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1970 GMC Jimmy - Grandfathers Unfinished Business

I'm an EFI guy every time, but yeah, it'll be way more expensive. As far as rebuilt vs new goes, You'll probably need to tune the new carb as well anyway, so if the rebuild includes tuning it, I'd be leaning that direction. Of course I've never been able to properly tune a carb myself, so paying to have it done right makes sense to me (assuming no EFI).
 
What's the problem with it now? Have you pulled the filter in the front of the carb yet? Have you put new gas in it yet?

I would rebuild the Q-Jet if that's what it needs. This truck is too OG for aftermarket EFI and this is coming from someone that's added EFI to a bunch of old cars and trucks.
 
I want to ask, how are you planning on using this truck? Just cruising around?

If so, I personally would just leave the Quadra-jet and get it cleaned up. I have one on my '70 K10 with a big block and I like how it works, even with some mold off road driving. I did have Sean Murphy Induction go through it after I did the roller cam and build of it. That took care of lots of things. It was less than $300 back when I sent mine in.
You should be able pull the carburetor yourself to send it in, the main things that you need are a 5/8" flare nut wrench and a 1" wrench to hold the fuel filter housing from moving when you take the fuel line loose at the carburetor.

Fuel injection is nice when everything is tuned properly. You will be into a decent system for over $1K if you go with a system that doesn't control the distributor timing. The fuel system can take some time and work to install, and could push the cost up even more. Then you also have to get an O2 sensor installed in the exhaust and make sure that it doesn't have a leak upstream that causes improper readings.
 
6872xtc said:
I want to ask, how are you planning on using this truck? Just cruising around?

If so, I personally would just leave the Quadra-jet and get it cleaned up. I have one on my '70 K10 with a big block and I like how it works, even with some mold off road driving. I did have Sean Murphy Induction go through it after I did the roller cam and build of it. That took care of lots of things. It was less than $300 back when I sent mine in.
You should be able pull the carburetor yourself to send it in, the main things that you need are a 5/8" flare nut wrench and a 1" wrench to hold the fuel filter housing from moving when you take the fuel line loose at the carburetor.

Fuel injection is nice when everything is tuned properly. You will be into a decent system for over $1K if you go with a system that doesn't control the distributor timing. The fuel system can take some time and work to install, and could push the cost up even more. Then you also have to get an O2 sensor installed in the exhaust and make sure that it doesn't have a leak upstream that causes improper readings.
Click to expand...

Yes. Car's just for cruising around. Not offroad. For right now I want to get it reliably driveable around town. And knowing that I'll keep it forever, I'd prefer not to do stuff twice...I would like to just fix it once.

You're all talking me out of the EFI. Glad I can cross that off list!

Haven't been able to pull the fuel filter. I've got the flare nut wrench but that thing is freaking on there.
 
skunked said:
What's the problem with it now? Have you pulled the filter in the front of the carb yet? Have you put new gas in it yet?

I would rebuild the Q-Jet if that's what it needs. This truck is too OG for aftermarket EFI and this is coming from someone that's added EFI to a bunch of old cars and trucks.
Click to expand...

Symptoms:
- Hard start. A lot of feathering to get it going. Once warm it does ok, but the initial start takes a little work. ~2-3ish minutes of feathering the gas until it will idle on it's own.
- Running rich.
- When I accelerate it loses energy for a split second before it catches up. Not slipping gears. Maybe fuel/air mix is off?

It's running premium fuel. New spark plugs. New battery.
Once warm it is good. This week I took it on it's first real destination. Drove it to my softball game, played the game, and 1.5 hrs later I came back and it started right up.
 
Dan_P said:
Symptoms:
- Hard start. A lot of feathering to get it going. Once warm it does ok, but the initial start takes a little work. ~2-3ish minutes of feathering the gas until it will idle on it's own.
- Running rich.
- When I accelerate it loses energy for a split second before it catches up. Not slipping gears. Maybe fuel/air mix is off?

It's running premium fuel. New spark plugs. New battery.
Once warm it is good. This week I took it on it's first real destination. Drove it to my softball game, played the game, and 1.5 hrs later I came back and it started right up.
Click to expand...

Sounds like typical quadrajet problems.
Chokes not working... rebuild and a tune with a guy that knows what to do and you should be good!
 
Yeah, but when asking people about carb tuning, make sure you specify Quadrajet. They are not as easy as Holley's which most people can tune.
I'm sure it's just dirty inside. Having it rebuilt is good. If it was mated to the engine back in the day by your Gpa, it probably was tuned good then. Wouldn't need adjustment now.
 
K85 Octane said:
Yeah, but when asking people about carb tuning, make sure you specify Quadrajet. They are not as easy as Holley's which most people can tune.
I'm sure it's just dirty inside. Having it rebuilt is good. If it was mated to the engine back in the day by your Gpa, it probably was tuned good then. Wouldn't need adjustment now.
Click to expand...

might need some tweaks, it's gone from 6200+ feet down to sea level.
 
