Overhead Cam "356" Packard engine

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Dave Czirr
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Overhead Cam "356" Packard engine

Post by Dave Czirr » Mon Oct 07, 2013 5:32 am

I have a very clever friend, previously on CCCA's Classification Committee, prior owner of 2 Packard Twelves,who is a very talented designer & machinist. He is working on making an overhead cam conversion of a Packard 356 engine. Though I'm all into authenticity, I thought some of you might find this project interesting and I have no doubt he will ultimately bring it to a successful conclusion. His description of his plan is attached, and he promises some photos as he progresses.

To all,
A few of you are aware that I have embarked on another automotive “science project.” This project is to create an overhead cam straight eight using a mixture of Packard, Dodge and probably Ford parts, combined with many parts of my own fabrication. The original plan to use the crank, rods, oil pan and the lower half of the Packard block and to fabricate the “cylinder block” has been scrapped because there is insufficient thickness of the crankcase at the area where the new steel cylinder section was to be attached. Subsequent investigation of the bare Packard block and consultation with knowledgeable “Rodders,” led to the conclusion that it is possible and practical to deck the block .080” and add a deck plate with a thickness of .250’’ to .280” to provide some additional combustion chamber volume to keep a compression ratio between 9 and 9.5 to one. The 7/16 – 20 studs that secure the head will still be anchored in the Packard block. The new cylinder head created from two right side Dodge truck/Jeep Cherokee 4.7 liter engine cylinder heads combines well with this approach. A prototype camshaft to deal with the Packard firing order appears to be an easy project. It is likely this cam will be usable, but I will probably have one manufactured by Crower. The Packard crank has a 4.625 inch stroke and the plan is to use 3.58 inch pistons in the block with the deck plate and sleeves. This results in a displacement of 372 cubic inches for this engine.
In the Dodge engine, the 1:2 reduction of crankshaft speed to camshaft speed is accomplished through the use of an idler sprocket driven by the lower timing chain, then two upper chains turning 1:1 with the idler, drive the two camshafts as used in the Dodge/Jeep V8. I will use the Packard camshaft and timing chain to drive the oil pump and distributor, providing the 1:2 reduction from crankshaft speed, and then drive 1:1 from the Packard camshaft to the fabricated cam in the eight cylinder head. I expect the timing cover fabrication to be a rather complicated project. It appears a Ford 300 inch 6 cylinder water pump, fitted to a fabricated housing and manifold, can easily be used to feed coolant into the block through the three core plug holes. The intake manifold will be fabricated from aluminum and will probably have a changeable flange to permit different carburetor options. The exhaust manifold (two maybe) will be likely fabricated from butt weld fittings as was done on my Chevelle. The camshaft/valve cover will be an aluminum weldment. The Packard distributor, will be used in some form. I anticipate using the Packard bell housing and flywheel with an adapter plate between the bell housing and my choice of transmission which has not yet been made.
The selection of vehicle will be made later, but is likely to be “THIRTYISH” in style and dependent upon available choices of vehicles at that time.

wilkinson92
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Re: Overhead Cam "356" Packard engine

Post by wilkinson92 » Thu May 01, 2014 9:23 am

Fascinating.is the project still going? I'd love to hear more about this

Dave Czirr
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Re: Overhead Cam "356" Packard engine

Post by Dave Czirr » Thu May 01, 2014 10:57 am

Yes, the project continues to move forward. I'll try to get an update from the person doing the work.

