In need of 6.2 help

Hi all, long time lurker, just joined. I have a couple q's if someone could help me out👍🏻

1. I am putting togather a "mild" 6.2 for my son. Its a original Redblock, with a set of 1407762 heads/D cups. I built a girdle, installed ARP's, also has low compression pistons and a .310 pump.
Heres my issue:
I found one of the valves "broken" on top of the stem. Like the plating/hardness has cracked apart. No biggie i thought. I dug through all of my other extra exhaust valves, probably 20 or so, and the stems are all to big for this heads guide. So i checked, and the original valve was .366", and all my extras are .370". So i went ahead and pulled another exhaust valve and it was also the smaller .366". What gives?

2. Having a heck of a time finding studs for my main girdle. Called ARP and they have AU3.800-2lb, but that will just barely be flush with the nut. They want about $20 apiece for them. I hate to spend that and not be 💯 comfortable with the results. So im checking with another company that may be able to help me out, but they have to see if the studs are over 125,000 tensile.
Any ideas?

3. Lastly, what factory exhaust manifolds were the largest/best performers? I am thinking about a 6.5/4l80e swap into my '05 trailblazer, but the factory exhaust will not work at all. So i am gonna try to do a front/right side turbo mount.

Thanks all

Also, the larger stem valves have a much more "concave" valve seat face than the others.
I have seen many like this, but never thought about it until now. Whats the reasoning for this?

The valve on the right is the fatter one, as well as the concave seat area.

I was gonna run the valve after i found none of mine would work, but i remembered something from the aluminum rod days; hit it with a hammer, that way you cant be cheap and run a bad part, lol

Welcome to TDP :):):)

The concave face on the valve is from wear and time.

This is not an intentional thing.

A valve and seat grind is in order.

The 6.2/6.5 also has a spec on the distance from the head deck to the valve face (depth into the head)

The stem that's showing the chipping is a case of the hard surfacing failing.

That valve is a paper weight now.


The valve/valves with the concave faces ???? were these exhaust valves ???

If so the anomaly may be due to the engine having been operated under very high exhaust gas temperatures.

Hi, the exhaust valves are concave, but they were all in an engine that ran great. It was pushed "kinda" hard, but nothing excessive. It saw 1300*,25psi and 4000rpm pretty regularly. The next one will be 30-35psi, should be up around 1500*. Same girdle, same head setup as the current build, just more fuel. Never really lugged though, i am a firm beleiever of higher rpm rather than the low rpm lugging.
I think these engines are tougher than they get credit for, especially when they are screwed togather correctly and cleanly. Assembly is a big part. I see guys have issues at break-in and blame it on the motor. Huh???

So about the rest of my questions...

1. Has anyone ran into different valve stem thicknesses?
2. Exhaust manifolds for largest outlet/maximum flow.
3. 4" double ended studs at least 150,000 psi tensile strength with the m12x1.75 pitch.

Thanks

Howdy
WOW!:eek: "1300*,25psi and 4000rpm pretty regularly. The next one will be 30-35psi, should be up around 1500*"

Those are some smoking numbers from a 6.5....
Are you using an intercooler or water injection?

As to your manifold question...Have you thought of using a custom header shop to make your system? I have long tube headers on my blazer made by Headers by Stan. They work great and he was a great guy to work with, seemed very open to just about any kind of custom project.

As a fabricator and gunsmith I know that the cost of any type of custom or low production high grade bolt/stud is VERY expensive. I am surprised that ARP does not have an on shelf item.
Good luck!

With the low compression pistons i felt ok with it. This ome and the next one will have the girdle/studs.
"I think" with a good pump, fresh injectors, good gaskets and hardware, they are alot more capable. But thats how we get them so cheap, cause everyone else thinks their junk, lol.
Im not out to break records, i know it has its limits.. but they are cheap to build, and easy to work on.

The header deal is something i dont want to get into. I have a set of hummer headers, and i thought about buying another right side and using them. But for durability purposes, id like to use a heavier factory manifold. It would be nice to have something with a 2.5" outlet.

If i get a lead on these studs from this other company, ill post up the info👍🏻

Dr. Lee once did an improvement on factory manifolds(NA application). I think he got them into the 2.5 inch range. Some machining and re-engineering the flange/coupling area and parts.
You can check with Banks and see what they have for manifold specs. ATS also made their own manifolds.

Ok so i got some news back on studs.
The company is "MSC"

Part #74365727
"Rolled thread 'stressproof' steel"
m12x1.75
overall 95mm
31mm threaded each end
125,000 psi tensile black oxide finish
$3.44 each

Part #86777489
"Medium carbon steel"
M12x1.75
Overall 95mm
16mm one end
31mm one end
125,000 tensile black oxide
$4.31 each

Part# 85559011
"10.9 metric rated at 145,000 psi tensile"
Overall 100mm
63mm one end
15mm one end
$5.23 each

You can go on their website and look at all the different studs, but these are the closest i found. They are on page 1335 of the catalog.

I also looked online at a few different sites for new valves. They all show the stem diameter of .370-.371 for the exhaust. Only difference is head size between the 6.2/6.5 years.

So i dont know whats toing on. I pulled them all out of these heads and they are all at .366-.367" of an inch. So apparently someone at some point has put oversized guides and smaller valves in these heads???
I cant find ANY replacement valves with this stem diameter. I am at a loss.

Anyone have any experience with this or seen it before? I dont want to ream out 1 valve guide to fit the larger .370", but at this point i may have to.

Dvldog thanks for the info. I dont want to do machining on the manifolds, i remember seeing a chart somewhere on the www before that had ALL the different years exhaust manifolds and outlet sizes.
Also was a chart that had all the different injector line ID sizes for various models.
Maybe someone here has that info? Am i in the wrong section, doesn't seem to be much traffic here?

Thanks all