Towing with a 305 V8?

Velder · Jun 6, 2023

Okay, here are some more recent pictures of the thing. Hopefully these will help diagnose the problem,
These are how she sits right now.

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Here you can see the gasket maker oozing out. I only put a very thin layer on both sides of the gasket in this area.

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CheemsK1500 · Jun 6, 2023

@Velder, it appears you have a computer controlled q jet. If any of your sensors are dirty, or anything on that engine is out of adjustment, that thing will never run right. I suggest getting an older Q jet (or any other decent 4 barrel with a CFM low enough for a 305.) and and performing an ESC delete. Doing this, will give you a nice reliable and easy to tune setup.

Ricko1966 · Jun 6, 2023

Grit dog said:
^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.

They raised compression when they went esc. High compression 305s have 9.5:1 an lm1 350 is only about 8:1 real world.Real world on the 305s is about 9.9:1, 305s ping without esc and egr. Yes you can eliminate all the stuff but the truck won't run as good,and won't get as good of gas milage, to eliminate ping youll have to retard initial timing,and limit vacuum advance,both hurt power and milage,ask @SirRobyn0 I told him don't eliminate esc. it will create more problems than it solves. He tried for a year to make it work right and went back to ESC. @Rusty Nail look at that fuel line.

Velder · Jun 6, 2023

@Ricko1966, and @Rusty Nail, If ya'll are looking at the rubber fuel line to the carb, that is temporary, I tried buying a oem pump to carb line from LMC, but it wasn't even close to the right shape, so I tried bending my own, but that one leaked at the union, so to just try out the thing I ran a rubber line.

Ricko1966 · Jun 6, 2023

Velder said:
@Ricko1966, and @Rusty Nail, If ya'll are looking at the rubber fuel line to the carb, that is temporary, I tried buying a oem pump to carb line from LMC, but it wasn't even close to the right shape, so I tried bending my own, but that one leaked at the union, so to just try out the thing I ran a rubber line.

Okay Id try bending one up again,I've seen two cars,maybe 3 actually, catch fire from a leaking rubber hose.

Ricko1966 · Jun 6, 2023

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Did you rebuild this without buying a rebuild kit?

Shoote · Jun 6, 2023

I used to tow a 4,000 pound boat with the same truck. On flat land it would max out at 65 mph. I put on a set of headers but they did not make any difference. It will work if you drive without pushing it. Put on the largest Trans cooler you can find. B and M has one that is 28,000 cooling. I ended up changing out the drive train.

Ricko1966 · Jun 6, 2023

CheemsK1500 said:
@Velder, it appears you have a computer controlled q jet. If any of your sensors are dirty, or anything on that engine is out of adjustment, that thing will never run right. I suggest getting an older Q jet (or any other decent 4 barrel with a CFM low enough for a 305.) and and performing an ESC delete. Doing this, will give you a nice reliable and easy to tune setup.

That is not a computer controlled Qjet it is a dual capacity accelerator pump Qjet. It is the same as any old Qjet except the electric solenoid changes the capacity of the accelerator pump reservoir,to vary pump shot based on engine temp. In.op. worst case would be an off idle stumble. ESC delete is a terrible idea on these trucks. Find and follow @SirRobyn0 adventures trying to make his truck run right for a year,before making the ESC work again. The ESC 305s have got too much compression for the fuel we have,that's why they have ESC. ESC pulls timing only when it senses knock,without ESC you will have to run with less timing always,and if you delete EGR you will have to lose even more timing.

CheemsK1500 · Jun 6, 2023

Ricko1966 said:
That is not a computer controlled Qjet it is a dual capacity accelerator pump Qjet. The electric solenoid changes the size of the accelerator pump reservoir to vary pump shot based on engine temp. In.op. worst case would be an off idle stumble.

My mistake, I saw the big solenoid and mistook as the ones on the computer q jets.

SirRobyn0 · Jun 6, 2023

Ricko1966 said:
They raised compression when they went esc. High compression 305s have 9.5:1 an lm1 350 is only about 8:1 real world.Real world on the 305s is about 9.9:1, 305s ping without esc and egr. Yes you can eliminate all the stuff but the truck won't run as good,and won't get as good of gas milage, to eliminate ping youll have to retard initial timing,and limit vacuum advance,both hurt power and milage,ask @SirRobyn0 I told him don't eliminate esc. it will create more problems than it solves. He tried for a year to make it work right and went back to ESC. @Rusty Nail look at that fuel line.

Yes, This the above. I've run my truck both with and without the ESC. The only way a guy could possibly be happy with removing the ESC is if the old system is in really, really bad shape. Properly functioning ESC is meant for these trucks and improves the fuel economy and power over removing or bypassing the ESC.

@Velder Was asking about towing, and I haven't read though the entire thread to see if he posted his axle ratio, but the short answer is yes. Your truck can tow. Forget about the people that say 305's are crap. Are they the best SBC engines, no, but they are very competent at what they do. I think the biggest thing is they are different than a 350, and differant from the older 305's and guys just misunderstand them and there idiosyncrasies. My truck is a C20, and I have towed my open trailer loaded combo about 6K. I live in the hills, and where there aren't hills there are mountain passes. Is the truck quick on the pass or up a steep hill with a loaded trailer, well no. And I use my truck for work, she gets worked, has towed and hauled everything I've asked no complaints.

