Just finished my Howell V4

[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

[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