The Stovebolt Site Forums The Shop Area Engine Shop Rochester B - 7024009 Accelerator Pump Issue

Starting issues on my 63' 1/2. I took the top off the carb. Found the c-clip that holds the accelerator pump plunger assembly to the accelerator pump rod was off. I found it in the fuel bowl. I crimped it and put it back on and re-assembled. The throttle stuck again. This time I did not find the clip.
Can it somehow fall down the bore and into the manifold? Should I worry about this making it's way to a cylinder? Maybe get me an extendable magnet and run up around there and maybe get lucky?
I've took the carb off for total rebuild, further inspection power pumps froze up, generally nasty, number suggests it is for a 64' 292 - jet is a 73 so seems to validate.
All of this because I was getting gas to the carb and none into the the throttle body when depressing throttle. No filter either, explains sediment in bowl I guess. Must have been sitting a while.
It ran when I got it. Drove up in the driveway and parked it. Has not started since.
Cavebull

So complete tear down, all cleaned up and kit ordered from Mikes Carburetor Parts. Question now is with Power Piston Assembly. A used one on Mikes Carburetor Parts site shows a length of 2.625. Mine is "buggered" up on the end a bit and is coming in about 2.562. Is this difference of enough to worry about?
Also this power piston stem is hollow, maybe I can just replace it with a piece of brass rod to make up the length.
Where is the Carb King when I need him?
Cavebull

Cavebull - carbking offers very little advice when it comes to the Rochester B.

But there is no way an entire clip could find its way out of the bowl into the manifold unless it were dropped.

There are several different power piston assemblies, yours may be OK, it may not be.

Jon.

Why don't you ask Mikes carb parts? Seems like they are your preferred source and would be glad to help?

I have left Mike a couple of notes on his website, one pre and one post order. Hoping the order sweetens the pot a bit.
cavebull

LOL, Chief!

Cavebull, I'm not going to leave you in the dark on the bartamos dry humor (well...I thought it was funny); carbking also has a shop . It's all in good fun, but we hope you get a response & on the road- that's all that matters. I do not have that exact carb (I checked my two Rochesters) or I'd mail you the part. I'll never need it.

Brad

This post indirectly points out one of the major problems with online websites.

A part is listed that is a given size. A customer measures his part and determines the size is different.

Is the customer's part bad??

Who knows!

The ONLY way to know for certain is to pull the bill-of-material for the carburetor in question BY TAG OR OTHER IDENTIFICATION NUMBER, determine the original part number for the part in question, and then measure a new old stock part.

A little carburetor design information (this is above carburetion 101):

The power valve assemblies are TIMED to come in at a specific point (generally vacuum related). Different length power valve actuating values, and also different length activation plungers on power valves are used to have the power valve open when the engineers want it to open.

Example: all other things being equal (same vehicle, same engine) the power valve for an automatic transmissioned vehicle will normally be set to open SOONER than a valve for a manual transmissioned vehicle; as the load created by the losses in the fluid coupling are greater than the load of direct mesh gears. Thus more fuel is required earlier.

Thus, without being able to positively identify the carb (and most B's are missing the tag), it is impossible to answer Cavebull's original question.

If we were going to list individual carburetor parts on our site; rather than size, we would list the individual ORIGINAL part number so the customer could verify he/whe was getting the correct part (and maybe Mike's did list the number, I have not checked their website).

At this point in time, IN THE ABSENSE OF OTHER INFORMATION, I would suggest Cavebull try what he has, rather than ordering a part that may be incorrect for his application..

Jon.

One other comment on new parts in general:

The user needs to be as knowledgeable as possible to minimize getting something that is not what he/she thinks he/she is getting.

An example:

Rochester made some really wonderful carburetors called quadrajets. In 1967, these carburetors were identified by tag only. As many of the tags are missing, or the different colors have faded to aluminum color, those doing numbers-matching showcars want to replace the tags.

There were 18 different quadrajets for Pontiac in 1967. Each tag has a different number, and each tag is also a different color (the different colors aided in engine assembly). Additionally, beginning in 1966, California introduced smog emissions. So the California tags have a square hole in the center, and the Federal tags have a round hole in the center. If you check ebay, you will find many DIFFERENT numbered reproduction tags, ALL maroon in color with a square hole (the California 400 S/T GTO used a maroon tag with a square hole). The other 17 new reproduction tags are just plain wrong.

So the knowledgeable hobbyist is not going to buy, and others are going to learn when they show their car, and lose points.

Hard way to learn.

Jon.

I did contact Mike and the followup rendered the following - "I do not know which measurement you you should go with, but we do not have any of these anyhow". In fairness, it is a picture of "a" power valve, and noted a used part with no guarantees on the website.

