Custom 6.2l build - new guy here

[Mikey von]

Hey there,

Many of you know me from dieselplace or thedieselpage. This forum looks pretty nice and about my speed. I am getting close to finishing this thing up and will have lots of questions. I have some real recent health problems (carpal tunnel surgery became infected - emergency surgery tomorrow) that may slow me down some.

My engine is a custom built 6.2l, with some 6.5l parts. It was built by MaxPF and bought by me when he decided to go some other direction. To save me some typing, I am copying much of my build thread from the other forums.

Here are some highlights;

bottom end-

* 1991 660 block, crack free, bored & honed .030 over
* Custom full length .500" thick main cap girdle
* 12mm ARP studs in ALL positions on the main caps
* New Melling HV 6.5 oil pump
* Brand new GM 6.5 crank machined to fit 2 piece 6.2 block (yes, really)
* rods resized, rebushed, shot-peened, and fitted with new GM rod bolts
* New .030" Mahle pistons w/rings
* Main bearings are Clevite, rods and cam bearings are Sealed Power
* Custom aluminum oil pan (to clear the girdle) with fittings for turbo
oil return and bypass filter return
* Good used stock camshaft
* Pete Jackson Gear Drive (PJ makes them for all the other vendors)
* New Sealed Power lifters
* New pushrods
* ARP head studs

heads-


* New aftermarket castings
* New hardened intake seats and high nickel exhaust seats
* New wear resistant iron valve guides
* New SI valves (exhaust valves are stellite faced)
* Valves unshrouded - resulting volume increase yields 18:1
compression
* positive-type teflon valve guide seals
* big block valve rotators on all valves (spring seats machined
to accommodate rotators)
* Comp cams 1.462" diameter springs, 109# seat pressure
* Comp cams retainers and locks
* Comp cams 1.7" Magnum full roller rockers on custom tool steel shaft
setup. Head machined to retain custom shaft pedestals and will NOT
accept stock shafts
* New GM diamond precups

pics (i have a bunch more if you want to see anything, just ask) -

 

[Mikey von]

Here is what MaxPF has said about his awesome build;

Hey everyone,

Just wanted to say thanks for the comments. This engine has been my slow project for the last couple years. It was near completion when I changed directions on my Blazer. Originally this engine was destined to replace the tired old TBI350 that it originally had. Then I got a used 6.2 from my roommate and swapped that in, so I could benefit from better fuel mileage while I fussed over this engine. Finally, earlier this year I decided there weren't enough K5's running around with 12V Cummins under the hood, so I bought one. That left me with a basically orphan 6.2 project.

I finally posted it for sale, with a "make offer". Mike made an offer, I accepted, and the rest is (almost) history. I'm not going to disclose how much I sold it for; lets just say Mike got it for literally pennies on the dollar, compared to what the parts and machine work alone cost.

I will try to answer some questions about certain aspects of the heads and valvetrain. First, the valves are stock 6.2 J code size. They look larger because the 45 degree reliefs around the valves have been opened up. This does two things: it unshrouds the valves at low lift, and it increases chamber volume. As a result of the latter this engine has an 18:1 compression ratio with stock height pistons. The common method of dropping the piston .030" in the hole to get 18:1 leaves you with less "squish" and slower moving air in the cylinder. My method increases low lift valve flow and maintains the high cylinder turbulence of a stock compression engine (at least, that's the theory).

The valve springs are comp cams. They give 109# seat pressure (vs 80# for stock springs) to reduce the chance of valve float in case of an accidental overspeed (i.e. missed shift). The retainers and keepers are also Comp, and are 10 degree performance type. In order to maximize valve life both intake and exhaust are fitted with rotators. Since the stock 6.2 rotators fit smaller springs I had to use big block rotators. Their diameter and height required machining of the spring pockets and stems.

