Crankshaft mystery

2384 Views 19 Replies 6 Participants Last post by 95classiclwb, Jul 21, 2018

greddm

Discussion Starter · Jun 29, 2018

1995 RRC w/ 3.9L engine

I just purchased a new set of con rod bearings from eBay and when they arrived they were way smaller than the ones I had removed. I thought they made a mistake but I checked the part number with similar listings and they are all the same. The parts place also verified that they are listed as the correct fit for my vehicle.

Are they all wrong or is it possible I have a crank and pistons from a different engine?

Also recommendations on where to get a correct set.

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annette

· #2 · Jun 29, 2018

What is your journal and crankpin diameter? might solve the mystery.

greddm

Discussion Starter · #3 · Jul 7, 2018

annette said:
What is your journal and crankpin diameter? might solve the mystery.

The plot thickens...Crankpin journal diameter ranges from 55.51 to 55.53 mm – Specs in the manual say it should be 50.800-50.812 mm. Whats going on here?

annette

· #4 · Jul 7, 2018

In a 4.0 or 4.6 engine that is normal.
¿¿ But you said you have a 3.9 ??

Can you possibly post or link a picture of the underside of your head or the top of the block?

greddm said:
The plot thickens...Crankpin journal diameter ranges from 55.51 to 55.53 mm – Specs in the manual say it should be 50.800-50.812 mm. Whats going on here?

Enviado desde mi SM-A720F mediante Tapatalk

greddm

Discussion Starter · #5 · Jul 7, 2018

It's not attaching photos for some reason, I'll keep trying. It does appear that I have 4.0 parts, but the plenum is labeled 3.9

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5

greddm

Discussion Starter · #6 · Jul 7, 2018

Hope these attach

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95classiclwb

· #7 · Jul 7, 2018

if you look at the bottom of your block, right about the oil pan line. does it have a line of bolts along the sides of the block?, if so you may have a 4.0 dressed as a 3.9.next to the serial number at the oil dip stick, you should have a number followed by a letter it would be a 36D or 38D if a 3.9, a 4.0 would be something like a 95D , check out this link.https://rimmerbros.com/content--name-Rover-V8-Engine-Numbers

annette

· #8 · Jul 7, 2018

Sorry no pics.
Can't do it on my computer either. I can only attach in Tapatalk on my phone.

Try to link to some free photo gallery, like I did in my signature

Enviado desde mi SM-A720F mediante Tapatalk

greddm

Discussion Starter · #9 · Jul 9, 2018

Solved! I have a 4.0 block. Wish I knew how many original miles were on it though.

greddm

Discussion Starter · #10 · Jul 15, 2018

Well, I thought I had this all figured out... Until I noticed this on my crank as I was measuring piston rings (not sure how I missed this). So now I suspect I have a 4.6L engine not a 4.0. I know as far as rings and con rod bearings go, this makes not difference since they use the same, however I would just like a definitive answer as to what this engine came out of originally. Thats when it got even more confusing - I can't find this serial number on any of the Engine Identification lists I've found. Anyone got ideas?

Pictures attached (in case they don't show up for a few days like last time) are as follows:

Picture 1 - looking down my #2 cylinder to see a "4.6" stamped on the crank

Picture 2 - serial# on the block "S06D00106A"

Auto part Engine Automotive engine part Vehicle

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Lockettc

· #11 · Jul 16, 2018

I believe you are running a similar setup as me.

The block is from a 4.6l from a Disco without secondary air injection. Mine has a 4.2 plenum (LWB), and the block serial number is S08D38860A with a CR of 9.37.1.

You likely have a shim for the front pully as the shaft lengths are different.

greddm

Discussion Starter · #12 · Jul 16, 2018

Lockettc said:
I believe you are running a similar setup as me.

The block is from a 4.6l from a Disco without secondary air injection. Mine has a 4.2 plenum (LWB), and the block serial number is S08D38860A with a CR of 9.37.1.

You likely have a shim for the front pully as the shaft lengths are different.

That sounds right - I did notice a seemingly superfluous piece when I took the pulley off. I assume they also used the 4.6 ECU (ECM whatever it's called) when they did the swap?

Lockettc

· #13 · Jul 16, 2018

I am running a stock ECU (14CUX) with the upgraded ‘Ford’ four nozzle injectors, and a upgraded cam.

The 4.6l ecu requires a harness change++.

I now have 20K miles on the build – really would like to upgrade the ignition/dizzy, as it seems as it I am not fully leveraging the full performance.

xalt

· #14 · Jul 16, 2018

It's a 4.6 dressed up with late 3.9 acessories, 14CUX, gerotor pump, serp belts, etc.

All Rover V8 accessories can be swapped out between generations, save for the spacer to mount GEMS and later engines onto older cars.

greddm

Discussion Starter · #15 · Jul 16, 2018

Off topic, but what type of ignition upgrades are available? What kind of performance increase would you expect from an upgrade?

xalt

· #16 · Jul 17, 2018

greddm said:
Off topic, but what type of ignition upgrades are available? What kind of performance increase would you expect from an upgrade?

Buick-Petronix dizzy and an MSD 6A control unit\coil are what I'd think of first.

Razorbeam

· #17 · Jul 20, 2018

xalt said:
Buick-Petronix dizzy and an MSD 6A control unit\coil are what I'd think of first.

I just put the MSD 6A on my truck with a Blasster 2 coil and I love it. It made a big difference in how the truck starts, idles, and revs. The higher RPMs are so much stronger now, the thing just pulls.
As for the Pertronix unit, I know they get a lot of good reviews, but the one I got was defective. I ended up going with a new OEM dist. and now my ignition is spot on.

greddm

Discussion Starter · #18 · Jul 20, 2018

Thanks for the info, I need to look into a set up like that.

Razorbeam

· #19 · Jul 20, 2018

Vehicle Motor vehicle Auto part Car Engine

I've attached a pic of my setup. Let me know if you want the specifics, there are a few writeups/youtube videos about it. I would also recommend some Champion copper plugs (not platinum or anything fancy). I opened the gaps to ~0.042 (stock is ~0.036) and bumped the timing to 12 degrees advanced. The performance gains were noticeable, but it's still no Porsche. Still, I feel better about merging onto the highway or overtaking on a 2 lane road. Too early to tell, but my fuel economy could improve too.
The MSD and new coil accounted for some of that, but a lot had to do with getting the thing tuned in just right. Adjust the timing and spark gap until it behaves the way you want it.

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95classiclwb

· #20 · Jul 21, 2018

not a big performance upgrade but you do get better spark with a dis conversion.

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