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Heads Up!
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1. Heads Up!
1. The 54cc heart shaped combustion chambers of the Edelbrock heads precisely match the quench zone and shape of the Diamond pistons in the block. Our 10.75 CR and ability to run on pump gasoline could not be realized without this combination. With “Dog Leg” exhaust ports and CNC machined intake opening, these heads are ready to run out of the box with 2.02 intake and 1.60-in exhaust valves installed.
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2. Heads Up
2. Remember to follow the torque values and sequence laid out for you by the manufacturers. Edelbrock supplied the sequence and we used ARP’s 110 lb-ft final value.
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3. Heads Up
3. With the Proform timing cover attached and sealed, we used Summit Racings Balancer installation/removal tool to slip the BHJ balancer into position.
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4. Heads Up
4. An Edelbrock water pump with a cast impeller found its way onto our motors snout.
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5. Heads Up
5. The Speed-Pro oil pump gears were slathered in AMSOIL assembly lube before being slid home for the final time. We checked for proper clearance between the gears and housing cap with Plastigauge. Between .002-in and .006-in measured from the end of the gears to the cover is preferred. We were just fine with .003-in.
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6. Heads Up
6. The Canton Racing pan is a stout unit with many additional features to alleviate oil starvation. With long duration, high rpm hill climbs, this is a much bigger issue then many would think in a 4X4.
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7. Heads Up
7. Many will deem this unnecessary if you are pre-lubing an engine before start-up, but we still like soaking the lifters overnight to sop up all the oily AMSOIL bearskin goodness they can.
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8. Heads Up
8. With a dab of sticky assembly lube on the foot of the lifters, they are dropped in place and drenched with more oil.
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9. Heads Up
9. The reason for the altered length pushrods is to insure that the roller tip of the rocker contacts the center portion of the valve stem so it doesn’t assert a lateral force on the valve. This would create premature wear of the valve guides and excess friction. You can see by the marker line in this picture that the rocker tip stays in the center of the valve stem.
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10. Heads Up
10. With the rockers installed and lubed, you “can” set valve lash (ours was 0 lash plus ¼ turn) but this is best done once the motor has had oil circulated through it to pump up the hydraulic lifters.
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11. Heads Up
11. Redneck oil bath.
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12. Heads Up
12. 12-point ARP intake bolts make it easier to get a wrench in to tighten them and they fit our “metal” theme.
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13. Heads Up
13. This area is known as the “China Rail” and normally has a gasket to seal it off. Throw that gasket as far away from you as possible. They are evil and leak. A good layer of RTV will last longer.
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14. Heads Up
14. We deviated from Edelbrocks recommended use of their gasket set because we could not get the boltholes aligned with the extra gasket thickness. With a block that has been to a machine shop a few times or has a 0-in deck height, this will work. We just used a standard AMC valley pan gasket set.
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15. Heads Up
15. It looks messy and is, but the best way we have found to seal an intake manifold on a V-8 is a combination of Permatex Right-Stuff and Aviation Gasket Sealant.
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16. Heads Up
16. A DUI “dizzy” dropped right in. We did not put the plug wire, plugs or other accessories on at this time as it will all have to come off to get the motor pre-lubed and mounted on the dyno for next time.
Story & photos by Bryan Irons
Merican Metal Menace buttons on some heads
Our vehicular request for silly amounts of torque and a smooth idle on pump gas are almost ready to be realized. The remaining steel bits adorning our shop floor include the heads, front cover assembly and induction system in preparation for a lashing on K&S Machine’s engine dyno. The 407 CI AMC V-8 has given us very few issues to this point proving that quality components and methodical work can certainly pay dividends, even when performed by meatheads like us. A few specialty tools are required at this point, including an engine builder kit from Summit Racing, modified it to our exact needs… not everyone rebuilds a small block Chevy… yawn.
ARP hardware has been used thoughout the process thus far and we’re not going to stop here. We could have easily gotten by with their head bolt kit, but the added clamping force of head studs when combined with future power enhancers is insurance we will gladly pay for. The studs allow for better gasket alignment during installation and assert more vertical force on the hardware rather than a twisting force associated with bolts. The aftermarket heads we chose have some design changes that requires different length studs for two locations per side. Proper length hardware is included, but we picked up some correct ARP studs from K&S machine (our machine shop) so we are not mis-matching materials. Even if you don’t require the added strength of the studs, the sinister “race motor” look is undeniably “bad ass.”
Factory iron heads for the AMC blocks came in many designs and sizes. Back during our teardown, we found a set of large chamber, late 70’s 360 “dog leg” heads saddled to the motor. The valves were burnt and guides had more slop then a feed bucket. Edelbrocks Performer RPM 401 heads were the perfect choice for us. Features like rocker studs with guide plates, 54cc combustion chamber volume and flow numbers that blow any of the factory units away make for a great starting platform. We say, “starting” because there can be improvements made with some smoothing of the intake and exhaust ports if you wish. The ports are CNC gasket matched from Edelbrock, so we felt comfortable bolting them on in “out of the box” form. They come assembled with springs set up for flat tappet hydraulic lifters, but it is best to check with the camshaft manufacturer to ensure the spring rates and lengths are within spec. Comp Cams gave us the green light.
Squished between the heads and block are Edelbrocks recommended head gaskets made by, well, Edelbrock. We used the crushed thickness (.045-in) in our calculations to achieve our 10.75:1 static compression ratio (CR). We went as high as we thought we could get away with on pump gas and used our camshaft selection from Comp Cams to achieve a dynamic compression ratio of 8.93:1. Should this prove futile, a thicker gasket can be swapped in to drop the CR slightly, or a camshaft swap will be required. With fastener lube and a torque wrench set, we followed the recommended torque sequence and settings to clamp it all down.
