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red blocks. myth or oddity?

Vombrown

Vombrown

Mountain Man
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Great Falls mt
Guys I've heard this tale for decades. Red block 6.2 engines were special. Has anyone been able to verify this? I've personally owned three. I currently have one. I have never seen anything special about them. I've heard all of the rumors. Just never seen anything different about them. I've heard everything from forged to stainless crankshafts to larger ports in the head. Opinions? Observations? Is really love some fact based personal experience versus rumor. I got plenty of those.
 
All I know for sure about them is they use the coarse thread injectors. I don't think there is anything really exotic about them to be honest. They sure didn't make more power...
 
I think someone was pulling your leg or having some fun with you at your expense...
 
I saw only one '82 Chevy K10 in a junkyard with a red painted 6.2 that was likely the original--truck also had the rare A833 Mopar 4 speed overdrive manual tranny in it too...truck had less than 50K on it,it had been T-boned on the passenger side of the bed,but only had sheet metal damage..

I wanted to buy the truck and the guy at the parts counter said "500 bucks"--I left to go get the money,30 minutes later I returned to find it squashed flat as a pancake,the roof was level with the dash..they shoved it in the crusher as soon as I left!..:mad:..

All I have read about the red engines being different is like what Rene said--coarse thread injectors--also supposedly GM used higher nickel content in the early red blocks,probably because they were trying to overcome the disaster of the 5.7 Olds based diesels..
I have read the Caddy 472's and 500's and some of the Nailhead Buicks also had high nickel content blocks..

I doubt any 6.2 had a forged crankshaft,not from the factory at least..but they SHOULD have !..(especially after so many broke,GM should have had to recall them and upgraded them to a forged one)..but many 6.2 blocks cracked at the main bearing webs too...seems to me they could have engineered it a little better..
 
I didn't mention my truck has the np883 in it. As well as the red block. I thought it was a standard four speed until I saw the OD on the factory shifted knob.
 
I will say. This is number 8 or nine for me and I have not had one that purred like this one does. Where most sound like a box of nickels, this one sounds clean. Just random thoughts.
 
Advance your pump timing...they're not supposed to be super quiet.
 
Red blocks are supposed to have a higher nickel content

I looked for em for a while found two. Both cracked where most 6.2s crack.

On the other hand my run of the mill mid 80s 6.2s show no cracking in the block.

I think it really amounts to not much.

Especially with the upgraded stuff available
 
Allegedly the strongest 6.2/6.5 block was the 599 casting 6.5. Pretty late in the production run and probably upgraded in certain areas.
 
I read they went to 10mm bolts for the main bearing caps vs 12mm,and thickened the casting some in the problem areas..

I kind of wish the 6.2's had a remote cable for advancing the pump timing,like my old VW diesel had--there was a cable with a handle kind of like a choke cable you'd pull out to advance the timing for cold starts,and you could leave it slightly out to make it idle faster and have a bit more pep and get better fuel mileage..

I know the injector pump on the 6.2 has that solenoid to advance the timing and bump up idle speed--but to me it doesn't seem to advance enough,I can barely tell the difference when the solenoid is on,it mostly increases the idle speed,but I don't think the timing changes much..could be wrong though..

My '85 Suburban's 6.2 is much quieter than my pickup--I think the timing is retarted on it,because it also is a hoe to get started,especially when cold...(with glow plugs working)..takes a lot of cranking and it'll finally chug to life and belch a white cloud..once its warmed up its fine,but seems doggy compared to the pickup...
 
diesel4me said:
I read they went to 10mm bolts for the main bearing caps vs 12mm,and thickened the casting some in the problem areas..

I kind of wish the 6.2's had a remote cable for advancing the pump timing,like my old VW diesel had--there was a cable with a handle kind of like a choke cable you'd pull out to advance the timing for cold starts,and you could leave it slightly out to make it idle faster and have a bit more pep and get better fuel mileage..

I know the injector pump on the 6.2 has that solenoid to advance the timing and bump up idle speed--but to me it doesn't seem to advance enough,I can barely tell the difference when the solenoid is on,it mostly increases the idle speed,but I don't think the timing changes much..could be wrong though..

My '85 Suburban's 6.2 is much quieter than my pickup--I think the timing is retarted on it,because it also is a hoe to get started,especially when cold...(with glow plugs working)..takes a lot of cranking and it'll finally chug to life and belch a white cloud..once its warmed up its fine,but seems doggy compared to the pickup...
Click to expand...

I know it's not the same, but you could wire a switch to the timing advance solenoid to engage it at will. I think mine is a tiny bit more peppy when in warm up mode.
 
Mine is already toggle switched!..:blush:..

The sensor in the passenger side head that operates the HPCA on the injector pump decided to spit out the plastic "guts" and then the wires dropped onto the hot exhaust manifold one night, on my way home from a friends house 4 miles away..when I parked the truck and got out,I smelled burning plastic,and looked underneath the front end and saw flames flickering!..

I quickly popped the hood open and saw the wires & plug were on fire!--two inches away from a rubber fuel line feeding the fuel filter too!--I was able to put it out by blowing on it and chucking a handfull of dirt on it..was lucky I decided to look,or the truck would have been a total loss in about 5 minutes..

I just clipped the burnt part off the wires and ran them to a toggle switch in the cab,next to the push button for the glow plugs..

I have to remember to turn the switch on when I go to cold start it,but I rarely if ever forget to turn it off--once it is warmed up,the fast idle will make the truck want to "creep" at a stop,and also not slow down as well when coasting..
 
The 82 blocks had a higher nickel content. GM only used them for one year for some reason. Why I'm not sure but probably partly for cost.

As for if they're better or not, me doesn't really matter from what I've found. Generally if a block is crack free after many years/miles it will remain that way.
 
Yup ^^^

Yeah, they were supposed to have a "better" alloy. In practice, it's not really worth the effort or any extra money to go seek one out.

The time and money would be better spent checking any block that's been run for a while - if it's not cracked it's likely not going to with the same usage.

These blocks either crack and run that way for ages, or they don't crack and run pretty well the same. Many guys with working 6.2s are running around cracked main webs and heads and never the wiser...there's actually few catastrophic failures - otherwise the 6.2 would have been dead long ago. Sophisticated they aren't, but with good maintenance they will chug along a long time...I mean, we're talking a few years ahead of a 1st-gen 12-valve Cummins here.
 
I don't know that I've ever actually seen a failure directly attributed to the cracks in the main webs, personally. I ran an 82 red block 6.2L with a no-egr 6.5L GM-3 turbocharger setup on it. It definitely didn't win any races, but that thing sounded wicked and got pretty decent fuel economy as well.
 
tRustyK5 said:
Allegedly the strongest 6.2/6.5 block was the 599 casting 6.5. Pretty late in the production run and probably upgraded in certain areas.
Click to expand...
I have one of these blocks still a 6.2
I also have the crank.
I was thinking about building a strong 6.2 or even boring it out to 6.5 but I look at the shed full of running 6.2s and I think why bother.
 
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