4.6 block

mikeinatruck · Post by **mikeinatruck** » Tue Oct 09, 2007 10:30 pm

I have got the chance of a 4.6 block crank and pistons with the front cover as well, it was took out of a RR cos it was pourous I am wondering if it is possible to replace the liners and rebuild it using my old 3.5 HC as a parts donor. I am sure though that I wont be able to use the heads.

So other than the oil pump front cover is it worth messing with?

ChrisJC · Post by **ChrisJC** » Wed Oct 10, 2007 7:23 am

Not really. You could get the block top-hat linered, but it would have a 3.7" bore which is too big for your 3.5litre pistons.
Also the crankshaft won't fit as the 4.6 litre has 2.5" journals, and the 3.5litre has 2.3" journals.

The front cover won't have a distributor (or place to fit one), so you'd need an engine management system of some sort.

You could build up the 4.6 using 4.6 internals but 3.5 externals (and some minor adaption) as I have done in my Landie.

But it's not a straight swap of parts.

Chris.

Nick Moore · Post by **Nick Moore** » Thu Oct 11, 2007 6:19 am

mikeinatruck wrote:I have got the chance of a 4.6 block crank and pistons with the front cover as well, it was took out of a RR cos it was porous I am wondering if it is possible to replace the liners and rebuild it using my old 3.5 HC as a parts donor. I am sure though that I wont be able to use the heads.

Mike,
fitting top hat liners will cure the porous block syndrome. I don't know if they're available for standard bore, meaning you could reuse the current pistons and just fit new rings, or if they're all 20 thou oversize, meaning new pistons and rings. New bearings are easy. As for heads, I don't know if the 3.5 ones will be best, but they will fit. The 4.6 block doesn't have the outer row of head bolts, but most builders leave them out anyway, to avoid tilting the heads.

Chris is right, with no distributor you'll need to fit an alternative ignition system. Something like MegaJolt should be pretty straightforward.

I say go for it, there are no apparent show-stoppers I can see!

mikeinatruck · Post by **mikeinatruck** » Thu Oct 11, 2007 9:48 am

hmmm... no ignition was something i forgot about well i will have a look and see, if nothing else i might make it into a coffee table!

russell_ram · Post by **russell_ram** » Thu Oct 11, 2007 11:53 am

There is only one real question here - can you get the block repaired at a cost that you think is reasonable.

If you can, then everything from your original engine will fit - heads and manifolds, front cover with distributor, sump, all ancill mounting brackets, engine mounts, crank pulley, oil pump etc etc. You will need to fit a 'distributor drive' cam in the 4.6 block but any will fit with no mods ie any of the std or after market 3.5/3.9 cams. The only bit you need that won't come from either of the two engines is a crank nose spacer to take up the gap filled by the oil pump on a 4.0/4.6.

All depends on getting the block fixed, to take the std 4.6 pistons it will most likely come with, at a cost you think is reasonable.

Russ

mikeinatruck · Post by **mikeinatruck** » Thu Oct 11, 2007 11:11 pm

russell_ram wrote:There is only one real question here - can you get the block repaired at a cost that you think is reasonable.

If you can, then everything from your original engine will fit - heads and manifolds, front cover with distributor, sump, all ancill mounting brackets, engine mounts, crank pulley, oil pump etc etc. You will need to fit a 'distributor drive' cam in the 4.6 block but any will fit with no mods ie any of the std or after market 3.5/3.9 cams. The only bit you need that won't come from either of the two engines is a crank nose spacer to take up the gap filled by the oil pump on a 4.0/4.6.

All depends on getting the block fixed, to take the std 4.6 pistons it will most likely come with, at a cost you think is reasonable.

Russ

Thanks Russ I was wondering if I could do what you suggested.. I will need to look into the cost of repairs as you say, from what I am led to believe the block was not too bad, but as its costing me nowt it wont do any harm to inspect it fully and then decide. Its complete with pistons crank and front cover. AS you say it depends what the cost of re lining it will be and if i can re use the pistons. Well it'll be fun to try.

The other thing is heads I have two options the heads on my engine which are of the high compression type 9.35:1 or I do have a normal pair of heads.?

chodjinn · Post by **chodjinn** » Fri Oct 12, 2007 8:22 am

should be able to get the top hat liners done for about 600 if you shop around. Dont pay more than 900, and go to someone who has done it before.

mikeinatruck · Post by **mikeinatruck** » Fri Oct 12, 2007 10:43 pm

600 quid! Blimey no wonder no one bothers.... Found out today that the engine I am getting was the first replacement engine, was put in fired up smoked like mad. Had a look at it today, looks like new pistons in it. Long story as to how it went in and came out again. Anyway its got a sound block and crank thats for sure. I'll strip it and see what I can see. It'll keep me off the streets for a while

mikeinatruck · Post by **mikeinatruck** » Sat Oct 20, 2007 6:26 pm

Well stripped it down today, not that it took long! it has two cracked liners and one liner has a rough spot, a bit like sand paper. So considering the cost I think this idea is a non starter.

I was a bit concerned to see all the con rod bearings had been worn down to the copper layerr on the rod half as well. The crank looks good though.

Think it might become a coffee table. Unless anyone wants some 4.6 bits?

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