[Jack Gifford]

Bringing this back to the top, after reading the Jul'12 issue of Hot Rod. Second part of their "Early Hemi" article includes a chart of flow data for various heads- which I had never come across before. It turns out that Mickey designed a KILLER exhaust port into his heads! Jim measured as much as 277 CFM @ .625" lift for a stock exhaust port of my head (I had merely blended the bowl after installing a seat). This is more flow than any exhaust in the chart- even the modern aftermarket Hot Heads "race port" exhaust is only 267 @ ,800" lift!

[Steve Barcak]

Originally Posted by Jack Gifford

Bringing this back to the top, after reading the Jul'12 issue of Hot Rod. Second part of their "Early Hemi" article includes a chart of flow data for various heads- which I had never come across before. It turns out that Mickey designed a KILLER exhaust port into his heads! Jim measured as much as 277 CFM @ .625" lift for a stock exhaust port of my head (I had merely blended the bowl after installing a seat). This is more flow than any exhaust in the chart- even the modern aftermarket Hot Heads "race port" exhaust is only 267 @ ,800" lift!

Yes, it is a great head design. Neat stuff.

[johnta1]

Is there a link to that chart, Jack?

Here is Stan Weiss' charts on head flow:

Head Flow Chart

[Jack Gifford]

John- the chart I mentioned was in the Hot Rod article, page 84 I think.
Wow, the Weiss site shows about a million hemi heads! I'll have to look that over "at my leisure".

[Jack Gifford]

Originally Posted by Steve Barcak

... great head design...

Not disputing that, Steve, but I was talking strictly about the exhaust port. I'm guessing that Mickey assumed that most of his heads would get a blower on top, so he went wild with exhaust capability.

[Jack Gifford]

Some DOHC pieces taking shape...

[misterp266]

Glad to see you're making progress Jack. Thank for sharing!

Rob...

[Jim Robertson]

Those are some interesting parts Jack. Glad you posted the progress. Neat engineering going on there. Will cams be totally one off or did you find an OEM core with lobe and journal centers you could use? What are the approximate lobe lifts and durations you are planning?

[Jack Gifford]

Hi Jim! Cams will be made from Pontiac billets, with only four lobes being utilized on each cam. The front four journals will be unaltered, using Pontiac cam bearings. The rear of the cams (#5 journal and gear) will be cut off and the rearmost lobes turned round to serve as small-diameter journals running directly in the #5 cam stand (with provisions to drive the dry sump pump and magneto, directly out the rear). #1 stand is 1" thick 7075-T6 (due to extra load of drive belt) and others are 3/4" thick 6061-T6. #2/#4 journals will have the old-style drillings (which Pontiac used for short-duration timed oiling of rocker studs)- I've built #2/4 stands to direct this time-metered oil to the pivot balls of the cam follower fingers (in which I'm using Isky EZ-Roll wheels/axles, to avoid needle bearings). For max valve lifts of not more than about .650" (based mostly on your flow data), lobe lifts won't need to exceed .325" (followers are just a whisker under 2:1). I'll use lobe profiles very similar to what's in my V8 hemi- 280-something degrees @ .050", "gentle" accelerations, max power up around 8,000 - 9,000 RPM.

I made this task much more challenging by requiring it to all fit under a normal M/T hemi rocker cover (other than cam snouts/seals protruding out the front of the cover, and ports/seals out the rear for pump/mag). I'm happy, though, with the way I've worked out the oiling distribution so there will just be a single NPT port in the edge of the 1" base plate to plumb from the oil pump. That will leave only crank oiling to occur in the block.

[Tom Vaught]

Good idea adding the EZ-Roll wheels and axles to the system. They should live forever and keep the friction down to a minimum.

Are you going to use a Spud shaft in the normal camshaft location (like SOHC Ford) and drive the cams that way? Also to sync the intake and exhaust for each bank are you using the small "companion" chain to transmit drive force from the primary cam to the secondary cam? Or are you going to try and do it all with one long chain? Not the best idea in my mind. 4 Valve Modular Engines offer some nice engineering ideas on that deal as well as chain adjusters that are very durable material to support the back side of the chains.

Tom Vaught

[Jack Gifford]

Nothing will be in the original cam location.
Answer to the cam drive question is 'yes'... I'll do it one way or the other.
Only one bank, Tom- inline four cylinder.

[Tom Vaught]

Forgot about the 4 Cylinder deal Jack, sorry about that.