This thread does show the positives of the internet and forums like these. When I saw the picture and length I began questioning. Now I know there are a bunch of different ones and are not available anymore. I have pictures and measurements, have a solid suggestion of how to proceed. I'll clean, polish, reinstall, see if the shortness makes a difference. It is on my list so if I run across one I'll pick it up.
Thanks,
Cavebull

I have solved all the problems in my Rochester B carbs by replacing them with a Carter YF. This has proven to be a foolproof solution that has always worked.

I would second the Carter YF solution as it solved my Rochester B problem.....

A recommendation that I received from Hotrod Lincoln:
Cavebull, good luck with that Rochester B!

I may have a solution to my power piston problem... I have built and replaced a power piston stem on the power piston using a drill press. It is cut to a slightly longer length but is much better than what I had before the rebuild. Fine adjustments and attention to the vacuum requirements i think this will work. I work at a university in a science dept. I placed both stems (old and new) on a balance and there is negligible difference in weight so should not compromise the spring rates on other side of the Power Piston Assembly (no pics of this weigh out). Will update on the final outcome. Pictures on the Flickr site.
Rochester B - rebuild

Cavebull

Very innovative solution!

I just want to know why a man in Texas, in the USA, is measuring in mm? Measuring a part on a carburetor that was built in the USA?

?
edit- but the second one is measured in English, so... maybe it was a progressive photo bomb(?).
Brad

CRAP, and I thought I had covered up the crime by deleting the pictures of the balance reading grams!
Cavebull

The carburetor does not mind which increments you use.
Good innovation & thanks for sharing.

Brad

A reasonably good effort even though you measured in mm sometimes. Here is what I think you did, with a few observations. I may not have your procedure correct therefore have been misled by your pictures. You measured the O.D. of existing tube. .0862203 INCHES! Then a picture shows you "measuring" I.D. by using a .052 drill bit. Then you purchased tubing with .09375 O.D. and .06575 I.D. Approximate. We don't know the tolerances of the new tube and we don't know how much wear on the drill bit. Sometimes using the shank is better. Then it seems like you may have inserted an unknown drill bit into the end of tubing so as not to crush during chuck up in drill. Hopefully it was a no. 52 size bit. Then you are seen sanding the end of the new tube to .0862203 O.D. I do not know if the entire old tube was .086. You do not show measuring the portion that was inside piston. (It does look like it has a step or maybe just a mark). This would involve taking .00376 off of the tube. Then it seems you shined it up with steel wool? I do not know why you worked on such a long unsupported piece of tube instead of shorter pieces if you wanted extras. Mechanically you are after a press/JB weld fit and a proper remainder O.D. for parts interface. Your wall thickness at install end is now only .010. Flow wise, you are after same I.D. as existing. You are off there by .01375 or 25% larger. This could cause some kind of problem. Carb King will know. I know a scientist will appreciate this study. It shows I care about you and your carb. USA! USA! USA!

It is my understanding there is no "flow" through the piston/stem assembly. The power piston itself operates on vacuum and the power stem is along for the ride - putting and relieving spring pressure on the power valve ball. If this the case, the internal diameter of the power stem are mute regarding flow.
Second, careful making the assumption that one who works in a university science department is a scientist, a janitor might think you were just being an [censored].
Cavebull

Sorry about scientist. Not meant to dis in any way. You seem plenty capable/knowledgeable whatever your title. I have rebuilt enough Quadrajets that I known that, in them, the power piston raises and lowers the primary metering rods. But I thought some carbs had flow thru that tube. I've rebuilt many carbs but don't have a great understanding about the finite operation of them for sure. I read all about it and forget most of it.

Actually, I am a marine biologist.
Cavebull

Cavebull,

Too bad the USA never fully conformed to the 1866 law to go metric. However, all US measurement standards have been "standardized" by metric standards (since 1893).

I was a Marine Biologist.

Good luck with your carburetor. You have probably noticed that even the jokers here (and the sarcastic posters) provide useful advice.

The U.S. aerospace/supplier industry decided in the 90's to be worldly and switch to metric. Upon realizing there were billions of engineering drawings, billions of MIL AN NAS specs/drawings, billions of tools, billions of measuring devices, millions to be trained, that tolerances and tolerance analysis had a "rounding" issue when converting, vendors would have to be revisited for compliant audits, and a billion other issues...the idea was summarily dropped. I believe Boeing, Airbus and others use the Imperial for most parts. The scientific community usually uses metric. The medical field uses metric. Doctors think you pronounce centimeter "sonometer", weird schools they go to. A sonometer measures plucking.

God Bless America! Every last square MILE of her.

Yeah! That's another thing. Think of all the land that would have to be re-surveyed......and what's a dozen eggs called? darn communists.

Thanks to the Arabs, we have long had a metric numbering/counting system.
A dozen eggs are 12 eggs in the Arabic numbering system.

