I've gotten my 72 F-250 w/390 out of storage from the winter and now need to get it ready for 1st mud race. It has the 4 speed manual w/410 gears, MSD 6al ign, 9.5-1 comp pistons and run the timing at 38 deg. when racing. The crane cam thats in it is a high RPM CAM(3500-7000) and switched over from hyd lifters to solid clam type with adj roller rockers and heavy double valve springs to match. Right now its got an Ed Performer manifold with a 750 Holly which I am told doesnt work for high RPM applications. Now I've read all the posts on intake manifolds and I'm confused, according to the tests the ED street makes most horse at higher RPM's. Does someone have real life seat of the pants testing with a high RPM 390 and steer me twards the right manifold. I'm also looking for a set of long finger drip rails, anyone got a pair they would sell, thanks-Jay.
The 750 is good to about 6650 rpm. An 800 would be good to 7090 rpm. What are you talking about with the cam? Did you change from a hydraulic to a mechanical? You can't just run solid lifter on a hydraulic cam, it will ruin the cam and lifters. You need to find new friends, some that either know enough to not talk about carbs, when they know nothing about them or some with with sound carb knowledge. A 750 will work fine at high rpm, the limiting factor is how big the engine is and/or how many rpms you can turn with it. In your case the carb is not big enough to run to 7000. If you are running that 390 to 7000, I hope you did some oils system up grades and got the rotating assembly balanced.
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Bear 45/70
Gimp Racing
Don't pick a fight with an old man. If he is too old to fight he will just kill you.
Isn't there some work required on the rocker shafts, pedestals, and support for the ends of the shafts when you're talking 7000 rpm? I remember reading about the "7000 rpm kit" for 427s back in the day. Not sure what it all was, but the last FE build I saw showed additional work (supports on the ends, other) on the rocker shafts.....
Hope you have a steel, approved scattershield and not a pot metal bell....
Isn't there some work required on the rocker shafts, pedestals, and support for the ends of the shafts when you're talking 7000 rpm? I remember reading about the "7000 rpm kit" for 427s back in the day. Not sure what it all was, but the last FE build I saw showed additional work (supports on the ends, other) on the rocker shafts.....
Hope you have a steel, approved scattershield and not a pot metal bell....
Supports are added to the ends of the rocker shafts so that both sides of the end rockers are supportted. That was for Nascar where they ran at 7000 for hours at a time. Normally drag cars didn't do it.
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Bear 45/70
Gimp Racing
Don't pick a fight with an old man. If he is too old to fight he will just kill you.
Supports are added to the ends of the rocker shafts so that both sides of the end rockers are supportted. That was for Nascar where they ran at 7000 for hours at a time. Normally drag cars didn't do it.
Do tell. I've always wondered who,what,where the endstand concept came from. Do you know when it was first used? The 7000 rpm kit was the std steel crossdrilled crank and LeMans rods. The 10,000 rpm kit was the NASCAR steel crank and NASCAR rods with widened 1.835 journals and rods.
Bear- I normally put the 6000 RPM limiter chip in the MSD box for race day. It does have the mechanical cam. My friends have nothing to do with this project, I have very good friends. I was told at the race by people that race FE's I need a different intake manifold for running higher RPM's. If you read my thread I'm not concerned about the carb, it functions perfectly. What I need to know is what would be the best manifold to use with this application. Last year I ran 10 races with no problems + I drive it on the street occasinally. Maybe someone can give me some positive feedback. Thanks-Jay.
Is the present setup port matched ? IIRC the shootout on the intakes was a real toss up for a few intakes. I'd think in real world conditions the end all would come down to the driving during the race vs the intake make/model. JMO.. if the heads are nicely ported and the intake port matched then IMO it'd be up to your skill from there on out. Maybe someone can post up a link to that shootout on the intakes for a closer look but I'm pretty sure an RPM or BT or F427 or S style will be hard pressed to prove it's weight in gold when crossing the finish line. Just my .02¢
The Edelbrock Streetmaster or Holley Street Dominator are 2 very good manifolds for your application with the proper mods done in the plenum. The Performer RPM (not the plain performer) is also an excellent choice. The Performer is basically an aluminum version of a stock manifold (performance wise). End stands on the rocker shafts are a good idea. Once you break a shaft, you'll understand. Lastly, I'd go with an 800 - 850 cfm carb. for 7,000 rpm. BTW I've got a .030 over 390 in my pulling truck.
The Performer RPM is a good intake for the price. I've made over 600 HP with one after some port match work and blending.
FWIW we ran a 445 inch stroker on the dyno and tried going from a 750DP to a 850DP. Engine picked up 30 horsepower and lost NOTHING down as low as 2500.
I consider end stands a MUST for high RPM. Its that "risk vs reward" equation...
The performer RPM is a good choice its a aftermarker version of the ford 428 intake but has a slight advantage over the stock version and you might want to considered a open plemun intake like the old school 390 Streetmaster alum intake it has some impressive # on making HP over the 428 versions better than most thought it would, and can be had for around $100 on Ebay, some roller rockers with the end supports is a very good idea as well, in the end the cam is the big factor on the RPM range but you need the valve train setup to handle the RPM too.
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High RPM 390 questions
