Yet another GMC build

[6DoF]

i don't know man, that hood inlet might be the best thing going for ya! keep under-hood temps down and keep that air filter from sucking just hot radiator air. can you duct it down to ram air wash the filter with fresh air?

or what about rear opening louvers on the back of the hood to help hot air and higher pressure out? same in the back of the fender liner?

[OKGMC4]

Originally Posted by 6DoF

i don't know man, that hood inlet might be the best thing going for ya! keep under-hood temps down and keep that air filter from sucking just hot radiator air. can you duct it down to ram air wash the filter with fresh air?

or what about rear opening louvers on the back of the hood to help hot air and higher pressure out? same in the back of the fender liner?

All good ideas. May even use more than one of them. I need cooler air going in but also need all that turbo heat going out. Started hanging the Old Air Hurricane. I kind of think it’s ugly as sin hanging out like that and there have been mixed reviews on whether they are good or not but it’s the only unit I could find that would fit in there. My Vintage Air Compac II worked great but just too big. It would freeze you out but had issues with sweating on HOT days and some with defrost fogging. I bet this one won’t have the arctic power I had but as long as it blows cold I’ll be happy.

[6DoF]

a buddy with a vintage air in a square body recently said something i hadn't thought of yet. the aftermarket HVAC's aren't set up for a fresh air draw, just the cabin recirculation. if you start getting too much moisture in the cabin it'll just keep pumping it onto the cold window until you open a window for a quick air change-out.

i've been wrestling with this and how to make a fresh air duct, with a swappable vent to recirculation. but then i think i never turn on recirc, so i should probably just draw outside air all the time.

[6DoF]

i hadn't found the Old Air stuff yet, that little guy is nice and small! the air intake is also really well set up to make an external air duct easier ... but their website layout kinda sux

[OKGMC4]

One of the fun things about Oklahoma, we have 100 percent humidity about 90 percent of the time. I figured that was some of it. The ac vents and the plastic housing would both sweat on a 90 degree and up day.

I liked the look of the restomod air stuff but sooooo expensive. And still wouldn’t fit my cab.

[Gregski]

Originally Posted by OKGMC4

And I probably have the coolest wife ever. She had a t shirt custom made for my birthday. Of course I can’t wear it while driving the truck. That’s like wearing an AC/DC t shirt to an AC/DC concert!

OMG I laffed so hard at that, worse, it's like Lars Urlich wearing a Metallica T shirt while drummin' for them

[OKGMC4]

Originally Posted by gregski

omg i laffed so hard at that, worse, it's like lars urlich wearing a metallica t shirt while drummin' for them

yes!!!!!!!!!

[OKGMC4]

The first time I built the truck I just cut a hole and stuck the radio in it. You could see the silver mounting case around the sides. I didn’t have the rear supported well and the radio tilted a little. I spent the day building a 1/4” recess and welding it in so now the radio is more flush and there are support tabs on the rear. Won’t sound any better but I think it looks a lot smoother.

[6DoF]

with the other dash work being down, now was the time! the frenched radio was 110% worth the time.

[OKGMC4]

Built all my ac hoses. Been a challenge but none worse than inside that kick panel. That there, fellers, is what u call 10 pounds o’ manure in a 5 pound sack. Now I can go to the next item on the list, though.

[OKGMC4]

Working on a way to make that giant hole in the hood actually useful. It won’t be pretty but should be super useful on keeping IATs down.

[BIGglaSS]

Nice work. Hey, I was going back through your build. How much did you cut off the rear spring? Think I will have to do the same.

[dsraven]

I have thought about an air intake from the GMC hood hole but around here it gets rainy etc so it would need a baffle of some sort in front of it. I may just use the hole for air to keep the under hood temps down. Maybe draw air for the engine from the cowl or those louvered areas in the rad support. Dunno yet.
Post up what you end up with and how it works

[OKGMC4]

Originally Posted by BIGglaSS

Nice work. Hey, I was going back through your build. How much did you cut off the rear spring? Think I will have to do the same.

The reason I went coil overs on the rear this time is that my spring shaving experiment did not produce the best results. I think i shaved 3/4 or 1/2 off each side, and tried super hard to make the cuts as even as I could, but the spring still ended up slightly lopsided. I had to adjust one side more than the other to get an even height and then when you got a bumpy road the rear would not compress or rebound evenly. It would wallow around like a drunken sailor on shore leave on bouncy old bridges or railroad tracks. Rode smooth on a straight new road but it did make left vs. right handling feel different in a turn. Hoping the coil overs correct that mess this time around.

