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1. Ménage a trois? We just sat and drooled while manhandling the high performance perfection that Diamond, Molnar and Total Seal had for us before we began. We may actually have more pictures of this setup on our phones than we do of our kids.
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2. Diamond Pistons’ attention to detail produced a set of pistons and pins ready for a heavy hit of nitrous or a blast of boost if we ever decide to go that way. The valve relief and combustion chamber design perfectly match the Edelbrock heads that we will bolt on next time.
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3. The thin 1.5mm rings will equate to lower drag in the hole and more power out where it matters. An interlocking 2-piece top ring and Napier second ring were spec’d for longevity and durability. The piston ring grooves were machined to match these specific ring designs.
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4. Get a sharpie and start number everything; pistons, rods, pins, ring sets, cylinders etc. to keep track of all the parts. Remember that in an AMC, the pistons are asymmetrical and the valve reliefs must correspond to the valves in the cylinder.
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5. Summit Racing had all the specialty tools we required including a ring grinder, a ring-squaring tool, and set of feeler gauges.
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6. After calculating what your ring end gap needs to be, square the ring to be filed in the piston bore. Power adders, total diameter, ring material and intensions for the engine all determine what your end gap should be. When in doubt, make a call!
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7. Measure your end gap with the feeler gauges.
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8. And grind them a little at a time until you are on spec. Plan on a few hours of “Me” time to get it all done.
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9. Molnar Technologies connecting rods are truly “second to none”. The AMC design requires a slight offset in either the small or big end of the rod. Molnar units are offset on the big end to keep the transfer of force squarely on the rod. The brass bushed small end is ready for business and all the rods are matched in weight.
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10. With the pistons rings filed and assembled, it’s time to slide the floating pins home. Ensure that the ring end gaps are in the correct location according to the paperwork, and the connecting rod offset is correct.
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11. Spiral Lock retainers, despite having a horrible reputation for installing nightmares, are not that difficult to do. A small pic and flat blade terminal screwdriver are all that’s needed.
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12. Checking your engine clearances between your bearings and rotating components is not that difficult, but very important. For our application, we required .001-in of clearance for every 1-in of journal diameter. Our plastigauge shows us to be right on the money! Check your main and rod end caps.
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13. Unless specifically required, Amsoils Assembly Lube was generously utilized on every bearing surface to keep the initial fire up wear of the MMM to a minimum.
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14. Using a Summit ring compression tool, the lightly oiled slugs were pressed home using a smooth push. No force or pounding required!
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15. The Molnar rod caps are pre numbered, so getting them crossed up is only a problem if you can’t read.
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16. Molnar recommends either the “Bolt Stretch” or “Torque Angle” method of installing the ARP2000 rod bolts. We were running low on skrilla at this point so we used the Torque Angle recommendation; we torqued the bolts down to spec, and then another 60-degrees.
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17. The Comp XE262h extreme energy hydraulic flat tappet cam will sacrifice a little top end power for low RPM drivability. We’re OK with that. Squeezing out every last ounce of power would be a trade-off of low RMP drivability.
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18. Take your time when installing a cam as to not nick the cam bearings. Use plenty of lube! We threaded a large bolt into the end of the cam to act as a handle.
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19. Installing the cam “straight up” with the Comp double roller timing set was a breeze. Now it was time to check the cam timing. The Summit Cam Degreeing Kit has everything we needed including dial gauge, piston stops, adapters, and instructions. Find the #1 pistons top dead centre point and bolt your degree wheel on, align the wheel to the zero position and lock it down.
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20. With your dial indicator, follow the directions to compare your measured intake centreline to your cam cards. We use the Intake centreline method just for simplicity. Many will argue one method or another.
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21. Our cam card shows a 106-degree and we measured 107. 1-degree is now worth us chasing after for this power level but different timing sets or offset key stock could be used to correct this.
Story & photos by Bryan Irons
Merican Metal Menace gets bolted together
This being our 4th installment of the Merican Metal Menace build, we’re finally ready to start bolting our AMC 401ci V-8 back together. Lofty goals like 400 hp on pump gas, a stable idle and enough engine vacuum to operate the brakes require a stout foundation; we’re going to leave you this issue with a finished short block.
Catalogue engine building is an easy enough game to play, but the outcome can be a crippled Frankenstein if the parts don’t mesh together. Many builds start with a camshaft and have an engine built around it. We like to start the other way around by deciding on a power level, RPM range, fuel type, static compression ratio, and piston material that can withstand of punishment and run the fuel we plan on feeding it. Diamond Pistons’ Mike Panetta helped us settle on a compression ratio of 10.75:1, with a set of custom machined pistons. During our chinwag, we informed him of the cruel intentions we have planned for the motor, and it was suggested that we ceramic coat the top of the new slugs for improved heat dissipation, and have the skirts moly coated for friction reduction. Who are we to argue? These services are done in house by Diamond. Edelbrock Aluminum heads are slated for the motor with a 55cc combustion chamber volume. Head gasket volume, deck height and crank stroke are all prerequisites for calculating the compression ration whether running custom pistons, or using an off the shelf unit. Diamond filled in the blanks and turned out a set of custom pistons to fit our .030-in overbore 4.195-in holes. The dished reliefs perfectly match the cylinder head quench zone dimensions, and the valve reliefs are good for much more cam lift then we are going to use. Full floating pins were spec’d as well so we could assemble the goods at home.
