Hey guy, can anyone tell me about how much hp i have gained on my truck so far?

engine is a stock 84 460 out of a 1 ton truck. originally rated about 245 hp.
now its in a 66 f250 2wd

so far, I have swapped the stock single 1.75" exhaust for dual mandrel bent 2.5" with flowmaster flow through mufflers, removed the clutch fan for dual electric, removed the emissions equipment, removed the air conditioning, removed the power steering pump.

Still has the stock cast exhaust manifolds due to a space issue.

Also, what can I expect from swapping the stock manifold for a weiand stealth, with and without porting?

Thanks in advance guys,
Chris

 

You may have gained 5-15 HP by removing the fan and power steering pump.
Depends on the RPM's and fan clutch.
The A/C only loads the engine when it's in use and emissions controls mean nothing.

What carb do you intend to run on that intake?
You won't gain much without headers and porting of the thermactor humps in the exhaust ports. (that's where the real restriction is)

More compression (9-9.5:1) and straight up cam timing will gain a lot.
Matching distributor advance curve to your build will help when you have the pieces in place.
Once the exhaust side can flow a cam can make a big difference too.
Depending on your intended use larger valves might help.

Strap it to the dyno and see, but I doubt you have 210 at the wheels.
Personally, I'd be afraid of 400HP in a '66 pickup that has crap manual brakes and steering.

 

running a stock vaccum secondary holley 650, did the exhaust help much? I haul a 2200 pound cabover camper in it and am just trying to make it a little easier to get out of the lake when i go fishing.

 

Nothing wrong with a 4180 in your application.
The annular boosters do a great job of atomizing fuel.

Change the timing chain to a 'straight up' set.
Aftermarket roller like the Cloyes 9-1122 I have, or a 1988 and up timing set for an EFI engine.
You will notice a big gain in torque.

It's really hard to say what gains would come from your exhaust unless you dyno'd it before and after.
Louder does not necessarily equate to more horsepower, although it may sound that way.

I can't imagine a 1 3/4" exhaust stock...
Mine was 2 1/2" from each manifold into the flat muffler and a single 2 1/2" outlet.

I now have a huge school bus muffler that is dual 2 1/2" in and 3" out, through a universal stainless Magnaflow tailpipe.

Lessening exhaust restriction is a good thing, but the majority of the restriction is in the exhaust port and the manifolds.
Opening up everything on the other side is just reducing velocity and harming scavenging, IMO.

I'm sure others will be along with their opinions.
There a lot of members on this board with more experience than me.

I had a camper similar to yours for years.
Body roll was more of an issue than getting going.

 

1.75" = 2.404" sq
2.5" = 4.906" sq
3" = 7.065" sq

The area of a circle goes up fast with the increase in diameter.

 

yep, body roll is a huge issue, airbags and rear sway bar are on the list

 

My truck came with the towing package, so the big sway bar was already there.
I'd imagine if my cabover was heavier, the truck would sit on the helper springs and that would have helped.
I never considered air bags -but then- I only used it once or twice a year.

 

one of my favorite places, when the lake is low we go way upstream and the road leans one way pretty bad, so being able to drop air pressure on one side and raise the other will help me there.