Ben Bruce aka First Born

Modified 263 for my 1950 41D

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7 hours ago, First Born said:

 

 But it is not a triangle.  The manifold is two "U"s joined by another "U". I do not know how to draw in a post.  Take a sheet of paper . Near the left side, draw a U about 3" wide at the points. Move right 4" and draw another same size. Then connect the two with another attached at the center of each U. Now in the center of this one drew in a square about 1 1/2". This is where the throttle body sets.

 I just went to the garage and measured this thing. All runners are 7".  The throttle body base [box] is 6"x5"x3". I can't see where the runners are different. ALL measure the same. NOT trying to be argumentative, just do not see this as the reason. May well be...

  Keep the ideas coming.

 

  Did not get anything dont last two days, due to working on the Park Ave.

 

  Thanks

  Ben

 

No worries, it's kind of hard to explain so I made a graphic real quick. It's really crude but illustrates what I mean by a triangle. Figuratively, from the carburetor, the outside runners will take the vapors longer to reach the block than the inside runners, even though they are all the same size, same length. The sharp 90* angle in which the vapors must make at the second U is what dictates your volumetric efficiency and is probably what causes your issues. If you look at the stock manifold, the inside runners and outside runners are separate and run off of one of the two barrels on the stock 2bbl carb.

 

Lets say that the engine is pumping vapor at 230. CFM and you have 1" pipe. Your flow rate (v) is equal to volumetric flow rate (q) divided by the surface area (A), which is v = (3.83ft^3/s)/((.0417ft)^2*pi) = 701ft/s. Now if the runner is 7", or .583ft long, then in a perfect system it will take (.583ft)/(701ft/s) = .00083s for the vapors to reach the block from the carb (or throttle body) assuming laminar flow. By design, and by human error, this is neither a perfect system nor laminar flow since the vapors that exit the first U from the throttle body hit a flat spot at the crest of the second U. So lets say that the efficiency of the inner runner is 57% and the efficiency of the outer runner is 43% (an exaggerated example of course). To simplify, if 100lbs leaves the throttle body, then 57lbs goes to the center and 43lbs goes to the outside ports. Due to conservation of momentum, m1v1=m2v2 (where m1 = 57lbs/(g=32.2ft/s^2) = 1.77slug and m2 = 1.34slug), and assuming that we'll keep the center runners constant (v1 = 701ft/s), then v2 = (m1v1)/m2 = (1.77*701)/(1.34) = 926ft/s. Basically, this says that in order to deliver equal amounts, the outside runners must flow faster than the inside runners. So because the engine pumps constantly at 230.CFM or 3.83CFS (assuming compression is equal on all cylinders), and the outer runners in this example must flow 926ft/s, then the diameter of the tube is derived from first finding the surface area, A=q/v=(3.83)/(926)=.00414ft^2. The radius of the pipe would thus be r = sqrt(.00414/pi) = .0115 ft, or .138 inch. Obviously would not be this severe, especially without proper flow rates, volumetric efficiency and the like, but I hope this helps to explain what I'm conveying. Back then, I really think they eye balled this stuff with their castings, or got "close enough", because it wasn't until the early to mid 60s did they get inline intake manifolds right.

intake runner.jpg

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Yea like Wow to the third power ! I guess that's an example of "applied educational dollars" 

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On 11/22/2016 at 9:47 PM, First Born said:

   Something I noticed has me scratching my head.  The four center cylinders look to have beer running rich. Very sooty. First two and last two look good. Observed this in exhaust as well as plugs.  I presume this is due to fuel distribution.   The home made intake manifold I have is essentially two  "U" pieces tied together with another "U"  which has the throttle body attached. I am not sure what is going on. Need to determine reason, though.

Depends on how the engine was run before analysis:  if after a long high speed run, probably all cylinders would be nearly the same; if after some cold starts with little warm up then any engine will show differences like this.

Beemon's analysis?  is this valid for all flow rates or WOT vs conservative cruising?