Dave Czirr
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Re: Overhead Cam "356" Packard engine

Post by Dave Czirr » Wed May 07, 2014 7:00 am

PROJECT UPDATE, 2/24/14
The first step of preparing the Packard block to accept modified Dodge heads was using a pair of Dodge head gaskets to determine the “match-up” problems between the head(s) and block. The cylinder spacing of the block is 4.125”, except between cylinders 4 and 5. An additional .325 inches between centers exists here, another .5” would have been even nicer. The cylinder spacing of the Dodge heads is 4.07”, not perfect, but workable to proceed with this project. By aligning the center line of the between cylinders 2 an 3 of the “front “ head with the center line between the cylinders 2 and 3 of the Packard block, the off center misalignment of the combustion chambers to the cylinder bores is only .0275” and for cylinders 1 and 4 the misalignment is only .0825”. The diameter of each of the combustion chambers is less than the stock Packard and certainly less than the intended new bore size. The same condition exists comparing the “rear” head with cylinders 5 through 8. The first issue to be dealt with is that the head bolt holes on the intake side of the head(s) align almost perfectly with water passage holes on the Packard block. Go to attached images IMG_1482 and IMG_1483 and notice these holes have been plugged, drilled and tapped. Solid steel hex head ½ npt pipe plugs were used for this purpose, with loc-tite applied and torqued to 82 lbs. ft., then trimmed flush with the block deck. Head studs, 7/16-20, will eventually be placed in these holes using permanent loc-tite to secure them. The head bolt holes on the exhaust side of the head(s) align with locations suitable to be drilled and tapped. The center front to read row of head bolt holes in the Packard block align well with coolant passages of the Dodge head(s). To enhance the coolant flow these holes have been drilled out to .5 “. Close examination of this image reveals some additional, smaller, coolant holes drilled in the block and a few smaller holes plugged.
The upper section of the valve guides, those which protrude into the valve port in the block, have been machined away. Six of the Packard valve recesses will be used as conduits for oil return from the heads into the Packard lifter area then draining into the oil pan. The six conduit ports will be sealed with welsh plugs, and all of the ports of the block will be sealed with a block-off plate on the passenger side of the block. A deck plate between the head(s) and the block will be permanently attached to the block and seal any area of the block deck not covered by the head(s). The final thickness of this plate is subject to details yet to be finalized, but will be between .200 and .300 inches after attachment and final deck machining. I have been advised by John of JandM Machine of Southborough, MA, that cast pistons supplied by Egge Machine may not withstand a 9:1 compression ratio. I will be investigating having Ross Pistons supply a custom set for my purpose.
The machining operation to prepare the two Dodge cylinder heads to become one head was one of multiple cycles of cutting and fitting and cutting again. Both heads were repeatedly fixtured to the Bridgeport table for a “little more” stock removal as I re-envisioned how the mating surfaces must be sized and shaped to assure the combustion chamber center spacing between cylinders 4 and 5 equaled 4.125+.325+2(.0825) inches. Each head had five stanchions with bearing caps which serve as camshaft bearing pedestals. The oiling system to the moving parts of each Dodge cylinder head assembly is quite extensive. In original application on a Dodge block, pressurized oil reaches the head passing upward through oil passages on the inside of the block “vee,” connecting with a 5 mm hole on the head gasket surface of each head. This oil hole is adjacent to the middle head bolt on the intake side of the cylinder head. A short channel connects the oil passage to the 13.1 mm hole through which the M11 cylinder head bolt passes as it is threaded into the engine block. At about 25mm up this hole, another 5 mm hole intersects, becoming the passage to carry pressurized oil to the central horizontal oil gallery running the length of the cylinder head. This gallery is a 10 mm blind hole “gun drilled” from rear to front for the length of the head. The rear of this gallery in the head is drilled, tapped and plugged ¼ NPT. This gallery feeds this “posts” in which the hydraulic valve silencers are located, feeds the camshaft bearing pedestals, and also feed spray holes aimed at the rocker arms linking the cam lobes to the valve stems. The machining necessary to the front of the rear “head,” and necessary to the rear of the front “head,” has caused the need to weld the mating (middle) ends of the galleries closed to prevent oil from possibly leaking into the coolant passages of the newly created 8 cylinder head. This means the rear oil gallery must be fed from the rear of the new head and the front gallery must be fed from the front of the new head. This will be achieved by the use of two ¼ inch steel lines, each tapped into the block’s main oil gallery located on the passenger side of the block. This gallery is already drilled and tapped at each main bearing web location as a result of the need to connect this gallery to the Packard camshaft bearings. To feed the front head, I drilled the front “head” open at the front of the gallery by entering the gallery from the rear with a long drill bit. The new opening was drilled and tapped ¼ npt for the front oil line fitting.
The 8 cylinder head will have nine camshaft bearing pedestals, the front pedestal of the “rear” head” was removed during the machining process. Attached images IMG_1459, IMG_1460, and IMG_1461 show the mating surfaces prior to the cleaning of the castings and before the welding process needed to create an 8 cylinder head. Image IMG_1471 shows the gasket surface of the new head between cylinders 4 and 5 before welding. Image IMG_1471 shows the gasket surface of the new head viewing all eight cylinders. The front two head bolt holes of the rear “head” are partially machined away to achieve the necessary overall head dimension.
The most critical part of this project is assuring perfect alignment of the camshaft bearing bores of the nine pedestals. The bearing caps are numbered and marked to show which side of each cape must face front. The pedestals and the caps are themselves the camshaft bearings. The bearing bore is 1.025 inches, and the camshaft journals are 1.023 inches in diameter. A three foot length of 1 inch drill rod combined with “bearing inserts” made from .012 thick aluminum flashing, and torqueing the cap bolts to specification is the primary fixture for aligning the casings for welding. A length of angle iron drilled to match the location of the nine intake manifold bolts is a second fixture. Likewise, a length 3/8 thick cold rolled flat stock attached to the exhaust side of the head by the exhaust manifold bolts is the third fixture. Lastly, a 36 inch piece of 6 inch wide, ½ inch, cold rolled flat stock is the base to which both “heads” will be bolted for additional alignment. Each of the last three fixtures can be removed when any one of them interferes with the welding operation once some of the welding has been performed and only one fixture is removed during any welding process. There should be no need to remove the drill rod fixture until all welding has been complete and the new head has normalized. Images IMG_1446 and IMG_1449 show the drill rod resting in the bearing saddles of the two halves of the head positioned atop the Packard block.

