Milling Head for 2bbl

StarDiero75

VIP Member
Howdy guys,

So here is the time to start in on my 1980 hex head that will get the 2bbl conversion. I'm taking a machine shop class in school and the teacher said he'd help me as well as a pretty skilled guy in the class as well.

First thing i noticed when setting it up today on the mill was that the carb spot is not flat, its tilted slightly as well as the log. I knew that b/c the engine sits slightly back so that counters that. My question is, can i mill it parallel to the head gasket surface? If i mill it flat the angled way, its gonna be a lot harder to set and lose a lot more material on the lower side to try to keep it the same angle.

I've seen this discussed before on other forums but i just wanted to make sure. I don't think its super important but I'll let you experts tell me otherwise. I'll hopefully be back at it on Monday.

Thanks guys,
Ryan
 

chad

VIP Member
"I don't think its super important..."
no, it is.
Not the expert U mention here. But I research well. U R missing a 1st step again.

Plez ck the tech archive (crossed screwdriver'n wrench above) for some good pic, also the Handbook.

Most do a 'fill" 1st, machine, may B nother fill'n final mill pass.
Some use a forge weld techn for the fill.

We also have many pic of mistakes (more of them than those properly done). Remove frm table , design a 2, 3* wedge, do the fill & re-bolt to table. Trying to 'make up' w/the adapter will leave a vac leak.
 

frozenrabbit

Well-known member
You need to stay parallel to the carb mount surface.

Most every carberated engine angles down in the back as installed in the vehicle. The carb mount surface and log angle up in the back compensating for the engine install angle.

Ideally the carb should be level with the ground as much as possible. You want even and level fuel in the bowl of the carb.

Your shop teacher should know that.
 

Econoline

VIP Member
You could make a custom adapter that has the angle built into it. Since the carb is bolted to studs in the adapter it shouldn't be a problem so long as the adapter mounting screws are parallel to the log surface. I've been looking at my cracked D5 head and have decided that the easiest route is to mill it like you say. When I find a good head I'm going to cut off the majority of it like forum member stanyon with a 6" angle grinder w/ a cutting wheel. Then take it to a local machinist I work with when we need things done for work to mill it the rest of the way down and leave as much meat as possible. It looks feasible with a large flat log at least. If I go TBI it won't matter the angle. Otherwise I'll do the angled adapter thing.

63falcon4drwagon":8g9bftr4 said:
I just installed a China made $72.00 Carter BBD lowtop 285 cfm two barrel on my large log 1978 200 head.
Both the cable throttle and cable C4 kickdown cable are connected to the gas pedal under the dash.
I welded an arm on to the carb choke linkage to use my stock 1963 choke cable.
The Carter BBD has 1 1/4" throttle bores which are closely spaced making it an easier conversion than a Holley or Autolite.

I was just looking at those! How is the carb performing? Holley makes a sniper version.
 

StarDiero75

VIP Member
frozenrabbit":1ovj4do8 said:
You need to stay parallel to the carb mount surface.

Most every carberated engine angles down in the back as installed in the vehicle. The carb mount surface and log angle up in the back compensating for the engine install angle.

Ideally the carb should be level with the ground as much as possible. You want even and level fuel in the bowl of the carb.

Your shop teacher should know that.

I knew i wanted to have the carb as level as possible for the float but i didn't know it'd be that far off.

I didn't ask the shop teacher about that, I wasn't gonna get him involved till i needed to cut.
 

StarDiero75

VIP Member
Econoline":1y2706fc said:
You could make a custom adapter that has the angle built into it. Since the carb is bolted to studs in the adapter it shouldn't be a problem so long as the adapter mounting screws are parallel to the log surface. I've been looking at my cracked D5 head and have decided that the easiest route is to mill it like you say. When I find a good head I'm going to cut off the majority of it like forum member stanyon with a 6" angle grinder w/ a cutting wheel. Then take it to a local machinist I work with when we need things done for work to mill it the rest of the way down and leave as much meat as possible. It looks feasible with a large flat log at least. If I go TBI it won't matter the angle. Otherwise I'll do the angled adapter thing.

63falcon4drwagon":1y2706fc said:
I just installed a China made $72.00 Carter BBD lowtop 285 cfm two barrel on my large log 1978 200 head.
Both the cable throttle and cable C4 kickdown cable are connected to the gas pedal under the dash.
I welded an arm on to the carb choke linkage to use my stock 1963 choke cable.
The Carter BBD has 1 1/4" throttle bores which are closely spaced making it an easier conversion than a Holley or Autolite.

