LT1 and a T56 in a 55 Chevy

Fitting together the fuel and exhaust systems

Had to pull off this right side header to get a drill in
for the last two fuel line mounts....
55HTfuel050s_Jan2018.JPG

The header is going to be close...
55HTfuel062s_Jan2018.JPG

Yes, I'm going to need some insulation for those fuel lines
to protect them from the exhaust heat
55HTfuel063s_Jan2018.JPG

Or, wrap the exhaust system to keep the heat away from the fuel lines...

More Later....
 
I need to learn about how this efi system works....
Think: '93 Camaro Z28, LT1 system, stick shift....
What are these ports on the rear of the plenum for?
55HTfuel059s_Jan2018.JPG

Also on the left side....
55HTfuel061s_Jan2018.JPG

And on the right side....
55HTfuel060s_Jan2018.JPG

More Later....
 
First picture on the left(with a triangle gasket mark) is for the EGR valve.
 
Decided to block off the EGR (Exhaust Gas Recirculation) Ports...
A ball peen hammer and sharp edges make cutting templates easy....
55HTfuel065s_Jan2018.JPG

Gotta transfer that to some 1/8" plate....
55HTfuel066s_Jan2018.JPG

Get the holes drilled accurately first....
55HTfuel067s_Jan2018.JPG

And finish shaping them to fit the templates....
55HTfuel068s_Jan2018.JPG

Paint next....
 
55HTfuel035s_Jan2018.JPG


Trying to figure out how to connect these fuel lines on the fuel rails....
The rear tube is 3/8" and I'm told is the fuel in connection...
The front tube is 5/16" and I'm told is the fuel return line...
I've ordered an AN-8 connector for the 3/8" line,
and an AN-6 connector for the 5/16" line.

And a tee with both AN-6 and AN-8 connections for the fuel
return connections at the fuel PR valve...
55HTfuel069s_Jan2018.JPG


The upper tube in this pic is the 5/16" fuel return line.
Under the fuel rail it is connected to that black device....
I'm guessing that device connects to engine vacuum??
This one is pretty old and gnarly, think I need to get a new one...
55HTfuel037as_Jan2018.JPG


Any Comments?

More Later....
 
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Thanks for all the info, that helps a lot....
http://garage.grumpysperformance.co...oblem-sources-1987-corvette.15596/#post-93275
It's been rainy here, humid, it took these block off plates for the EGR openings in the plenum forever to stop being "sticky" so I could install them...
55HTfuel073s_Jan2018.JPG


More pix of this fuel return setup at the fuel rail....
55HTfuel070s_Jan2018.JPG


I'm trying to find info on exactly what this device is, it looks like a manifold vacuum
operated device to control fuel pressure in the fuel rails....
55HTfuel071s_Jan2018.JPG


It's obviously not adjustable, and I'm trying to find out how it operates,
and what the specific parameters are, and if I can just dump it and
plug the hole in the rail? Or find another one that is adjustable so
I can tune it to my particular requirements?
After all my fuel pressure regulator is a constant flow return type, and is mounted right next to the motor, and feeds directly into those fuel rails, so I am trying to figure out just what this device does in addition to my PR, like maybe it adds additional pressure when the manifold vacuum drops??
Hmmmmm.....
55HTfuel072s_Jan2018.JPG


These are the fittings I found to attach AN hoses to these fuel lines at the fuel rails....
55HTfuel074s_Jan2018.jpg


More Later....
 
Last edited by a moderator:
#3 in the diagram, its your OEM fuel pressure regulator the vacuum line changes the effective fuel flow and pressure slightly to compensate for the engine loads
manifold vacuum changes under engine load
The spring pressure is what governs your fuel pressure/flow at any condition (pressure and flow are inversely related). Engine vacuum acts on the diaphragm which compresses or relaxes the spring, thereby opening or closing the valve. Under high engine loads (low vacuum) the spring overcomes the vacuum diaphragm, opens the valve and more fuel flows. Under low engine loads (high vacuum) the vacuum overcomes the spring and the valve closes (not all the way, obviously) and fuel flow is reduced.
Click to expand...
fuel_rail_assembly_and_parts.gif


Regulator-ReturnStyle03d.jpg

9th2.jpg


afpr2.jpg

http://static.summitracing.com/global/images/instructions/hly-199r10036-1.pdf
swapping to an adjustable versions usually good for a couple extra ft lbs of torque
 
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AEI-13301_ml.jpg

I would think this Aeromotive fuel PR valve mounted right next to the motor would provice all the fuel control I need, and I think I can remove the stock, non-adjustable unit on those '93 fuel rails, and eliminate the fuel return directly from the fuel rails, but I am only guessing!

Aeromotive also suggests running two inlets to the fuel rails from a tee, and at the other end of the fuel rails, combine the outlets into the Aeromotive PR and then return to the fuel tank. That seems excessive to me for this particular application, the most likely setup from what I can see now, is to eliminate that stock unit on the fuel rail, plug that hole, and feed the fuel rails inlet directly from the Aeromotive PR unit.

