Yeah I think you're right. I'll just not ask for the conversion unless the professor has done similar things in the past and wants to tackle it. A rebuilt 4.0 will still be nothing to complain about.

 

The 4.0 runs much smoother than the 4.6. Thats according to a buddy (I agree) with an 02 P38 a 03 DII and many rides in my truck. I will say the 4.6 pulls you into the seat when you stomp on it but it's still civil in doing so. Yes, there is a difference between the Bosch and Gems in relation to the CkPS mounting position and trigger on fly wheel. Not worth your time to find/bore new location. From what I've read only the crank, con rods and cam are different to give it the .6 increase. If your going to go the 4.6 route find one (GEMS - P38 donor, hear it run first) and send it to school. As far as reliability the number one issue is cam annealing properties. Buy an American made replacement cam (or mild upgrade since ECU is largest handicap unless you live in Mexico...poor fuel). I've heard of massaged Buick 300 heads being used on these motors. Probably the number one upgrade is replacing the ECU with either a Black Box modified (months of waiting) or Mega Squirt. If school has a dyno that would make that type upgrade very worth while, easier to dyno then fix instead of drive and yank. Check into it. We (the Army) dyno every motor/tranny rebuilt before putting it back into national stock......so if this school is all you say I'm sure they have an engine dyno. Great project for them and you.

When you say your 4.0 is steaming on warm up is it from an intake coolant leak or are you positive it's the head-gasket. Most owners do not check their intake bolts and I'll bet five bucks 99% of motors here have at least one loose intake bolt because most do not remove the plenum and check those underneath............pressure check your cooling system, that will ferret out your leak for sure. To keep them from loosening use Loctite Blue. Most common leak area is rear intake coolant port, don't know why (heat soak). Coolant dribbles down back of motor, not easy to see.

Another point that comes to mind is spun bearings. It's so common it actually overtakes the head-gasket issue in occurrence but most don't even know what they're hearing. I also replaced my low end bearings with motor installed. It's not rocket science and necessity is the mother of all invention....my truck is my dd. You just might have a spun bearing......or one that isn't far. My motor had a lower end knock as well. The other knock you'll hear is wrist pin, usually drowned out by rocker clacking when in beginning stages.

No matter, good luck with your project and sounds like you have a REAL plan. Check into engine dyno.

 

Where do you recommend getting a cam? I think I'll have to shop around a bit. Also is there anything wrong with just having the existing one re-ground, or does that not always work?

 

watch for spun bearings, if you find one the motor will really need a line bore for the bearing bores and oversize bearings to get the bearing crush back, or you will just end up with another spun bearing.
i would think if you have a teacher watching the students put the motor together like a hawk, and checking everthing they have done then you are probably gonig to get a successful rebuild, vs a lone mechanic in a workshop who just wants to go home for theday....


cheers

Pedronz

 

Yeah they're planning to take the whole semester on the rebuild, which tells me they should have time to be meticulous.

 

It really sounds good. The only thing I would like to add is possibly arrange a visit/tour of the school. That should convince you whether or not to do it. Sounds like a good option to pursue.

 

Having the existing cam ground is possible. The issue is the original hardening process, it's too thin hence the surface failure (and lifter face deformation) at relatively low mileages. Crane has been a go to for Rovers since way back. Go to their website to call them on blank availability. Here's a great site; http://www.v8tuner.co.uk/category.php?id=9 to mull over with many Crower cam offerings although you'd want to dial them direct as well about a mild 4.0 kit offering. Prices are high but cams are the heart of the motor, worth the price to me.

 

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Funny you mentioned the line bore. I was reading an article awhile back about Rover cranks. The guy had a pile of them in his shop, all warped, out of spec. The reason I was reading the article was about using the 4.6 crank to hit the 5 liter ceiling.

 

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