manifold
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Category: Other Topics
Forum Name: Pulling Forum
Forum Description: Forum dedicated to Tractor and Garden Pulling
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=146407
Printed Date: 27 Nov 2024 at 3:09pm
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Topic: manifold
Posted By: allispuller
Subject: manifold
Date Posted: 12 Jan 2018 at 8:44pm
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was wondering what you guys suggest as far as a manifold for a pulling engine thats around 315 ci.
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Replies:
Posted By: bigcountry48
Date Posted: 13 Jan 2018 at 10:43am
I’m wondering the same thing, my motor is at the machine shop right now. They’ve got everything else ready and told me that manifold is one of the worst possible designs for making power. It’s fine for normal operation, just hard to get power out of.
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1950 B, 1952 pulling wd, and 1954 wd45
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Posted By: DougG
Date Posted: 13 Jan 2018 at 1:27pm
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I'm just wondering exhaust or intake? What engine AC 301 ? Wd ?
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Posted By: allispuller
Date Posted: 13 Jan 2018 at 1:51pm
Posted By: wi50
Date Posted: 13 Jan 2018 at 6:34pm
Here's the quick and dirty on the manifolds for these things. The carb neck to manifold junction is nothing more than a T shape. So stand there with your arms out in a T shape..... you need to radius the armpits. This isn't so simple. I weld the corners with many passes and build it out near the carb flange, I fill that area because when I grind the inside it's going to get wide and it's going to bread through the original casting.
Next I clamp the manifold in a milling machine and I cut 2 1" holes in the back side (engine side) in the right location of the manifold body on each side of the carb neck. This hole will allow me to put a 1" round wheel on an extended die grinder to fully radius the corners. I also drill and tap the front of the manifold where the runners go into the head, there's a dimple there from the casting process, that's where I drill for a 1/4" bolt, this bolt is simply for a mechanical bond for epoxy. I also drill straight up from the carb through the top of the manifold, centered in the carb throat and tap for another bolt to serve as a mechanical bond.
Now I grind the throat and taper it, I start the taper and radius into each runner. Then I work through the back side holes I cut to finish that radius.
Then I grind the floor of the round portion that mates to the head in a teardrop shape, from the head mating surface I taper down and flatten the bottom of the round runner and roll a radius around that corner.
Now put the 3 bolts in those holes that I drilled and tapped. I mix a epoxy called "Splash Zone" By wetting my fingers it does not stick to them and I can kneed it around and work it like play dough. I build a wedge above the carb, centered in the throat to take up the volume that increased up there and this gives the air some direction to go as well as helps the robbing when the engine pulses front to back, back to front in the breathing cycle.
Then I put epoxy on the top corners of the runners that go into the head to hold the air on the floor, tip the manifold 45 degrees and build a wedge in the top corners.
When I say wedge, they are not straight like an inverted V but they are a radius shape.
Then fill the 1" holes with some expansion plugs flush with the inside of the manifold and tac weld them.
Stock manifold will flow 115 CFM if I pull air through a runner, cap off the other runner and put a radiused inlet on the carb flange. If I simply die grind the corners a bit in a few minutes, figure 140 CFM. If I work at it a while and do everything I can do without cutting more access holes they will flow about 180 CFM. If I really work at it and cut the access holes and build the radiuses, the divider, fill the corners, etc. 225-230 CFM. Yes, they double in flow and I didn't increase the runner size. I just made the inlets to each stage as efficient as I can in the manifold and fill the corers, air hates to expand. It's easy to keep it moving and make gentle corners as long as it can't expand. By filling the corners I can keep a higher velocity air stream attached to the floor. Once it becomes detached it tumbles and gets confused.
Try running down a set of spiral staircases, you can't go very fast, but if it's narrow and you have a railing to keep you attached, you can go twice as fast.
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"see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet"
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Posted By: Robacpuller
Date Posted: 14 Jan 2018 at 7:45am
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Marty is the best at making these manifolds flow. He definitely knows his chit.
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Posted By: wd45tim
Date Posted: 29 Jan 2018 at 11:17am
Does anyone port allis 226 manifolds? I would be interested in having one
done or buying one.
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Posted By: O.P.S. Heads
Date Posted: 29 Jan 2018 at 3:41pm
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WI50 just gave a detailed explanation on how to do it and make them work. Read through it. I think he was giving the info for those who want to try it themselves. I doubt you will find anyone that does them on a regular basis or really knows how.
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Posted By: Robacpuller
Date Posted: 29 Jan 2018 at 9:04pm
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WI50, did my manifold last winter. I ported it myself when he checked it was putting out 170 cfm, when Marty got done with it, it put out 220 cfm. I gained 20 lbs of cylinder pressure. I have mine off right know I can send u some pics of it. Pm me with cell number.
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Posted By: SteveM C/IL
Date Posted: 02 Feb 2018 at 9:37pm
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Marty is the best guy around.Seriously. He freely gives good advice and even specific advice.Just tells it like it is. All you have to do is follow it and good things will happen.If you don't feel like you know what you're doing,well,jump in with both feet and gain some experience. I'm pretty sure he wasn't born with all his knowledge.
I have always appreciated his stories and experiences that he has laid out here over the years. He is very good at analyzing "problems" and finding solutions.Thoughtfull,simple solutions.
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