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1973 C10 "The Purple Truck"

Basic build
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Turns out the fuel starvation was due to a dirty filter.

When I installed the system @folkeset me up with a washable filter. It's sintered brass. There weren't any kind of chunks but it had a black tinged coating covering the element. I washed that out with brake cleaner and blew air thru it.

As soon as I started the engine the fuel pressure was up 10psi over where it had been at idle. I even had to turn back the idle speed screw.

I am curious what it was plugged with. Everything is new except the bit of factory hard line on the frame rail. I wonder if the new in-tank pump had some gunk in it? Seems like either that or it's just getting dirty over time. I'm thinking this system probably has about 10K miles on it.
 
mrk5 said:
Turns out the fuel starvation was due to a dirty filter.

When I installed the system @folkeset me up with a washable filter. It's sintered brass. There weren't any kind of chunks but it had a black tinged coating covering the element. I washed that out with brake cleaner and blew air thru it.

As soon as I started the engine the fuel pressure was up 10psi over where it had been at idle. I even had to turn back the idle speed screw.

I am curious what it was plugged with. Everything is new except the bit of factory hard line on the frame rail. I wonder if the new in-tank pump had some gunk in it? Seems like either that or it's just getting dirty over time. I'm thinking this system probably has about 10K miles on it.
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You could have easily picked up a load of bad fuel from a gas station. Or just crap over the 10k
 
That stupid little rubber hose between the pump and the sending unit could be coming apart. I’ve had one I pulled apart that the hose was breaking down due to ethanol in the fuel.

That would be my bet for the source of black substance on the filter.
 
ZooMad75 said:
That stupid little rubber hose between the pump and the sending unit could be coming apart. I’ve had one I pulled apart that the hose was breaking down due to ethanol in the fuel.

That would be my bet for the source of black substance on the filter.
Click to expand...
That piece is new, but you are probably right, only about a different piece of hose. At the engine end of the fuel feed I have the factory hard line and then a short piece of hose followed by the 10 micron filter and about a foot of hose up to the fuel rail. When I pulled the filter apart to clean it, that little piece of hose left black all over my hands. I didn't think that was a good sign, so I replaced it when I re-installed the filter.

I couldn't tell what hose it was. I'm pretty certain it wasn't original hose because of the pressure of EFI over carb, I know better than to trust that. But it didn't have the green markings on it like the Earl's Vapor Guard hose I used everywhere else in the system.

Based on what you're saying, I think it definitely was breaking down.
 
Just before I figured out the fuel filter issue, the engine developed a choppy idle. I figured it was related the to the fuel issue. Now that I have full fuel pressure, I still had the choppy idle. I started investigating and found this.

20221101_114605.jpg

Yes, I have an intake leak. The other side is nearly as bad.

I have rechecked the intake bolts a number of times. Is there something else going on? I'm also reminded that I found this on the original engine when I did the swap:

2022-04-02 16.59.25.jpg

Looks to me like the same thing happed on 2 different blocks. Could there be something going on with the intake?
 
If the heads have been milled then the intake might not fit square anymore. Or maybe the intake is warped some.
 
Are the valve covers on when you tighten the intake down?

I've seen intakes before that interfere with the valve covers, it almost looks like your gasket is snagging on the valve cover, and then when you tighten the intake down, the center of the gasket is held up and the ends are pulled down and torn?

I have had to mill or grind on intakes and also trim gaskets to clear before.

You can put a straight edge on your intake to check it. But I am guessing something is interfering and preventing a good seal. I would do a dry fit without RTV to test everything out without the valve covers on so you can see everything.

Also, is the felpro gasket in the upper picture the correct size? Is it too big or did it get pulled up that far?

I typcally look down in the ports after install before I tighten it to make sure nothing shifted.

I have also drawn a silver sharpie line on the gasket at a few places both sides so I can see from the top if the gasket is correct still before I tighten it down.
 
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"Never put an intake manifold on with the valve covers on." As my dad drilled into my brain. I never asked why. I assumed it was so he could clearly see if the gasket creeped while torqueing the bolts.

I think Heath is correct that the gasket snagged on the valve cover. The bottom is in the correct alignment with tears at the bottom of the ports. If the gasket just creeped up, it should not be at the side of the valve cover. Are both sides doing that? I have also seen intakes with a slight misalignment on the angle of the head mating surface. It will cause that also.

Did you have to push those bolts in when you assembled it? They should just fall into the threads. If you have to push past the gasket, something is not correct.
 
You can glue the gasket to the intake with some aerosol high tack. Then it will definitely stay put. Or glue it to the head. Just not both.
 
I don't remember if the valve covers would have been on or not. I'm inclined to say they probably were installed in order to minimize the risk of anything falling into the heads. I do remember when I first installed the intake on the original engine, I had to do something to clear the valve covers. IIRC @6872xtc had the same issue and that's where I read what I needed to do on mine.

I do use gaskacinch to glue the intake gaskets to the head.

@folkenheath I do think the port openings on those gaskets were larger than they needed to be. It fits but it was right at the outside edge with plenty of room from the port opening.

For what it's worth, they held for about 5 months and 4,000 miles.
 
Is the bottom picture the old gasket and the top picture the new gasket?

Because you may have two different things going on here.

The blue line showing is not a good sign, that means hardly any gasket was actually sealing the intake...

I typically RTV around the ports on the head side, but not the intake side, except I RTV around the ports on both sides for the water jackets on both ends along with the end rails of course.
 
The bottom picture is the original install on the old engine.

I only RTV'd around the water passages. These are supposed to be the print-o-seal gaskets that don't need RTV.
 
I had to clearance the valve covers at the injector bosses, so at the valve cover bolt area. I saw a PF4 intake getting the sides of the injector bosses milled for clearance on a Ferd small block so that the aluminum valve covers didn't have to provide all of that clearance.
 
I checked everything with a straight edge and it all looks good. I dry fit the intake with and without gaskets and it fit right with no gaps where there shouldn't be. I also rechecked the bolts a couple times after the initial install.

The only thing I can think of is when I first noticed the fuel pressure issue it was because I was getting some backfire thru the intake like would happen if you're running out of fuel. That's what tipped me off to the low fuel pressure.

All cleaned up, ready for install.

20221106_115550.jpg
 
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