Slow progress on two-cylinder hemi
 

The billet Moldex crank was cracked in #2 rod journal and #3 main journal. Rather than throw all of it away, I cut out the bad section and adapted two 1350 series U-joints as a connection between the two end cylinders. After beating up many carbide toolbits machining the cranks and U-joint yokes, the bottom end is finally together.
Cylinder walls were beat up from detonation- had to bore/hone to .028" larger. So now I'm waiting on new pistons to be made.

Just crazy! Seriously outside of the box thinking!

Will be interesting to see how well the U-joints deal with torsional/harmonic vibration. Clever solution and hope it holds up!

Jack what is going to absorb the thrust of the foward section of the crank?

Also are you running no Dizzy ?

Wow. Amazing. Just for curiosity. How did you come up with this idea, and how are u joints fastened to crank? T.hanks

Wow! That's some impressive work Jack.

You didn't think outside the box you put the box in a shreader and said ok lets start..

Jack,dry sump?Hope you have a total engine blanket!Tom

Just curious WTH are you making here? Back in Tech school I helped the automotive teacher build a V-2 SBC. Everything was cut n welded. (circa 1987) IIRC he made 105 hp around 90 ft/lbs @ 4800. got almost 28 mpg in his CHEVETTE. FWIW that's almost twice the HP and torque of the little isuzu 4 banger in the shuv-it WITH +10 on mpg.

I would love to see some better focus, different view angles of the U-joint/crank/bottom end solution. Best of luck with the rest of the build. Mickey Thompson 2.0 !

Whats the power stroke management going to be like?

i see the 2 crank pins look aligned

a big one cylinder firing or 2 consecutive power strokes or evenly staggered

The connection between cranks is fixed length, so thrust is taken in the normal manner at #4 main.
The magneto drives off the rear of the exhaust camshaft..
The connection to the cranks is by TIG welding to U-joint yokes, after center-drilling for alignment dowels.
Yes Tom, dry sump- with separate systems for bottom and top end of the engine.
Sorry Mike- my shaky hands prevent in-focus high-resolution images!
It will be an even-firing twin. Any other arrangement would not allow use of the existing DOHC camshafts ($3,200, custom-created from billet).

Mickey preceded me with his two cylinder Pontiac back in the early sixties- half of a Tempest four. But it wasn't hemi-headed nor DOHC!

Mike- a slightly better photo, without the huge main caps blocking the view. This was a mockup prior to welding, so it doesn't show the weld bead that joins the two center yokes.
There isn't any center main bearing, but the cap will be used to help strengthen the block.

U-Joints are up to the challege. Just perforate their seals to let em get oil. Rotational balance seem correct.

Power balance pairs, for a fully populated V8: 1&6 8&5 4&7 3&2.

Power Balance for 1278 population, wrongly ASSUMING stock cam lobing & dizzy wiring:7218-0000-7218. Maybe power balanced, i dunno, but the 1-rotation no-power gap will be a very interesting idle and acceleration experience.

Light vehicle will allow a stock front damper.

A new twist to "Half a V8". Liking it.

Re-read the "even-firing twin" : power-Balance achievable depending on 2=7 power, and 8=1 power. I think to assume the Cam will have a "cut&reclock" for 2=7.

Will this be like a Harley da-dut....da-dut idle?

Oh funny, the u-joints allow 90* clocking flexibility.

Just throwing this out. I have always been told to not run u-joints completely straight (they need an angle or bend in them). Will this be an issue?

Thanks for the better pic, Jack. Was I seeing a couple jack screws in the block to help support the #2,3,4 mains? Or was this part of the weld fixture? What's the induction system going to look like on this new configuration?

Jack that’s f**%g amazing!

That is truly a concern. I can only hope that the small amount of run time will minimize it. LTA is down to just one event per year now. And as old-and-feeble as I'm getting, I don't foresee many more years.

Mike- you were probably seeing the threaded rot which holds the cam bore plugs in place. They are a light press fit to strengthen the empty cam bores, but I didn't want to worry about them moving out of place, since they also close off the cam oil feeds.
The Hilborn 4-port and scoop will look the same on the outside (except 2 hoses missing!), but I've fitted an internal plate to block off the rear two ports. The "big empty box" manifold doesn't really care where it's fed from.

That all makes sense. When the engine is finally ready to fire and make noise, there are plenty of people on here that would love to see and hear a video of that little beast running. Best of luck with it.

Them U-joints will be fine, for the duration. If not then go back into it after awhile and upgrade em;

Particularly fine if them needles are replaced with brass or hard steel sleeves.
They wont flat-spot, Oil film or not. Load Reference: Rear Diff spider pins to spiders and case.

I was thinking about those universals ... correct me if I'm wrong, but doesn't the typical U-joint, after the torque multiplication of the gearbox handle a lot more torque than the crankshaft as a whole?

I know the shock loading would be way different, but sure seems like a U-joint would handle the torque. Not something I would have ever even considered, out of the box for sure.

"Shock" certainly seems like the greatest concern here. Maybe the magnitude of a "shock" is no greater than a driveline sees, but the number of shock events will be thousands (millions?) of times worse.

i've been to four county fairs and a decent number of *ss-kickin's - and I have never even thought of something like this. WELL DONE!!!!