To me the biggest down fall of your truck isn't that it has the 305, it's that it's a C10, so it has smaller brakes than a C20 or 30. Make sure your trailer brakes are good, and take your time on the hills would be my advise.

SirRobyn0 · Jun 6, 2023

Grit dog said:
@Velder
Your pic looks like you just painted it, do you have a bumper/hitch for it?
What do you tow the trailer with now?
My suggestion was gonna be hook it up and see how she does.
Some might be totally satisfied towing with 1980s small small block smogger power, many will not be.
In general, it’s going to be a challenge to press a 40 year old truck into daily heavy work duty regardless of whether it’s anemic under the hood or not.
Guys like @SirRobyn0 are the exception, but he has several things going for him. Not the least of which is that he’s a certified mechanic, so diagnosis and repair come much easier and cheaper to him than someone who is still trying to figure out how to tell what gears it has.
Just trying to add some reality to this. Maybe save yourself some headaches and keep the nice old truck nice. Lots of $10k or less lowish mile GMT 400 HD and half ton trucks out there in good shape. (Gotta find them though. Ain’t like going to the car dealer and picking out your favorite and driving it home though.)
Low altitude and only a few little hills if you’re lucky enough to not live in the 90% of Texas that is board flat will help. But think about the days you’re gonna be headed home at night westbound with a 30mph head wind. How big of hurry you in? Those 80mph speed limits will leave you looking like an Amish buggy while the rest of the traffic flys by at 90mph.

For the record my truck will do 80, but not far north of 80 she gets to twitchy for my liking. But I'd never tow at those speeds.

Taking your comment about being satisfied with an 80's small block smogger power. Yea, I mean for me I'm not exactly happy with it, but just like picking an transmission or rear end ratio picking an engine size is a compromise. Will I replace my 305 with a 305 when it's done. No I wouldn't even consider it, but I also won't pull a perfectly good engine just because it's a little under powered. And that's exactly what I'd advice the OP to do. Tow with the truck a little and see how you feel about. Make sure the trailer brakes are good. Stopping is more important than top speed or speed up a hill.

Sure it helps that I'm a mechanic. I hear it can be a challenge for guys to find a mechanic that knows what they are doing on our old rigs. But also there is a lot of stuff that is easy for a guy of average ability to repair or maintain on these trucks vs newer.

Ricko1966 · Jun 6, 2023

@SirRobyn0 he wants to daily tow 5k his gears are 2.73 I have 3.73 and said I reccomend at least 3.73 for his. The bad thing about 3.73 and towing top cruising speed is going to be about 65,and I wouldn't hope for much in the mpg dept.

SirRobyn0 · Jun 6, 2023

Redfish said:
@Velder if it's the stock transmission it is NOT a 5 speed. Probably a 4 speed auto, 700R4.

The right gears and the right mindset make the tow vehicle work. A man with realistic expectations and some common sense can do a lot with a 305. @SirRobyn0 has a very nice C20 that has a 305 and he tows whatever he wants to. He lives and tows in an area with higher elevations and steeper hills than I do.

If you want modern power, invest in a modern diesel. But a 5K load should not overwhelm a decently set up square body.

Oh boy. Sorry all your guys that tag me I was out of town and just got home!

Wow, it's really obvious you have paid attention to my stories. Yup, that's it realistic expectations, good maintenance and she's my only full sized truck so she does all the heavy work from hauling feed to towing the trailer with the tractor on it!

CheemsK1500 · Jun 6, 2023

@SirRobyn0 Would you consider the modern MSD ignition systems a viable alternative to the old school ESC? I've thought about trying one on a 305 to see what would happen.

bucket · Jun 6, 2023

Ricko1966 said:
They raised compression when they went esc. High compression 305s have 9.5:1 an lm1 350 is only about 8:1 real world.Real world on the 305s is about 9.9:1, 305s ping without esc and egr. Yes you can eliminate all the stuff but the truck won't run as good,and won't get as good of gas milage, to eliminate ping youll have to retard initial timing,and limit vacuum advance,both hurt power and milage,ask @SirRobyn0 I told him don't eliminate esc. it will create more problems than it solves. He tried for a year to make it work right and went back to ESC. @Rusty Nail look at that fuel line.

Just spit balling here, not arguing...

My '84 C10 had the original ESC 305 when I got the truck. I drove it everyday and recorded the mileage on every tank. After a while, I started having a bunch of troubles with the quadrajet, so I put on a 650 Holley that I had on hand. At that time, I also removed all the vacuum hoses and temp switches... got it down to a vacuum advance and a PCV hose. After a while longer, the pickup coil in the dizzy started to crap the bed, so in went a standard HEI. Pretty sure it was a Street Fire unit, but I don't remember now. I may have just stuck in a random HEI unit.

But anyway, the truck always ran great, didn't ping and the mileage was always the same. With a mix of city and highway, my average was 14.5 mpg. Best tanks were on long drives at 55 mph (no OD, 2.56:1 gear) which 18.5mpg could be achieved. The carb/dizzy situation didn't seem to make a difference.

Towing with a 305 V8?

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