The Aeromotive unit has a vacuum tap available, but I'm thinking I probably won't need to use it. Leave it at atmospheric sensing. But I can hook it up and see what it does also, it might really be a useful option.
 
THINK,
EFI works at higher pressures (a 1985-1991 TPI corvette as an example generally operates in the 38psi-42 psi fuel pressure range)
THINK,

fuel tank...to .fuel filter....to .-fuel pump....to feed into fuel rail& injectors. then out too....fuel pressure regulator...then too..return line to fuel tank



Fueltpsystem.jpg

fpregv3.jpg

fpregv4.jpg


the vacuum line to the plenum drops under full throttle,
so the diaphragm and check ball,compensate, to maintain max flow rate to the injectors,
the diaphragm and check ball in the regulator become, or are just a tiny bit harder for the fuel pressure too force open,without the plenum vacuum above the the diaphragm and check ball
thus maintaining fuel rail volume and pressure before any of the fuel can exit the return line

fpregv2.jpg

fpregv1.gif

fuel_rail_assembly_and_parts.gif


efisystem.jpg


it might help if you think, fuel pump provides fuel flow volume,
fuel pressure is a measure of resistance to fuel flow,
the fuel pressure regulator acts as a valve that opens if the pressure exceeds about 42 psi (YES some versions like yours are manually adjustable) but the reason its there is to maintain a consistent 39 psi-42 psi to do that you allow the fuel pump to stack or pressurize fuel in the fuel rail and in theory the fuel pressure regulator only allows excess fuel volume to flow back to the fuel tank through the return line if that fuel pressure exceeds the 42 psi, the pump is designed to provide a bit more than the required 42 psi too insure fresh cool fuel is cooling the fuel pump while maintaining that consistent fuel volume at the fuel pressure, when you tromp on the throttle the flow of fuel drastically increases, the regulator momentarily restricts out going fuel to maintain the fuel rail pressure and volume, until the flow demand drops enough, for excess volume and the resulting increased pressure that results to open the regulator again,
 
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I'm assuming the vacuum connection on that return line regulator allows the regulator to add a little more furl pressure in the fuel rail when the accelerator opens suddenly and the vacuum in the plenum drops, offsetting a possible lean situation.
 
yes thats correct the vacuum line to the plenum drops under full throttle,
so the diaphragm and check ball,compensate, to maintain max flow rate to the injectors,
the diaphragm and check ball in the regulator become, or are just a tiny bit harder for the fuel pressure too force open,without the plenum vacuum above the the diaphragm and check ball
thus maintaining fuel rail volume and pressure before any of the fuel can exit the return line
 
Too many delays in my life right now, but am getting back on the '55 HT project.......
Willy

UPDATE:
Finished fitting and hanging the mufflers, a pair of long body 2-1/2" glasspaks, will probably be loud !!!
55HTexhaust010s_Apr2018.JPG


MORE pix here

As I rebuilt the floors in the '55 HT as piece work, using galv. 20 ga, there's a lot of welding slag, etc underneath needed cleaning up...
So I have been laying under the body on a creeper, grinding, smoothing, seam sealing, and will do a fresh undercoat. Nasty work, head all covered, breathing protection, am covered head to toe with dirt when I scuttle back out from under there...

IMG_5572S.JPG


One of the rear wheel tubs cleaned and ready for seam sealer, then undercoating...

IMG_5573S.JPG
 
2Loose said:
Too many delays in my life right now, but am getting back on the '55 HT project.......
Willy

UPDATE:
Finished fitting and hanging the mufflers, a pair of long body 2-1/2" glasspaks, will probably be loud !!!
55HTexhaust010s_Apr2018.JPG


MORE pix here

As I rebuilt the floors in the '55 HT as piece work, using galv. 20 ga, there's a lot of welding slag, etc underneath needed cleaning up...
So I have been laying under the body on a creeper, grinding, smoothing, seam sealing, and will do a fresh undercoat. Nasty work, head all covered, breathing protection, am covered head to toe with dirt when I scuttle back out from under there...

IMG_5572S.JPG


One of the rear wheel tubs cleaned and ready for seam sealer, then undercoating...

IMG_5573S.JPG
Click to expand...

Welcome in my world. I had to do the same work for 5 month on my 55. The undercoating was cracked and rust was under there.

My exhaust is very similar. Hooker headers, than cut outs like you, short pipe and two Smithy's muffler, than I went over the rear end and straight pipes to the back. The pipes ending 1/2" behind the rear bumper with turn down tail pipes.
 
WHAT, nothing about that small event in your neighborhood ????

IIRC, you live on a volcano, but hopefully not the one with a problem!!!
 
That lava flow is on another island, 100+ miles away. We watch it on the news like everybody else...
 
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