VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Bogging 216

Okay 1947 Chev. Original Engine. Had the head shaved .010, hi-lift rockers, hydraulic valve adjusters, mcgurk pushrods, champ valve caps, ported/polished head, re curved ignition, and and Fenton style Headers. Engine runs alot stronger might even be up to 100hp Any ways, I haven't found a good 2x1 intake yet, so I am running the stock with a heat riser from the headers and a W-1. The problem lies here, about 1200 rpm the engine wants to stall unless I choke it. Did I increase the demand for gas that bad or is something not jiving here. I checked the accelerator pump. All of the passageways are clean. No vacuum leaks. I tried several different jets in the carb, but, I only had a few different ones, nothing really seemed to help. If it weren't for that dead spot I would be tempted to run it in the quarter mile, might get a 22sec 60mph run out of it
And if anybody thinks it is the undercarb problem, then help me find a nice 2x1 setup. Thank you.

How can you run hydralic lifters in a block that is not drilled for oiling to the lifters?Also hydralic lifters can be used only on a cam that has been ground for there use.
Did you try advancing the timing a little more?
Metering rod out of adjustment?see shop manual.
On a W-1 its necessary to change both the jet and the rod to correctly change the mixture.
Does the carb. have the spring type accelerator pump link that the 1947 used.They always gave trouble and were replaced with the straight, solid link the the years before 1947 and after used.Spring type has a loop or two....straight is U shaped.
The header heat system may not be getting enough heat under the carb....especially for colder weather.

The low speed jet has decreasing performance up to approx. 1200 rpm. That suggests the transisition between low speed and high speed jets is the problem. Without exhaust gas analysis or a dynomometer determining what needs to be done to correct the problem it will be a trial and error process.

When the displacement, valve timing, gas flow, compression, etc. are changed the gas/air mixture as well the amount of fuel required changes. As the flow through a carburetor increases past the designed amount the potential for turbulent flow also increases. That can dramatically increase the resistance and engine fuel starvation can result. It is critical to match the components for maximum performance.

The "hydraulic valve adjusters" I speak of are not the lifters, these are a vintage set of valve adjusting screws, they are loaded with a ball bearing and a spring, they screw into the rockers, ideally, they eliminate valve lash, and thereby valve chatter (the greasers around here always asked me if I had a typewriter under my hood...) The motor is super quiet with them. And my cold engine runs as if it were already warmed, (as far as noise is concerned and performance) As far as the needles and seats of the jets, does anybody sell "tuning kits" where you can mess around with different pairs? The accel. pump is cantalevered by a small rod, and the jet has an eye at the top, and is held in place with a particularly small wire-spring. I didn't change any seats when I changed rods.

One more thing, the header heat riser setup... This might sound kinda dumb, but, I didn't know if I was to drill out the "bungs" on the headers, So I didn't. I didn't know if it was a good idea to open up for full flow of exhaust through that plate. Let me know what you think. Thank you.

Sounds as if you are running without a heat riser.This will cause the engine to take more time to warm-up, resulting in more hesitation when accelerating.In summer weather this will be less noticable, perhaps for only the first 15 minutes of driving,In cold weather, say below 50 degress it will take much longer.Does it bog down after highway driving and its complete hot??
I am familar with the QT adjusters you have,I have several but not a complete set.
You stated above the head is milled .010"....did you mean .100"?The lesser amount would be too small to have any improvement in power.

It bogs whether it is completely warmed or cold. It doesn't do it if the choke is partially closed, which tells me it is running too lean. Unfortunately it loads up on gas if I have the choke pulled and I am at idle. It is only .010" I didn't want to worry about valves crashing into pistons, or other misalignments such as the side cover or. I did shim the rocker tree to compensate for the .010". Also like I said, the heat riser tubes aren't drilled out of the header plugs, so the actual temperature of the air making it up there isn't near as hot as exhaust in the down pipes.

Chevgene, my hat goes off to you...

I dug around through my junkpile, and found another w-1, with the rod link. The accel pump linkage that was on the car was the spring type, so I changed it out to the rod type. That took care of it all. It had me fooled, the spring type looked absolutely perfect, still in its original golden color. Wierd. The car growls now.Thanks.

Your welcome-When I began my life at the dealer in 1950 it was standard practice to replace the spring with a link on the 1947's....didn't think there were any around that still had the spring in them.
The spring/link story.
The reason for using the spring was to eleminate a problem that some times happened.Dirt would restrict the tiny opening in the pump jet.This would prevent the gas pedal from being depressed and if it was forced the long rod running from the lower linkage uo to the metering rods and plunger would bend.The spring allowed flex and not bens the long rod.There was a bulletin in about 1948 warning dealers to not remove the spring.They said it was there for a reason.Try to tell the customer with a bulky car that story.Some where in 1948 Chevrolet/Carter saw the light and began using the "straight link" in production again.1946 may have also had the spring and possibly most '48's,,,can't remember all applications.
The jet can be removed and cleaned or the outter plug above the jet can be removed and the jet blown out with compressed air.The shop manual will show the location of the plug and jet.

This has nothing to do with subject at hand but I must say what a treasure trove of knowledge chevgene has, hope to meet in person some day. Ross

You may be in for a big disappointment.