I was just looking at those! How is the carb performing? Holley makes a sniper version.
I was just thinking about angling the carb adapter. Do you happen to know what the angle is? I'm gonna use my angle gauge to get it exact but do you know what it should be so i have a reference?

I might try to do the carb adapter angled b/c with this hex head, its gonna eat the front side a lot thinner than the back side. If i make the adapter angled it'll take off roughly the same
 

62Cometman

Well-known member
Obviously always verify with what you have before milling but it should be 3 degrees give or take. You are correct that you could also mill the adapter to makeup for it but that just makes it that much harder cause now the holes are off and at the wrong angle too. So either customer make an adapter and mill the head level or mill the head to the needed angle and everything else sits square.

Good luck :beer:
 

drag-200stang

VIP Member
It does not matter what the angle of the carb. as it came, what matters is that it is level as it sits in your car...some like the boat look , I like my car lower in front than the back...
Mill the head even and and make a custom adapter with the angle cut on the top of the adapter and and make the carb. studs straight with it.
If you try to put the angle all in the head you will get too thin to hold threads on one end.
 

powerband

VIP Member
.. a few $ .01's on related discussion :

... most popular performance carbs will need to be raised and offset with a spacer or other means if milled to original 1 bbl flange and original pitch angle maintained.

... 'had an idea for a carb adapter for small six cylinder log heads. The idea is to cut steel plate mounting flange copied from a carb base gasket with steel thick enough to prevent warping when welding to a steel plenum or riser. The OEM 1 bbl manifold opening would be opened as typical and ADapter bolted to manifold with carb bolted to flange on top. Drilled steel Flange on top could accommodate offset mount larger 4bbl's , turbo pipes or any carb setup. Bottom drilled plate flange would simply bolt to opened log manifold.

I had someone with access to a CNC plasma cutter try to cut mounting flanges for a Holley 2Bbl 2300 series carb. The 1/8 inch thick test were cut ok but too thin to weld without warping, a 1/4 " plate wouldn't cut clean enough with his equipment.

'kind of like:
(if photobux allows)

.

similar to:


have fun
 

Econoline

VIP Member
I'm looking fwd to seeing what you find with your angle finder. When I had my engine on the stand I did my best reckoning and came up with 3* as well iirc. I didn't say for the same reason drag-200stang brought up. If you like the rake of your car, check it in place. I think you know the deal, the float should be basically level as the car sits.
 

Econoline

VIP Member
I'm running one of the chinese yfa's on my 250. I made my adapter from a thick piece of phenolic we have laying around at work. It's on a lrg log head but it's otherwise basically the same. With the stock linkage pivot rod threaded into the side. I had to add a lever extension onto the throttle arm on the carb.

[bbvideo=560,315]https://www.youtube.com/watch?v=dCBCLF76E1w&feature=youtu.be[/bbvideo]
 

bmbm40

VIP Member
63falcon4drwagon":1m3ahp8w said:
Econoline":1m3ahp8w said:
The Chinese YFA is a great carb for a good price.
The BBD carb will outflow the YFA at higher RPMs.
The strange thing about this BBD conversion is the exhaust tone of my hated old droning turbo muffler that I wanted to replace has changed.
At full throttle + higher RPMs it sounds like a 6 cylinder race car!
Tonight I floored it until the C4 full of 303 tractor fluid shifted at 35 mph then I held it in second at until 70 mph then shifted it to high.
All the while enjoying this new 6 cylinder race car exhaust sound!

That is pretty awesome! Flogging the old c4. And having it sound better is a big plus.
 

StarDiero75

VIP Member
63falcon4drwagon":18mtf95c said:
It might be easier to adjust the float level and or the air fuel ratio;
or put big tires in the back and small tires in the front?
I got hijacker shocks so i can lift the rear, if need be
 

StarDiero75

VIP Member
Finally did the 2V hog out and cut. I got to use the mill machine at school, so this was really cool to do myself. Now I'm working on making the adapter plate. I woulda cut lower to hog it out even more but i don't have equipment to braze or the time to JB Weld the low spots. It looks pretty good to me though.

Should i cut my own gasket for the adaptee plate and this, or should i JB weld it to the head? I was told the expanding and contracting at different rates will crack the JB weld so i should cut my own gasket

What do you all think?

Ryan
 

Attachments

  • 20190430_171138.jpg
    20190430_171138.jpg
    2.6 MB · Views: 488
  • 20190429_175159.jpg
    20190429_175159.jpg
    2.2 MB · Views: 488
Top