Should be the baddest Pontiac 4 Cylinder of all time.

There still are some 4 cylinder Bonneville records that are waiting for you to break.

Still think that a small "companion" chain would work great and be easy to degree in if you could make it work. We use oil driven or electric "camshaft phasers" these days to move the cams where we want them in the performance curve.

Tom Vaught

Tom Vaught

[Jack Gifford]

Originally Posted by Jack Gifford

... there will just be a single NPT port in the edge of the 1" base plate to plumb from the oil pump...

Oops! I just added a second port near the other end of the baseplate. In typical cart-before-the-horse fashion, after layout/fabrication of many of the pieces I finally did some calculations of worst-case oil flow (loss) from cam bearings/journals; feeding all that oil through a single port would have been marginal at high engine speeds.

[Jack Gifford]

Yeah, this is an old thread; but so is this project- four years since I bought the lakester and started scheming a killer DOHC hemi four-cylinder to power it. [I'm definitely getting even slower, the older I get!]

I've actually accomplished quite a bit, but I find ways to extend the completion even more. Some progress to report on my full-circle-style counterweight scheme (magnesium alloy segments to fill in the spaces between leading- and trailing-edges of counterweights). The goal isn't so much for eking out more power, but to reduce aeration of the oil, as I'm building the engine to run up to 10,000 RPM for longer periods than my hemi V8 used to run in tractor pulling (a number of minutes vs. 10 - 20 seconds). The first step is to spin-test a sample of my design (to about 12,000 RPM) to prove its validity. I've built a housing that I hope is explosion-resistant and machined a replicate of one of the crank's webs (already got the Moldex billet crank, to take dimensions from). It took forever to get my hands on a sample piece of Elektron-43, a new-age high strength magnesium alloy (~49 KSI tensile). The sample finally arrived last week and I'm close to finishing the machining of one sample filler segment. When that's done, it will go to the balance shop, and then it will be destruction-derby time!

[Elarson]

Have you calculated the centrifugal force that will be trying to liberate your magnesium filler pieces? I've done some rotating disk design and I'm curious how you'll attach the filler pieces?

I've done some calculations on containment cases too. How much will the filler weigh ?

Eric

[Jack Gifford]

Eric- thanks for your interest. I've only done "ballpark" design- calculations based on center-of-mass of major segments of the fillers (center portion, end portions, etc.)- no finite element analysis, nor integral calculus of varying-cross-section portions. At the mean radius of the filler, the radial acceleration is 8,500 G at 10,000 RPM. My calculated weight of a filler is about 6.4 oz.- I'm real close to finishing the machining of the test filler, then I can weigh it. Using these ballpark numbers the stresses at the attachment points (at the worst-case locations and directions) are within the yield values of the Elektron-43 at 100 degrees C, although not by large amounts.
I've done no calculations of stresses due to accelerations other than radial (angular and longitudinal) because I don't have knowledge of representative values of these accelerations. I've seen titles of some SAE papers that might offer this insight, but I don't have an SAE membership. My "gut" feeling is that they are a couple of orders of magnitude less than the radial 8,500 G; if so, then they won't be a problem. Of course, the "best laid plans of mice and men" are subject to failure due to harmonic motion!

Disclaimer: I've only said that I'm determined to explore this scheme; haven't said that it's assured of success...

At this point, I'm more concerned about what the V-belt on the test setup will do at 150 ft. per sec.! I've built a sheet metal shield, but might decide to beef it up some!

[Elarson]

Attaching the filler will be the key to success/failure. Watch carefully the center of gravity in the axial direction. If the C.G. is offset from your attachments, it will cause a moment that can distort parts. I participated in an "autopsy" of a rotating disk with blades (running in a test lab). The G-forces had caused the blade retainers to twist and come unseated...causing complete destruction on the test rig.

My Dayco handbook indicates that they like v-belts to be limited to 100 ft/sec. You've correctly defined another area where you're pushing the envelope.

Eric

[Jack Gifford]

The finished filler segment weighs 7.0 ounces. Need to get it to the balance shop, then it's show-time!
(A friend suggested putting name/address on the parts, with a request to "return fragments to owner")

[twooldgoats]

Originally Posted by Jack Gifford

.....
(A friend suggested putting name/address on the parts, with a request to "return fragments to owner")

With friends like that........

Good luck, Jack!

Jim

[Jack Gifford]

Dang... gotta' wait while the balance guy finishes up mundane balance jobs- Mopar 440, SBC, etc.