Dave Czirr
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Re: Overhead Cam "356" Packard engine

Post by Dave Czirr » Wed Mar 11, 2015 6:36 am

Link with more explanation and some photos.
Posted with permission from the copyright holder.

https://rlg0613.wordpress.com/

Dave Czirr
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Re: Overhead Cam "356" Packard engine

Post by Dave Czirr » Thu Apr 23, 2015 8:49 am

A recent status photo.
Attachments
SOHC 356 copy.jpg

bobhattler
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Re: Overhead Cam "356" Packard engine

Post by bobhattler » Wed Sep 23, 2015 1:51 pm

Dave has anyone boosted horsepower on Packard engines without so much expenditure? Realizing Packards are not hot rods, I miss the acceleration and passing capabilities of my 300 HP cars. Can the 282 be boosted?
Bob Hattler

34PackardGuy
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Re: Overhead Cam "356" Packard engine

Post by 34PackardGuy » Wed Sep 23, 2015 2:26 pm

Ross Miller is perhaps the best person to answer that; he doesn't visit here often so you might want to give him a call. The 282 in his little speedster is pretty hot. I'd guess you can get another 10-15 hp by doing a good porting & polishing job and raising the compression ratio a bit but I suspect the trade-off beyond that would be loosing Packard's legendary smoothness.

bobhattler
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Re: Overhead Cam "356" Packard engine

Post by bobhattler » Sat Sep 26, 2015 3:45 am

The engine redo has been completed so any more tear down is not available. I had a flat head Ford, we added headers and dual carbs and were able to increase the top speed until such time a valve hit a piston, as the springs were not replaced with heavy duty ones and we experienced valve float with disastrous results.

JWLawrence
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Re: Overhead Cam "356" Packard engine

Post by JWLawrence » Thu May 12, 2016 10:09 am

Bob, how did a valve hit a piston in a flat head engine? Did the valve head come off? Otherwise, can't see how this happened. Just curious.

(o{}o)

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