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George and other Forum Members - Please comment on my proposed build.

427 CI BOSS Clevor motor
Dart iron 9.5 deck height block, 4.125 bore, Cleveland mains
Forged Crank, 4.00 stroke (Standard weight, lightened, coatings?)
CHI 3v 218 head, CR between 10.5 and 11.0 to 1
Forged pistons(please comment: brand, valve reliefs, ring pack, pin height, skirt, coatings, etc.)
Forged rods, length TBD (please comment)
Comp Cams Beehive valve springs
Crower 1.7 ratio stainless steel rocker arms
Cam with around .585 -.595 gross lift, other cam specs TBD
Hydraulic Rollers
Blueprinted oil pump
10 quart road race wet sump oil pan
Induction: TBD Am considering Kelly Coffields IR EFI manifold and set-up, but need to have a carbuerated option (Please make reccomendation here.)

Goals: 600HP @ 6500 RPM
Used in a 1973 Pantera that see 90% street and 10% track use.

Thanks - Chris Lewis
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Should be a piece of cake to make 600 HP with those type of parts. Here is my engine that is similar to your combo without the cleveland heads and just about 50 less HP

Mine is not installed yet but don't forget about all the other upgrades that will be needed now or in the future for the increased HP

Better cooling system
Larger fuel tank pick up
Half shafts
Rear billet axles & bearings
Chassis Braces

The list never seems to end!

I'm sure George and the other members will have specific information on your questions, but looks like your on right track for a solid engine build.
Chris, after reading your post here's the things that come quickly to mind;

Bearings: I have used Clevite 77 bearings my entire life. They're tough bearings. I don't know anything about King bearings.

Compression ratio: let the cam grinder specify the compression ratio

Cam specs: Let a competent cam grinder spec your camshaft. You should plan on a bit more lift, on the order of 0.630" to 0.650". Off the shelf cams that fit the Windsor block will not work with this combination, a custom ground cam will be a must, but don't stress, you'll find the difference in price is not that much. (Even with a Cleveland block, off the shelf cams are designed around the 4V heads, to get the most out of the high velocity CHI 3V heads you would still need a custom ground cam) Another benefit, the high velocity ports of the CHI head will allow you to run more duration without penalty in drive-ability.

Valve springs: your cam grinder will want to spec your springs for you too. Cranes hydraulic roller lifters allow more rpm than the Comp Cams lifters (Comp uses Ford oem style lifters). If you're going to run Comp Cams lifters, beehive valve springs would be a waste of money. Consider the Crane lifters & beehive springs as a necessary pairing. However, for red-lines below 7000 rpm I doubt you need the beehive springs. Your cam grinder should have final say on this issue.

Pistons & Rods: buy the crank, pistons & rods as a kit from the same supplier. Just like the compression ratio & cam specs, let the crank kit supplier decide what connecting rod length & ring package to pair up. Scat would be my recommendation. Choose a kit supplier who will custom grind the dishes in the piston domes to match the shape of the CHI combustion chamber. I like floating pins for the ease of assembly they allow. There are other options here for a supplier of your crank kit. I could recommend an engine builder for you that would make one stop shopping for your crank kit, head work, cam grinding, etc ...

Intake system: CHI makes a manifold for this application (3V heads on 9.5 Windsor block). Their manifold will work best with their heads, period. Top it with a 750 cfm Holley...

By the way, I don't remember Kelly C casting an IR manifold for the CHI heads, especially on a Widsor block. The CHI 3V intake ports are 2V sized but raised approximately 3/8" vertically from the standard 2V location.

Rocker arms: 1.73 to 1 is the stock Cleveland ratio. Crower's enduro rocker arms are available in 1.73 ratio, however, they are also available in 1.75 ratio, so I would recommend the 1.75 rockers. Why? Because they allow more lift without any more duration. Gives your cam grinder more options with the cam lobes. For a bit more money, the Yella Terra rocker arms would be a step up in valve train stability.

Misc: you'll want 3/8" push rods (or heavy wall 5/16 push rods), heavy duty oil pump drive shaft, double pin the distributor drive gear, high pressure oil pump relief spring, and a high pressure oil filter like the Fram HP1. The Dart block is good stuff, good choice. If available, install a main cap girdle, it controls main cap squirm much better than four bolt mains alone. 600 bhp is a lot of bhp, you need to build all the strength into this assembly possible. Rollmaster timing chain, Romac balancer. Before final assembly have the reciprocating assembly dynamically balanced.

With a goal of 600 bhp & a displacement of 427 cubic inches, don't be surprised if your cam grinder recommends some head porting.

To achieve 600 bhp at 6500 rpm your motor will have to be making 484 ft/lbs of torque at that rpm. This should give you an impression that your powerband must be skewed towards upper rpm. If you will be operating your Pantera a lot on the street & on the track only once per year, I would advise you to build a "street" motor, the motor you propose is not a street motor. A street motor gets on the pipe not too far above idle. In my opinion, the thing that wins stop light drag races is a low rpm powerband. Drag racers side step the clutch at 4000+ rpm, they don't need low rpm powerbands. But at a stoplight, you'll leave the line just above idle. So my advice is to build for as much torque as possible over as wide of a powerband as possible and let peak bhp numbers fall where they will. That powerband should commence between 1500 & 2000 rpm. A car with a street friendly powerband is less of a chore to drive, easier to relax and enjoy the car & the trip.

