Small V8

[stevehuckss396]

Awww its an ittty bitty dominator. ;D Too cute!

Yes it is and I expect to see a little Weber on your's!!

 

[kcmillin]

Wow, this thing just gets cooler and cooler.

That carb is awesome.

Is the air bleed in the idle circuit? I am trying to design a carb for my Tiny 4 cylinder, and would like to incorporate an air bleed into the main circuit with perhaps an emulsifying tube, but I can only find info on large carburetors, and I am thinking I might just be adding more potential problems.

Kel

 

[stevehuckss396]

Wow, this thing just gets cooler and cooler.

That carb is awesome.

Is the air bleed in the idle circuit? I am trying to design a carb for my Tiny 4 cylinder, and would like to incorporate an air bleed into the main circuit with perhaps an emulsifying tube, but I can only find info on large carburetors, and I am thinking I might just be adding more potential problems.

Kel

The air bleed is a hole thru the body of the carb that leaks air thru the barrel when it is "almost" closed. All I did was put an adjustment screw between the hole and the barrel to make adjustments. When I did the Peewee, the carb had a tiny hole in it. The hole size is increased and test. Increase and test until it works good. Problem is, when you over shoot, there is no going back.

If you need some help or want to see what I did, I can try to post some pics of my bleed circuit.

 

[steamer]

Looking Awesome Steve! I like the Dominators!....

Dave

 

[George_Race]

Hi Steve:
The parts you make are absolutely a work of art!

I am curious as to what kind of tooling you use to make something like the little carburetor shown in your recent post.

2 flute, 4 flute, end mill, ball end, carbide, HSS, diameter, etc...

Also, are you hand milling everything? Do you use CNC for some? What is your milling machine?

I don't live very far from you and wonder if there would be any opportunity to visit your shop, and see first hand your work in progress?

Thanks,
George in Albion

 

[T70MkIII]

I am secretly pleased you couldn't put this project down for too long. Looking great, Steve.

 

[LongRat]

Steve, very glad you are still moving forward.
Does your design have space for a built-up crank? I mean the design with the large ball bearing mains. I wonder because there is certainly a following for them and some people might prefer to go that way, using your plans. Having read around quite a lot, I'm sold on them personally. A lot of people will be following this thread and thinking, "damn, if HE is struggling with the crank, how the hell am I going to do it?". I know you say you are not a master machinist, but the pictures and previous builds paint a somewhat different picture ;D

 

[stevehuckss396]

I am curious as to what kind of tooling you use to make something like the little carburetor shown in your recent post.

2 flute, 4 flute, end mill, ball end, carbide, HSS, diameter, etc...

Also, are you hand milling everything? Do you use CNC for some? What is your milling machine?

I don't live very far from you and wonder if there would be any opportunity to visit your shop, and see first hand your work in progress?

Hi George! I think I can kill 3 birds with one stone here on questions 1, 2, and 3. The top and bottom were made in a home made CNC mill using a 4 flute, 1/8 inch end mill and a few drill bits. The 4 sides were machined and drilled in a Bridgeport mill. Then the float bowls were made on the CNC mill 8 at a time. The rear bowl still needs some fuel passages drilled and milled into them so I will do them by hand in the BP.

I sometimes have to work weekends but when I don't, you could stop in on a saturday or sunday. Those are my lazy days.

 

[stevehuckss396]

Does your design have space for a built-up crank? I mean the design with the large ball bearing mains. I wonder because there is certainly a following for them and some people might prefer to go that way, using your plans.

I have, and will include in the plans, both a one piece and a modular crankshaft. I know I could make a modular crank. I started one but was not happy with it. I'm sure I could pull it off. My problem is I want to push myself and make a one piece crank. If I push myself, I think I will keep learning and improving my skills. I don't want to keep doing the same thing over and over.

I know you say you are not a master machinist, but the pictures and previous builds paint a somewhat different picture.

That is very kind of you to say, Thank you! The truth is I'm just like everybody else on this forum. I started machining parts about 4-1/2 years ago. I started on the Bugatti and made 80% of it. Then I realized how poor the work was so i fell back and made a few air engines including the micro V8. I made some wobblers and a radial air engine. I also made 3 Cox based engines using Cox cylinders and pistons. Then I went back to the IC engines when I built the Peewee. Peewee was my first IC engine to run. The Bugatti got new cylinder liners, pistons, rings, and water jackets last year but is still not ready to run.

Point is, I'm in the shop slugging it out just like everybody else. I read things and go out and try them. I ask advise and then try to follow it and for the most part things go pretty well. Some things are still a struggle but if i keep pushing myself, those things get easier. You will never know what you are capable of until you try something you don't think you can do. I guess I just push myself harder than most.

 

[agmachado]

Steve,

Know that kindness is you share your knowledge here, in this forum !

Your projects are fantastics !!

Of course, here in this forum there are also many other fantastics projects... but of the internal combustion engines with multiple cylinders are my favorites.

Thank you,

Alexandre

 

[steamer]

"That is very kind of you to say, Thank you! The truth is I'm just like everybody else on this forum. I started machining parts about 4-1/2 years ago. I started on the Bugatti and made 80% of it. Then I realized how poor the work was so i fell back and made a few air engines including the micro V8. I made some wobblers and a radial air engine. I also made 3 Cox based engines using Cox cylinders and pistons. Then I went back to the IC engines when I built the Peewee. Peewee was my first IC engine to run. The Bugatti got new cylinder liners, pistons, rings, and water jackets last year but is still not ready to run.

