Reply to "B. Goyaniuk's motor questions"

Bohdan,

I understand you would like to retain your current intake manifold and exhaust headers. This would lead me to advise you to retain the iron closed chamber heads already installed on your motor.

However, I also understand at some point you would like to upgrade to alloy heads for both the savings in weight and the increased intake velocity they provide (i.e. improved throttle response and possibly more bhp). Unfortunately, none of the available alloy heads are a match for the Edelbrock Performer 4V intake on your motor.

To select alloy heads you will need to consider a change in intake manifold as well. Edelbrock makes a Performer 2V manifold that is physically identical to the Performer 4V, even the ports are relatively similar in volume. This manifold will work just fine with Edelbrock, CHI 2V or AFD 2V alloy heads. It can also be used with the CHI 3V heads using the spacers sold by CHI.

My only caveat regarding installation of alloy heads is that none of them provide for a manifold heat crossover, and since you live in a relatively cold climate, this may have an undesirable effect on drivability. With a conversion to fuel injection this would not be an issue.

You may want to wait and combine the upgrade to alloy heads with a possible future upgrade to fuel injection. Since keeping the intake system below the engine screen is important to you, you'll want to select one of the 2V heads (Edelbrock, CHI or AFD) to minimize vertical height.

Your exhaust system will bolt up to the 2V alloy heads; however the exhaust ports in those heads are smaller than the flanges of your headers. The engine will operate just fine with this mismatch, but it will not be ideal for maximizing the performance of your motor. A set of 2V headers would be a better choice for an exhaust system.

I am going to make my recommendations based upon the assumption that you will retain the iron heads for the present time. Your modest performance goal of 400 bhp allows me to specify a flat tappet hydraulic cam; there is no need to use a roller cam at that power level.

I have learned within the last few weeks that Scat is in the process of offering a new stroker kit for the 351C, with a 4.00" stroke crankshaft. I write this to make you aware of it; I can't recommend it until I have spoken with Bob at Scat and asked how the piston's ring package has been changed to accommodate the 0.075" increased throw of the crankshaft.

Until then my recommendation is the 3.85" Scat crankshaft kit in forged steel, with their premium 4340 fordged I beam connecting rod (6.00” length) featuring a doweled cap and 7/16” cap screws, and Scat’s fordged pistons and rings. Bob at Scat told me they can dish the piston domes to mirror the shape of the combustion chamber in the iron closed chamber heads for an extra fee, I strongly advise this extra expense. You will want to have the pistons dished to adjust the compression ratio of your motor to the ratio recommended for your camshaft (more on that later). The Scat crankshafts have a crank snout diameter the same as that of the Windsor motor, so a standard 351C timing set or balancer will be a loose fit (by 0.010” I think). Rollmaster manufactures a timing set for this application, and a Windsor balancer will also be required (I recommend the Romac balancer).

Since I have recommended the expense of custom dishes on your pistons, you will need to “zero deck” your block to take advantage of the squish area of the cylinder heads. During the machining of your block, the “decks” will be surfaced to remove approximately 0.025” material so that the piston domes will sit flush with the decks at TDC. The goal is upon final assembly the clearance between the piston domes and the cylinder heads at TDC is 0.045” +/- 0.010” (Ideally the thickness of your head gasket).

For a camshaft I recommend the Comp Cams XE274H. The duration figures at 0.050” lift are 230 degrees intake & 236 degrees exhaust, the valve lift figures are 0.562” intake and 0.565” exhaust. The relatively high valve lift of this cam, combined with the increased displacement of stroker crank will do wonderful things with the throttle response of your motor. So much so that you may change your mind about needing alloy heads. With 393 cubic inches this cam will be very drivable, have great throttle response, provide a power band of approximately 1700 rpm to 5700 rpm and perform like a tiger when you need it. With good springs your motor will easily rev to 6500 rpm, so long as you have adequate carburetion (750 Holley) and exhaust (2 ½” tubing from collector to Ansa minimum, perhaps 3”). The compression ratio recommended for this camshaft was not listed on Comps web site, I can guess it will be approximately 9.0 to 1 or 9.5 to 1, but you’ll need to speak with Comp to verify their recommendation.

A must for your cylinder heads is installation of one piece stainless steel valves, good quality steel valve spring retainers & single groove style keepers, bronze valve guides, port matching, valve pocket clean up and a 5 angle valve job. I also strongly recommend porting by somebody familiar with the 351C motor. You’ll find most of the port work is in the exhaust port, some relieving in the combustion chamber and some basic clean up in the intake port. This will be necessary to allow the motor to make every ft/lb of torque possible; otherwise the head will limit the potential of this combination.

For rocker arms I recommend the Ford Racing Performance Parts (FRPP) “bolt on” rocker arms, part number M-6564-C351, no head machining necessary. The rocker arms are made of extruded aluminum, not as beefy as some of the others on the market, but I think plenty durable for this application. They bolt down to the slotted rocker pedestals of the iron head. They are attached to the head with a 3/8” cap screw, not quite as strong as the 7/16” stud of a fully adjustable push rod guided rocker system, but again I think it will be plenty durable for this application. To achieve adjustability you’ll combine the rocker arms with a set of Crane 3/8” adjustable push rods, part number 99748-1. You must specify tips & length to order those push rods.

Your first alternative choice in a rocker arm system will be to have the rocker arm pedestals cast into the heads machined & tapped for a fully adjustable push rod guided rocker system using 7/16” studs, guide plates, hardened push rods and a suitable rocker arm of either extruded aluminum (Crane 27771-16 or Crower 72815-16) or cast stainless steel (Crower 73615-16 or Comp Cams 1130-16).

A second alternative choice in a rocker arm system is the individual shaft mount rocker arms made by Yella Terra (part number YT6321) which also require the same machining of the rocker arm pedestals as the push rod guided system.

I’ll mention once again that this motor will need a Holley 750 cfm carburetor and a free flowing exhaust system. Headers are not enough, the pipes & mufflers downstream of the headers must also be of adequate size & capacity so as not to choke the motor.

Finally the carburetor & ignition will require tuning on a dynamometer. My personal preference is chassis dyno because it allows the drive train friction to load the motor during tuning, but an engine dyno is OK too. This step is essential for this combination to work properly. If all is done correctly, your motor should idle smoothly and accelerate from any rpm without any hesitation, the more you press the accelerator the HARDER the engine will pull, like an electric motor, all the way to 6000 rpm before any sign of leveling off.

Your long winded friend on the DTBB, George