by Hib Halverson
The third part of the Big Block from Hell starts with a hell of a problem!
The final act in the cylinder head preparation discussed last month was to balance the combustion chamber displacements. The final figure was 113.5 cc.± 0.25. That was substantially less than the 121.5 cc. I specified when I ordered our Bill Miller Engineering pistons. As a result, the piston dome volume was too large and the actual compression ratio of the engine, 10.3:1, was excessive and certainly a problem with 92 octane fuel.
Anticipating the usual rush to meet a deadlines, I hoped save time by ordering pistons before the engine was even removed from the car before I had a chance to actually measure the combustion chambers. But noooo first, my source of information for combustion chamber size was off by 3.5 cc. 2) the heads we used had stock chambers on the small side 3) sometime in the engine's past, these heads came off for a valve job. In the process, they were surfaced, probably .010-.020. That would make the chambers smaller and 4) last month, we also took a surface cut off each head. That made the chambers smaller yet!
The fix for this was to reduce c/r to 10.0:1 by sending the pistons back to BME to have the domes machined. Bill Miller demonstrated his professional operation and support for our project by remachining the pistons in three days and doing it at no charge. When you need quality racing pistons and good customer support; go see Bill Miller Engineering. As this reduced piston weight, reciprocating pieces went back to Evans Speed Equipment to be rebalanced.
Since we were 10 days late, the Edelbrock crew had to work extra hard for this article. They started the assembly from scratch thus repeating the short block work done before. They are to be commended for their efforts. Lastly, thanks to the Vette production staff for getting this piece into the magazine in spite of its delay in completion.
My advice on how to avoid a problem such as this? (best way) Do the heads first and know the exact chamber displacement before you order pistons! (acceptable way) Measure your combustion chambers before you begin head work. A knowledgeable cylinder head porting shop can estimate finished chamber displacement figure. (no matter what way) don't try and cut corners.
We checked the Edelbrock Torker-Plus 5062 camshaft to compare its actual cam profile against the Edelbrock's specifications. None of the camshaft lobes we checked varied more than 3/4-1 degree from ideal. That is within accepted industry standards. It is not the intention of this article to cover the camshaft checking (or "degreeing") process in depth. An excellent discussion of the technique is in Rick Voegelin's book, The Step-byStep Guide to Engine Blueprinting. If you lack proper equipment, Crane Cams markets a great tool combination called a "Tune-a-Cam Kit" (p/n 4395) that contains most everything one needs to degree a camshaft.
Robert Jung tapped into each cylinder head deck two new cup dowels from an Edelbrock Brass Freeze Plug Kit (p/n 8086) and Mike Eddy set our DeGroff heads in place. Fel-Pro PermaTorque Blue head gaskets (p/n 1017) were used to seal them. The standard among engine builders for the big block, they have valve reliefs to go with those in our block, steel wire rings encased in a stainless steel shields for excellent compression sealing and blue teflon coating to seal small imperfections in the head and block. We used new head bolts (p/n 3811) from B&B Performance. They are SAE 8740 steel and use 12-point bolt heads, a valuable feature if your engine uses larger than stock valve springs. Special head bolt washers must be used and are included in the B&B kit. The threads were coated with antiseize compound and the bolts were screwed into the block then torqued to 70 ft/lbs. in the pattern found in the Chevrolet Power book or a factory service manual. Caution!!! Do not use head studs on big blocks to be installed in Corvettes. If you do, you can not remove the heads with the engine in the car.
Assembly of the valve gear began with Edelbrock Torker-Plus hydraulic lifters. Part of the Torker-Plus camshaft package (p/n 5062), they are an anti-pump up design ideal for use in a street high performance unit such as the BBfH. Before installation, Edelbrock's Mike Eddy filled each lifter with Red Line Synthetic 15W-40 Break In Oil. This is done with a squirt can and prevents problems with collapsed lifters on the initial fire-up of a new engine. Mike added a set of 3/8-inch, factory heavy-duty pushrods (p/n1013407 int., 10134308 exh.) recommended by GM Performance Parts for a "moderate performance" unit like our 6000 rpm 454. The ends of each pushrod were coated with Red Line Assembly Lube then set in place. Pushrods are two different lengths. Remember, intakes are short exhausts are long.
Rocker arms were next and we picked a classic the Edelbrock Red Rocker. This piece is the best aluminum roller rocker in the business. Since it is a recent effort, Edelbrock was able to capitalize on the short comings of older designs. To verify their work during development, Edelbrock used an Optron, an expensive piece of equipment used to simulate valve train motion and perform real-time examination of that motion without actually touching the parts. Edelbrock R&D ran valve train pieces at up to 11,000 rpmÑway past valve float in any pushrod engine. Once everything broke, they determined why other designs failed and incorporated that knowledge into the Red Rocker.
RRs are made of SAE 2024 T851 material and have a 1.7:1 ratio. They have larger trunnions and bigger trunnion bearings for improved load distribution. They have clearance for cams of much higher lift than what we are using and plenty of clearance for larger-then-stock, racing valve springs.
