrel carburetor ever made that has such a ready supply of parts!

Only after I starting doing lots of these, did their other attributes for multiple set-ups (leather accelerator pump, mechanical power system, and tuneability) become apparant. And of course, I have tried to use Carters for the last 60 plus years due to their metering rod technology.

Jon

FWIW ... several observations from a non-expert.

1. Ghost-rider -- I do not know everyone personally who uses this site, but I *do* know Jerry personally and consider him one of my very closest friends. One of the things about Jerry I admire most (aside from his sheer knowledge) is that I *never* have to wonder what he thinks about something. He will give it to you straight (whether you ask him or not ... ) He personally supervised the rebuilding of my 261 (did a lot of the work himself in front of us). Most of my ensuing comments are based on my 4 years' experience living with that engine in my '49 1-ton. Jon (CarbKing) I have gotten to know over the many years of his participation in growing this site. I consider him *the* foremost authority on carburetors. The info and advice they offer freely is absolutely gold-plated. You will not get better advice. Anywhere. From *anyone.*

2. I do not understand any of the negativity regarding the Rochester carb. Admittedly, my Rochester experience and knowledge is based on two carbs... My carb has been performing flawlessly on my 261 (pushing a stock SM-420 and an HO-72 rear axle with a 4.10 ratio). My truck keeps up in traffic light traffic and will cruise the Interstate all day long at 65 MPH. Since Jerry rebuilt it on my workbench and we reinstalled it on my engine 4 years ago. I have not touched it since. Admittedly, I have to squirt a little fuel into it to start the truck if the truck isn't run for a couple of weeks. But that's life with an old truck. Some people hate these carbs, others love them. I am neither a hater or a lover -- mine works, I don't think about it.

3. I once messed with dual Webers on one of my VWs (a Type 2). It was truly a miserable experience. I never got them right. I gave up and went back to a single Solex and lived Happily ever after.

4. Over the years, I have watched a lot of guys come and go trying to do things that they are advised not to do. They seem to be looking for validation rather than useable advice. The ones who go against the advice of people like Jerry and Jon (and George and Evan and a host of other experts who grace this site). The ones who plunge ahead against advice ... a *very* few of them might return at some point to admit that they should have listened to the advice. Most of them disappear and never return. They are probably afraid to tell us, after a lot of wasted time and money. You'd think that if they persevered and succeeded, they'd want to come back and tell us about it. I wish they would. They never do. Which leads me to conclude they failed, probably gave up on their project and may have even sold it at a loss just to get away from their dismal failure. An overstatement? Perhaps, but it's not been disproven yet

Bottom line: I like the "Less is more" approach. Sometimes, the best approach, as Jerry has said before (despite his well-known disdain for "engineers") is to not attempt to out think the original engineers. They got it pretty darn right out of the box. We mess with it at our own peril....

Food for thought ...

Thanks,
John

Ghost Rider You ask for any recommendation of a better carb choice in your first post. I have 2 set-ups of dual carbs with fenton split that start,run,work fine ,no choke,no fuel pump,no heat riser,never cold natured. I assume that here in the hipo shop it would be OK to mention this propane outfit to you. It's all I use in my AD trucks. They mentioned butting your head against the wall and how good it feels when you stop ! Shish buy one of those sniper outfits for 1500$ my .02 cents. Welp gonna go fire-up and truck ...not fight it all day!!

Jon I'm wearing my armor so it's safe to throw rocks at me. I get where Tom is coming from.

Tom:
"I agree with your opinion concerning W1 vs. YF. I'd make this change if the W1s were more readily available."
Jon:
"As well as the carbs being common, so are parts; ever single component of the 483s/574s (with the exception of the choke cable bracket) is readily available."

I was curious so I started looking specifically for 483s/574s to see what I could find as far as good used carburetors. Disappointing. None.
It looks like the rebuild/resell hounds are hoovering them up.
Added to the dilemma, I can only think of one rebuild service I trust and he is a Stovebolt member.

Search results (for examples only):

ebay USCARBURETORS, $399.99 w/ $17.50 Standard Shipping
https://www.ebay.com/itm/403626436106
The base has been machined.

ebay CARBS6V4O, $1,999.99 free ship
https://www.ebay.com/itm/183558809560
No pictures

Classic Parts rebuild service , $279.95 + $125 core + shipping
https://www.classicparts.com/1949-Carburetor-Rebuilt-Carter-W1-216/productinfo/81-017

Chevs of the 40s rebuild service, $340.50 ($150.00 included in the price) + shipping
https://www.chevsofthe40s.com/detail/10646/Chevrolet_Carburetor_Carter_W1.html

I did not try posting for W-1 483s/574s carburetors in the Swap Meet mainly because I'm not actually buying.