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5 hours ago, old-tank said:

Depends on how the engine was run before analysis:  if after a long high speed run, probably all cylinders would be nearly the same; if after some cold starts with little warm up then any engine will show differences like this.

Beemon's analysis?  is this valid for all flow rates or WOT vs conservative cruising?

 

These are just general numbers. For the CFM, I took the max HP RPM of the stock 263 engine off of a web address and put it into a mid 60's muscle car calculator for WOT. There will be different values for different engine loads (idle, part throttle and WOT), which requires in depth analysis. Furthermore, in order to even calculate efficiency, there would have to be an analysis of carbon build up on the cylinder walls to properly assume an approximate vapor distribution in the runners. One would have to dive further into the density of the vapor and vapor pressure within the intake. Since idle is usually a 14.7-15 A:F ratio, and WOT is approximately 12, or should be thereabouts, your mean vapor density would be constantly changing between those two points. Also to my knowledge, engineers didn't use CFM as a unit of measurement until the mid 60s, which means there isn't an equation readily available for use. In order to accurately predict CFM of the engine, one would have to take into consideration the bore, stroke, intake valve timing/overlap and firing order to properly model the air pump. This also assumes, as you said, that the engine is fully warmed up and operating at peak efficiency within idle-WOT conditions and definitely not a cold start.

 

All numbers above are simply just numbers and not reflective of the actual application. I was just trying to convey what I mean by how distance from the carb/throttle body and design of the runners influences intake. In the example above, the difference was 1" pipe and 1/4" pipe. In reality, it might be like 1" pipe and 7/8" pipe. You wouldn't necessarily need smaller pipe, but rather a cone effect used in gas turbines ( >< ), where gases entering are accelerated at the tip of the cones and leave with higher pressures. I think the biggest issue with the design of the runners as they stand right now is the U on U shape, the gases leave the first U and then hit the apex of the curvature of the second U, disrupting flow and forcing the vapors to make an immediate 90* turn either left or right. Because of the triangle analogy, majority of vapors will always go back towards the center, as you experienced with your last engine.

 

As you can see, this becomes a very complex problem to solve, something that 30 or so engineers solved together at the Buick division of GM. That's why I suggested ported injection, because then it doesn't matter what your intake looks like as long as the injectors are equal distance from the intake valves (approx. 1-4", as I've read from others who have done so), but then comes the added cost of equipment, new ECM, more wires, the addition of a fuel rail... doable, but not cost effective. I think, if you wanted to look at remaking the intake manifold, is copy the design of the OEM manifold where the inner and outer runners were separate and not conjoined. That way, you essentially make two independent tracks that do not rely on each other and would have equal flow instead of a divided flow.

 

How come you scrapped your stock manifold? If you don't mind me asking. Did the stock manifold lean out the outer cylinders and burn up the inner cylinders, too?

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Ben, the stock manifold was/is good.  Due to problems we all have with our exhaust manifolds, I elected to build a set of headers. After mounting them it was discovered the intake manifold would not clear same, so the intake was thrown together. May just go back to the stock set up, even though the end exhaust runners are mis aligned vertically by about 1/4 inch.

 

  Ben

 

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   Have not done a lot. I have transferred some items from the 248 onto the 263.

 

   I have inspected the "good" original manifold I have. I just don't believe I can make myself put it back on.  The warp on the end ports is too great.  Since the original intake has an equalizing "channel"  , I wonder if an equalizer would help on the homemade one. Any one on here that has made their own manifolds ?  How about the after market ones? I know they were few and far between, but perhaps some one with one can chime in. Beemon, comments accepted and appreciated.

 

  Ben

Edited by First Born (see edit history)
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Beemon - your math and physics are good, history less so ;)

 

I have CFM engine and carburetor charts from the late 1920's, and manifold volume/velocity figures from the pre-teens.

 

I hate to use the phrase "good enough"; but with low compression, low RPM engines, "good enough" was really good enough; even though the engineers knew more than they were using.

 

However, there were always those not content with "good enough". Buick was actually playing with compound carburetion as early as 1935, because of cylinder distribution.

