Projects Old school cool 248 Gmc

Shotguns all on the left and turn downs with a bologna cut that are hidden floats my boat. 2.25 is good. On my 49 pickup in HS both came out in front of the left tire.

 

Probably not a bad idea and the H/X pipe easier to run. I just worried that it would crowd up the side with the clutch and master cylinder. I am sure this won't win me friends but the ear piercing sound of a six is far from what I am looking for. Once at work I replaced the blown muffler on a 292 with a straight pipe, never again. I have loud cars because of the horse power they make but my big block chevelle has Dynomax super turbo mufflers that make it just have a mild rumble. I want this to be like Doc Hudson on Cars or a Jag. Nice deep tone but no ear splitting BLAAAT.

 

ladder bars? What rearend is that?

 

Went and finished my wires, Cracked my Mallory top piece if anyone has a used one for sale.

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57 Pontiac. Ladder bars are a creation of Blair’s Speed Shop for the original owner Noel Melovich. Only a bracket is welded to the housing and the ladder bar is U bolted to it. They are almost to the u-joint and I’ve heard made from some GM suspension parts of the late 50’s.

 

awesome!

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Well another hitch, one of my matching BXOV-2s is damaged. Not sure how unless it was dropped. I should have inspected it better when I bought the intake but I guess "buyer beware". It was missing the seat but I guess I didn't know what I was looking at. I will try and straighten it but I don't think I will have much luck.

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I have straightened worse, use heat and proceed slowly.

 

well I would say that is going to be good enough. lots of heat and time

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does anyone have any experience with 2 1-7/32 BXOV-2 carbs? The first one has a 68 jet which is about 10 bigger that a 14-22 has stock. These are meant to be used as dual bit for an American LeFrance V12. Just to be clear I have a Stromberg jet socket and didn't scar these up.

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Nice job on the straightening. Carb King is probably the only one on here with metering info on these carbs.

 

he told me not to run these carbs or my zenith's. I am sure he will win but I am stubborn I will check the second carb and buy some smaller jets.

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I was told not to use my Zenith 28s also. But I've liked them on Chevy & GMC 6s in the past and like them.

 

I have 3 zenith 228s I was going to use the Strombergs because the are matched and slightly bigger. The Zenith's I have are all 30mm venturis and the Strombergs are 1-7/32 which is 30.95625 so obviously better.

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The pair of 28s I'm using came off of a 2X1 GMC small port intake 228,248,270? I assume they were used as a pair as all linkage was there and adjusted. They have 30mm venturis. They flow 195 cfm and one is good for an engine up to 300 ci. Venturis are available in 32mm, 30mm, 29mm, & 24mm. You could change to 32s or even cut them larger if necessary.

 

I was going to use to larger 270H zenith but they are expensive a different bolt pattern and hard to come buy. Where can you get just the venturis?

I had it figured these 2 BXOV-1 flowed about 360 cfm combined at 3hg or 254 at 1.5hg. Even figuring 85% VE they are too small. I flowed a zenith and only found 137 cfm but that was at 1.5hg so 195 might be close at 3hg. I you are running a pair of Zenith's and are happy with the power I won't keep fretting about not having a Howard 5x2 with 3 94s or 97s to make good power.

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The American LaFrance V-12 is 527 CID. The two Stromberg carbs were rated at 196 CFM each at 3 inches Hg. Dividing by the square root of 2 gives 139 CFM each.

From memory, the 32mm Zenith was not available for the 28 size 10, but was available in the 28 size 12. I believe 30mm was the largest size for the 28 size 10.

Jon.

 

I know you told me not to run them but do you know the stock jetting? Too big an engine should require smaller jetting since it has a stronger depression in the carbs.

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Not without pulling the microfilm.

Jon.

 

Well, using the unscientific method of using the area of each venturi and jet from a chevy 14-17 that has a venturi 1-3/32 and a 61 jet, if I cross multiply with the 1-7/32 venturi I get the area of a .068 jet. So that says that should be close. Of course the high speed air bleed is likely different, so that changes the whole thing. I do have another 1-7/32 I am using for parts that I will check the high speed and main jetting on.

 

I can not find the link I had to the place with the venturis. It may have been this place and they changed something. http://www.zenithfuelsystems.com/downdraft_228.htm

More that may help.
http://www.zenithfuelsystems.com/documents/RR15P68-71.pdf
http://www.carburetor-blog.com/manuals/zenith_28_128_rebuild_manual.pdf

 

Made a coil mount since my GM finned coil won't fit above the dist. Pulled apart a 10-39 stromberg for parts, same 1-7/32 but smaller high speed air bleed is smaller 60 jet. The other 99-25 that I have has a 62 jet. Tried alodine again, meh

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If I can get the idle air bleed swapped out of the 99-25 mIn body I might just use the 10-39 body because it is straighter. Idk yet. Does anyone know how to get the power valve out of a Stromberg BXV? They appear to have the same K but I wanted to clean the port.

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measured some carb specs tonight and lots of rust parts going into and coming out of vinegar bath. Also using my new ultrasonic cleaner on the bodies. Anyone know if 97 idle tubes fit a BXV 1bbl? Where do you get jets and idle tubes? Carb king?

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apperently I mixed up the accelerator pump outlets and the idle air bleeds, the air bleeds are much bigger (.055) considering reducing their size. Not sure yet. Emulsion tubes don't come out the same as 97s. A small punch and a light tap and they are our. The dual 99-25s are much different than the single 10-39.

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Isky LDB for GMC 6.
IN 26/69
EX 68/26
Cam lift .285
In cl. .012
Ex cl. .015

 

I actually had it measured and it is different than the old catalogs suggest.

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This is what it degreed on 3 I installed in engines back in the mid 50's.

 

How did you think it ran? I was thinking about building a 248 with 270 pistons and the LDV cam with a 819 head and dual zenith and the rest of my left over parts.

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Started bluing carb parts today. Just a few pieces and another base to do. waiting on Yellow Chromate from Caswell to do the tops, probably won't turn out as good as I hope with out zinc plating but I am hoping just for some yellow color.

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