Difference between 4.0 and 4.6

Dan Erickson

Dan Erickson

Well-known member
May 27, 2005
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Cincinnati, Ohio
Maybe after more tests this weekend, I will know for sure, but there is a possility that I have a dropped liner in #7.

I have read that they can be repaired, but I have also read that they can't.

I'm going to risk getting flammed for this but...

If the block were taken out, would it be possible to replace all the liners with larger diameter ones and install larger pistons to make it closer to a 4.6, or are there other differences like in the crank etc?

Even if it were possible, would be easier to just buy a short block?

Dan
 
J

Jack Straw

Guest
4.6 is a longer stroke. It's a different kind of power than if you make up the displacement in the bore with same stroke. If you want a 4.6 buy a SB or fix yours and change the crank.
 
Dan Erickson

Dan Erickson

Well-known member
May 27, 2005
1,268
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56
Cincinnati, Ohio
Jack Straw said:
4.6 is a longer stroke. It's a different kind of power than if you make up the displacement in the bore with same stroke. If you want a 4.6 buy a SB or fix yours and change the crank.
Click to expand...

I know I'm probably getting ahead of myself because it may not be a dropped liner.

But...

1. If it is not too far gone, can I drill and tap into the block from below to hold the sleeve up or is it a matter of not having a seal between the block and the liner anymore?

2. Is it really just the 4.6 crank that needs to be installed?
 
MotoBando

MotoBando

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Aug 16, 2005
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I'd imagine that it'd take more than just a crank - a longer stroke crank would push the pistons into the heads...
 
RVRSRVC

RVRSRVC

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May 7, 2004
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Elizabethtown, PA
www.roverlab.com
I took my 4.6 block to the machine shop-it was a used engine from a customers vehicle that had been overheated badly-and they fitted a set of liners that had a lip at the top to prevent the liner from dropping. It required machining of the block of course, but I don't remember it being hugely expensive. (Keep in mind I got the engine for free...)
 
Z

Zarati

Well-known member
Nov 16, 2004
328
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Spokane, WA & Belize Central America
My understanding from the Book "Tuning Rover V8's" which I just started reading, is that the Crank and Pistons are different but that the Connecting Rods are the same dimensions.

I had to derive that from readinga few different sections and looking at the specs for the Bore and Stoke of the 4.6 online but it appears the the crank Changes, and the pistons change. The "Deck Height" or whatever htey call it of the piston is different. I think this is WHERE on the piston the Pin for the Conn Rodd mounts.

SO, I THEORY if you had a Crank and some new Pistons and Liners you could use your old block. I THINK.

Can anyone confirm this???
 
F

frickjp

Guest
4.0 / 4.6 blocks are identical within their ranges with the exception of the number stamped near the dipstick tube. . Ie: Bosch - Bosch, GEMS - GEMS. The crank, rods, and pistons are different. Those 17 parts alone differential a 4.0 from a 4.6. My block is from a 1999 GEMS 4.0, crank, pistons, rods from a 2002 4.6. Of course, I never changed the ECU, so it's no better than my 3.9 :rolleyes:
 
J

johnvigg

Well-known member
Nov 25, 2004
52
0
nj
So all one would need to do is put a 4.6 crank in with 4.6 pistons and 4.6rods. Use the same block, oil pan, and head setups from the stock 4.0
There is also issues with the ECU where many different options are available
 
F

frickjp

Guest
If you have a tin pan, the forward most rod may hit the pan. I tweeked mine a smidge with a ball-peen hammer. ECU is a non-issue. I'd take this point in time to upgrade the cam as well. www.aluminumv8.com has a nice setup for $5-ish
 
Dan Erickson

Dan Erickson

Well-known member
May 27, 2005
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Cincinnati, Ohio
OK...

I have 1 broken piston (and another that is questionable) and 1 broken rod. I also have 2 bent valves.

My block is now bare and being hot tanked and inspected.

I'm seriously considering making the change to 4.6 components.

My big question is:

Where to find the 4.6 crank, rods and pistons for a FAIR price.

AND

Is there a "1 stop shop" for getting all the other bits I need to get the motor re-assembled.

I would imagine that a few parts from here and a few from there would probably save some money, but I would like to be able to just go to one source if it is not too much more.

Oh yea...thinking of a decent street cam while I'm in there.

lanocharacing.com has the whole short block for $3,650 (if that is still current). Just wondering if it would be cheaper to just buy the SB.

Any advice would be appreciated.

Thanks,

Dan
 
D

D Chapman

Guest
Check with aluminumv8.com Mark can tell you straight up what will work and what will not. Plus, his prices are awesome.

To be honest, though, unless you get a super great deal, I don't know that swapping everything into a 4.0 to make it a 4.6 is very cost effective.

IMO, a cheaper set-up would to be just install a new cam/lifters, headers, free flow exhaust and have the heads ported and pollished. The horse power difference you are looking to get with a 4.0 and a 4.6 are not that huge for what you want.

I'm betting the block maybe trash, though. A broken piston and rod is pretty major. Be nice if you can get by with just a new sleeve or two...
 
DiscoveryXD

DiscoveryXD

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May 1, 2004
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where i'm at right now, duh...
My truck had the #7 slip too... I just got the truck back yesterday afternoon with my new 4.6. I'm taking it easy for a while, then i'll be able to see what the power change really feels like.

Is this a common problem with these truck?

good luck Dan
 
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