Need a range of advice... :)

[CamraMaan]

So I've had a '78 Chevy C10 (manual, 2wd, 250 inline 6) for a long time, and two days ago bought a '79 GMC Sierra Classic 35 Trailering Special (2wd, 1 ton, auto). With 10k miles on its rebuilt 454, about 2k miles on a rebuilt tranny, and a very nice interior (and straight body), all things considered, the price of $950 was way too good to pass up. But I'm new to the truck, and there are some problems with the truck that I need to fix, and not all the answers are easy to find out there. In no particular order...

This has dual tanks, but the ability to switch tanks is "broken". I'm stuck using the right tank, and the gas gauge doesn't move from about 1/4 tank, which makes me think it might be showing my left tank. But I have no idea whats going on with that, and I would really appreciate having a working gas gauge, nonetheless the option to use my left tank, since I ran out of gas the first night I bought the truck....... rude awakening. Any ideas/advice?

Next, the truck has A/C, but it doesn't work. And I mean nothing works, not just the A/C. Flip the switch on, no blower motor hum, no air movement, etc. Fuse? Blower motor? Short? I can obviously replace the fuse, and the blower motor is easy too (or at least it was on my '78, but that didn't have A/C), but I'm just curious if there are any other ideas out there that I may be forgetting.

Windshield wipers... need new motors, and would like new arms as well... I hate the flimsy metal arms, because at freeway speed (65+) with nice/expensive wiper blades, they just hop around and don't get the job done. Anyone know of a way to upgrade the wiper blade arms? Maybe a swap from a newer truck?? And any recommendation of wiper motors? I'd like to buy new, versus the scrap yard, but quality and inexpensive never hurts!

The truck already has headers, and sounds like it came stock around 230HP and 360Tq, and I just bought an Edelbrock top-mount air filter assembly. But I may want to upgrade the carburetor down the road. Anyone know what the stock carb's CFM is? What's the max recommended CFM on this engine without having to change any internals, just bolt on, adjust, and go?

I have every desire to drop the truck, since it has a 4x4 stance, but are there any lowering kits for this thing out there?? Seriously, I'm getting skunked in my searches. Would love to drop about 2-4" both front and back, or somewhere in that ballpark...

And along with the drop, I would like some more performance oriented tires, versus the (new) 80psi towing grade tires already on it. This has 16" 8-lug aluminum wheels, and I'm fine keeping those, but what are some tire recommendations? Assuming it will be lowered. My other truck already has the tires/look I want, but its a 5-lug bolt pattern with 15" wheels... and with that I went with a slightly larger performance tire on the rears.

And last, what gear ratio does this truck have? And what's recommended for better mileage, without sacrificing too much of the fun, but also assuming more power could be coming in the future?

Thanks!!

[TwoFiftyShifter]

Gears? Probably 4.11 but might be 3.73
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[CamraMaan]

I was guessing 4.11, but it was just a guess.

Tomorrow I'll do some more visual inspection and see what more I can learn about this beast. Must admit that in only a couple days I've really started to fall in love with this truck... but its mostly because my old truck leaves a lot to be desired. Old truck: 250 I6, lacks power, no A/C, bench seat (I have a bad back, and this doesn't help), one piece rear window, AM radio with shot speakers, ugly inside and out (driver side door replaced before I got it), lots of rust, can only unlock the truck from the passenger side, and windows roll up/down with a lot of effort... mentioning all of that, you can guess some of the obvious differences. The biggest bennies of the new truck are the 454, A/C, bucket seats (and center console box with cup holders!!), straight body and clean interior, potential for a real stereo (new one doesn't actually have a head unit, but the speaker wiring/housing is all there), much less deep rust, and I can unlock the driver's side door! Don't get me wrong, I still love my old truck (hard not to...), but for $950 this new truck has filled a lot of the previous voids. Only thing I really will miss is the manual transmission. I already miss it. And yes, I still have the old one, but it needs some clutch work to be drivable again, and until the finances are there its parked and waiting... and the new truck will be eating up some cash for a week or two, since it sat for 4 years and needs some TLC. I live in rainy Seattle, so the wiper motors are next on the list, then getting the heater and A/C working, and last the shocks need to be replaced... then the old truck gets my attention again.

[CamraMaan]

What are recommended spark plugs for a 454? I want the best combination of performance and price...

[Ziegelsteinfaust]

Just get replacement plugs from a quality manufacturer. At your engines level plugs are plugs. Throw alot of cam or boost, and then they come to play.

[CamraMaan]

Makes sense. Thanks! And while I love my trucks, and love to work on them, I'm not a mechanic, so there's a lot I don't know...

[POS1]

Here's a few answers:

Fuel Tanks Broken:
There's a switch in the dash and there's a valve between the tanks. Both are common failures and both are available at auto parts stores (NAPA, etc.). I'd start with the switch - pull it and put a test light on it and see if the power is coming and going the way it should. If the switch is bad, replace it. If the switch is good, buy the valve and replace it.

No AC or Blower:
Your blower motor is not blowing air. More than likely you don't have any Freon either, but start with the dead blower motor. They fail often, so common issue so far. Start with the fuse. Then put your test light on the connections to the blower motor (passenger footwell under dash, I think). Buy new blower motor if have to. Once you have air moving, then you can start on why it isn't cold. Probably a leak, so pump it up with R134 or R12 (whichever was in there last), and see how long it lasts. Garages have 'sniffers' that can tell you what Freon was in there last and from where it's leaking.

Windshield Wipers:
Motor available at auto parts store again. You can get arms at parts store too, but I have no idea which are thin and flimsy.