Arriving in the Diamond Pistons box was a set of top shelf Total Seal rings carefully chosen for our motor. The 1.5mm top ring is a 2-piece setup designed to keep all the cylinder compression where it belongs, in the cylinder. A 1.5mm second ring is a Napier design, which is intended for better oil control as well as blocking any gases trying to escape. The 3.0mm oil ring is a standard tensions piece, as we would rather sacrifice a little power for longevity, and reduce any possible oil consumption. You can source “pre fit” components, but for the few extra hours spent in the shop with an adult beverage, file fit rings are worth the extra effort. We scored a Summit Racing hand ring grinder and ring-squaring tool and spent some quality time following the included directions.
Our 401 wheezed its way out of Toledo’s factory like a hot girl in a muumuu (for the fashion challenged it’s a long loose Hawaiian dress – Ed). Under all that crap was a high nickel block with a forged crank shaft and forged connecting rods; that’s right, the stuff of legends surrounded by smog pumps, substandard ignitions and faulty wiring. Like we stated in the last MMM, we’re keeping the fancy crank shaft and block, but after we priced out the cost of new hardware, shot peening, plus getting the piston pins pressed in, we were right at Molnar Technologies’ price for set of 4340 H beam replacement rods that come with larger ARP2000 bolts. It was an easy decision after chatting with Tom Molnar, as he explained (using small words for our benefit) why we needed a torque angle meter to get the connecting rods cinched down properly.
Engine bearings are another field that has progressed immensely over time. Poor oiling is what originally annihilated our motor, as we discovered during the autopsy. When we dropped the block off at K&S Machine, they didn’t whittle away any metal until they had our Speed-Pro bearings in hand, just the way it should be. It was a bit of a shock to hear that our block and crank were in great shape and we did not require any oversize/undersize bearings for the rebuild. Standard sized Speed-Pro bearings were all that the machinists required as the crank journals measured out perfectly. Some may see the lack of an oiling chamfer in the bearings as detriment, but we like having the extra surface area of the bearings we chose.
With an open mind, we called Comp Cams for a bump stick. Cam swaps can be done in a weekend at minimal cost if you want to change things up in the future. Tech Chris Ryan calmed our urge to go with a radical solid lifter cam, and actually suggested a much milder hydraulic flat tappet unit - “let's go with the XE262h. It specs at 218/224 @.050 493/500 110lsa. This will give us a 1500-5500 rpm operating range with strong mid-range torque and a mild but noticeable idle.” It’s hard to argue the numbers and experience of the Comp Cams crew. The XE262h cam should deliver a smooth and wide power band whether we’re idling over rocks or powering through snow. Although a roller cam would be great, the large lifter footprint with the AMC design allows for much faster ramp rates negating the added cost of a roller setup for our mild specs.
While installing the cam, we took a little extra time and degreed our camshaft and rotating assembly with a Summit Racing Cam Timing Kit, which we picked up with the rest of our assembly tools. Machining variances can alter the exact position of all the components as a whole, so we prefer to see exactly where the cam lobes are sitting in relation to the rest of the rotating assembly. Most times we hear “cam timing was dead on”, but in our experience, this is rarely the norm if you’re measuring carefully. Our setup was actually retarded by 1-degree (cam card shows a 106-degree intake centreline, we measured 107-degree). This machining difference can be changed, but our Comp Cams adjustable timing set only has 4-degree increments. Not to worry, although this will move our power band up the RPM range slightly, it’s not enough to make us want to advance the cam by 4-degrees to a final 1030-degrees.
With hardly a hair left on our smoldering cranium from all the head scratching, we figured that this would be a good time to wean you off until next issue. Final assembly including cylinder heads, dampener, intake manifold, front cover, distributor and our ever delicate oiling system will be bolted on as we prep for a blast on K&S machines engine dyno.
- Amsoil - www.amsoil.com
- Diamond Pistons - www.diamondracing.net
- Total Seal - www.totalseal.com
- Edelbrock - www.edelbrock.com
- Comp Cams - www.compcams.com
- K&S Machine - ksmachine.ca
- ARP - arp-bolts.com
- Molnar Technologies - www.molnartechnologies.com
- Speed Pro - www.federalmogulmp.com/en-US/Brands/Speed-Pro/Pages/home.aspx
- Summit Racing - www.summitracing.com
Read last issue's Machine Shop Stop - 3rd installment of Merican Metal Menace.