The V8 Owners Forum -

Is it possible to add cross bolts to a non cross bolt block?

Well, I suppose it's possible, but has anyone done it. Anything to consider?

Not really possible. You would have to add a lot of material to the block and use different or make new mains caps to do it the way rover did. After you paid for all that you could probably have bought 2 new proper cross bolt blocks. It would be better to use a girdle with integrated mains caps but again this would cost big money unless you got it cast and then it wouldn't be as good. Next option is a girdle but use the original caps which you would shim to be a tight fit on the girdle and use long mains studs. Not as good as the others but at least at £300-£400 installed its fairly cost effective.

or you could get a late 3.9 block and get that drilled out - they have the capacity to take x-bolts. They are basically a 4.6 block but with smaller mains for the 3.9 crank. I think.

Think Gav still has his for sale.

chodjinn wrote:or you could get a late 3.9 block and get that drilled out - they have the capacity to take x-bolts. They are basically a 4.6 block but with smaller mains for the 3.9 crank. I think.

Think Gav still has his for sale.

You need to be careful on that one as some don't have enclosed main caps even though they have the bosses on the outside. Kinda interim interim block

Min has the cross boltable caps too just not drilled. I did have another block which had the bosses on the block but early style caps. Mine is the very last of the 3.9 blocks.

Anyone got a 3.9 proper cross bolt block, crank and con rods for sale then. I have my eyes on a 3.9 on Ebay, but is two bolt mains. I wanted a bullet proof bottom end, so that I could go absolutely nuts with it.

Yes, ^^^^ Gav just said he does! Well, it would require drilling.

Think Hairbear had one of the ultra rare 3.5 cross-bolted blocks. Woudl have been perfect for me for my spare engine, but there is no way I'm pissing money away at another Rover V8. Well not just yet anyway!

Whilst the x-bolted bottom-end with larger journal crank is undoubtedly stronger, I've built a few real hairy 3.9's with just the addition of an ARP mains stud kit to reinforce things and I've never had any issues. One of the engines had mech. cam, solid lifters, GPA rocker setup with adjustable pushrods and revved freely to 6800rpm.

chodjinn wrote:Yes, ^^^^ Gav just said he does! Well, it would require drilling.

Think Hairbear had one of the ultra rare 3.5 cross-bolted blocks. Woudl have been perfect for me for my spare engine, but there is no way I'm pissing money away at another Rover V8. Well not just yet anyway!

I know but he said it wasn't drilled and like Marki said, may aswell just buy a proper cross bolt block that is drilled. Also he lives in hampppppshire which is miles away from me. Although if it has the bosses and the caps, then drilling may be easy enough.

How much would you want for it gav?

Its in the classifieds for £150.

Dhl or parcel force can deliver it for about £40.

ppyvabw wrote:

chodjinn wrote:Yes, ^^^^ Gav just said he does! Well, it would require drilling.

Think Hairbear had one of the ultra rare 3.5 cross-bolted blocks. Woudl have been perfect for me for my spare engine, but there is no way I'm pissing money away at another Rover V8. Well not just yet anyway!

I know but he said it wasn't drilled and like Marki said, may aswell just buy a proper cross bolt block that is drilled. Also he lives in hampppppshire which is miles away from me. Although if it has the bosses and the caps, then drilling may be easy enough.

How much would you want for it gav?

Not what I said, gavs block just needs drilled and tapped. I was on about trying to crossbolt the normal 3.9 block which would take shed loads of work. By the way if your waiting on a cross bolt 3.9 block to be avaliable next door to you then give up now as these things are about as rare as things come in the rover world. You can get one but your going to have to go get it.

my engine is a standard 3.9 block with arp studs only and is now 7 years old and i have never had any problems with it ,it also revs to 7300 rpm all the time.

If you want a 3.9 litre cross bolt block, just get the 4.0 litre cross bolt block as both the 3.9 and 4.0 litre have the same bore and stroke......

Chris.

I have a mint set of 4.0 pistons, rods and a crank. You'd need to turn the cranks mains down to fit but it'll go in there.

You'll have a better bottom end than a 3.9 then.

Hi, bringing up an old thread here but saves starting a new one...

After getting my 3.9 block into the machine shop and them telling me it needs a bore, hone, +20 pistons, rings, crank grind, etc etc I decided to buy a 4.0l cross bolted block (for the price of the bore & hone alone!). I'm not going to go too mad on power as can't afford it so my question it this:

I fully intend to stay within 6000rpm and max power will be around 300bhp, light car so not going to be under too much strain all the time so as I have twice as many main cap bolts can I get away with new standard bolts or should I still go with a stud kit?