I was going to build a more radical street engine for my wife's black 73 Thunderbird a couple of years ago and I bought a set of P51s, but the bad economy stopped me in my tracks.
I can now proceed, and common sense or not enough cash to do what I really wanted to do prevails. I think that the P51s are too big for this combination, so they will set on the shelf. Here is what I am commited to.
Stock block with straps on the 3 center mains.
Scat cast crank 4.15"
Scat "I" beam rods. 6.7"
10.3 to 1 compression from Probe forged pistons, 21.8 cc dish, 1.525" CH
C9s ported with valve sizes to be determined.
Blue Thunder, dual plane, dual quad, standard port intake manifold. (ported)
Custom, solid lifter cam, Max power at about 5200 RPM
But, what carbs? I am thinking about Demon's new 625 CFM carbs. Polymer bodies, small primarys, large single secondary.
Ceramic coated headers from Stan at FPA.
If anyone has any thoughts to help me, I would be appreciative. I am trying to build a strong mid range torque engine to strongly move a heavy car.
I think that sounds like a pretty good plan!!
The carburetor design sounds good but would be better if it were in the 650-750 cfm range.
The 650 I am using right now pulls mine to 5200 easily. And it is pulling to 5200, not carrying from a lower rpm.
For a dual 4v carb application those carbs are a good choice especially given the relatively low peak rpm and 500' displacement.
This is a 5000 pound T bird guys. Its all about generating as much torque and HP under the curve as possible.
An update of sorts on the 1973 Thunderbird project. The heads and intake are being prepared at a professional porting shop and are almost done. The short block has been machined and is being assembled now. I drove the bird home from the chassis shop where it has been for a while. With the orginal engine in it, we installed the headers and fabricated a full 3" exhaust system with an "H" pipe and 3" straight through Magnaflows. Also flanges just before the mufflers so the front half of the exhaust system can be dropped for tranny servicing.
The 2.75 gear ratio open differential was replaced with a nodular iron cased, 3.73 geared, Detroit Locker. The stock axles were replaced with Moser 31 splined axles and a big bearing kit. As for the rear axle housing control arms, the plan was to replace the stock rubber bushings with polyurethane bushings and box the lowers. We ordered a bushing kit from PST for $98, changed the bushings in the 2 upper control arms, and wouldn't you know it, there were no bushings large enough for the lower control arms. Damn! Called PST and they could not help us. So I ordered a kit from Energy Suspensions for $58. Same thing, no bushings large enough for the lower control arms. Energy Suspensions was helpful and told us our control arms were from a performance package from Ford and that no one made a polyurethane bushing for it. Soooooo, we made our own lower control arms from thick walled chrome moly tubing and used the smaller polyurethane bushings and sleeves. What we learned is that PST buys the Energy Suspensions kit, puts it in a plain box, and cuts Energy Suspensions' name from the instruction sheet. Oh ya, and increases the retail price from $58 to $98.
The suspension on the bird already has coil springs 25% stiffer than Ford's heavy duty option. The ride height is stock in the rear and 1 and 1/2 inches lower than stock in the front. Also it has sway bars front and rear from ADDCO.
As soon as the engine is together, it will be broken in and tuned on the shop's new top line dyno.
The bird is being set up to be a big, comfortable road car that will be fun to drive.
Sounds like an interesting build. :)
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