Oddly enough... Today I learned first hand why the springs were there on that accelerator pump linkage. I bent the rod from the throttle to the meter/pump. I put the car in the barn again, because I didn't want it to get snowed upon. Any who, since I replaced that "spring" with the "solid link" the accelerator pedal has been rather firm. So after I parked it, I popped the hood to make sure all was well. I revved it, from under the hood, all of a sudden, it locked in around 2700rpm. I had to shock myself by pulling the coil wire :cry: Anyways I checked the linkages starting with the foot feed. Everything was free until I got up to the carb. The accel. pump wouldnt go down. Anyways, took the carb apart, found the pump was full of junk, couldn't even see the drilled orifice hole up to the venturi. I found the little tubular screen, plugged solid. Lucky for me I have a parts carb, its NOS with a broken flange. My new question is...How do you load that leather accelerator pump into the brass sleeve without destroying it?

You load it vaey carefully.Can use a tiny screw driver and kind of tuck in the leather moving around the plunger.
To clean the pump jet remove the plug on the left side of the carb.Its sits at an angle towards the top of the cast iron body.Its between and slightly below the left bowl cover screw and the left front air horn screw.You will see the plug with the screw driver slot.After you remove the plug remove the jet which is a bit below it.Will need a narrow screw driver.Note that the tiny openig in the jet is like a funnel.Opening gets smaller as it goes down.This traps the dirt and it gets wedged in,The passages should also be blown out with comppressed air if possible.Time for a good fuel filter.Also clean the fuel pump screen and the area below the screen if you have the original type pump with a glass bowl.
Yes, the spring was used to prevent bending the long side rod when jet was obstructed.For a temperoary fix on the road the acc. pump link could be removed.With a clean gas tank it is not a common problem.

For loading the accelerator pump a special accelerator pump loading tool is used. It works slick!

:) :grin:

A trick I have found to work. Sit the plunger over the hole and twist the plunger as you apply light pressure.
Tony

first up gene is no differant in person his wife is the one you need to meet . i have had the w1 carb pump to stick and bend the linkage especially if they are not run for a while . now i take a few minutes to pull the air cleaner and the cover off and check before i stomp on the petal . saves a lot of time if you have to reset the linkage

I have had no luck finding a rebuild kit for the W-1. So, I am rebuilding a Rochester to take its place, the kits are readily available. All the linkages and hookups are the same. The fuel line is about an inch over, no big deal. My question is as follows. Is this a equal or better carburetor? Are there any particular quirks? Is it capable of greater cfm than the W-1? The design from my standpoint of the Rochester appears to be superior as far as simplicity is concerned. Tell me what you think.

W-1 kits are readily available but a little expensive.They are a good all around carburetor.I have never found any performance difference between the W-1 and a Rochester.
I would not waste muy time with an early low cover Rochester.They had many problems when new and the only one that I would recommend is the 1952 high cover style.These are the least common.There were several tweeks made in the low cover model in 1950 and 1951 but the 1952 was the best (for a 216).The one possible problem with all Rochesters is the warping of the bowl cover.The front of the cover tends to warp and the gasket will not seal at the front of the cover/bowl.
The low cover has a very thin edge around the outter edge of the cover.The high cover has about a 1/4" verticle surface around the edge-making the outter portion higher and cover stronger.They also have internal changes.
Also if a Rochester is used either a thick gasket with a cut out for the base vacuum port is necessary or the insulator block with the "built-in" cut outs must be used....See hole in surface of base that contacts insulator....it must be exposed to manifold vacuum.

As Chev Nut stated, repair kits for ALL Chevrolet W-1 carburetors are easy to get. The Filling Station has them and the kits range in price from $39.50 to $48.00.

:) :grin:

Thanks guys

Okay, its time for the latest chapter in my huge embarassing failure. I rebuilt the Rochester B. I think it was off of a '49. Went perfect. That carb was so clean you could have done surgery in it. Garaunteed. Put the car all together again. Made a thick gasket out of wood with proper vacuum slot. No vacuum leaks at all. Checked with ether. Car runs better than ever at half throttle/hiway speed, and revs quick and hard. Problem is, it wont idle at all. Just kills. Pull the choke out a bit, which in turn moves the throttle stop screw up a tad, it will run about 1500 rpm, anything lower, kills out. With the choke pulled, and engine spinning around 1500, I will open the choke blade manually, with the Air Cleaner off, and the motor dies. Sprayed carb cleaner down the mixture screw hole, and it affects the engine, so I know its not plugged. Whats going on here.

Fuel flow through idle circuit is not functional. Blocked? parts missing? Maybe it was not as clean as thought.

Did you take the cast iron throttle body off the bowl? The idle mixture screw (with the screwdriver slot and small spring) can be pulled and use the extension tube on the B-12 carb cleaner and spray into the hole you pulled the jet out of. it should come out inside a small hole in the throttle body just below the throttle flapper. Replace the idle jet screw and screw in until it bottoms up real easy, then lossen it a couple of rounds, see if that will,fix the problem, also be sure the line to the distributor vacuum advance is tight and not leaking.

Its funny you say that about the dist advance vac. When I put the carb on, I didn't tighten everything right away, I slowly work them all. Well I didn't fully tighten that one... I logged on here to report that I found the problem, and MrMack had already beat me to the punch. Good job.

Long story short, car sounds, and runs great.
Thanks. Tune in next time, when I find a 2x1 setup and can't set that up right.

...I learned this the same way you did......

Yup, vacuum leak is another source for poor idle. If only a slight leak then rough idle. If greater leak then not idle at all and the engine will only run when the volume of gas through the carburetor throat exceeds the leak enough so a combustible mixture is fed to the cylinders.