That's just my advice, I respect the choices you make because I realize we all have different ideas about what OUR ideal Pantera should be.

Your friend on the DTBB, George
...I ran your specs through the 'DeskTop Dyno'. You can get what you want, provided you use a Roller Camshaft, it can be a Hydraulic! I used the standard sized Valves, I.E. 2.196" Intake and 1.715" Exhaust. Here are the numbers at two levels of comprssion ratio; believe it, or Don't, + or - 4%: Single Plane Manifold with 750 CFM at 11.0:1 Comp. Ratio equals 582HP @ 6500 RPM and 555 Lb/Ft @ 5000 RPM...if you lower the comp. ratio to 10.5:1 the figures come out as: 569HP @ 6000, 546 Lb/Ft @ 5000. REMEBER this is with a ROLLER Camshaft; It makes THE difference. If you use a 'Standard' Hydraulic Cam (with 10.5:1 Ratio), the numbers drop to: 504HP @ 6000 and 497 Lb/Ft @ 4500-This is pretty low on the power band! Anybody else wish to have their numbers ran??...

You'r putting together a killer combo! I just have two things to comment on:

I've only used Clevite 77 bearings and have never had any kind of failure in several street/strip motors.

I would never build a motor without a roller camshaft. It makes a HUGE difference in idle quality, engine tractability, fattening up the powerband, and could even deliver a bit better gas mileage (not that it matters!). You ARE leaving horsepower on the table if you don't go with one!

Good luck, and keep us posted.

George- A couple of things after reading you response

1) Kelly has the pattern for the CHI 3V head and has agreed to cast one up for me when I am ready. Deposit is down on that item.

2) Valve train - The 1.7 ratio was based on input from Dan Jones that said 1.73 or greater would create unacceptable bind with the beehive spring. I did realize that I was probably going to have to combine the beehive spring with Crane lifters to get the rpm out of a hydraulic roller valve train

I was thinking Jesel Nascar timing belt. Your opinion hear would be valued.

I had already planned for an upgraded oil pump drive shaft.

The distributor drive would be one of the new composites and I will have a machinist attache and align it properly as the gear on my last motor

I had 60,000 miles on a roller cammed 5.0L in a Mustang that I had. The motor was running beautifully, and I only took it out to swap it for a more aggressive roller cammed 5.0L. That motor had about 30,000 miles on it and was running awesomely when the car was stolen.

I firmly believe in roller cams.


You have some great choices there, but that motor is going to ruuuuuuuunnn. But its sounds like a race motor to me. Street is going to be real difficult with those choices. My experience with racing Fords ? They love heads work as long as you have a strong bottom end. Thats where the 351 C block worrys me. I aggree with George call SCAT they will put together a package balanced with the balancer and flywheel of your choice. The engine builder, Cerelli in NJ has always used Vandervell engine bearings and Speedpro 0 end gap rings on my FORDS. The Vandervells are steel backing not tin or copper and the 0 end gaps prevent blow by on a race motor that gets very little break in time. Talk to Bill Cerelli, he is the man in my book.
Hi Chris,

the beehive springs are a new item in the hot rod market, I've never had an opportunity to build a motor with them. If there is a coil bind issue then of course that takes precedent over other concerns. If Dan Jones has explored this issue for his motor, his advice would be wise to take. Based on what you have written it appears your choice is between max power which requires valve lift & more rpm which is the idea behind beehive springs. Of course, lots of racers have been turning lots of rpm without beehive springs for a long time. I'll write this one more time, let your cam grinder have the final say, let him pick the springs, rocker ratio, etc. Don't second guess the professionals you hire. Don't purchase every "go fast" goodie you read about & don't run certain parts because "so and so" is running them.

The belt drive for the cam will be a high maintenance item. Do you like working on your car? I do not think the belt drive is a street car item, it is a device designed for constant high rpm, high valve spring pressure, high valve lift. You will not notice a difference in the way your motor runs.

The money you save on the cam drive, apply it towards a set of Yella Terra rocker arms (or a Crower, Jesel or T&D shaft system)

Why run a composite distibutor gear? A steel gear is the proper material to run with a steel billet cam. Steel gears are available & people are running them without failure. I would not install a composite gear in my new expensive motor until I read & heard lots of good feedback, they are new to the market.

Charlie, to answer your question regarding reliability: the aspect that most often shortens the life of a valve train is high valve spring pressure (or insufficient oil to cool the springs). The retro fit hydraulic roller cams come from the manufacturer with springs that run approx 130# on the seat and 365# at full lift, those pressures aren't that extreme. Comp & Crane rate their roller cams with these springs for 6500 rpm. What they are carefully juggling are those 2 factors, max rpm verses valve train life. I think the Cam makers have made good decisions, but I don't care about running my motor to seven grand either!

your frind on the DTBB, George
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