These guys copied your idea Jack! Don’t think it’ll see 10,000RPM though . . . .😜

https://forums.maxperformanceinc.com...1&d=1737138496

My press would have a problem working with those u-joints!

Total Seal just (finally!) shipped my rings, so I can gap them and begin assembling the hemi-twin.

The nuts on those flanged tip the scales at over 55 lbs!

Rings gapped (Total Seal, Gapless 2nd), pistons & rods installed. Torque to rotate is under 20 INCH pounds! [Lots of Torco assembly lube, and cylinder walls micro-honed to near-mirror finish; Smoky Yunick would approve!]
Head (with copper gasket and O-rings) and DOHC base plate installed and torqued.
Now upside down on stand, installing piston squirters and crank scrapers and windage screen.

Can you share some photos?

X2 on the photos! I have a folder with about 25 pics of your 4-cyl version and some pics of the car too. The folder is titled, "Jack Gifford wild DOHC Pontiac"

The twin is coming together. Dial-indicating the two pistons shows them to be together at TDC within half a degree!
The blower manifold can't be in place when installing engine in the car. Which means that I need to decide whether to test run it before installation. I know I should, but the support systems (oil, fuel, coolant, gauges, etc.) are such a hassle.

Beautiful work that's to be proud of Jack!

Jack, simple AWSOME!

It didn't take me long to decide to test-run it before installing it. I fixed a couple of coolant leaks yesterday, and then realized those fixes would have been almost impossible in the car!

Good thing you did that.
Time well spent!

Were those leaks fixed during a run-in? Or just during inspection and fill? If it ran, how did it do?

The coolant leaks showed up by just applying small pressure to the block/head coolant passages.
Still some work to go to test run it- starting with reorganizing the clutter in the shop.

That makes sense. Also way much mess if there is a leak. Look forward to more updates.

Getting closer to test-firing the hemi twin. What a rat's nest of plumbing and wiring to support it!
Only missing the blower belts which should arrive in a few days. However, I might wait until this bitter cold weather quits, since I'll need the overhead door open.

This is how to slow a blower down to 19% of crank speed!

it's going to be seriously out of balance with the torsional loads only on far ends of the block.
take a regular Pontiac V8, pull the middle 4 spark plug wires, start it up.
or better yet, take the old Pontiac 4 cylinder half v8 engine, pull the middle spark plug wires,
start it up.
those ran wobbly rough as schit even with all 4 cylinders firing brand new,
like they had a constant miss.

that's how it's gonna run.

the drive shaft connection is like going to hell to light a match,
why not just put a regular crank in, and remove all the pistons/rods you don't want to use ?
you're reinventing the wheel but making it square to see how it rolls
yes you can sit on a rocket, light it, and go really fast like the cartoon Coyote
would you really want to do it though ?
it's a great thread attention getter, but that is engineering silliness.
there's an old saying, you can't make chicken salad out of chicken schit...
and you can only polish a turd so much...
no offense intended, just being honest.

sure it will make HP. I can put a blower on a Yugo 4 cyl it'll make tons of power too.
why bother ? build a real V8 hemi with those heads dude !

Jack has been building and RACING Pontiac Hemis for years!He has nothing to prove with a V8 or even a 4 cyc Hemi!Tom

Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons?
... or has built a record breaking DOHC hemi four cylinder Pontiac?
... or has driven a couple laps of Nuerburgring with Tri-Power Pontiac power?(back in 1967)
... or has a Pontiac born the same year as Jim Wangers? (1926}

“it's a great thread attention getter, but that is engineering silliness.
there's an old saying, you can't make chicken salad out of chicken schit...
and you can only polish a turd so much...
no offense intended, just being honest.”

Nice work good Jack. Your engineering silliness is outstanding! Looking forward to hearing how it runs. Mickey would love it!

So am I.:rolleyes:
I don't know about producing power, but I'm guessing it will SOUND even nastier than the four did. CR is up to 12.8:1 (from 12.4), and cranking compression is 180 and 170 PSI prior to break-in (was in the 150's for the four).

Finally got a good test run of the twin today. The tune is close enough to see A/F ratios in the ballpark- 4.8 to 5.4 with a throttle hit. No unusual vibration or shaking. So I'll start re-installing it, shooting for the July event in Loring.
Strange- how the exhaust doesn't sound like a twin, just sounds mean like the four did! And totally unlike my odd-firing John Deere.:rolleyes:

Very good to hear Jack!

I hope all goes superb for you.

Glad to hear it's running, looking forward to seeing/hearing any videos of it. Nice job!

Great to hear it's running once again! Pics and/or video please. Like keeping up with your progress.

I had always installed just the long block into the lakester, then did the cramming of all else. With the engine/drivetrain assembled from the test run, I decided to try installing it "whole". Only a couple pieces needed removal, such as the exhaust which protrudes out through the frame rails. Modifying some points of interference took me about three days, but it's now bolted in place. Adding fuel and oil tanks, plumbing, wiring, linkages, etc. will take at least a few more days.