Sturdiness & Avenue Energy (Half 2)

Sturdiness & Avenue Energy (Half 2)


Final month, we launched you to the 331ci “Avenue Stealth” constructed by MCE Engines.

The late Marvin McAfee of MCE Engines in Los Angeles was the architect and builder for this effort utilizing a brand new 5.0L curler block stuffed filled with Probe Industries rotating mass consisting of JP cast and coated pistons, 5140 cast I-beam rods, Fluidampr harmonic dampener, Comp Cams curler hydraulic know-how and extra.

Though a few of what we’re about to impart doesn’t make a lot sense in an atmosphere with dozens of nice aftermarket aluminum heads on the market, we need to present you what might be carried out with manufacturing facility iron castings if you wish to keep a stealthy inventory look on the surface.

This engine construct was carried out utilizing what was out there again within the day, and far of it stays out there now. PowerHeads, now not in enterprise, took a pair of 1969 Ford 302 truck heads with 64cc wedge chambers and carried out good port work through CNC know-how and hand porting. You may obtain the identical outcomes through an excellent head porting store at the moment. PowerHeads turned a 331ci 300 horsepower stroker right into a 400 horse powerhouse. MCE’s personal blueprint work helped improve the remainder of the construct by lowering inside friction and doing additional port clean-up work on the heads and consumption.

Though we used the 1969 truck heads, they weren’t the most effective Ford casting to make use of. Earlier 1963-67 289 heads with the 54-57cc chambers had been essentially the most optimum alternative as a result of we might have gotten higher compression and quench from these chambers. Though extraordinarily uncommon as of late, 1968 302-4V heads are the best choice due to petite 53cc chambers. As a result of Ford made so few 302-4V engines in 1968, the percentages of discovering a pair is a protracted shot.

Marvin opted for the Edelbrock Performer RPM Air Hole consumption and Holley 750 cfm carburetion. As a result of this can be a avenue engine, Marvin regarded to Pertronix for a billet distributor with vacuum advance for effectivity and energy. Marvin has accomplished the brief block and is prepared for last meeting.

Head Journey

If you happen to suppose manufacturing facility iron castings received’t make actual stream on a stream bench, take a detailed have a look at these PowerHead numbers. There’s a dramatic enchancment in airflow with porting. It can save you cash by doing this job your self, nevertheless, it’s good to know what you’re doing earlier than taking a die grinder to your heads. It makes extra sense to permit a head store to do the port work and set up stable bronze valve guides, hardened exhaust valve seats, and an entire set of 1.94/1.60 inch chrome steel valves.

Cylinder Head Circulate Numbers for the 331 Ford
Inventory 289/302 Ford Heads
Raise/Inch 0.100 0.200 0.300 0.400 0.500 0.550
Consumption CFM 51.8 94.7 131.7 139.2 140.9 150.9
Exhaust CFM 39.2 73.7 95.7 100.4 103.6 105.1
Ported 289/302 Ford Heads
Raise/Inch 0.100 0.200 0.300 0.400 0.500 0.550
Consumption CFM 63.6 122.3 174.1 189.8 203.4 212.0
Exhaust CFM 62.4 109.1 150.2 161.8 168.6 171.9

How Energy Is Made

MCE’s 331 Avenue Stealth sports activities a broad torque curve that comes on sturdy at 2,500 rpm, a whopping 350 lbs.-ft. of torque down low the place it counts on the road. It begins making torque round 1,200 rpm, which is strictly the place you need it. Torque by no means falls beneath 350 lbs.-ft. of torque, topping out at 396 lbs.-ft. at 4,000 rpm.

This was Marvin’s trademark as an engine builder. Practically 400 lbs.-ft. of torque from 331ci. This implies actual avenue energy on the site visitors gentle and on the drag strip for bracket racing.

After we took this 331 to the Westech dyno, it was a scorching day with ambient temperatures above 100 levels F—a drawback on dyno day as a result of it hurts energy. We would have liked a cooler day. With higher circumstances, our 331 Stealth would have blasted by means of 400 lb.-ft. of torque and delivered a stable 400 horsepower at 6,000 rpm. Add a warmer curler cam, single-plane consumption manifold, and elevated carburetion, you may rely on 450 hp and 450 lbs.-ft. of torque from this bundle.

