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Just as the topic states.... does anyone know anything about these mods/conversions ?
I am lookin at one at the moment doen about 75000ks Whats is involved in the block work (bore etc etc) and stuff to do this, I am thinking its borde to fit the 4.6 pistons and crankshaft etc etc, but is this possible ? ? ?
Its currently carb fed but I will be bolting my wolf and efi head to it I want more power.... more more more
No seriously any info would be greatly appreciated.... websites/general knowledge, thigs to look out for or common faults in this setup
Never heard of it, can you give us a link?reference? source?
The 4.6 has a completely different bottom end with larger journals on the crank and four bolt main bearing caps.
There are a lot of old conversions around that are 4.3 litres from a stroker crank and standard 3.5 bore. lots have gone for many years with no problems, as long as they are not revved to high. A 4.7 can be made by boring out to 92MM, or 3.9 bore. these in theory are pretty weak in a 3.5 block as the sleeves are then quite thin.
Bruce Davis has made a club member of my club a 4.9 using a 3.9 block and Falcon pistons.
Most go for a short 4.6 these days and use all the 3.5 stuff like heads as it is cheaper and more reliable, as its new. Or is that what you mean?
regards Philip A
The machining costs alone would make it un economical plus to fit the 4.6 pistons in you will have to bore out and fit larger sleeves - better off buying a 4.3 stoker kit for the 3.5 or a 4/ 4.6 ltr short.
Saddle up tonto, its the not so loanrangie! . 98 TDI DISCO lightly modded with more to come.
Loanrangie wrote:The machining costs alone would make it un economical plus to fit the 4.6 pistons in you will have to bore out and fit larger sleeves - better off buying a 4.3 stoker kit for the 3.5 or a 4/ 4.6 ltr short.
Hey loan r the 4lt shorts still going for around $3500?
The 4.6 blocks have added strength - cross-bolted mains, larger journal crank. Converting a 3.5 to 4.6 would end up with a weaker engine. See http://www.v8engines.com for the tech specs of the various blocks & what combinations can be done.
[url=http://www.juracid.co.uk/lr]109 in a million pieces - it shall rise again![/url]
Well i havnt been to have a look at this thing yet but goin buy what your saying maybe it is a 4.6HSE short block with the 3.5heads.
I have email afew V8 engine specialist and rover specialist incuding RPI i am confident there responses will be the diciding factor in all this
Philip A wrote:A 4.7 can be made by boring out to 92MM, or 3.9 bore. these in theory are pretty weak in a 3.5 block as the sleeves are then quite thin.
Isn't a 3.9 block just a re-bored 3.5 anyway? They have the same stroke and the external dimensions are all the same so how did Rover bore the 3.5 to make it strong compared to anyone else doing it?
Philip A wrote:A 4.7 can be made by boring out to 92MM, or 3.9 bore. these in theory are pretty weak in a 3.5 block as the sleeves are then quite thin.
Isn't a 3.9 block just a re-bored 3.5 anyway? They have the same stroke and the external dimensions are all the same so how did Rover bore the 3.5 to make it strong compared to anyone else doing it?
thast what i was thinkin, and a 3.9 block bore is 94mm
Nup! I am sure that a 3.9 block has larger holes to fit the bigger liners. reference is Tuning Rover V8s by David Hardcastle. Ie the casting is thicker around the bores. So a 3.9 can be overbored to a larger size than a 3.5. the 4.7 has a 20 thou overbore on a 3.9 block.
It may well be physically POSSIBLE to bore & stroke a 3.5 to a 4.6, it doesn't mean it's a good idea. Rover wouldn't have bothered casting stronger blocks if they could get away with it...
[url=http://www.juracid.co.uk/lr]109 in a million pieces - it shall rise again![/url]
Anthony
Philip A is on the money here. If you find an old block(3.5) and compare to the 3.9 you will see the casting differences also when you go to look at this engine the cross bolted mains are visable from the outside or at least the bolt heads are if it is a 4.6 short with 3.5 heads or you could read it of the engine no. Then we get back to what was done to the heads and what gaskets were used to work out the compression ratio etc I looked at one advertised as a 4.6 HSE motor it turned out to be a P76 Cheers
Ok can someone explain exactly what to look for to define weather this is a 4.6 short or a dodgy bore job So i can go there equiped with the info and dont come off second best
by the way 37" Creepy Crawler went on my pos this mourning I is very happy happy joy joy
The easy way is to look at the side of the motor. If it is a 4.6 it will have bolts through the side of the block just above the sump these bolts screw into the mains from the outside. When they say cross bolted they mean cross bolted. The other main bolts are in the normal position. Also there is a hole cast in the block for electronics to pick up flywheel on the oposite side to the stater where they may have fitted a big welch plug its on the bellhousing flange just above the webbing. the Block should also have 4.6 stamped on it along with the Comp ratio and engine number. PhilipA may be able to give you an indication of the engine number sequence.