I was unhappy with the induction hardened seats and rather loose guides in the heads, so I replaced both with superior aftermarket pieces. The guides are sintered iron with spiral oil retaining grooves inside, and are topped with teflon positive seals. The intake seats are hardened steel, while the exhausts are a high temp nickel alloy designed for use with the stellite faced exhaust valves. The valves themselves are made by SI, and are their HD replacements for J code 6.2's. It should be noted that the use of seat inserts in the exhaust side will positively prevent the formation of a crack between the exhaust and intake valves. This crack is caused by the high operating temp of the integral induction hardened seat (which is brittle and crack prone) while being pounded incessantly by the valve. IH had the exact same problem with their prototype 6.9's, and they solved it by using seat inserts.

The rocker arms are Comp Cams magnum roller rockers. They are 1,7:1 ratio big block units. I removed the trunnions in them so I could mount them on shafts. The shafts themselves are made from ground O1 tool steel hardened to 60-62Rc. This hardness is needed so the needle bearings don't brinell the shaft and eventually destroy it. The shaft pedestals are made from 1018 that has been carburized (case hardened) to 60-62Rc for wear resistance (the rockers can rub on the sides of them). They have caps aligned to the bodies with 1/8" dowel pins, and each body/cap pair is numbered and fitted as a pair, similar to rods and their caps. They are mounted to the head using special studs that have 1/2-13 threads on one end and 3/8-24 threads on the other. The studs are machined from 17-4 stainless steel and precipitation hardened to give a strength of 200ksi (for comparison, standard ARP fasteners are 160-170ksi). They are retained with thin walled ARP 12 point nuts. I even had to machine down a socket to fit in the tight well - a standard socket has walls that are too thick. Besides holding the shafts, the mounts also offset them toward the intake side of the heads. This is necessary because the distance between the fulcrum and roller tip is greater with these 1.7 rockers vs. the stock 1.5 rockers. The pushrods are new Sealed Power stock length 6.2 pushrods. Pushrod geometry is identical to a stock engine since the roller tip to rocker ball distance on the big block is nearly identical to the diesel.

Since these rockers are higher ratio the valves gain more lift. Valve lift on a stock 6.2 is .420". With the 1.7 rockers it increases to .476. Piston to valve clearance was checked and, while VERY close, it is better than the specs for the International 6.9. The 6.9 gives an exhaust-to-piston vlearance of only .009"! This is WAY too close IMO, and thankfully the advance built into the 6.2 cams gives around .030". The intake is much tighter, but it can be since the piston is retreating from the valve. Exhaust clearance is much more critical in any engine because the piston is approaching a retreating valve, and any valve float risks a collision. This doesn't happen with the intake valve. BTW, as a point of comparison gassers, especially race motors, try to have at least .100" clearance between the exhaust valve and piston at their closest approach. This is because valve float and lifter pump-up is much more likely with a high revving gas engine.

So, anyway, that is the bulk of the technical detail. The bottom end is pretty basic except for the girdle and the ARP studs. The aluminum oil pan was needed to clear the girdle, nothing more. As Mike mentioned, the crank is a new old stock 6.5 one piece seal crank that I machined to fit the 2 piece block. Main bearings are Clevite and rod bearings are Sealed Power. Cam bearings are also Sealed Power. Pistons are .75mm over Mahle, and the cylinders are plateau honed as is common for modern engines. The gear drive is a Pete Jackson unit that I bought from Jegs. It is the EXACT same one you get from the 6.2 retailers except for a much lower price Lifters are also brand new Sealed Power units. The only thing I reused in this engine was the camshaft and IP gears, because these parts practically never wear out.

Finally, in case anyone is wondering, I have no intentions of making any more of these rocker setups. I just don't have the time or money to donate to such a side venture, and I doubt it would be profitable anyway. Honestly, the main reason I made these was because I could... the fact that the stock setups are a bit cheesy was also a minor reason

 

[Mikey von]

As far as plans for this thing, I have collected the banks turbo setup, fluid ampr, db2-4911 pump, poly motor mounts and trans mount, serp setup, ho water pump, dual stats, stock serp fan, and some other parts.

I need to get my injectors pulled out of the old motor and have them rebuilt. The old motor still has not been pulled. I need to replace the tie-rod to move the suburban into the garage. I have a upgraded beefy one ready to go. I also just got permission to purchase a new aftermarket oil-cooler. I did not want to take a chance with any metal or coolant in the old one.