I am betting that it's running lean from the description, and when @skunked tells the difference in elevation, it makes sense.
But it is also likely that the choke isn't work the greatest either, and it looks like it probably has the choke coil mounted on the intake manifold like original. It may be that Grandpa didn't have it set to come on heavy because those often took some time to back off. This would help avoid an over-rich condition but makes it a little tempermental for a little bit.

You and @skunked should just fly @Bent77 out there so that he can take care of both of your Quadra-jet equipped trucks!! That shouldn't be TOO expensive!
:rotfl:
 
6872xtc said:
I am betting that it's running lean from the description, and when @skunked tells the difference in elevation, it makes sense.
But it is also likely that the choke isn't work the greatest either, and it looks like it probably has the choke coil mounted on the intake manifold like original. It may be that Grandpa didn't have it set to come on heavy because those often took some time to back off. This would help avoid an over-rich condition but makes it a little tempermental for a little bit.

You and @skunked should just fly @Bent77 out there so that he can take care of both of your Quadra-jet equipped trucks!! That shouldn't be TOO expensive!
:rotfl:
Click to expand...
I don’t drink but I like steak and Dr Pepper...
 
max 02 said:
Sounds like typical quadrajet problems.
Chokes not working... rebuild and a tune with a guy that knows what to do and you should be good!
Click to expand...
Rough guess, what’s the range of how much this costs?
 
As usual, thanks for the input in thread above! I'm following the general advice and rebuilding the Quadrajet. The carb has been dropped off and is getting rebuilt, should be done mid next week.

In the meantime, I've got three questions that have come up:
1. Oil is pooling around the manifold bolts (see pic). Looks to be pooling around 4 of the bolts. I pulled one and the threads are oily/black and showing some signs of degrading (Grade 8 bolt).
Initially thought it was the manifold gasket (haven''t replaced) but with close inspection i dont think it is gaskets.
Maybe it's oil + fuel leaking from carb? It really looks like the manifold bolts. That make sense to you guys? Familiar with this issue and any advice?

2. I can see a crack in the manifold around threaded connection (see pic). Signs of corrosion...unless you tell me it's critical I'm going to leave this until something more problematic comes of it.

3. Lastly, unrelated to the engine/manifold...I continue to leak from Power Steering Box. I've tried Lucas leak stop but without success. It looks like it's coming from where the ram (from steering wheel) inserts into the power steering box assembly. Based on the corrosion of the paint it looks like it's been doing this for some time. Any input to solve this?

CarbOff.jpg

IMG_2575.jpg

IMG_2574.jpg
 
The center 4 bolts for the intake manifold need some sealer on the threads. If you pull one at a time and clean the threads on the bolt well, brake cleaner should be good, then spray a SMALL amount into the threads in the hole, you don't want to put much at all into the engine. Use compressed air or canned air to blow them out. Then put a little sealant on the threads, install and tighten. You can then torque all of the intake bolts after you get done with the center 4.
The crack in the manifold doesn't appear to be leaking, so I would run it until you are ready to swap the intake out, or when it starts to leak. It looks like that fitting got tightened too much since pipe threads are tapered.

The power steering box probably needs a new seal, but considering the truck has sat, I would run it some more since the stop leak would need time to have a chance to do anything. If it starts making a bigger mess, then look into a new seal. Those aren't the easiest to install, but it can be done.
 
Yup, sealant on the middle 4 manifold bolts. Common problem, no big deal.
 
I'd just run the gear box until you grab yourself a new unit and an XJ shaft.
Take the time and swap it all out at once.
Till then, cardboard under it :D

Same with the crack. It ain't leaking so run it. Maybe pick up another manifold and gaskets and keep it on the shelf till it starts to leak.
 
WOO
I just noticed the "firing order" casting in that intake. That's cool. Never seen that
 
J-B Weld would probably seal up that crack ,since its not leaking that much or under a lot of pressure..hardest part will be cleaning it off good so it'll stick--a dremel tool with a wire brush would work for that job..
Seen a few guys use green locktite on cracks like that with success too.

Teflon tape on the fitting would probably seal it up also,but removing it and putting it back in may only open the crack up more...eventually rust will seal it up probably too..

Pipe threads are like a wedge--too tight and they split the female part open..they only need to be snugged ,not torqued real tight..

I have replaced the pitman shaft seal on the bottom of the P/S box with success a few times,but some were a fail because the bearing had enough play in it to let the shaft move side to side and the new seals quickly failed..

I tried putting a new seal in the steering shaft end where yours is oozing,and had no luck,it leaked worse,and taking the big lock nut off and the adjuster plug where the seal goes affected the pre-load of the gears inside--I ended up getting a used P/S box from a salvage yard for $50 that looked nice and had low miles on it..
I've never had much luck fooling with P/S boxes,its best to just replace them ..every one I tried to adjust the play out of always ended up feeling "sticky" or the truck wanted to veer off suddenly,I didn't trust them..
 
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