[mayhugh1]

Here are some pictures of a twin cam 4-stroke Howell V4 that I just completed. I spent two years and probably have some 3000 hours of effort into it. The total displacement is about 2 cubic inches and the engine has a pressurized oiling system and a closed loop cooling system driven by a magnetically coupled water pump. It was machined entirely from bar stock including the intake and exhaust manifolds which I tried to make look like cast parts. I modeled much of the design in SolidWorks and created some 200 Sprutcam programs along the way for my Tormach mill and Wabeco lathe. Here is a link to it running

http://www.youtube.com/watch?v=tEWLg...ature=youtu.be

[stevehuckss396]

Congrats! She's a beauty.

[dynosor]

Sweet!

[Zygoat]

looks good

[RomanLini]

Good is an understatement!

That is a beautiful work of art, almost jewelery. Seriously, an art gallery would be proud to display it.

[Ken_Shea]

That is one nice job, Sounds really crisp also, Jerry Howell would be well pleased with your efforts.

[dsage]

Beutiful job Terry:

Runs really nice too!!

Have you seen my V8 version?

There's a video of it running on the Sherline website at the end of their Howell V4 build page.

Sage

[mayhugh1]

Sage,
Thanks for the complement. I'm very familiar with your engine. I met you at the Cabin Fever and NAMES shows earlier this year and we talked quite a bit about these engines. I was the guy who made his own intake and exhaust manifolds because the castings were no longer available. The Craftsmanship museum has actually put a photo and short write-up of my engine just below yours on their website! - Terry

[dsage]

Terry:

I figured we might have met. I remember well (Now). It's difficult to put faces to on-line names. I wasn't sure because I thought I could see TX (Texas) on the name tag on your engine (picture). So I thought you might have never been east to Cabin Fever and NAMES.
Will you be at either of the shows this year? I'd love to see your engine in the "flesh" (so to speak).
The V8 is running a bit better. I found one camshaft a bit mis-timed and have compensated by bumping it a gear tooth in one direction. I'm still not too happy so I may have have to remove and reassemble the lobes on the shafts. I think this was why it had a funny popping sound (like a cork from a bottle) while running. I'm also not sure the CDI ignition is able to keep up with a V8. Every run is a new ball game but at least it hasn't flown apart.

Sage

[mayhugh1]

Sage,
I think there is an error in the design of the cam lobes for this engine. I
carefully checked the timing of all my cylinders with a degree wheel and
found that there is no overlap between intake and exhaust events as Jerry's
timing card shows there should be. I carefully checked my CAD work, and the
lobes on the actual parts came out exactly per Jerry's drawing. I then carefully transformed the lobe shapes into tappet lifts and found that there was theoretically no overlap there either. So, I think the lobe design in the planset I have cannot provide the timing that his cam timing diagram specifies. The strange thing is though, with no overlap I would have thought that the top end would be limited. But mine easily revs up to 6200 rpm. The idle, though, will reliably go down to only about 1600 rpmor so.
I also tried the CDI ignition but the spark was much less intense than
with the TMI6 board and Exciter coil so I elected not to use it. The CDI is actually not spec'd for more than a few thousand rpm with a V8 and this includes Jerry's V4 design with the 90 deg spacing of the single pin piston pairs.
I'm not sure we will make any of the shows this year. My wife and I are
still negotiating :>) Terry

[dsage]

Terry:

Did you develop a timing diagram for what you found? I'd be interested in seeing it. I also used a degree wheel for each cylinder but I didn't plot a complete diagram. I just measure the angles for start open, full open and just closed. Generally speaking I found what you did, not much, if any overlap but also intake opening pretty late, sometimes after TDC (should be well before TDC). This was quite severe on cylinders 2,4,6,8 which is one side of my engine so I moved the camshaft one tooth advanced to get earlier intake opening. The two sides are - somewhat - more equal now but I still have quite a variance between cylinders. I don't like the method jerry used to set the lobes on the shaft. Sometime I will set up the cams on a jig and use a degree wheel to set them properly and then re-install the shafts.
I had a look at the Crane Cams website where you can find the specs for hundreds of cams. Jerry's timing diagram more or less is like a very mild street / economy cam. With no load on the engine almost anything will work though.
I side side milled my cams with a 1/4" cutter in O1 drill rod and a CNC program for the profile (outside profile) which I got by redrawing Jerry's drawing in Autocad. I had a jig with a female recess to hold the one finished lobe down and to get the angle right for the second lobe. They look right But I always wondered if, like a cam grinder it matters what size stone (in my case cutter) is used. I've never had any trouble getting outside profiles to work out with almost any reasonable sized cutter so I assumed no problems.
What process did you go through?

Dave Sage

[mayhugh1]

Sage,
This is what I came up with:
intake start to open = 12 deg ATDC (actual lobe)
= 6 deg BTDC (Jerry's spec)
exhaust start to open = 118 deg ATDC (actual lobe)
= 120 deg ATDC (Jerry's spec)

intake centerline = 124 deg ATDC (actual lobe)
= 112 deg ATDC (Jerry's spec)
exhaust centerline = 237 deg ATDC (actual lobe)
= 245 deg ATDC (Jerry's spec)

intake closed = 241 deg ATDC (actual lobe)
= 230 deg ATDC (Jerry's spec)
exhaust closed = 0 deg ATDC (actual lobe)
= 10 deg ATDC (Jerry's spec)

