440 HP Street Build - Using Stock Manifolds?
 

I have a '70 Satellite with a tired (non-original) 440, Torqueflite. Car will not be raced, at least, not by me. I want the strength to lite 'em up at will, yet be a comfortable highway cruiser.

I want to use some 915 heads that have not been re-done yet, or possible 440 Source Stealth heads, depending on how much work the 915s need.

I currently have Hooker headers. I don't like headers. If I use the 2 1/2 stock iron exhaust manifolds, that should be my limiting factor, at least in terms of ultimate horsepower. However, I prefer lower-end torque and taller rear gears.

I may keep the header setup if I'd be choking the engine too much. But I like the idea of a "sleeper" setup.

What kind of RPM will torque and HP peak at with stock manifolds?

Will a Holley fuss too badly w/o the exhaust head on start-up? (I have run BBCs with the transfer in place in winter, and w/o the butterfly in summer.)

I intend to use 7/16 rods, floating-pin pistons, and hyd flat-tappet.

Thoughts?

HC -

Using stock manifolds, you will slightly reduce exhaust flow and add weight, not to mention loosing some of the "Hot Rod" look and sound. Since you're talking about a street car, the advantages are less under-hood heat and better fit/clearance. That might be a pretty good trade off. You can also give the engine bay a more stealth/stock look. And you can maintain the full duel exhausts and "X" or "H" pipe.

Bottom line, it has to be your call.

I've been running Hooker headers for 30 years, since my racing days and every time I have an exhaust leak or have to change plugs, I keep thinking about going back to the stock HP manifolds.

Sorry can't give you exact HP numbers, but assuming a stock cam, I'd guess around 20 HP loss.

Archer

I would run the manifolds and keep it sleeper stock.

I had a couple of BBC Corvettes back when, street only, and I used the factory iron manifolds. Never a hint of trouble. I've already had trouble getting at the starter with the Hookers in there.

I would agree with an overall 15-20 hp loss , scavenging will suffer especially at higher Rpms running large pipes off the manifolds will help , I always port match the manifolds as far as I can get to & port the outlet as well , every bit helps !!
I have also used stock manifolds on 440 Stroker builds , one is an original 70 440+6 shaker Cuda built to 512 but it looks bone stock , a mechanic friend figures it is one of the most powerful street engines he has ever driven , I did use 3" TTi exhaust though LOL !!

Psycho, did you keep the exhaust crossover open? (Stealth heads don't even have the crossover.) I've had my carb freeze up on cold, humid days.

The factory manifolds are 2 1/2 at the exit. How does using 3" pipes help scavenging? I would think they'd do the opposite by slowing down the gases (more volume, more mass).

What kind of climate do you reside in? I've had no trouble with deleted heat crossover, headers, open six-pack hood scoop, open element air filter, DP HP Holley carb (no choke), and 20* F temps.

I always block the heat cross overs , kinda stepped header theory , create some velocity in the small manifold & open it up away from the head
I have run car below freezing on the highway with the carb sealed to the hood scoop & had the car start to misfire the carb & intake were so cold !!

I froze up last in Washingon, DC. Not that I ever want to return there. I live by the Gulf in N FL. Carb last froze up in DC in 40 degree weather, very damp, in the AM. Had the exhaust xover blocked and the butterfly omitted.

I still don't understand opening up the exhaust to 3" after a 2 1/2" passageway out of the manifold. I need to read up on it. My impression is to keep it the same diameter all the way out for velocity. 'Course, mufflers change all that, right? Hmm.

Florida is special for cold humid winters my 2bbl on my first work van use to freeze up but i have not had a recurring issue with the 4bbl's
of course this new combo is going into its first winter so we will see, this air gap manifold doesn't have the option of heat crossover .

I think you hit it there! Accomodating the intake manifold of preference. Point may be moot.

Not one exhaust side. I think I'll run 2 1/2 pipe, no muffs until the tip-tipes out the end. In front of the rear wheels. I'd like to H-pipe it in somewhere to reduce "blatt."

HC -

Without an aftermarket radiator and a pretty low thermostat, most 440's run pretty hot. Never had a carb freezing problem, but I don't run the car in the dead of winter either. (That's with an old style Eddy Torker manifold.)

Right now for the street, I'm using 1 7/8" primaries into 2.5" custom pipes (with an X pipe), exiting out the rear. 3" pipes might be better, but at 500+ HP, the engine hasn't complained yet. The mufflers should left be in the stock location.

For racing, the exhaust pipes were disconnected at the header flange. (Didn't see any difference between that and using a 14" extension off the flange.)

Archer

Would be nice if there were cast iron manifolds in the 3" variety...

early 60s Max Wedge !!

That is true! How interesting! Thanks for the tip!

Well, too bad they won't work without a lot of sheetmetal carving.

Yeah not really a serious suggestion !!