Point is, I'm in the shop slugging it out just like everybody else. I read things and go out and try them. I ask advise and then try to follow it and for the most part things go pretty well. Some things are still a struggle but if i keep pushing myself, those things get easier. You will never know what you are capable of until you try something you don't think you can do. I guess I just push myself harder than most."




Talk about understated.. ;D...your a damn site better than most seasoned vets I've met....by a long shot.

Dave

 

[kcmillin]

The air bleed is a hole thru the body of the carb that leaks air thru the barrel when it is "almost" closed. All I did was put an adjustment screw between the hole and the barrel to make adjustments. When I did the Peewee, the carb had a tiny hole in it. The hole size is increased and test. Increase and test until it works good. Problem is, when you over shoot, there is no going back.

If you need some help or want to see what I did, I can try to post some pics of my bleed circuit.

That would be awesome Steve. I need as much info as I can get when it comes to carb design. I am also interested in making an air bleed in the main circuit, due to the small size of the fuel inlet and adjusting screw, but I have not yet seen this in a model carb.

Kel

 

[LongRat]

Steve, I fully understand. I am designing my 1st engine now. I am at the point where I think I know how far I can push myself while still ending up with something that works. I do not want to invest time pushing myself TOO hard. My enjoyment comes 50-50 from building and then running in practical RC applications. I offer my thanks to you and many other people on the board for inspiration and mostly, useful technical knowledge that only experience really gives.
A thought on the 1-piece crank. What about setting up the blank vertically on the CNC mill and using a slitting saw or T-slot cutter to rough out the bearing journals? Then you could transfer over to the lathe and do the finishing accurately, having got rid of most of the pain of the offset turning and intermittent cutting. It is a method I intend to try as I think a full camshaft could be done this way too, using a vertical CNC rotary table - possibly with a 'tailstock' to support the free end of the blank at the top (a special fixture would need to be made to achieve this). Then, grinding wheel in the mill spindle to grind the cams with pure X axis movement and synchronized rotation of the rotary axis.

 

[stevehuckss396]

That would be awesome Steve. I need as much info as I can get

Here is a pdf file with a drawing of the air bleed circuit. Very simple thing. Just need to make sure that the hole lines up with the barrel when the carb is almost closed.



View attachment Carb1.pdf

 

[stevehuckss396]

Steve, I fully understand. I am designing my 1st engine now. I am at the point where I think I know how far I can push myself while still ending up with something that works. I do not want to invest time pushing myself TOO hard. My enjoyment comes 50-50 from building and then running in practical RC applications. I offer my thanks to you and many other people on the board for inspiration and mostly, useful technical knowledge that only experience really gives.
A thought on the 1-piece crank. What about setting up the blank vertically on the CNC mill and using a slitting saw or T-slot cutter to rough out the bearing journals? Then you could transfer over to the lathe and do the finishing accurately, having got rid of most of the pain of the offset turning and intermittent cutting. It is a method I intend to try as I think a full camshaft could be done this way too, using a vertical CNC rotary table - possibly with a 'tailstock' to support the free end of the blank at the top (a special fixture would need to be made to achieve this). Then, grinding wheel in the mill spindle to grind the cams with pure X axis movement and synchronized rotation of the rotary axis.

I am going to hold my crank horizontal in the mill to remove as much as i can.

As far as the cam goes, I'm going to do it the old fashioned way with a fixture in the lathe. I am going to make 3 cams so it will be worth the effort of making the fixture.

 

[jpeter]

I suggest you drill 5 centers in each end (First lay the stock in a tslot and mill a flat on each end for indexing). Next, chuck a piece of bar and turn a point on it for a live center; don't remove it from the chuck. Mount your blanked out piece from the mill between centers and rough out the mains. Then, turn the throws to final size making sure to dress the throws so you've got enough width for the rods. As a final step finish turn the mains. If your careful to not squeeze the crank to tightly you won't need to block the center spaces. Take it then back to the mill and mill away the counterbalance part of the throws.
I shouldn't even be telling you this cuz your work is as nice as I've seen. You should be telling me how to make a crank.

 

[kcmillin]

Thank a lot Steve, I really appreciate it!

That does indeed help out.

Kel

 

[stevehuckss396]

I suggest you drill 5 centers in each end (First lay the stock in a tslot and mill a flat on each end for indexing). Next, chuck a piece of bar and turn a point on it for a live center; don't remove it from the chuck. Mount your blanked out piece from the mill between centers and rough out the mains. Then, turn the throws to final size making sure to dress the throws so you've got enough width for the rods. As a final step finish turn the mains. If your careful to not squeeze the crank to tightly you won't need to block the center spaces. Take it then back to the mill and mill away the counterbalance part of the throws.
I shouldn't even be telling you this cuz your work is as nice as I've seen. You should be telling me how to make a crank.

That was my plan. I am waiting for Rick to finish grinding my angle plate so i'll have something to hold the bar on end to drill the centers. I need to drop him a line.

 

[jpeter]

After I have a flat on each end I stand it up in a vise for drilling. I put the flat against the solid jaw. I'm thinking extremely accurate indexing is not really important cuz any inaccuracy in the indexing will be taken out by the turning, but maybe not.

 

[stevehuckss396]

Hello All!!

Made some pieces for the carb. The adjustment screws were done using a scrap piece of round stock that was faced and drilled and tapped. Then the screws were inserted and the heads were turned down to fit into the faux float bowl.

Then for the air bleed adjust screw, I took off the chuck and inserted the screw from the back. Then I ran the lathe in reverse and cut the angle from the back so the screw wouldn't unscrew itself from the holder.

It also worked perfect for drilling the fuel adjust screw and inserting the needle.