Towing with a 305 V8?

[Bennyt]

As mentioned by others, find a reputable Quadrajet builder. You may have to ship it off.

If you swap to Holley, expect a drop in mpg.

If you are in love with the truck, add a Gearvendors overdrive. That'll split your gears making it easier to accelerate, maintain highway speeds, etc and you could tow in OD. I'd give them a call.

I'd still definitely consider a 3/4 ton or larger. Heavier frame, bigger brakes, bigger axles. Designed to work and tow and safer.

 

[Ricko1966]

This thing keeps getting deeper,I definitely think desmogging it is a great idea if you want it to ping have less power,and worse gas milage. The Quadrajet on your truck was designed jetted,correct metering rods,air bleeds etc.etc. for your truck,if your truck had other engine mods than a one size fits all carburetor might be a better choice for ease of tuning,but a stone stock truck the factory quadrajet was built by engineers way smarter than us to get optimal mpg with minimal emissions,etc.

 

[oldretiredafguy]

If you have a 700R4, DO NOT tow in OD (This warning should be in the Owner's Manual under "Towing").

 

[CheemsK1500]

This thing keeps getting deeper,I definitely think desmogging it is a great idea if you want it to ping have less power,and worse gas milage. The Quadrajet on your truck was designed jetted,correct metering rods,air bleeds etc.etc. for your truck,if your truck had other engine mods than a one size fits all carburetor might be a better choice for ease of tuning,but a stone stock truck the factory quadrajet was built by engineers way smarter than us to get optimal mpg with minimal emissions,etc.

All valid points. Many Q jet issues tend to stem from sticking the wrong Q jet on the wrong set up.

Another thing to remember, is that many '80s small blocks originally had computer controlled Q jets. They rely on sensors and such to work properly, similar to the TBI system that replaced them. A lot of people swapped these units out for earlier Q jets or entirely different carbs for easier adjustment and tuning.

 

[85 Squarebody76]

Thank you all, that is a lot more response than I thought I would get.
I am not sure why I thought it was a 5 speed, you are right it is most likely a 4, but how do I tell?
@fast 99 I will definitely add a transmission cooler. How do I determine what gear ratio I have?
@Turbo4whl Yes my trailer has electric brakes, I just need to add the control module to the truck. I have the owners manual, but I don't remember anything about towing, but I will double check.
@Ricko1966 I am pleased to hear that yours will do it, could you tell me what type of terrain you pull in? I will be hauling this rig pretty much daily, I am trying to break out as an independent mobile welder, and I opted for the trailer rig because service trucks now cost upwards of $80k even used.
@75gmck25 the bumper pull was stamped 4,000 lbs so I built a new hitch setup for it. If I go for a 4.10 gear ratio, what will that do to my top speed? That maybe a stupid question, but I am still learning about engines so bear with me.
@Rusty Nail yes I need to set my timing, it will be the first thing I do after installing my new carb, before I try tuning. What servicing to the transmission would you recommend? When you say Rear differentials need service to, would you mind elaborating? I have had it flushed since inheriting it, but that is all.
@Redfish thank you for the encouragement, I know that it will never have the power of a true hauling truck, but those, like the service trucks, are beyond my financial ability at the moment.
Here are a few Pics of the truck and trailer in question.

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I have the exact model but with GMC flag on it... 305cuin Th350 3 speed with locking converter

 

[Grit dog]

As mentioned by others, find a reputable Quadrajet builder. You may have to ship it off.

If you swap to Holley, expect a drop in mpg.

If you are in love with the truck, add a Gearvendors overdrive. That'll split your gears making it easier to accelerate, maintain highway speeds, etc and you could tow in OD. I'd give them a call.

I'd still definitely consider a 3/4 ton or larger. Heavier frame, bigger brakes, bigger axles. Designed to work and tow and safer.

With due respect, a gear vendors is virtually useless in his scenario imo.
And for about the same money, find a new 300hp small block to dump in it and it’ll drag that trailer like nothing.
But bottom line, it looks like a healthy truck and is beautiful but being realistic the OP needs something that is not that truck for his use.
And almost too nice to work it!

 

[Rusty Nail]

Yeahhhhhh oh man.... De smogging is a rabbit hole. It don't run correctly right now! That's a terrible idea - no offense.

Let's consider something different first. I'm not gonna help you take stuff off of it... Somebody else might... but you'll have to leave me out. You will have to part ways with whatever sources gave you that idea. Make that choice - the decision is yours and that is two entirely different directions like east and west.
It doesn't run correctly right now but we're getting warmer. You touched on key issues and backed up previous statements on accident Pictures are good!
Somebody said about no experience / get a new truck type jazz? A point to him. In that respect sir, you are already in over your head...But it's only a small block. A $400 carburetor is s smarter buy then a $10000 truck in my book.
AND THEN
You made mention of modifying some designs of the carburetor and diverting certain parts from stock?
Incorrectly repairing a FUEL LEAK?!
**DANGER WILL ROBINSON! DANGER!**
Don't set your dead grandpa's truck on fire dude. That would suck. See the fuel puddled on top of the accelerator pump? It's gonna suck, I'm warning you.
Which IS the direction you're headed with that bullsh*t. That mother f- will WHOOSH! in a heartbeat. You don't know what your doin - remember?

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Well the good news is that we're knocking on the door of your engine's running problems - and they can be fixed.

Silicone is NOT impervious to gasoline and has less than zero business inside that carburetor. That's part of the problem and that clock is ticking. I forward the motion that silicone debris has degraded and made it's way to the needle, causing the flood, which is where the black smoke comes from.* Something in the carburetor is the culprit right now.

