Looking to buy our first 6.2

[Frankenchevy]

We are looking for a 4wd Burb with a 6.2 for my wife. Looking for any advice and tidbits of knowledge I can get on these engines.

First one we are checking on is an 83 with a supposed 70k on the clock. Current owner states they started to swap it, but lost interest. They stated that they just pulled the radiator, but I see that the fuel system is also somewhat disassembled from this picture they sent.

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I was thinking I’d get one of those had pump filter perches if it’ll help prime it. Do I need to crack each line on this engine to prime it?

 

[Ricko1966]

All I've ever had to do to mine is take a plant sprayer bottle full if diesel and spray it in the intake a few times,while cranking it,don't know if that's a recommended method but it's worked the couple of times I've needed to.Ive never cranked lines or primed the IP.

 

[backwoodsman]

I see that the fuel system is also somewhat disassembled from this picture they sent.

The only part of the fuel system you can see is the primary fuel filter/water separator, and it looks to me like both lines are attached. If you're looking at that disconnected pipe on the right side, that looks like an A/C line they removed when they pulled the radiator.

I was thinking I’d get one of those had pump filter perches if it’ll help prime it. Do I need to crack each line on this engine to prime it?

It can prime itself, but does take a little cranking if the injection lines are empty. It helps to add an electric fuel pump, preferably upstream from the primary filter, so it's easy to fill up the fuel filters when you change them, and just for backup to the engine-driven pump. You don't need to crack the injector lines because there are fuel return lines on all the injectors, which will bleed off any air.

I'd want to see it run, or at least do a compression test, or get it cheap enough that it's OK if the engine needs major work or changed.

 

[Frankenchevy]

The only part of the fuel system you can see is the primary fuel filter/water separator, and it looks to me like both lines are attached. If you're looking at that disconnected pipe on the right side, that looks like an A/C line they removed when they pulled the radiator.



It can prime itself, but does take a little cranking if the injection lines are empty. It helps to add an electric fuel pump, preferably upstream from the primary filter, so it's easy to fill up the fuel filters when you change them, and just for backup to the engine-driven pump. You don't need to crack the injector lines because there are fuel return lines on all the injectors, which will bleed off any air.

I'd want to see it run, or at least do a compression test, or get it cheap enough that it's OK if the engine needs major work or changed.

Oh, now I see…both lines come into the filer housing on the same side.

 

[Frankenchevy]

From what I’ve read 81-83 6.2s are not as desirable. Also, I’d initially thought that J-codes were supposed to be a bit more reinforced or stout in a few areas, but now I’m reading that it’s mostly injection pump, manifold (lack of egr) and a few other minor differences with the exception of 1993 599 blocks. What say the experts on better years than others?



I know very little, but I’ve read to be concerned if the harmonic balancer is already bad or separating. I’ll probably steer clear of that.

 

[Frankenchevy]

Most of the 6.2 4x4 burbs I’m seeing are lifted. If a lifted unit is purchased, I will be returning it to stock height.

Trying to be frugal on this and curious what length 2500 rear springs are? I’m thinking I could use my CUCV springs after removing (many) leaves from the rear pack.

Also looking for opinions on what a good tire size is for these trucks at stock ride height. I’ll need to check each truck’s axle ratio for the ultimate answer, but likely sticking between the original 30.7” and maybe up to a 32ish” tire, but want to keep it skinny.

 

[Frankenchevy]

We just got home from looking at a disaster. Good news is an average unit will look that much better to my wife.

 

[bucket]

Most of the 6.2 4x4 burbs I’m seeing are lifted. If a lifted unit is purchased, I will be returning it to stock height.

Trying to be frugal on this and curious what length 2500 rear springs are? I’m thinking I could use my CUCV springs after removing (many) leaves from the rear pack.

Also looking for opinions on what a good tire size is for these trucks at stock ride height. I’ll need to check each truck’s axle ratio for the ultimate answer, but likely sticking between the original 30.7” and maybe up to a 32ish” tire, but want to keep it skinny.

Most (if not all?) 3/4 ton Suburbans have 56" rear springs. How many leaves are in your m1008 packs? Iirc, my set has 9 and I'm going to use them as-is in my Suburban. My other Suburban has 8-leaf packs from an '83 C30 and they ride pretty similar to the 5-leaf 52's that were originally installed in that Suburban.