Carb:
650 CFM is common and basic. I dumped the Edelbrock carb off my 1971 because it never would start or run correctly. I bought a QuadraJet with elec choke from NationalCarburetor and was very pleased. Most Chevy mechanics I talked to hate the Edel carbs, but the forums LOVE them. I'm not buying another - I know that. Both are bolt on and go except for the electric choke power wire.

Lowering:
No idea.

Tires:
Research is the only answer. High Performance tires on an 8-lug truck - no idea again.

Rear Gear Ratio
Research. If you have the sticker in the glove box, the codes will tell you what your rear end was from the factory.

[CamraMaan]

POS1, thanks a ton! You answered a lot and gave me some good things to work on! Much appreciated! As a follow up, any idea what my max CFM carb would be without having to change the cams or something? If I'm starting with 650, then 700 or 750...? Again, thanks a bunch!

[donut]

Carb CFM is a can of worms. Factory Q-jets, I believe, were either 750 or 800. However, because of the vacuum secondaries, engine only used what was needed.
Pretty sure some folks on here are running 600 cfm Edelbrocks on mild big blocks.
Holley, really don't know what they have in their line-up.

As far as a carb "upgrade" what were you thinking of?
IMO, it's hard to beat a well tuned Q-jet, providing your willing to put in the time to learn it. (or pay to have yours reworked.)

[POS1]

Originally Posted by CamraMaan

POS1, thanks a ton! You answered a lot and gave me some good things to work on! Much appreciated! As a follow up, any idea what my max CFM carb would be without having to change the cams or something? If I'm starting with 650, then 700 or 750...? Again, thanks a bunch!

Sorry, I'm a sucker for stock original, not modified. Search forum prob for 1000 opinions, then form your own from what you learned.
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[INSIDIOUS '86]

...

[CamraMaan]

Originally Posted by donut

Carb CFM is a can of worms. Factory Q-jets, I believe, were either 750 or 800. However, because of the vacuum secondaries, engine only used what was needed.
Pretty sure some folks on here are running 600 cfm Edelbrocks on mild big blocks.
Holley, really don't know what they have in their line-up.

As far as a carb "upgrade" what were you thinking of?
IMO, it's hard to beat a well tuned Q-jet, providing your willing to put in the time to learn it. (or pay to have yours reworked.)

Forgive me for not knowing the best route to better performance. While I'm sure there are many ways to skin this cat, and some that are more efficient than what I "know" of, the fact is I only know of so much. I was under the assumption that more CFMs, to a degree, would be beneficial to more power... of course without going too far (without other modifications). My goal is more power (HP and torque) to be combined with a better gear ratio for mileage. Might sound weird to some, because most want either one or the other, but I would like a happy balance of both. Like I want to cruise at 75 with the same acceleration pep, shall we say, but with better mileage overall, or at least the same as I get now. Or a higher top speed (based on gearing), but the same fuel efficiency that I have now. I don't have the money to drop a different transmission in, but I kinda wish I had more than three gears, so I'm trying to find an alternative to my current woes.

Originally Posted by POS1

Sorry, I'm a sucker for stock original, not modified. Search forum prob for 1000 opinions, then form your own from what you learned.
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Well, unfortunately this truck no longer qualifies in that department. I found that out yesterday when the three belts my truck/engine was listed to use were either smaller or larger than it was supposed to need. And I unfortunately figured this out after one of them snapped on the road. Luckily I had already bought the belts, and the smaller one was enough to turn my water pump and alternator and get me to an auto parts store... albeit the alternator tensioner placement was much closer than it should be. Anyway, it just seems the rebuild they did was aimed at "functional" more than "stock", kind of like a good hack job.

Anyway, as much as my performance desires are there, the money currently is not, so if they happen they will be down the road a bit. Primarily I need to get this thing into satisfactory condition (like getting the windshield wipers/motors purchased/installed... I live in Seattle with fall/winter on the horizon), and then getting my old truck back into good running condition for my niece. Then I'll worry about my secondary desires like more power...

[POS1]

They do tend to eat money, but the Suburban is a helluva lot cheaper than the Porsche. Tis all relative.
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[king-918]

Originally Posted by CamraMaan

POS1, thanks a ton! You answered a lot and gave me some good things to work on! Much appreciated! As a follow up, any idea what my max CFM carb would be without having to change the cams or something? If I'm starting with 650, then 700 or 750...? Again, thanks a bunch!

I had a 750 edelbrock (1407) with no issues on my stock 455 started right up every time
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[Skunksmash]

Didn't read most of the thread but the part you need to fix the tank switching issue is sold on rockauto. If its the switch, you can get a brand new one from autozone for $12.

[Recian]

For the blower check your basics. My blower was inop when I bought my 81. I had a blown A/C fuse and they kept blowing until I traced it back to a shorted connector at the sliders. I went and invested $20 into a chilton's manual since Shopkey and Prodemand (both our shop's online manuals) didn't have wiring schematics. Removed and reinstalled all the system connectors at the blower, at the resistor and slider and it worked good. I bypassed it at first thinking the switch that controls speed was bad since every time I plugged it in the fuse would blow but a couple days later I plugged it in and its worked ever since. I removed all the other connectors and cleaned them. The resistor pins were covered in rust. Some penetrating oil and a wire brush fixed them.

And btw my truck is probably as bad as your 78. It's covered in rust so bad I can see out the doors and both kick plates and the only thing going for it is the perfect bench seat but I've fallen in love with it and my 305 leaves a lot to be desired too lol I plan to buy a donor truck with no engine for like $500 eventually and swap over cabs.