The actual lobe values are those I got from graphically transforming his lobes into valve lift (I used .002" valve lash). The actual measured values on my engine were typically within +/- 3-4 degs of these values, but consistently different from Jerry's spec. I used exactly the same technique to machine the cam lobes that you used. I don't think there is anything wrong with the method he suggested for machining the cams except for positioning the pairs at 180 deg with respect to one another. That is a tricky operation especially if you have well prepped surfaces for the bearing retainer which starts setting up almost immediately before you can get the lobes rotated properly. All four cam lobe pairs measure out to be very similar but I have a 5-7 deg phase error in both my cams due to the lobe pairs not being exactly 180 deg apart. I really think there is an error in the CAD files that spec the lobes. But, mine's finished and running consistent and as well as an unloaded display engine as I could have hoped for so I'm off to a Hodgson 9 radial. - Terry

[dsage]

Re the method of cam manufacture, I guess great minds think alike.
As you know the resulting action you get from a given cam depends a great deal on what you are using as a tappet (lifter). The shape, diameter etc. A roller rocker cam has a different profile from a flat tappet cam. So I'm not too surprised at the differences from theoretical to actual. If I read correctly you also observed actual operation of the intake opening late (Atdc) like me. Combined with a normal exhaust profile that would mean in lower overlap and less power than possible.
But then again - your right - it runs and who really cares. I'm not going to put it in a race car.
Wow - your jumping in with both feet building the radial. I think I read the Howell V4 was your first engine? If so you must be a natural engine builder.
I've decided to back off a bit and build some shorter completion time projects for a bit. Three years on one project was a bit much.
Keep us posted.

Dave Sage

[mayhugh1]

Dave,
The V4 was actually my second engine. Jerry's V-twin was my first. Here is a link to it running:
[ame=http://www.youtube.com/watch?v=McRGRD4lQY4]Early Run of My V-Twin model Engine by Terry Mayhugh - YouTube[/ame]

I was really lucky on that one - too dumb to know better I guess. When I got to the V4 I paid my dues doing and re-doing the ring fit and valve seating that I evidently lucked out on with the V-twin. I like to treat these big projects as a collection of small self-contained projects that get integrated together at the end. Otherwise a 2 year project would just be too overwhelming. But I end up testing and playing with each subassembly so much that the whole project takes even longer. I'm not sure how I'm going to like doing nearly everything 9 times on this radial. I tried to get Lee to sell me a set of plans for the 5 cylinder version but he really worked to discourage me to stay with 9 cylinders, and so here I go.- Terry

[dsage]

Wow !! You did a rellay nice job on that too. Especially for a first engine. You certainly have a nack.
Sounds really good. Are you using the TIM circuit for it as well. It's tough to tell on video but looking at the LED (which I assume is on the Hall sensor) I detect a miss that seems to correspond to the led also not flashing. Pehaps some adjustment required?

What are you driving with that nice wide belt. It looks cool.

Great job!! I'd like to see them both live.

As for making multiple parts, as you probably already figured out the first one or two take all the time. In most cases it's a pain to make just one part. The next few are easy once you have the setup. One approach is to make two engines at once. Then you can sell one and make a few bucks to offset the costs. Not something I've ever considered but a friend in my model club is currently making a 9 cylinder radial and a spare. I've forgoten the engine name but it's one of a larger scale.

BTW - do you do your own anodizing? I see the cylinder fins are black. I do quite a bit of anodizing here with good success.

Dave

[mayhugh1]

Dave,
I used the TIM6 also on this. It fact it uses two of them. The faux transmission housing just hides the big out-of-scale ignition coils and the fuel tank. I put a pair of belts driving a dummy pulley on it to simulate a primary drive just to give the engine something to do. I get a lot of questions about it though. I have an electric fuel pump that pumps fuel upto the bowl and maintains a consistent level through a re-circulating fuel line. I was going to do the same thing for the V4 but decided I'd try gravity feed because I hadn't done that before and because it is pretty simple.
The paint is a baked on Gun Kote paint available from Brownell's. Its often used to finish gun parts. It is good for something like 500F if I remember.
The single pin crank design has a natural lope that's a lot more obvious with the V-twin than with the V-4. Plus the V-twin will idle at a much lower rpm - something like 700 rpm - than the V4 and that accentuates the lope. I also have a timing led on the V4 but its not visible on the photo I took of the V4. Its real handy for setting/checking the static timing.
- Terry

[dsage]

Thanks Terry:
What did you use as a fuel pump? I was considering that apparoach as well. One question though - being that it does take at leat a bit of pressure to raise the fuel from below up to the carb - even of the fuel does pass right on by back to the tank - doesn't it cause dripping at the carb?
In the end - like you said - I opted for the simpler gravity feed. I generally don't like having a fuel tank visible and distracting attention from the engine so I have a very small stainless tube tank. The problem is the engine only runs for a minute or two on the quantity of fuel. (The V8 sucks a lot of gas).


Dave

[mayhugh1]

Dave,
I bought a fuel pump at at hobby store used for pumping fuel from a container to the fuel tank on a model airplane. I removed its housing leaving a 6V dc motor coupled to a fuel proof pump. I then installed this under the base of the display. This recirculating system keeps a small thimble-size capped container up near the carbs (the v-twin uses 2 carbs) full of fuel. The fuel level is a bit below the carbs so that carb vacuum is need to pull the fuel into the carb. There's no splashing until the fuel take runs out of fuel and then the fuel pump starts pulsing the remainder of the fuel and air and some dribbles out of the vented cap. I think a really great approach would be to integrate the tiny container into the carb and make it look like a carb fuel bowl. Then all the ugly stuff could be concealed. This didn't occur to me until after I had already built the V-4 carb or I would probably have it for that engine. I might do it on the radial. It also uses the Jerry Howell carb. - Terry

[dsage]

When I met Jerry at Cabin fever the winter before he died he had mentioned that he had a pump mounted below etc. etc. but I never could see what arrangement he had up at the engine. Perhaps what you have done is the same as he had. In any case it's a great idea. I wish I were so clever.

Good luck on the radial. Keep me (us) posted.

Dave