intake boring

Having owned and operated a Ford tractor for quite a while, I know the parts that wear out on them. The Asian made copies would likely have corrosion issues due to ethanol gas. I just had to replace a pot metal venturi in my 850 MS carb. It has a brass one now. The old one fell apart.
 
When you take your Model A manifold to most machine shops and tell them you want the center hole opened up they're going to indicate and line up on the center hole. You'll see in the pictures below that the center hole is a cast hole and is never in line with the bolt holes because of core float / shift. This is why extrude Home and media honing wouldn't really work because it's going to follow the hole that is already there and he will still end up with a step on one side. You must use a gasket lined up on the bowl holes and trace the new center hole onto the manifold flange. Doing this will correct misalignment it's called port matching. Often you will be taking more off of one side than the other, this is actually truing up the center hole to the bolt holes, which are the same as the carburetor bolt holes and throat. I recommend only chamfering a short distance because I've seen and have had people telling of manifold flanges breaking off because people made the walls too thin. And like I said, you get most of the improvement by getting rid of the step which causes circular turbulence this is air not moving forward but going in a circle around that step in diameter.
 

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Lawrie said:
I wouder how a carb of a pre injected harley would work,designed for gravity feed and a more modern carburettor
lawrie
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Our cylinders are 825 cc vs 670 cc for a 80 ci Harley, but they rev a bit higher. I don't know their carb outlet dimensions and the throttle and choke linkage would have to be developed.
 
Lawrie said:
I wouder how a carb of a pre injected harley would work,designed for gravity feed and a more modern carburettor
lawrie
Click to expand...




I think it could work well. Keeping it under the hood sides might be a challenge but may be possible. Certainly will flow enough for most any Model A,even modified engines. Interesting thought.
 
Isn't a Harley carb a side draft, not an up draft? If so, you will have to fab an adaptor/elbow.

i once saw a Pinto that had Honda 4 cylinder carburetors. Looked cool with 4 CV carbs.
 
I did some work on my sedan. I had 1/8 inch mismatch on the intake ports. what the heck, had over size valve seats installed. Then spent several hours with a Dermal tool
correcting mismatch the in block intake ports, and cleaned up the valve chamber,,,, polished enlarged it in a little.


What a difference. But a lasse, I needed money and had to sell. My friend that bought it put in his hot rod. He later told me he got up to 75 pushing 80 when chickened out
 
I made up a fixture to hold the manifold at the proper angle to bore it. I use a carbide
bit on a 8" shaft to round the corners at the top of the manifold.
Someone did back to back dyno tests on a stock and bored manifold using both a Model A
Carb and a Model B Carb and there was improvement with both the A and B Carbs.
 
1930artdeco said:
OK, I am going to install a brand new exh manifold to seal up the leak I have. I am going to send the manifolds in to be planed flat obviously. BUT, should I have the intake bore out so that I can use a Model B someday? I currently use a Marvel carb but who knows I may want to a Model B for kicks in the future.

So, here is the question-will boring out the up portion and 'runners' affect me using the Marvel in any way? Negatively that is.

Thanks,

Mike
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Mike if you don't have time and a little extra money, Snyder's is selling an A intake bored out. It was around $100.00 and is brand new. We've drilled out a number of them following the info from Dave Renner.
 
Hi Mike, when I was still working, I had the foreman in the machine shop bore out 3 intake manifolds, got 2 back. the first attempt he bored through the side! The second two he lined up with the bore and not the flange. I feel it makes a difference. Like the post above, you have options buy or machine.
 
Just checked Snyders and geez it might actually be cheaper to buy one already bored. Either that or do it myself and I sure don't have the time to sit there and do that. Thank you all.

Mike
 
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