This was not a Cinderella story. We didn’t meet our purpose of 400 horsepower. Our 331 topped out at 367 horsepower at 5,500 rpm. This teaches us to honor this engine’s benefit—avenue torque. A stable 400 lbs.-ft. of torque at 4 grand. To realize 400 horsepower, we would have liked a warmer curler cam, quite a lot of carburetors to play with, and a cooler day.

Marvin all the time tended to err on the facet of warning and ended our dyno session prematurely—significantly irritating as a result of we perceive this engine was able to making extra energy given further tuning time. Marvin’s intent was to carry out a cam swap and return to Westech for an additional dyno session.

Failing well being and different priorities prohibited him from returning to the dyno.

Getting Actual Energy

There are two methods you may construct a 400 horse 331ci small block. Marvin opted for the dearer method with a 4340 metal crank, heavy-duty I-beam rods, cast pistons, and quite a lot of particular consideration to element by MCE Engines to get sturdiness. If you wish to get monetary savings on an engine like this, do quite a lot of the labor your self, move on the 4340 metal crank, heavy-duty I-beam rods, and cast pistons. The manufacturing facility forged crank with aftermarket heavy obligation I-beam rods and hypereutectic pistons will endure 400 horsepower.

We’re working with 1969 Ford 302 truck heads with 64cc chambers CNC-ported and hand-ported by PowerHeads, which is now not in enterprise. These chambers are conservative by way of compression ratio. (Picture/Jim Sensible)
Essentially the most optimum heads for an engine like this are the sooner 289/302 heads previous to 1968, which have 57cc chambers and higher quench with good anti-knock qualities. (Picture/Jim Sensible)
Marvin factors out the quench qualities these chambers have—which give these heads higher “squish” across the chamber. The early 289/302 heads with 54-57cc chambers ship even higher quench and higher compression. (Picture/Jim Sensible)
If you will discover them, 1968 302-4V heads with 53cc chambers stay the most effective early Ford small-block heads going. As a result of Ford did so few 302-4V engines, these heads stay onerous to seek out. (Picture/Jim Sensible)
Marvin utilized his blueprinting efforts to the PowerHeads castings by checking valve steam to information clearances and ease of valve motion. He knurled the guides as crucial to scale back inside friction and enhance oil management. (Picture/Jim Sensible)
Marvin refined valve seat contact relying upon the efficiency desired. Marvin believed a wider valve seat improves valve cooling. By the identical token, an excessive amount of contact takes away from airflow. The very best method is a five-angle valve job. (Picture/Jim Sensible)
PowerHeads all the time opted for bigger 1.940/1.700 inch Chevrolet valves for its small-block Ford heads. That is a straightforward improve on your inventory Ford casting. You may additionally go for hardened exhaust valve seats or stainless valves. (Picture/Jim Sensible)
Marvin all the time used his personal particular low friction coating cocktail for valve springs and different shifting elements. These are Comp Cams valvesprings and dampers. (Picture/Jim Sensible)
The very best valve seal to make use of is a Viton seal (not proven right here, however just like this Teflon seal), which has an unbelievable monitor file for valve stem oil management. Valve guides needed to be minimize down for seal fitment. (Picture/Jim Sensible)
Valve spring strain is managed with shims positioned right here on the spring seat. Shims are added to extend spring strain or subtracted to scale back strain. Shim additionally controls put in spring top. Springs are chosen based mostly upon cam profile. (Picture/Jim Sensible)
Marvin opted for Comp 1.7:1 curler rockers to extend valve elevate. This method additionally reduces valve shrouding by extending the valve head deeper into the chamber. This may be achieved with a cut up ratio with two totally different rocker ratios—usually with a 1.7:1 consumption and 1.6:1 exhaust. You may even experiment by attempting totally different rocker ratios to see what the tip result’s on the dyno. Verify valve-to-piston clearances in any case. (Picture/Jim Sensible)
We’ve opted for the spider fashion hydraulic curler tappets, that are much less widespread at the moment than they had been 20 years in the past. The message right here is low friction. Though curler tappet cams are dearer, they pay long run dividends by way of effectivity and energy. Once you cut back inside friction, you release energy. (Picture/Jim Sensible)
Whether or not you’re constructing a stocker or an aggressive avenue/strip mill, it’s strongly advised you go for one-piece 0.080 inch wall Comp pushrods for limitless sturdiness. Marvin waited on ordering pushrods till he efficiently labored out valvetrain geometry. The curler tip must be centered on the valve stem. (Picture/Jim Sensible)