Imho, a 255/85/16 tire is a great match for stock ride height and stock type, narrow wheels. Although it is a fairly uncommon size. Otherwise, a 285/75 is a good size too, despite many people thinking they are "too wide" for a 6.5" wide wheel.

 

[Frankenchevy]

Most (if not all?) 3/4 ton Suburbans have 56" rear springs. How many leaves are in your m1008 packs? Iirc, my set has 9 and I'm going to use them as-is in my Suburban. My other Suburban has 8-leaf packs from an '83 C30 and they ride pretty similar to the 5-leaf 52's that were originally installed in that Suburban.

Imho, a 255/85/16 tire is a great match for stock ride height and stock type, narrow wheels. Although it is a fairly uncommon size. Otherwise, a 285/75 is a good size too, despite many people thinking they are "too wide" for a 6.5" wide wheel.

I looked at the 255’s briefly on tire rack. Most of them are MT’s with the exception of a Falken wild peak. I will look a bit more later.

 

[mcarlo86]

From what I’ve read 81-83 6.2s are not as desirable. Also, I’d initially thought that J-codes were supposed to be a bit more reinforced or stout in a few areas, but now I’m reading that it’s mostly injection pump, manifold (lack of egr) and a few other minor differences with the exception of 1993 599 blocks. What say the experts on better years than others?



I know very little, but I’ve read to be concerned if the harmonic balancer is already bad or separating. I’ll probably steer clear of that.

You are correct about the harmonic balancer. Whatever one you end up getting, changing the harmonic balancer would be one of the first things to do. Almost all the blocks develop cracks in the main webbing. I’ve seen many engines run way over 200,000 that are cracked. I think what usually kills these engines is bad harmonic balancers in combination with high RPMs and then the cranks break. The 599 blocks from ‘93 are supposed to be better, but they are hard to find.

I replaced the problematic box style fuel filter in my ‘90 with a newer 6.5 canister style. There are writeups on the interweb that describe how to convert them. They are less prone to air leaks. I made some drop brackets so I could mount it behind the intake manifold under the factory air cleaner in a similar location as the 6.5’s. It will fit with the stock air cleaner after making custom brackets to drop it low enough.

 

[mcarlo86]

Another thing to look for is the starter brace. If it is missing, the torque from the starter can break the engine block where the starter bolts go. Need to have that brace.

 

[backwoodsman]

Imho, a 255/85/16 tire is a great match for stock ride height and stock type, narrow wheels. Although it is a fairly uncommon size. Otherwise, a 285/75 is a good size too, despite many people thinking they are "too wide" for a 6.5" wide wheel.

Tire manufacturers specify the allowable rim width range for each tire. Most of the 285/75-16's I checked specify 7.5"-9", so yes they are too wide for a 6.5" wheel. It seems like a bad idea to run a narrower rim than the tire manufacturer says is OK.

I usually run the narrowest rim the tire specifies, because it pulls the sidewalls in a little, which protects them from rocks, curbs, etc. I run 31x10.50-15's on 7" rims on my '83 with no rubbing.

 

[bucket]

Tire manufacturers specify the allowable rim width range for each tire. Most of the 285/75-16's I checked specify 7.5"-9", so yes they are too wide for a 6.5" wheel. It seems like a bad idea to run a narrower rim than the tire manufacturer says is OK.

I usually run the narrowest rim the tire specifies, because it pulls the sidewalls in a little, which protects them from rocks, curbs, etc. I run 31x10.50-15's on 7" rims on my '83 with no rubbing.

Yes, I realize that. But in the real world of daily driving, offroading and towing heavy loads, the 285/75 works perfectly fine on a GM 6.5" width rim. Road manners, heat buildup and tire wear is not an issue, assuming it's not the front end of a wore out truck. It's a tire/wheel combo that has been run by thousands of people.

 

[backwoodsman]

Yes, I realize that. But in the real world of daily driving, offroading and towing heavy loads, the 285/75 works perfectly fine on a GM 6.5" width rim. Road manners, heat buildup and tire wear is not an issue, assuming it's not the front end of a wore out truck. It's a tire/wheel combo that has been run by thousands of people.

...most of whom haven't thought through why it might not be the best idea. Sure it'll work fine most of the time. But if you think through what happens to the geometry of a tire on a too-narrow rim when it gets a heavy side load, you'll see that it's going to compromise traction in emergency maneuvering on the highway. You may never be in a situation where that matters, but you don't know that. So, by all means run whatever you want, but be aware of what you're doing.