Our project was fortunate enough to receive one of the very last sets of Red Rockers as, unfortunately, Edelbrock suspended production of RRs in late 1990. In spite of the product's superior quality and durability it did not catch on with racers whom, I might add, often seem to be a stubborn enough bunch when it comes to change, that they pass up ways to improve performance and reliability. Perhaps, if demand rebounds, Edelbrock will reopen the Red Rocker line.
Why are we using a part that's for the most part, unavailable? Well, first there is the status "thing". I just like the idea of whipping the valve covers off our project motor and showing off those bright red rocker arms. Also, they're the killer parts they'll run 8500 rpm all day long. Perhaps this is overkill right now but, remember my comments in Part 1 about room to grow? If we ever went to go to a roller lifter camshaft, aluminum heads and 7000-7500 rpm; we'll need the Red Rockers' strengths.
If you can't have RRs but want equal rpm potential and durability, use Crower Stainless Steel Rollerized Rocker Arms. If you want to pay less and are willing to accept a slightly smaller margin of strength; the Crane aluminum roller rocker is a good choice. If you have no intention of building anything more than a street high performance unit and frequent 5500-6500 rpm use is not planned; the GM Performance Parts HD rocker arm (p/n 3959182) and HD rocker arm ball (p/n 5232762) are acceptable.
The ends of the valves, the rocker studs and the tips of the rocker arms were smeared with Red Line Break In Oil then the Red Rockers were installed. More Red Line was squirted into the open space on top of each rocker arm to prelube the bearings and trunnions. RRs use positive-locking rocker arm nuts and, to make the initial firing and break-in of the engine easy, the Torker-Plus valve lifters should be preloaded by tightening these nuts in a specific manner:
1) turn the engine until the lifter is riding on the base circle of the cam lobe.
2) while slowly rotating the pushrod, tighten the rocker arm nut.
3) when you feel resistanceÑie. the pushrod has just "bottomed" in the lifter and is now pushing against the lifter's spring pressureÑtighten the rocker arm nut an additional 1/4 turn.
4) lock the rocker arm nut by tightening the Allen-head lock screw
5) further tighten the rocker arm nut to 20-25 ft/lbs.
6) repeat this procedure for the remaining 15 rocker arm nuts. It is easiest to use the 1-8-4-3-6-5-7-2 sequence of the engine's firing order.
Next to go in the Big Block from Hell is another Edelbrock innovation called the "Camshaft Oiler" (p/n 8098). Big blocks have marginal camshaft lobe oiling, especially at low-end and mid-range rpm. All aftermarket intake valley shields prevent the hot oil spraying around inside the engine from striking the bottom of the manifold but the Edelbrock Camshaft Oiler does more by funneling the oil back down to the cam lobes, each one of which has its own little hole drilled in the apex of the Oiler's "V". Credit for this trick idea goes directly to Curt Hooker. He developed it through work done in the Edelbrock dyno room.
Edelbrock Torker 2-O intake manifold (p/n 5061) was installed next. This unit is a single-plane design intended for use with cast iron, low-performance, oval-port heads. It must be used with a carburetor having a manual or an electric choke. The Torker manifold was designed in parallel with the 5062 camshaft and the two together make an excellent combination in the 2500-6500 rpm range.
We sent the manifold to G&L Coatings for treatment. Its underside was treated with a "thermal barrier" material (p/n RFK0224) that reduces heat transfer through the bottom of the manifold. The upper side was coated with a "thermal dispersant" (p/n BTD0223) which promotes heat transfer to outside air. Simply stated, we're making it hard for heat to get in through the bottom and, what heat does get in, we are helping it radiate away through the top.
Sealing the manifold were Fel-Pro Printoseal intake gaskets. They have a bead of silicon rubber around the intake ports and the water passages. Once they are glued to the head, they stay there and don't need sealer between the manifold and gasket. This allows you to remove and replace the manifold many times before you need new gaskets. Use a razor blade or utility knife to notch the gaskets to clear the Camshaft Oiler's mounting tabs. The heat riser passage restrictors included with the gaskets were installed. They do not completely block manifold heat but they reduce it.
No one uses rubber or cork end seals any more. The prescribed method, even at the Chevrolet factory these days, is to use RTV silicon sealer. An Edelbrock manifold bolt kit (p/n8564) was used. Bolt threads were coated with antiseize compound and and bolts were torqued to 25 ft/lbs. in the pattern prescribed in the service manual. More of Fel-Pro's gasket wizardry is their new O-ring-filled, plastic water outlet gaskets (p/n 2202). Mike Eddy installed one of those under a chrome water outlet.