 

Ben - using multiple carburetors, the equilization channel is useful due to pulsing. Remember that the carburetor/carburetors do NOT directly feed the cylinders; the carburetor/carburetors feed the plenum/plenums which feed the cylinders. With fuel injection, I do not know.

 

Jon.

Edited by carbking (see edit history)
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Jon, thank you much for jumping in here.  I agree and understand the carb feeding the plenum.  The throttle body fuel injection I am using does the same.The main difference is the plenum vacuum draws the gas through the "jets" on the carb below the throttle plates, whereas the injectors squirt the gas into the throat of the throttle body just above the throttle plates and the vacuum draws it into the plenum along with the air.  I guess I will use it again and monitor performance and results, hoping the end cylinders do not lean out. And they do not appear to be lean.

 

  Thanks

  Ben

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7 hours ago, carbking said:

Beemon - your math and physics are good, history less so ;)

 

I have CFM engine and carburetor charts from the late 1920's, and manifold volume/velocity figures from the pre-teens.

 

I bow to you, the almighty Carb King. Would be interesting to get some numbers, since none of the published shop manuals I've seen have them supplied. 

 

My engineering instructor began his career on a steam powered destroyer in the US Navy in the mid 60s if I recall correctly, and "good enough" was their favorite phrase until the captain ordered a full stop after a full speed ahead and they blew a pressure main in the boiler room. Different times for sure, one I am far from being an expert on. 

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Ben - actually, except at idle, engine vacuum causes venturii air velocity which creates a negative pressure in the fuel wells, and fuel is pushed into the throat of the carburetor by atmospheric pressure ABOVE the throttle plates. The idle discharge port(s) generally do reside below the throttle plates.

 

Beemon - both Stromberg and Zenith (probably others as well) published engine and carburetor CFM charts in their carburetor sales/service manuals at least by the late 1920's. Both offered aftermarket carburetors for sale, and choosing the correct venturi size is necessary for good carburetion. Both actually flowed different carburetors, and learned very early that while the venturi shape and size is the primary consideration in carburetor air flow, the air entry (the airhorn) and exit (throttle plate) diameter also play a role. Quite interesting to compare CFM ratings of the same venturii and different throttle plate sizes.

 

As to the cylinder/manifold velocity equations; Automobile Engineering, published by The American Technical Society, Dykes Encyclopedia, and a host of other automotive engineering textbooks from the early days reference these.

 

Automobile service manuals are published to allow mechanics to service the automobile, not redesign the automobile; thus probably not going to see these figures in this type of manual. The ATS manuals show up on Ebay, and generally are not overly expensive. They are an interesting read. The same is true with Dykes.

 

As a historical aside, the figure used by most taxing authorities for automobile licensing ("brake horsepower"???) is calculated by an equation devised by the RAC in 1910 in England, and was actually quite accurate for an engine of the RPM available at that time. I have seen other sources attribute this equation to an engineer with Cadillac in 1912. One must be careful when one claims the "first" for anything. Google Wiki and RAC horsepower for more information. Good engineering has been around a long time.

 

Jon.

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Jon, I thought I replied and said thank you. Must not have hit submit. So Thank you!

 

  I am going to install and use the manifold as it is and monitor the plugs. Also will heat it with coolant. Presently not heated. 

 

  Hoping to get with the program this week. Probably later rather than earlier. Next two days are supposed to be "sitting by the fire " days.

 

  Ben

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 Today I will probably not even go to the garage. Maybe. Supposed to be high of about 42. Not cold to you folks up north, but cold for these old southern bones.

 

   Piddled with the engine some yesterday.  Installed the distributor.  Gapped and installed a set of AC R46 plugs I had.  My son, the welder, is coming in a few days.He is bringing the modified crank pulley/damper. Hoping all is well with it. I THINK serpentine is the way to go. He will also help finish the AC comp mounts.

 

  Ben

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On 12/8/2016 at 8:00 AM, First Born said:

 Today I will probably not even go to the garage. Maybe. Supposed to be high of about 42. Not cold to you folks up north, but cold for these old southern bones.

