Thread: 3.9 complete rebuild any tips, tricks, things to look out for?

Originally Posted by 400HPONGAS

Macman , sounds nice , but you may have missed some of the essential basics .
Not even considered a step these days ,REMOVE all core plugs ,oil rifle plugs ,block drain plugs, Now 48 hrs in the block cleaner Tank ,keep re-dipping until all scale is GONE!.(this is where we usually do a ultrasonic check of bores )
Step 1 is ALWAYS to have the thing line bored to re-establish centerlines and correct registers.This is the most important step / part ,this is where the use of ARP.The studs must be fitted and torqued before and during Line Honing P studs comes in
Step 2 is decking the block to the new centerline.
Step 3 Is clocking the cam bearings to see if the Cam journals are on the same center line
Step 4 , Now dummy fit pistons 1 and 8 to establish true deck height record and establish Comp ratio .
Re--compute Ratio and Zero deck the block
(Now heres one for you 3.9;s . TRY Filling The Block with Grout to Half way wqy up the Welchplug center lines)
Now who would fit unbalanced rotating assemblies ?
Static and Dynamic balance all rotating assemblies.
.Now we havent even got to the heads/cam yet , another can of worms , lets suffice to say the best thing you can do for then heads is make sure they are accurately CCeed.
Not a comprehensive list , (lots of little side mods to d0 with priority oiling
Alas ,just these small but significant steps would cost the punter in excess of $1000 alone, so its easy to see why you backyarders always disregard these steps and consequently why you get the results you deserve !

Why such negativity?

Negative ? - I would'nt say so. More the differance between doing a proper job and a cheap-quickie. Both have a risk of failure, but the %'s are (or should be) vastly differant.

There are some jobs that should be done properly.... and I also get pretty cranky when I'm landed with a cheap/lazy one.

Do aluminium blocks in general - and Land Rover ones in particular - have a fatigue-based lifetime? (- Hours of use.) I suspect they do...

Yeah ,Superquag, its probably a negative thing to say in the eyes of the true Landrover believer.For some unexplainable reason us true believers (Landrover lovers) always prefer to attempt a Home repair , a do it yourself, a cheapie first ,and only then after a failed attempt may consider an outside source for help. This Forum being far and away the best source for opinion ,help and guidance from the rest of the Landrover nuts/freaks/fanatics/one-eyed died in the wool LR lovers , of which I will always be one .

how is it getting what you deserve when you dont know any better...isnt this why a person goes to a professional machine shop??? And without prior knowledge of said business one isnt to know whether they are good or bad......But I guess some of us are born with all the answers and knowledge

Think about this, do you know as much about the human body as engines? If you go to a doctor and on his/her advice take a backward step are you getting what you deserve......some might say so

Originally Posted by uninformed

..... If you go to a doctor and on his/her advice take a backward step are you getting what you deserve......some might say so

Yep, if you've blindly swallowed what he gives you... (double-pun intended)

My doc and I consult, we both can read the same Independant Studies funded by Big Pharma...

I wish I was one of these guys that knows and see alls, never made a mistake and never had to learn from one....perfection must be boring to the point of wishing failure on others

so after reading the posts in order whats the consensus on starting point for a good range rover engine, 3.5 stroked, 3.9 stroked, or 4.6, then we can start discussing cam options for off road and towing, (not interested in fast but would like to hold speed on hills)

Yep , uniformed ,theres a big difference between UNinformed and Ill-Informed, but sometimes youve got to get out there and learn by the school of Hard Knocks,
chrisandebreg , so it all comes down to how much are you prepared to spend for what end game .(actually I like the idea of 3.5 stroked to a 4.2 , (pitythe next step would have been the square P76) avoid the inevitable liner/block failure)Raise the stroke ,increase the Piston speed ,(how bout that Uninformed,everytime you increase the stroke the piston speed increases )suck harder on the ports.Yep ,a 11.5 SC with a 205 even split (possibly back split )in at least 4 ADV will bring the Torque curve down to 1800-2000 .With the right headwork ,will eat a 4.6 !