Repair will involve removing the carburetor again and starting over with the "rebuild". .. This curve is kind of steep for lots of dudes but it's nothing you can't handle. They shy away and throw parts lacking intestinal fortitude. I dont get that vibe from you though, I think you can do it. First time I ever did one I had to do it more than once too and just. like. that! now we're in the same boat. Cue the P.E.

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That's a live band! They're in the Rock and Roll HALL OF FAME ffs. It's okay to like the music... You don't gotta tell anyone.

Let's go back to Ricko. Notice how he cut his reply short? Uh huh he did. He's older than me and more gracious by default. I've never been called humble...
He probably knows too but he is being kind and letting me play the Public Enemy because it's part of my schtick and we're buddies. Ahhh the price we gotta pay! Lament on your own time huh? That's private. Maybe part of him wants to see that I know too, that's all.

Back to the carburetor. Don't modify the parts, it's not for noobs. Buy another kit and start over but follow the directions this time. You'll have go remove alllllll traces of silicone and repair whatever was leaking ,correctly.
I must have missed that part about why it leaked?

I'm not trying to be a dick, I'm tryin to put the truck back to work because I like it and it's fun to play with.

Take some cleansing breaths and SLOW DOWN.

 

[Rusty Nail]

What is this? You are missing AIR HORN screws? Those holes are not supposed to be there. Wouldn't that be neat to fix it for a dollar worth of screws? Change rear gears for $1500 and fix it with TWO SCREWS.

Or you could buy a $10000 truck I guess. I'd clean the silicone out of it first though - just for kicks.


See how you've got the accelerator pump rod in the bottom hole? I bet you moved it there and it spent its' whole life in the top hole. I recommend moving it back to the top hole.
7 air horn screws? Did you lose em? That will flood it for sure and is probably why there is gas puddled at the accelerator pump.. Better keep looking.

SLOW DOWN.

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Ya know what? As a matter of fact I know you're having a hard time with it. I'll get you some money for your paint job back so you can get something more reliable to work in. You should probably just sell it to me so you'll know it found a good home. I'll take real good care of it and you won't have to mess with it anymore.

There there.

I'm in Oklahoma, come get it in a jiffy. Don't worry anymore. I'll get it out of your hair so it can't cause anymore trouble. No no, don't worry about the bumpers. Relax.

 

[Ricko1966]

@Rusty Nail post 30 pic 1 tell him what's wrong with that picture.

 

[Rusty Nail]

Oy very! No pressure right?

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Look 7 out of 8 ain't bad, I figured that is an illusion. Circled looks like spark plug boot without a wire. Don't catch it on fire dude...you're fixin to!
I made a dot on the carburetor showing a previously present air horn screw thats missing now? No? Maybe not..and for bonus they drew a little Paperboy Ditty on a thermostatic vacuum switch for you dudes watching from that other thread. See the check valve dude took a picture of?

And it's filthy. Looks gross. What do you see Ricko?
We're gonna get it fixed but he'll never sell it to me then.

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[85K304SPD]

I would say, just don't do it. You are going to kill that truck using it as a welding truck. Find a one ton, modern truck and get to work.

 

[Velder]

Okay this is getting fun.
First off, the de-smogging idea was just something I saw on YouTube, a guy had my exact truck and went after all the emissions stuff with a Sawzall. That idea is dead now. Just thought I would bounce it off of you guys and see if ya'll thought it was a bad idea. Seems every one does so that's that, emission control gets to stay.
On to the carb, I really appreciate the help, I will try to get more pictures on this afternoon of it in its current state.
@Rusty Nail, Yes the accelerator pump was leaking around it's seal, but that was pre-rebuild, I replaced both the pump and seal, and that leak is gone.
Missing air horn screws? that is what she looked like when I took it off, but I know the carb has been tinkered with before I got it, both idle mixture screw-plugs had already been cut out, so someone might have lost something then. I will investigate further.
I thought the gasket maker was a bad idea, but my dad insisted it would be just fine. I will get a picture of where I put it, but your right I need to tear it down again and start over.
Would you mind elaborating on the picture? The spark plug wires have been sorted out, I replaced all wires and the cap, but what about the thermostatic vacuum switch you marked, Is there something wrong there?
The screw with the dot is still there, but you can see the signs of the fuel leak around that solenoid thing, so it was leaking before I tore into it. (circled red in the pic below) that is where I added a little gasket maker.
Stay tuned there will be more pictures coming.

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[CheemsK1500]

If you're going into full desmog mode, do an ESC delete while you're at it, or spend some money to replace it with a modern programmable alternative such as the MSD ignition systems.

The ESC (Electronic spark control) is neat concept but when it doesn't work correctly or you start making modifications, it becomes a hindrance.

 

[Grit dog]

^Yup 80s 305s are sort of an all or nothing deal when it comes to emissions and electronic/vacuum controls.
Unlike the opinion of the feller responding who has a vibrant way of speaking and in some cases a wild imagination, you CAN gut everything off of an ESC 305 and have it run just fine. But (and it’s been a while), carb and ignition need to be old school for it to work.

 

[CheemsK1500]

I have the exact model but with GMC flag on it... 305cuin Th350 3 speed with locking converter

My '85 C10 had that same setup originally, but a previous owner swapped it over to a 350 mated to a non locking th350. I kind of wished he kept the locking th350, but I'm grateful for the 350 sbc though. I'm not sure why GM was using two different automatics on 1/2 ton trucks during these years to begin with.