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11-27-2020, 04:00 PM | #21 |
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Re: “Inside” part of road draft tube
Thanks 1940.....I'll look into that also.
Wayne at Dennis Carpenter says they have one in a NOS part #! I can't order it until Monday because they are running a short crew today(understandable). I'll call them Monday morning early! Very helpful folks.....just like the Ford Barn! Last edited by Norris McCarty; 11-27-2020 at 04:13 PM. |
11-27-2020, 09:29 PM | #22 |
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Re: “Inside” part of road draft tube
[QUOTE=51 MERC-CT;1956741]This is the way I checked for vacuum using the oil fill tube as the source.
Great idea! Sent from my SM-G973U using Tapatalk |
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11-27-2020, 10:32 PM | #23 |
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Re: “Inside” part of road draft tube
Special thanks to Mark, Bob and Richard.......I have had offers from all three to send me the tube I need!
Great bunch of guys on this forum! I’m looking forward to “paying it forward” Norris One more question...what is the inside diameter of the road draft tube hole in the late manifold. I’m going to have that hole machined into the boss on my early manifold. Last edited by Norris McCarty; 11-27-2020 at 11:06 PM. |
11-28-2020, 01:25 AM | #24 | |
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Re: “Inside” part of road draft tube
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11-28-2020, 03:29 AM | #25 |
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Re: “Inside” part of road draft tube
That’s where I’ve decided to put a pcv valve. The way my manifold is designed, I’m going to need to pickup vacuum from each side of the manifold.....so I don’t lean out any cylinders. I don’t really want all of that “plumbing” under the manifold. It’ll be easy to run a line from each side of the manifold below where the center carb would go and T it just before where the capped off road draft tube/pcv valve will be.
It won’t look as clean, but it’ll sure be easier to troubleshoot if there is a problem with the valve. I’m also considering just using a metal pcv valve that has a threaded end and threading a small hole in the boss instead of a full-size road draft tube hole. |
11-28-2020, 04:49 AM | #26 | |
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Re: “Inside” part of road draft tube
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Does it also have the associated pathway to the opposite side cast into it?
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11-28-2020, 09:54 AM | #27 |
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Re: “Inside” part of road draft tube
Yes it does have the machined hole and the pathway to the boss on the topside.
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11-28-2020, 10:55 AM | #28 |
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Re: “Inside” part of road draft tube
Then the method you plan on using rather than inside plumbing, makes sense.
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11-28-2020, 11:44 AM | #29 |
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Re: “Inside” part of road draft tube
Hey Merc!
What if I cut a 3/8” or so 1/2” deep slot between the two holes where the carb would go (which now has a block off plate)to join the left and right plenum. The left and right plenums are currently separated completely under the carbs..... this would join the plenums under the block off plate. I would then need only one vacuum fitting to run to the pcv valve?? I could just enlarge the hole/fitting to 3/8” that I currently have in my block off plate. This is all a question! I can be dangerous and screw up a lot of parts given too much time to think!!!!! |
11-28-2020, 12:41 PM | #30 | |
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Re: “Inside” part of road draft tube
Quote:
Secondly, in my opinion (and WTF do I know), if you leave your vacuum source fitting in the position shown, that front, right cylinder is likely to do the majority of the sucking, hence......run leaner than about all of the others. Air is like real thin water.....it follows the path of least resistance. To prevent any more unbalance in the mixture than necessary, that vacuum fitting needs to be pretty much centralized in the grand scheme of things. End cylinders (especially with ONE carburetor) always tend to run leaner as it is. I BELIEVE you'd be better off designing a plate (spacer, maybe) to go under that center carb, configured such that it draws from the center of both plenums equally. That's the best 'mix' you're going to accomplish as far as even distribution of what amounts to a tiny vacuum leak. But again, what do I know? DD PS......Don't forget (if you read my thread on our PCV project) that MOST PCV valves are designed to operate in a vertical orientation..........just sayin'! |
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11-28-2020, 02:03 PM | #31 |
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Re: “Inside” part of road draft tube
I’m running the two end carbs....center is blocked off. It runs much better running the two end carbs directly connected to each other than with 3 running progressive. I can, at this point easily add the center with a block off under it for looks, but I’m try to get the car sorted out so looks ain’t my thing at the moment. It runs great like it currently is. I was working on AFR tuning then realized with the weather change, this would be a good time to work inside the shop on the needed PCV system that than trying to tune which requires driving.
I cannot run a taller spacer/block off in the center section and still adjust the rear carb. Well, I could still adjust it, but I’d have to use needle nose pliers from the side like I did when I had the three carbs on it. I have every type carb adjuster made, and home made, but that’s not a huge deal. My whole reason for the above question was to see if I could just run one fitting on the one side of the top of the carb block off plate instead of two if I joined the right and left manifold plenums. I know that because the plenums are separated left and right I need either a common plenum or two separate vacuum fitting to pull from the PCV valve so I don’t lean out some cylinders. Obviously not a good idea to cut a slot to join plenums....I’ll just run two, one on either side on top of the block off plate. If it works well, I may put fittings in the side of the manifold. I have plans to run a near vertical PCV valve off of the road draft tube hole in the front of the manifold. I really appreciate your opinions. |
11-28-2020, 02:09 PM | #32 |
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Re: “Inside” part of road draft tube
My 4bbl. carb with PCV port has a 'Y' type groove to connect the ports.
The grooves are appox. the same width as show and half as deep.
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11-28-2020, 02:24 PM | #33 |
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Re: “Inside” part of road draft tube
Ah....Now I understand! I think you have it well under control. That is a very pleasant looking engine compartment. So happens we also have a '40 coupe. DD
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11-28-2020, 03:18 PM | #34 |
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Re: “Inside” part of road draft tube
Thanks Merc! I’ve seen those before! I think I can easily perform that minor surgery on my Navarro.
Thanks so much for your assistance! Maybe with that modification I can run one vacuum fitting without leaning out some cylinders. Gonna give it a shot. Thanks again my friend |
12-01-2020, 09:55 PM | #35 |
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Re: “Inside” part of road draft tube
Once I find out how well it works, I’ll change the rubber line to copper.
I should have the tube that goes under the manifold by the weekend. Thanks for everyone’s help. Norris Then I’ll get back to wideband tuning as the weather permits. |
12-01-2020, 10:07 PM | #36 |
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Re: “Inside” part of road draft tube
The setup looks like it will work well.
The only thing that may be an issue is the positioning of the valve. All the ones I am familiar with are meant to be mounted vertically not horizontally.
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12-01-2020, 10:26 PM | #37 |
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Re: “Inside” part of road draft tube
This particular valve is a Borg Warner PV255. It is built to use horizontally. Same valve that’s used on the road draft tube of a mid-late 60s SBC. 1/4” pipe thread on block end.
Hope it works well. At least the flow is in the correct direction! They are a bit hard to find. |
12-01-2020, 10:34 PM | #38 |
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Re: “Inside” part of road draft tube
That's great, you are well on your way to eliminating crankcase emissions and improving the atmosphere
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12-02-2020, 01:41 AM | #39 |
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Re: “Inside” part of road draft tube
.
How do you add oil to that critter? And where's the air intake for the crankcase? You must have an electric fuel pump, huh? DD |
12-02-2020, 08:08 AM | #40 |
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Re: “Inside” part of road draft tube
Yep, electric pump. Air and oil in via the rear breather/“fuel pump” stand.
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