 

   Piddled with the engine some yesterday.  Installed the distributor.  Gapped and installed a set of AC R46 plugs I had.  My son, the welder, is coming in a few days.He is bringing the modified crank pulley/damper. Hoping all is well with it. I THINK serpentine is the way to go. He will also help finish the AC comp mounts.

 

  Ben

I'm busy living vicariously thru U with your straight eight project and can relate about too cold temps!

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8 hours ago, 2carb40 said:
On 12/8/2016 at 8:00 AM, First Born said:

 

 

  Ben

I'm busy living vicariously thru U with your straight eight project and can relate about too cold temps!

 

 

  I'll bet you can.  Your temp probably makes ours seem positively balmy!

    I look forward to following your projects . 

 

  Ben

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Hey, guys and gals, does anyone have a picture with a "exploded" view of the parts in the flywheel housing on a '50 

special with 3 speed manual?  I have a "snap" ring, similar to the one in front of the front bearing on the transmission input shaft. I am not sure why. 

 

  Thanks

 Ben

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Well, the engine is IN and bolted down. Fought us all the way. Just did not want to line up with the transmission. We still don't know what we were doing wrong. It finally slid together, a little at a time.

 

  Thanks to my son, Allan, the compressor mount is finished. As is heat to the intake manifold. The exhaust needs one more joint welded. I changed the routing a little.

 

  I will do my darndest to bring the pictures up to date soon. I am having trouble with my computer. It hides my pictures. I eventually find them, but it is FRUSTRATING.

 

  Ben

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Wow, three weeks. Some kind of a goof off?  Probably.  We will see if I can bring things up to date.

 

 The 248 I pulled looks terrible on the outside. Internals look clean.  I attribute the external nasty to the pan gasket leak. I sure hope the new engine gasket holds better.IMG_5938.JPGIMG_5940.JPGIMG_5941.JPG

 

  This is after only 10,000 miles.

 

  Ben

Edited by First Born (see edit history)
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The full flow filter mounted.IMG_5947.JPG

 

  Hoses are run, just do not have a picture in the computer yet.

 

   AC compressor mounted.IMG_5950.JPGIMG_5948.JPGIMG_5980.JPGIMG_5982.JPG

 

  The coolant heat chamber on the intake manifold.IMG_5974.JPG

 

  Manifold is upside down in pic. We just used a piece of 3"  angle iron I had on hand. If this improves the running and performance, we may build a new intake later. Or not!

 

  Ben

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Pretty nifty compressor mount. What did you use as the core? Also I really like those green belts, just gives it an added touch. I also like how you mounted your alternator. Did you use a 9" thru bolt? I have thought about doing that but have been unable to find a long enough bolt.

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 Ben, The through bolt is a piece of all thread with a nut on each end.

 

  The plate the  "half moons" are mounted is a 3/16 plate.  The half moons are from Vintage Air. Modified to fit. The plate is mounted on the two front head bolts.

 

  Ben

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All thread... of course! Thanks for the clarifications! I want to do AC at some point; grandpa doesn't like cruising with wing windows anymore even though he said it didn't bother him when he drove from Michigan over to here in 58. Lol. Looking forward to your final product!

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Tuesday evening,  And front clip is BACK ON!!  Too late for pictures. Dark caught me.  Son-in-law came by and helped. Thanks, Michael.

  If life stays cool, hope, tomorrow, to get him ready to fire up on Thursday, Will see.

 

  Ben

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I THINK all is ready. Just install battery and hit the switch.  The AC condenser is in . Leaving the bumper/grill off for now. Will try to run AC hoses after engine proves OKAY.

 

  Fingers crossed!!

 

  Ben

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I would like to say "he started right up" but can"t.  Did start, just sounded like on 2 or 3 cylinders. Would not stay running.  Timing too slow?   If that is the case, I have to decide whether to move the distributor a tooth or move the wires one spot C W. If the distributor is turned  CW as far as it will turn, he tries to start.    

 

  Or may just be the lifters need to pump up?  

 

  Rolled it into the garage where I can work on it even if the rain does come the next few days.

 

    Ben

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