rovers2000

here is the pictures of my rebuilt 396 ready to go get dynoed. The car looks bear with no motor.


My scaner is on the frits so here are the numbers from my camera. The timing is at 37 degrees. The motor ended up making 390 hp at 6300 rpms.

Thanks to DMO motors in plattsburgh ny for the machine work and dynoing.

54greg

Love that motor

rovers2000

this motor build was a great project and cant wait to get it out on the road.

tjstarduster

great looking valve covers! roller rockers i presume!

Mark Lovejoy

I really like the Valve covers too, where did you get them?

jjtoma

They are nice !, might be from here: PML

http://www.yourcovers.com/valve_covers_11042.php

NORTY

That's too pretty to hide under the hood. That needs to be on display in your living room...

rgs

I have a couple questions about your dyno results.

It appears that you're a little rich at the beginning and a little lean on the top. Did you try re-jetting?

It appears you have a 160 degree thermostat. Isn't that a bit cold? Shouldn't it be at least 180?

Looks like you're running a lot of oil pressure, almost 90 psi. Did you modify the stock pump or install an aftermarket one? What distributor drive gear are you using to handle the additional stress?

rovers2000

Yes we went from 70 jets to 76 in the front of the carb and 76 to 80 in the rear of the carb. my remanufactured origonal pump only put out 2.5 psi so we had to use the shops electric pump set to 7.5 psi.

The car is dynoed with a different thermostate neck and no thermostat.

The oil pump is an after marker pump from summit racing with a weld on pickup and the distributor drive gear is stock bb gear.

rovers2000

this is where i got the covers

rgs

If you want to properly tune your engine on the dyno, actual operating conditions should be simulated as close as possible. In your case water temp and fuel pressure were noticeably off from as-to-be operated. Excess fuel pressure will cause a wider variation in the fuel level and variations in the results, and operation. Actually, I shoot for about 2 psi at the inlet to the carbs. Changes in operating temperature will affect many things but in general, warmer will produce more power.

You might want to re-consider either an aftermarket distributor gear and shaft or the pressure setting of the relief valve in the pump. You're putting twice the torque on the distributor shaft and gear from stock. I've seen the tip of the shaft twist on a stock shaft with a high pressure pump and the drive gear strip. What need are you filling by going with a high pressure pump? You can adjust this setting.

65tripleblack

I've gotta take issue with that.
Coolant temps @ 160 will produce more power than @ 180 because the heads and intake manifold temps will increase the density of the charge. If the OIL temp becomes too cool, then this will increase parasitic losses due to oil shear and friction losses.
If you can keep the coolant @ 160 and the oil @ 230, then that is close to ideal conditions.

rovers2000

2 psi at the carbs is to low. A factor pump producess 5 to 6.5. I am sending my distributor out to be rebuilt and a new gear put on.

rgs

In our mud drag race truck, we used 4 high pressure fuel pumps, 2 for the 1100 scfm carb, 2 for the nitrous systems. Together, the engine produced 1100 hp. The pumps were mounted in the back, plumbed through 10 micron spin on hydraulic oil filters, then through pressure regulators and dropped to 2 psi at the inlets to the carb (higher for the nitrous systems). I use pressure regulators on any performance application. I even put one of the cheap diaphram regulators on my 67 Fiat that I autocrossed. The key here is pressure at the inlet, not the pressure developed at the pump.

I don't doubt that the stock pump puts out 5 to 6.5 psi. The higher pressure is a factory compromise. Pressure is lost throught the line and filter. As the filter plugs, it drops more pressure reducing the available pressure at the inlets. Without a regulator, they needed to start with a higher pressure. Bear in mind, with a 2 psi inlet pressure, you need to use a pressure regulator.

The higher pressure requires higher force to shut the float bowl needle. The higher pressure is developed from a higher bowl level. With neoprene tipped needles, they become slightly deformed and stuck in the seat. This causes the seat to stay closed slightly longer as the bowl level drops. The fuel level can easily be adjusted back to correct, but this whole sequence allows a wider range to the fuel level. The lower the pressure at the inlet, the more stable the level will be as long as there is enough pressure to deliver the fuel into the bowl.

This comment was simply an observation of the pressure readings on your printout. I would have expected them to have used a regulator, and as such, set to a more appropriate pressure.

rgs

Your statement about increased charge density is absolutely correct, but in our road racing experience, the loss due to higher temps of the air charge are more than offset by the gains in the cylinder of the warmer combustion chamber.

lucky131969

[QUOTE=rovers2000;1572788136]here is the pictures of my rebuilt 396 ready to go get dynoed. The car looks bear with no motor.


Dynamite looking motor. Those are the valve covers that should have come stock.

rovers2000

[QUOTE=lucky131969;1572817652]thank you i do like the covers also.

rovers2000

when we dynoed the motor with 2 psi at the inlet to the pump we would only run 240hp and run lean. With the 7 psi we would not run out of fuel and put out 380 hp. I am not a profesional tuner but i would have to say we were running out of fuel in the bowls at 2psi. But psi is nothing with out the proper gph fuel flow.

65tripleblack

Float levels must be reset with any change in inlet pressure, for the reasons "rgs" stated above. His reasoning (about the consistency of the float levels) using lowered inlet pressure is SOUND.
Your float levels were obviously set too low @ 2psi, resulting in fuel starvation.

rovers2000

you set the float leaves till fuel comes out of the holes. They set that the same before both runs.