 

[ak diesel driver]

more pics please

 

[DEERE3594]

Awesome build! I want one!

 

[NVW]

Looks like a thing of beauty.:thumbsup:

Leo

 

[qwomack]

The machine work on the roller rockers is SWEET! What are you going to put it in?

 

[Mikey von]

more pics please

what would you like to see, more pics in general or certain aspects?

The machine work on the roller rockers is SWEET! What are you going to put it in?

Thanks, i wish i could take credit for doing more than sending $$$.

It is going in my '89 3/4 ton 4x4 burb. I blew a head gasket and then chunked the flexplate in my original 6.2: I was going to rebuild,then this fell in my lap and i could not pass.

 

[ak diesel driver]

what would you like to see, more pics in general or certain aspects?



Thanks, i wish i could take credit for doing more than sending $$$.

It is going in my '89 3/4 ton 4x4 burb. I blew a head gasket and then chunked the flexplate in my original 6.2: I was going to rebuild,then this fell in my lap and i could not pass.

more pics in general but I'd really like some good closeups of that valvetrain.

 

[3500GMC]

Nice indeed. The builders note (MaxPF) is a great read. Sure has my gears a turnin'.

Best of luck on the build.

Welcome to the Truckstop.

 

[Mikey von]

Nice indeed. The builders note (MaxPF) is a great read. Sure has my gears a turnin'.

Best of luck on the build.

Welcome to the Truckstop.

Thanks. This was a neat purchase as I followed MaxPF's extensive build thread on CK5. Never thought I would be throwing it in my burb.

 

[Woody35]

hope the surgery went well. we actually talked about this build up in a thread a month or so ago. its somewhere on here. just my 2 cents but with this awesome custom motor i would try to put a better turbo on there then an old banks setup. i can totally understand though if it fits in the budget though.

 

[Mikey von]

hope the surgery went well. we actually talked about this build up in a thread a month or so ago. its somewhere on here. just my 2 cents but with this awesome custom motor i would try to put a better turbo on there then an old banks setup. i can totally understand though if it fits in the budget though.

I will be putting on a bigger turbo, most likely an ATT. :thumbsup: The banks will go there now as that is what i have and I need to get this thing going.

The surgery went fine, it is the infection afterwords that is bad.

I will search for the build up thread on this thing.

 

[Matt Bachand]

ATT should compliment the RPM smoothness of that setup nicely I would think.

 

[buddy]

The ATT will compliment the increase in lift and duration caused by the higher ratio rocker arms and machining around the valve seat area.

The amount of squish is not any greater than other 18:1 engine, but managed to achieve it without replacing pistons or rods.

 

[Mikey von]

off to playa del carmen and tulum for a much need vacation without kids. see you in 10 days or so! ):h):h:smile5:

 

[6.5TD Burb]

Updates?

 

[Mikey von]

I have made some good progress (you must remember I am a rookie).

I have started getting the old engine out; the injectors are pulled and are being rebuilt, the suburban got its new tie-rod and made it into the garage (we pushed with another truck), the front clip and core support are out, and I am one stubborn ass bell-housing bolt (well it is a nut actually) away from having the thing pulled.

The new engine is progressing a little as well; the block is painted and I will be getting the flex plate on it tonight. I would like to get the oil system primed tomorrow and start getting the thing put together.

 

[Acesneights1]

OT sorry to hear about the surgery issues. That is why I have not had it. Fear of compications. I live with the pain.

 

[Mikey von]

I have made some decisions. I think I will be running 3" exhaust, as this can be custom done locally and MaxPF tells me it will be plenty. I am going to get a new oil cooler and lines from pmdcooler.com.

I need to decide between single or dual thermostats. Pros and cons???


I also need to find out if I can run an A/C compressor without any lines hooked to it? If not I need to get an A/C delete pulley. I will want A/C but will need new lines run as I am going from drivers side to passenger side.

One pain in the ass thing, it seems as my engine hoist ram (it is not even mine) is not working right. It pumps really easily and barely goes up with each pump. I will check the oil on it tomorrow.