Marvin was all the time fairly keen on Fluidampr harmonic dampers for his builds. He all the time degreed each the cam and the damper to make sure accuracy. A 36 diploma mark was utilized to the damper to assist decide whole timing at 3,000 to three,500 rpm. (Picture/Jim Sensible)
Marvin was all the time obsessive about easy fluid and oil stream. He would therapeutic massage oil galleys and coolant passages to scale back fluid turbulence. (Picture/Jim Sensible)
The Edelbrock Performer RPM Air Hole manifold goes almost each dual-plane manifold one higher with improved runner cooling and a cooler air/gas cost. Marvin port-matched each the consumption runners and cylinder head ports for diminished turbulence. He favored attempting totally different carb spacers to see what would occur to torque primarily. (Picture/Jim Sensible)
We like the traditional Holley 750cfm double pumper carburetor. It sports activities all the weather Holley carburetors are identified for, plus good refinements that make it essentially the most tunable carburetor ever made. We tried various totally different carburetors on the 331. In the long run, the 750 gave us the most effective numbers. (Picture/Jim Sensible)
Once you go for Holley carburetion, equip your store with quite a lot of Holley kits. We’re speaking jet and gasket kits, accelerator pump diaphragms, float needle valves, and extra. Few issues are extra irritating than going to a race or weekend getaway and discovering you may have a gas leak or inoperative accelerator pump. (Picture/Jim Sensible)
There are a few approaches to consumption manifold sealing. We like operating a stable bead of Permatex’s The Proper Stuff alongside the rail ends. Marvin would “dimple” the manifold and block rails to maintain the tip gaskets in place. This, coupled with a skinny movie of The Proper Stuff works fairly nicely too. (Picture/Jim Sensible)
Except you reside in a chilly climate atmosphere the place manifold warmth is a necessity, it’s advised you block off the manifold warmth passages to scale back manifold warmth. This retains the consumption cost cooler—which interprets into extra energy. (Picture/Jim Sensible)
One of the oft-seen errors we come throughout is improper gas line sizing for the facility that fans anticipate to make. When you’ve got a inventory 5/16 inch gas line into the gas pump, however have a 3/8 or 7/16 inch gas line between the pump and carburetor, you continue to have a 5/16 inch gas provide. The gas line between the tank and carburetor must be 3/8 inch minimal for 400/400 horsepower and torque. Appears like Marvin opted for 7/16 inch strains with this Holley pump. (Picture/Jim Sensible)
MCE Engines’ in-house tuner was Benton Jackson who employed a wealth of engine tuning information. Right here he’s tuning the Pertronix billet distributor with vacuum advance for the 331 Avenue Stealth. Each advance items should be tuned to realize the right fee of advance. The vacuum advance management advance fee as you begin out. It arms off to centrifugal advance as rpm will increase. Think about the vacuum advance “throttled” advance as you get underway. (Picture/Jim Sensible)
As a result of we’re operating a metal curler camshaft, the distributor gear should be both brass (proven) or a metal gear. An iron gear is smooth and can by no means stand as much as the hardness of a metal cam. If you happen to’re operating a flat tappet camshaft, run the iron distributor gear. (Picture/Jim Sensible)
Except you’re going drag racing, it’s a good suggestion to run a road-race oil pan, which retains the sump filled with oil once you’re cornering. The inventory entrance sump pan with a windage tray and baffles is appropriate for cruisers. (Picture/Jim Sensible)
Marvin all the time took blueprinting to critical levels, treating each engine construct to race caliber ranges to make sure sturdiness. Right here every part is polished for improved oil drainback, plus safety-wired for safety. Pink GE Glyptal coats iron surfaces to enhance drainback and seal the tough iron. Screens maintain particles out of the pan. (Picture/Jim Sensible)
Westech Efficiency throttled our 331 using various tuning approaches together with ignition timing, jet and carb swaps, and extra. The 331 Avenue Stealth, as its identify implies, reveals glorious avenue manners at 396 lbs.-ft. of peak torque. This implies terrific 60-foot occasions on the drag strip and sooner launch occasions on the site visitors gentle. (Picture/Jim Sensible)
Marvin favored checking spark plug warmth ranges to see what was happening within the chambers. He would carry out a jet examine by going full throttle beneath load for 30 seconds, then, examine spark plug situation. It is a excellent jet examine colour smart. Whether it is snow white, you’re too lean and probably have an excessive amount of timing. Too lean will kill an engine in nanoseconds. (Picture/Jim Sensible)


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September 2022