AMC used a horrifically designed front cover that includes everything that is essential to making the engine run (distributor, oil pump, water pump), all attached to a flimsy piece of cast aluminum. We would normally prefer to use an original AMC cover, but finding them in good shape is becoming more difficult all the time. We grabbed a Proform factory replacement piece from Summit Racing. After tapping the seal into the housing and coating the gasket in aviation sealant, we set it on the alignment dowels and bolted it to spec. With the oil pump housing built into the front cover, some trickery was used to ensure adequate lifeblood is supplied. We slid home a set of new pump gears from Sealed Power and capped the pump with a billet aluminum top. This is all to bypass the Rube Goldberg series of oil passages from the pan to the pump. We now draw oil directly from the pan bottom to the pump through a -12 JIC hydraulic hose, then out to a set of remote Perma-Cool oil filters, back to the block to be distributed evenly through our ported and radiused oil passages before it purges it’s lifeblood into the motor. Serious conditions call for serious hardware when it comes to an oiling system.
We talked quickly during our machine process on the M3 (Merican Metal Menace) about BHJ Dynamics, the company that manufactured the harmonic damper we used. Our few years of college level physics were spent in awe of our professors’ resemblance to a Chia Pet, so we have very little intellectual information of our own to add to BHJ’s Q&A page. In brief, as an engine operates through its multiple cycles, torsional forces twisting the crankshaft from front to back can cause a great deal of damage. Dampers have been utilizes to mute these forces for years with marginal success. Our unit is a fluid design tuned to be utilized with our forged crank and machined to compensate for our externally balanced crank. Most manufactures build a “one size fit all” piece that does little to extend crankshaft and bearing life in your engine. For what looks like a big chunk a billet machined steel, the science involved is staggering, so don’t hammer on a harmonic balancer, use a proper installation tool to keep you from looking like a tool, ours came from Summit Racing.
The normally boring oil pan is actually a trick piece from Canton Racing. Road racecars deal with some of the same oil starvation issued going around a corner as an off-road rig does on its side. Trap doors built into the deep sump allow for proper oil flow control and additional lube to be present. Unlike a conventional oil pickup, which is solidly mounted to the block, our pickup is welded to the pan so if we manage to bash in the bottom of it doing something exceedingly dumb we will not starve our motor. Canton’s craftsmanship and finish are second to none and small additions like copper drain gaskets, and an oil temperature sensor bung really stand out. Don’t get us wrong; this is not a full on dry sump racing setup, but for our beer budget, this setup will keep our motor pumping oil well after we’re done filling our shorts in fear.
Moving back to the inside of the block, we soaked the Comp Cams lifters in Amsoil high zinc 30 WT break-in oil. After a few hours of sopping up the blood red goodness, they were slid into their new homes after a dab of assembly lube was placed on the foot of the lifters. Comp Mangum 7694 pushrods were cleaned and are required to compensate for the new roller rocker about to be placed on top of them… that is, after a little more assembly lube was placed on the ends.
The original AMC 1.6:1 ratio rockers are another lackluster design (it’s hard to believe this motor belched out 335 lb-ft from the factory). The non-adjustable stamped steel pieces used a tire bar to keep them in alignment. High rpm’s have a tendency to twist the bars and throw the whole assembly into chaos. Not on our watch. Edelbrock 1.6:1 ratio small block Ford units are an easy retrofit on the performer heads. Roller tips and needle bearings go a long way to reducing friction and the lighter weight allow for a higher rpm window. The factory setup is so unpopular that the Edelbrock heads come assembled with pushrod guides and thread in studs designed for the Ford rocker swap. Following true to our “Merican Metal Menace” moniker, a set of stamped steel rocker covers were bolted in place to hide the Edelbrock jewelry held within.
Capping the top of the motor is an Edelbrock Performer RPM Air Gap intake manifold good for keeping the incoming fuel charge cool and still having provisions for bolting up the factory accessories. A Fel Pro valley pan gasket was used in conjunction with an ARP intake manifold bolt kit to cinch it all together.
The last piece to adorn this motor is our ignition system. A Davis Unified Ignition (DUI) HEI style distributor was plugged into the block along with a set of their Live Wires plug wires. We have used this setup in the past along with many others. We are returning to the DUI setup for a multitude of reasons. With a simple phone call, DUI had our motor specs and were setting up a distributor made for our motor. Notice how the word “custom” was not used? The DUI design lends itself to easily located replacement parts if something goes south on us, food for thought when building a reliable powerhouse.
The only thing left to bolt to the motor is an induction system. We’ll spill the beans now and tell you that a Holley Terminator EFI system is the last piece teasing us from the corner of the shop.
- Holley – Holley.com
- Edelbrock – www.edelbrock.com
- AMSOIL – www.amsoil.com
- BHJ Dynamics – www.BHJDynamics.com
- Summit Racing – www.summitracing.com
- DUI – www.performancedistributors.com
- Proform – www.proformparts.com
- Perma Cool – www.perma-cool.com
- ARP – www.arp-bolts.com
- K&S Machine – www.ksmachine.ca
- Speed-pro - www.federalmogulmp.com
- Felpro - www.federalmogulmp.com
- COMP Cams – www.compcams.com
- Canton – www.cantonracingproducts.com
Read last issue's Bright Shiny Objects - 4th installment of Merican Metal Menace.