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rodderforchrist 03-19-2007 04:09 PM

Supercharged 351W advice requested
I am building a fresh engine for my 47 ford pickup, running C-6 3.73 rear gears. I currently have a bone stock 69' 351w with 60,000 miles. I pulled it from the car and installed valve guide seals and a B&M 144 supercharger (currently 6psi of boost@ approx 3000rpm). It's tired and i would like any advice on how to build this engine. I have a .030 over stock shortblock I had planned to swap the pistons out in (9.0:1, purchase a set of 185cc AFR heads with 75cc exaust ports (for the blower) and a hyd. roller cam to put me somewhere in the 500hp/500ft/lbs of torque range. This is a street rod that i would like to take to the strip and play with. Primary operating rpm idle-6000. I have considered a longer rod (300 6 cyl or after market) to get the rod ration up. what do you guys think? Is it possible on a stock bottom end? Do I need a girdle? Thanks in advance for the help. I will try to post a pic of my ride.

rodderforchrist 03-20-2007 08:11 AM

1 Attachment(s)
Here is the truck in question:

MII front end v6 springs grnada rotors
9" rear (3.73 gears) with 4 link & coilovers
69' 4v 351w w/ 144 b&m supercharger
c6 tranny
locar shifter

NXS 03-20-2007 10:08 AM

Great looking ride, I think you know what to do, use a cam with about 230-235*@.050

firestone 03-20-2007 11:35 AM

That sounds good to me. As for the rod ratio, from what I have heard and read it seems like it sometimes gets blown out of proportion. As far as hp goes, I dont think you will notice a whole lot of difference between rods of different lengths. The longer rod should extend the life of the motor a little bit though due to a reduction of cylinder wall loading. I would see what pistons are available off the shelf, and see what rod lengths you can use with them. If you get too long on the rod, you will have to get a custom piston made which is expensive, and I dont think worth the hassle. As for a stock bottom end, it may work, but I would not do it. For piece of mind more than anything, I would by a nice street/strip assembly, Eagle seems to make some nice ones. The AFR 185 heads are a great choice. By "girdle" I assume you mean a stud girdle. I think they are always a good idea in order to create some more stability in the valve train, but unless you are running a solid cam I dont think they are really necessary. As for the cam, it will depend a little on how high your stall speed is. These heads are really going to react well as you increase the cam size, but you dont want to go too big so that you dont have a high enough stall converter. I would probably recommend a custom grind to get a supercharger cam. I would really try to get .500+ lift to try to take advantage of the head flow assuming that would not get you into valve to piston clearance problems.


rodderforchrist 03-21-2007 02:10 PM

Desk top Dyno requested
Ok guys thank you for the input. I have been crunching numbers ($) and I think I have a engine to build. I have decided to go with a non-roller hyd cam, see what you think. Would be great if someone could run this on desktop dyno for me, I think I have all the info. Exhaust consists of 1 3/4" primary 3/4th length headers to 2.500" duals through 2 chamber flowmasters.

Firestone, I meant a main stud girdle, but do you either is really necessary, I am pretty conservative (i.e. afraid of breaking things) behind the wheel so I really hope the stock rods/crank are ok. I scored a great deal on a fresh short block, all I planned to do is float the piston pins and turn a set of wrist pin buttons & put all my $ into heads & valve train (& ARPhardware). I have access to machine shop to build my own main girdle, that is the only reason I asked about it.

Here it goes.

B&M 144 Supercharger, 8psi boost max
Comp ratio: 9.0:1
Bore: 4.030
Stroke: 3.500
Rod: 5.956
Piston: SRP-138722
Head: AFR # 1387
Intake: 185cc
Exhaust: 69cc

Flow (int/ex)
.200 129/118
.300 189/153
.400 234/178
.500 267/185
.550 279/190
.600 282/191
Cam Specs:
Comp Cam Hyd flat tappet - custom grind
Dur @ 0.050 = 230/236
Lift = 520/523
114? lobe separation

I had planned to run a 2500 stall converter, currently using stock converter.

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