So I've got a scat 428 crank on order! This build is getting going. Still havnt got the block yet the guy is lazy and hasnt dug it out of his shed full of blocks. Anyways my next decision is the pistons. I may be leaning towards new forged ones now. How well will my 390 truck rods hold up? Is this something that should be a concern?

 

Your 390 rods should be fine. I strongly recommend you purchase ARP rod bolts for them though. Also, they should be submitted to the machine shop along with the crank, flywheel, pistons, wrist pins and retainers, balancer, cam gear, spacer and all bolts for balancing. The shop will balance each rod by grinding the top and lower balance pads to get them to the same weight, and then simulate that weight when balancing the crank.

I'd be very interested in what you finally come up with for forged pistons. Perhaps you can post info on the pistons once you identify them.

 

So i figure this build would be under carbed with the 650 so Im thinking i'll go with a 770cfm holley truck avenger. Ive been told that as far as the heads go bigger intake valves are not needed if i want bottom end really just a bigger exhaust valve for some better flow would be best for this engine. as far as headers go i have really long style ones and i also have a shorter pair that i may put on this motor. Do you figure these would perform better as well for my application??

 

Standard heads are reputed to flow quite well in stock form. I wouldn't go changin valve sizes. Just pick a cam that holds them open further and longer will do more or less the same thing.

Headers are a good choice, but I have no comment on wether you should use short or long ones. You may want to add a crossover pipe just aft of the header collectors, so collector location may play a factor as well as performance expectations when you decide which headers to use.

The math for selecting a carb may give you in the 650 cfm range, but I agree, a bit larger carb might be good. Others here may have alternate suggestions for you.

 

Already have a H pipe just past the collectors. I've been hearing quite a fewtimes now that these heads flow well in stock form. So would I be wasting time and Money for very little gain??

 

'73, why has your performer 390 been milled on the sides ? that isn't how things are supposed to be done. But you can throw the performer 390 out anyways.....those intakes are chokers, big time. Howsabout a Performer RPM or a Blue Thunder ? DinosaurFan

 

The performers are advertised for low end power!!?? thats why i got it. The performer rpm is not set up for my heavy 6500lb truck with 44's is it? I want power and LOTS of torque...
this is why i want the 428 because it makes mor power and torque in a lower rpm

 

Do not believe all the advertising you read. They lie as bad as politicians.

 

so your saying if I when from a performer to a rpm Id actually feel a noticeable benefit?? dual plane to single? What kind of #'s would I be looking at like 5 hp?
It couldnt be worse than a stock, heavy, 4 barrel, old technology intake though right

While on the topic what about a carb spacer? I currently run a 1 inch with 4 round holes.

 

Horsepower is rated at high rpm and is all about top speed, pretty much useless with your rig. Off the line acceleration is what you are looking for with your off road setup and in my opinion, which will be hammered by many, you would be better off with a plain old iron "S" manifold. Cheaper and you will not know the difference.

 

You're thinking correctly, you aren't building a hotrod Mustang or Fairlane for the street or the dragstrip, you want bottom & midrange torque- as you should for your application. The Performer is a disappointment on a hotrod car engine, because that's not what it's designed for- it's for torque, towing, throttle response, and mileage- which it does well. Another good setup on a 428 that can use a little more flow in your application would be an unported Streetmaster or Street Dominator, usually go for $150-$175 at the swap meets and craigslist. A few years back I had one of my 427's with flattop pistons in my old '77 F250 highrider 4x4, 14.5x36.5's and used a set of C4 390 heads with stock valve sizes, a 275/500 cam, a stock Street Dominator intake, 1" spacer, a 600 Holley, and short headers into Chrysler Street Hemi mufflers. That was one responsive critter, any time you touched the pedal something happened- started to get wheezy around 5500, but who cares- you're already there, and again, it's a 4x4, not a race car- and it got 13 MPG. Roll on the throttle about 2500 in 3rd and blow away the tires- now. Torque here, there, everywhere- and that combo would actually be torquier in a 428 than the 427. The 600 Holley works excellent on that deal for the RPM range and type of performance you're looking for

 

And if I recall correctly, many here and outside in the real world say the 390 Performer intake (which is just the plain Performer), is really the same as the old stock cast-iron 4bbls.

So, if he already has a Performer 390 intake, and it's useable, go with it.

I used one on my 11:1 390 with 292/292 .554/.554" cam build and it performed rather well pushing around a 5800lbs '74 highboy with 33's and 4.10's. Maybe an RPM would have been better, but I had a decent amount low-end torque to get that beast moving

 

I agree, shedding 50lbs on a 3 ton truck isn't going to make a dimes bit of difference and that's the only advantage the Performer intake has over the stock cast iron intake.

 

Yup.........................

 

Mean Jean ,You got 13 MPG. Thats impressive .