The engine we took out of our 1971 Corvette had Edelbrock Signature Series chrome valve covers and I saw no reason to change. A new set (p/n 4480) was unboxed and installed. Sealing was by Fel-Pro Cork-Lam valve cover gaskets (p/n 1630). The Cork-Lam units' 5/16-inch thickness allows "low-rise" valve covers to be used and still clear the Red Rockers inside. Conventional 5/32-inch rubber valve cover gaskets will not work as the rockers will hit the covers. Tall valve covers can't be used to clear the rockers as they will interfere with the power brake booster on '68-'75 cars.
The original Chevrolet timing chain cover, sporting new Chevy orange paint, was installed using a gasket from Fel-Pro's R.A.C.E. kit (that's Remainder to Assemble a Complete Engine cleaver folks those Fel-Pro people, eh?) for the big-block Chevrolet (p/n 2703).
Rather than using a stock harmonic balancer we chose one of the fluid-filled units popular with race engine builders. Made by Fluidampr¨ and marketed by the GM Performance Parts, this unit (p/n 10051171) has the external counterweights necessary for use on a 454. The Fluidampr uses a thick, viscous fluid rather than an elastomer ring to control crankshaft vibrations. Robert Jung installed the Fluidampr using a Damper Installation Tool from B&B (p/n 4067). This unit has a threaded pilot and ball bearing arrangement to smoothly press the damper onto the crank snout. Whatever you do, do not use a hammer to install a Fluidampr or stock harmonic balancer. Once the damper was in place Robert installed a B&B Damper Bolt (p/n 2640) and torqued it to 65 ft/lbs.
Once again, it was time for quality control work. Mike Eddy precisely determined top dead center (TDC) for number one cylinder using the "positive stop" method. He then compared that to the TDC mark on the Fluidampr. The purpose of this is to ensure that the TDC mark is in the correct spot so, in turn, the engine's ignition timing will be correct. In our case the timing mark was right on. Again, in the interest of space, I can't offer an in depth description of the TDC checking procedure. If you need that, I refer you to Voegelin's Engine Blueprinting.
In the remote chance that a foreign object has dropped into the engine during assembly of the valve train, the Edelbrock crew feels doing the oil pan last allows, you to remove it. The pan is an eight-quart, road racing type, wet-sump unit (p/n 31750) supplied by Milodon Incorporated. It is not a bolt-on as it's designed to fit other chassis besides the Corvette. It's not very deep in front and interfered with the two outside B&B Main Cap studs of the 454's front main cap and also with the adjustable windage tray mounts. The two studs had replaced with stock Chevrolet main cap bolts (p/n 3859927). The Edelbrock crew removed the center four main cap studs and machined about 3/8-inch off their ends to get adequate separation from the pan bottom. The moral of this? Before using a Milodon pan, do a test fit and be prepared to improvise if you are using anything other than stock main cap bolts. Those modifications complete, we measured the level of the oil pump pickup. Ideally, you want 1/4-3/8-inch clearance between the pickup and the pan bottom and we had exactly that. The pan was then installed for good using Fel-Pro oil pan gaskets (p/n 1804). (author's note: this part of the BBfH series was put on the web site, for the most part, as it was printed in Vette Magazine. Later in the project, there were significant problems with the Milodon oil pan. They are discussed in a later part of the series.)
The last part to go on BBfH this month is an Edelbrock Performer Series four-barrel carburetor (p/n 1407). This unit is rated at 750 cfm and is equipped with a manual choke. The beauty of the Edelbrock 1407 is that it uses metering rods and jets to meter fuel through the primary barrels and it is an air valve to control operation of the secondary barrels. This makes the 1407 easy to tune, it provides a more accurate fuel curve during part throttle operation and reduces the chance of overcarburetion through premature secondary opening. Edelbrock accompanies the 1407 with a good tuning manual. Extra jets and metering rods are available individually. A complete Calibration Kit (p/n 1480) can also be had containing jets, rods and power valve (or "step-up" as Edelbrock says) springs.
A reality of the magazine business is deadlines and lack of space. As a result, at times over the last three months, I have referred you to other publications for additional information on certain engine building techniques. Now that the blueprinting and assembly portions of the Edelbrock 454 series are 95% complete, I think it important to review these sources of information:
Chevrolet Power Catalog Seventh Edition, Chevrolet Division, 1994 an indispensable
source of technical information and part numbers. Can be had through some dealers.
1971 Corvette Service Manual, Chevrolet Division 1971, good for big-block info specific to the '65-'75 chassis. Other years '65-'75 will do. Dealers have information on how to obtain.
The Step-by-Step Guide to Engine Blueprinting, Rick Voegelin, SA Design Books 1985, another indispensable source of info. Additionally, as Voegelin bleeds Bow-Tie Red, the book has a distinctively Chevy slant.
Hot to Hot Rod Big Block Chevrolets, HP Books 1971, Certainly obsolete material in some places but sections on basic technique are helpful.
Next month, we'll put our money where our mouth is. I am going to spend the entire article on dynamometer testing the Edelbrock 454. Remember the 430-440 hp and 490-510 lbs/ft. of torque we talked about in Part 1?
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