Cheers
PeterO wrote:The easy way is to look at the side of the motor. If it is a 4.6 it will have bolts through the side of the block just above the sump these bolts screw into the mains from the outside. When they say cross bolted they mean cross bolted. The other main bolts are in the normal position. Also there is a hole cast in the block for electronics to pick up flywheel on the oposite side to the stater where they may have fitted a big welch plug its on the bellhousing flange just above the webbing. the Block should also have 4.6 stamped on it along with the Comp ratio and engine number. PhilipA may be able to give you an indication of the engine number sequence. Cheers
Other than the stamping you are also describing a 4.0 Cross bolted motor. So it can be a little harder to varify.
Other than the stamping you are also describing a 4.0 Cross bolted motor. So it can be a little harder to varify.
Yes I guess I am but if someone could supply the engine numbers prefix's I think Anthony should be able to work it out from there. I was trying to find where I wrote the prefix,s down but cant find it I think the paddocks site has a bit on engine numbers and how to read the prefix.
Cheers
Other than the stamping you are also describing a 4.0 Cross bolted motor. So it can be a little harder to varify.
Yes I guess I am but if someone could supply the engine numbers prefix's I think Anthony should be able to work it out from there. I was trying to find where I wrote the prefix,s down but cant find it I think the paddocks site has a bit on engine numbers and how to read the prefix. Cheers
PeterO wrote:The easy way is to look at the side of the motor. If it is a 4.6 it will have bolts through the side of the block just above the sump these bolts screw into the mains from the outside. When they say cross bolted they mean cross bolted. The other main bolts are in the normal position. Also there is a hole cast in the block for electronics to pick up flywheel on the oposite side to the stater where they may have fitted a big welch plug its on the bellhousing flange just above the webbing. the Block should also have 4.6 stamped on it along with the Comp ratio and engine number. PhilipA may be able to give you an indication of the engine number sequence. Cheers
Thank you
RUFF wrote:Other than the stamping you are also describing a 4.0 Cross bolted motor. So it can be a little harder to varify.
Thank you
Bush65 wrote:My 4.6 engine number starts with S46D...
G`day Anthony , if it has an S as the first letter of eng no prefix it will be one of the L/R flog offs , both 4.0 and 4.6 shorts have this S . Morgan plus 8s also use the S for 4.6 .
Some , not all 4.6 pre fixes are S46D , 46D , 48D , 59D , 60D , +?
To my knowledge 46D was the first 4.6 so any number lower will not be a factory 4.6
There is no way from the outside to tell if a crossbolted engine is 4.0 or 4.6 .
The other thing about prefixes is that our crossbolted 4.0 is S86D so a higher doesn`t always mean 4.6
As a matter of interest there was a supposed 3.9 on Ebay but it started with 398 which makes it a very early 3.5 so if you are able to get the prefix and the compression ratio stamped with it , may be able to tell more .
From what i`ve read a 4.6 crank will have trouble rotating inside a 3.5 block because the 4.0/4.6 blocks are actually wider inside and unless machining was real cheap it wouldn`t be ecomomical .
I think it can be done with the later 3.9 block with the B suffix but not sure .
If it is a 3.5 with 4.6 internals would it be possible to get a contact for the bloke as it would be of great interest to me , thanks .
The 4.0 and 4.6 have larger crank journals, so the 3.9 caps would probably be too thin/weak if you line bored them to suit the journals.
This is the major weakness of pre 4.0 engines with standard size journals, so it would be crazy to put in a bigger journal crankshaft
Regards Philip A
Yeah, I saw one in Ted Pritchards car. He was sold it as a 3.9 but it had bumps for cross bolts on the sides.
I said, that it wasn't a 3.9 but a 4.0 but maybe(perish the thought) I was wrong. Didn't know this one. So what are the caps like I wonder. 3.9 or 4.0 ???. What years? Maybe a good way to build a big capacity motor.
Regard s Philip A
I was told once that some of the later 3.9s had been built on the new cross bolted casting and still had the old internals it did not sound right to me but I guess they could machine the blocks enough to allow both cranks to fit. The story went that the block was externaly cast the same as the 4.0 cross bolt and the machineing internaly was the only bit left the same. ie the mains were just standard caps over the old 3.9 crank with a longer nose to accomadate the later timing cover and serpentine belts. From the out side they would look like a 4.0 but no bolts just raised casting that remained undrilled. Oh and the heads were the later style without the short bolts. That was why I relied so much on the engine numbers and RPI & Paddocks sites to work out what I was looking at.
I still done know if it was all just a story or based on some fact.
Whats is involved in the block work (bore etc etc) and stuff to do this, I am thinking its borde to fit the 4.6 pistons and crankshaft etc etc, but is this possible ? ? ?
I want more power.... more more more 
I think the paddocks site has a bit on engine numbers and how to read the prefix.