This is not a political post.

Oh, no land would have to be re-surveyed - just simply converted.

Regarding the darn Commies (who are no longer around) - pre-Commie Russia was a long hold-out, but they went metric around the end of WWI (a little after their Revolution).

This BS probably belongs in the Greasy Spoon - if it does not belong here - delete it - sorry

I've always had fun in life. The first metric comment to the last was just plain ol fun. I say blast it. If this bothers anyone who wants to remain serious all day long. Blast it. This is no place for anything but serious truck talk 24/7. I totally apologize for the off topic, bad taste. Sometimes my personality gets in the way. No hard feelings I hope.
Just a correction Tim. There are still several Communist countries full of...well, Communists...and by commenting you are greasing the spoon.

bartamos,

In looking for foolish facts about metric system in the US, I was surprised to find out that metric system standards/measures have been the USA fundamental standards/measures for "standardizing" weight/mass (ounces, lbs, etc) and length (inch, feet, miles, etc) in the USA since 1893. Somebody sneaked the metric system in here, but it wasn't the Commies.

Yeah, I was WAY off on the lack of Commies in the world.

Most of us use the metric system every day and never realize it...our money system is metric based

This really should be in the Greasy Spoon...just say'n

Mike B

Just to mess with Mike B -- our DAUGHTER is a Marine Biologist. This topic should stay here. Even the diversion is okay. It was a good thread with a virtual beer at the end, sorta.

Peg

Oh and I remember when they tried to teach us metric in elementary school - everyone hated it and back in the 60's, if the kids didn't like it, well, it was the beginning of "let them have their way" ... seemed to be anyway.

It's actually a pretty easy system. All you have to remember is 39 and 25.4. For linear that is. A 40 is how you measure beer.
As Tim states, the Mendenhall Bill was passed in 1893. All the years since have seen many, many mandates and bills introduced and SI committees formed to only partial avail (dual labeling and some departments). There were conferences in the 60's, 70's, 80's, 90's and finally a petition with a whopping 25,000 signatures to mandate SI reached the Obama administration in 2013 and they issued this response: "that using the metric system was a choice to be made by individuals". The American people will never accept a metric only system and the world never stop using fossil fuels.(Unfortunately there are about 56 trillion gasoline and diesel motors and jet engines already in existence). Now that is off topic on an off topic!
Congrats to the Milliman lady biologist. OK John, now you have a built-in advisor for starting a catfish breeding business. Start digging a pond.

To further one of the digressions:

Peggy M (John?) - regarding your DAUGHTER

What kind of Marine Biology?
Where?
My first profession was Marine Biology (algae).
We had a pea soup algae bloom in our NC saltwater swimming pool before/after the 20 degree day last week.

Digression continued: our youngest (35 next week). I'm not sure of the type but she worked for Scripts in San Diego when she first graduated. Now she works with the Navy's mammal program in SD. She loves it - she's in the nursery working with the new Momma sea lions and dolphins.

She actually was able to get a head start in MB while we were stationed in Hawaii. She was able to take classes at Hawaii Pacific University while she was a junior in high school. She was also volunteering to exercise the horses at the polo field there. So, we are glad she went with a degree and subsequent job that pays money!

I well remember when the schools were pushing the metric system in the early 1960's; I loved it. It was the conversion back and forth to English system that was a bear.

Then in the late 1960's, Uncle joined me, and a two year vacation to Japan commenced. There we lived metric. There is a huge difference in thinking in metric rather than thinking in English and converting to metric.

Then when I returned, the car manufacturers started using metric. I spent thousands of dollars in tools in both metric and S.A.E. so I could work on everything.

The silver lining (if there is one) is for those of us that tune carburetors, and find there are many sizes of drill bits (for drilling jets) that don't come in any of the 3 S.A.E. drill sets (fraction, number, letter). Think fractional metric. Most of the inbetween small sizes can be acquired in fractional metric (of course, you still have to convert ) So I still get to utilize some of the metric stuff.

As Bart mentioned, the cost of conversion to metric is too great. Unfortunate, but true.

Peggy - great that your daughter has a vocation she really enjoys. She will never have to "work" a day of her life!

Jon.

The so called metric conversion is what drove me (ha) out of auto mechanics for a living. That and front wheel drive in compacts...
Already had a small fortune tied up into SAE tools and didn't have the motivation or dough to duplicate them in metric.

I don't know what that has to do with Marine Biology but I knew quite a few Marines back in the day

No. 1 reason to own/work on old trucks: No metrics.
2. Thick, all steel.
3. Simple Artful practical design.
4. I fit underneath.
5. Brings back old fun memories just to look at one.
6. The smell.
7. The feel.
8. Room for any size motor.
9. Saving an American heritage.
10. The Stovebolt forum support.