[OKGMC4]

Originally Posted by dsraven

I have thought about an air intake from the GMC hood hole but around here it gets rainy etc so it would need a baffle of some sort in front of it. I may just use the hole for air to keep the under hood temps down. Maybe draw air for the engine from the cowl or those louvered areas in the rad support. Dunno yet.
Post up what you end up with and how it works

Since the truck is raked slightly and the filter will be just slightly high in the hole area, I think rain would have to travel uphill to cause problems. May only be an issue at highway speeds. Kind of hoping that the use of a K&N will help as well. Cotton should take a little damp better than paper? Odds are, if it's really storming bad I may not be driving it. Never been afraid of the sprinkles though. I think it's funny when people go running for car covers at a car show when it literally drops a spit of rain and they have 10 raindrops on the car. My original fiberglass filter box pulled air from the louvered area on the driver side and my IAT was usually about 5 degrees over ambient. Now the intercooler is in the way and that box would be WAY undersized for the turbo.

I have actually thought about putting buick portholes on the side of the hood at the back to vent all the air pressure the hood hole makes at speed. At 80-90mph the back of the hood starts shaking from all that air pressure. Of course, the truck isn't aerodynamic at all...the windshield wiper starts slapping the windshield around 100mph. Lol

[OKGMC4]

What they don’t tell you about c4 suspension swaps!!!!

If you look, not only are the cab body lines higher than the bed, but the distance from the body line down to the fender lip is farther on the rear. No big deal if you have a solid axle. If you have IRS it will make getting a 4 wheel alignment super fun. Only 1 in 5 tire shops I tried had a machine that would slip in the wheel and not hit the fender lip. I’m going to raise the rear arches 1.5” so the distance from the body line to fender lip matches the front. Hoping that and setting the top of the tire right at the bottom of the lip will stop getting me turned out from alignment bays. And that my truck won’t have that ultra raked stink bug stance.

[hotrod1]

Well, I am interested to see how this looks. I prefer a level-looking truck also.

[OKGMC4]

One way would have been to convert to completely round wheel arches. The black truck gives an impression of what that would look like. I just didn’t want to have to cut the front fenders as well. I think I may put tires on it and set it down just to see how 1.5” looks. Even if the lip to body line distance matches the front fenders, the two body lines are still about 3” difference in height. I don’t want to radically alter the look of the truck, I just want to be able to get an alignment without too much fuss.

[dsraven]

good thing raising the wheel opening on the fender is a quick job......eh?
nice work, it will be one of those subtle things done that a lot of people won't notice but then there is that guy who is staring at the truck until he figures it out. should look great when done. post up some finished pics. how will you handle the line up of the arch openings? it's like chopping a roof, the parts don't line up anymore.

[dsraven]

what you are doing looks better than the round arch look in my oinion. I seen one where the guy had raised the whole box off the frame a bit and then added metal to the fender at the front and modified the step upper area so the step was where it was supposed to be, lined up at the lower edge of the cab. it looked off, nice job but didn't look right to me.

[dsraven]

how much rake angle does your truck have? do you have a full side pic you could post? seems a shame to cut into that nice looking paint.

[OKGMC4]

Originally Posted by dsraven

good thing raising the wheel opening on the fender is a quick job......eh?
nice work, it will be one of those subtle things done that a lot of people won't notice but then there is that guy who is staring at the truck until he figures it out. should look great when done. post up some finished pics. how will you handle the line up of the arch openings? it's like chopping a roof, the parts don't line up anymore.

The front lines up pretty well. The rear is off. I see two options…
1. Cut the rear lip completely off and scoot it back to match. This might be easy to do but makes a big wheel opening even bigger.
2. Slice both the upper and lower lips and pull them till they match each other. I think this might involve more work, might even be a lot of pie cutting to get there, but the wheel opening doesn’t get any longer that way.

At least either way I have a pair of junk fenders to cut up to fill the gaps in the lips.

[OKGMC4]

Less rake after I stopped using staggered wheels but have always had the fender overhang the rear tires.

[6DoF]

the rear fender chop is an interesting fix, makes sense to me. to get the height inside the fenders to tuck the bigger tires, i'm actually moving the whole bed up for the body line to line up. also gives me a deeper bed with the floor moved up over the frame.

[OKGMC4]

I think 1.5” is going to work. Looks like I can come down another 1/2 to 3/4” but since I’m missing several parts of the truck right now I’m going to hold off adjusting the coils until fully assembled. I think I have enough space for the alignment guy to get his equipment in the rear wheels now that I’m not tucking tire as much.