You sure can learn a lot if you spend a day in a junkyard taking things apart. <img src="/forums/images/graemlins/kewl.gif" alt="" />

I stripped a 3.0L DOHC engine from a '95 Diamante today. The first thing I learned was that I really feel sorry for anybody who owns one of those engines. <img src="/forums/images/graemlins/lol.gif" alt="" /> Yesterday, I stripped a '90 SOHC Montero engine in 2.5 hours. Today's follies took 6 hours of steady work. <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/shiner.gif" alt="" /> Granted, it was the first DOHC engine I've stripped, but it's not something I'd look forward to repeating. <img src="/forums/images/graemlins/barf.gif" alt="" />

I did get 2 DOHC heads that appear perfect and should be worth more than the $150 I paid for the engine:

I also got a very nice steel crankshaft to use in the blower engine:

And... I pulled the rods, since the DOHC rods are the same part number as the VR4 TT rods... should be fine for my engine and a lot better than paying $600-1200 for aftermarket hi-po rods. I can't tell any difference between the Montero/Raider, Diamante SOHC and Diamante DOHC rods except the numbers on the sides, but maybe they are rated differently since the Montero rods have a different part number. Here are all three shown together.... Diamante DOHC on the left (marked "72-H"), Diamante SOHC in the center (marked "72-Y") and Montero/Raider on the right (4 marked "72-R" and 2 marked "72-S"):


Perhaps the most important thing I learned was wrt the head bolts, because I've been trying to find head studs to use in the blower engine... without luck. ARP lists studs for the 24v DOHC engine only, so I called them a couple of days ago to see if they had something generic that would fit the 12v SOHC engines. I gave them the size and they said they had nothing in that thread pitch.... bummer. When I pulled one from the DOHC engine today, I thought it looked familiar, so I brought it home. Here's the DOHC head bolt (bottom) and a SOHC 12v head bolt (top) shown together:

Yep, they're the same..... meaning that we can now use ARP head studs in the SOHC 12v engines. <img src="/forums/images/graemlins/kewl.gif" alt="" /> I was concerned that some applications might use different tensile strengths, so I asked the ARP rep about it and was told that everything they sell is rated 200,000 psi. <img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" /> Oh happy day! <img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />

All-in-all.... a good, but long day!

Frank

Nice discoveries Frank...When I get around to rebuilding my 89 engine it looks like DOHC crank and ARP head studs might be a nice improvement for piece of mind if nothing else...

I wonder how different the DOHC 3.0 is from the SOHC 24V and the DOHC 3.5. I'll more alike than not.

On that note, do you know how that DOHC 3.0 head compares to the DOHC 3.5?
(Prolly already been covered somewhere in the 17 pages. Sorry for not looking. <img src="/forums/images/graemlins/zombie.gif" alt="" />)

Here's another discovery.... When I pulled the main bearing saddle, I thought the main cap bolts looked different.... so I brought 'em home. Sure enough.... here's the SOHC 12v bolt head with weird markings:

Here's the DOHC 24v bolt - note the flange:

The bolt head markings indicate a grade 10.8:


I haven't yet pulled a SOHC 12v main bearing bolt to compare length and thread, but assuming they're the same, these will also go in the blower engine. <img src="/forums/images/graemlins/kewl.gif" alt="" />

The SOHC block is plenty strong as is and should be good for more HP than I'll ever attempt, so while the 4-bolt main '95+ DOHC VR4 block might be desirable, many of the stronger parts can be found in the cheaper Diamante DOHC 24v engine and it appears to me that the upgrades can make an even stronger SOHC 12v engine. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Frank

I don't know nuttin' 'bout no 3.5L. <img src="/forums/images/graemlins/lol.gif" alt="" />

Frank

Y'all are from thea south orant yeeuuw <img src="/forums/images/graemlins/smile.gif" alt="" />

With the mangled head bolt finally removed, it's time to see what differences there are in the '93 Diamante SOHC block. The front and rear are identical on the Montero and Diamante blocks. The first difference is on the driver side where the Montero block has an unused oil passage - perhaps utilized by the Chrysler cars:

The Diamante block does not have that passage - but it doesn't matter for our purpose. Note that two dowel pins are installed in the Diamante block, though.... and those are in the way of the Montero A/C bracket:

A few minutes with a grinder fixed that issue - note the beam band near the skirt for extra strength:

Everything needed now mounts on the driver side:

The main difference on the passenger side is the extra gusset in the block. Here's the Montero:

Here's the Diamante - note not only the gusset/knee that reinforces the area of the engine mount, but also the horizontal beam band near the skirt flange:

Everything needed mounts to this side just fine, with no modifications necessary:

So, it looks like this block is an even more bulletproof version of the 6G72 and a good choice for an upgrade path - certainly not an expensive one. <img src="/forums/images/graemlins/kewl.gif" alt="" /> The bores look good, so tomorrow I'll order pistons..... and wait some more. <img src="/forums/images/graemlins/baby.gif" alt="" />

I did pull some main bolts for comparison... Montero on the left, Diamante SOHC in the center and Diamante DOHC on the right:

The Montero and Diamante SOHC are identical, and the Diamante DOHC is the same size, except I suspect it's stronger. Since the Montero and Diamante SOHC bolts have a circular step seat under the bolt head, I think I'll have the saddle area milled a hair just to make sure the larger flange area of the DOHC bolts get a good seating area:

I still want to see if the 4-bolt main 3000GT studs supplied by ARP will work, though.

Frank

Some parts arrived today.... the ARP head studs are a perfect fit and a purty sight on a 3.0L:

Tested the fit on the heads - no interference issues:

Unfortunately, the DOHC 4-bolt main studs are smaller than the M12x1.25 main bolts used on the 2-bolt main blocks, plus too long - maybe I can find another main stud that will cross over:

The rod bolts appear to be a good fit, although, there's no turned down guide post end that can be used for a hammer or drift pin striking blow when removing pistons - not a big deal since I usually use a wooden hammer handle:


If nothing else, the exercise was worth it to find out about the head studs - that should eliminate some issues for those that are willing to pay the price of admission.

I sure hope I can find a main stud that will fit.

Frank

I'm not sure but international made bulldozers ( TD 9 and TD 14 had 2 sets of valves and started on gas then switched to diesel--Tough old dozer. My Best friend back home has an old TD 9.

The wheels of progress have a crawl ratio. This sure doesn't seem like two days work until you do it.

Trimmed and painted ECU mounting frame:

Relay board bracket cut/bent/drilled and mounted:

Relay board harnesses sorted and connected:


Two cabin entry holes drilled and grommets installed - upper is for the ECU main harness, lower is for the MAP sensor hose:

Relay board wired and mounted:

Aside from the neater look of hacking the OE harness, another reason to avoid the relay board is the extra harness needed between the ECU and the relay board. Here are all three harnesses nearly ready for final connections... the one coiled on top of the relay board connects to engine sensors/injectors... the one on the battery connects to switched/unswitched power, fuel pump, engine ground, o2 sensor heat... and the one coiled on the cowl is the connector harness between the ECU and the relay board:


A KnockSense translator is on the way, so I won't final install the harnesses until I see what changes I may have to make to run the knock sensor.

It can get very confusing mentally... sorting the connections that do and don't run through the relay board.... perhaps a good reason not use one. If things work as hoped, the relay board may be eliminated later and the OE harness hacked to suit..... which would eliminate nearly all of those three harnesses.

Frank