The V8 Owners Forum -

I now have a cross boltable 3.9 block.

ref drilling the holes for the cross bolts would you either

A: do it yourself or

B: get someone else to do it?

Has anyone on here done it before?

Does anyone know what thread size it is?

LOL Gav! that is B for me! If you can find a firm that has performed this operation a few times go with them, i cant imagine its too expensive. Out of interest did the block come with suitable main caps?

This one did, my other one for sale in the classifieds section didn't lol!

Just a thought, would the main caps on your new engine originally been line bored without the cross bolts in place?
And if so, would it not deform the hole if you do use the cross bolts?
Or are you going to line bore the block anyway?

As for your original question, I go for B too.

Hi,
Have you got cross boltable main caps?

My engine is a non crossbolt engine with appropriate castings but the mains are non crossbolt type(std journal size), you will need cross bolt main caps, are you running a std 3.9 crank or later 4.0 large journal crank?

Might be difficult to source std size cross bolted mains, if to use later mains you will need to get your block modified for large journals, more expense

Will need to be line honed anyway

its it worth all the hassle???
would a complete set of ARP bottom end studs be better?????

I suppose that was my point

It is a lot of graft, would look for a complete crossbolt short engine (4.6) if I was going that route, and then there's the risk of a porous block with all 94mm bored engines(3.9, 4.0 and 4.6), and I've been there

I've fitted ARP main bolts to both of the V8's I've rebuilt 3.5 and 3.9 with no problems - so far

I suppose it depends if you are building a high spec engine and want all the belts and braces, you could stiffen bottom end with a girdle accross the mains/block bottom as an alternative

Yes it does have the proper caps to go with it.

I've spoken to a fair few people about this and the majority reckon it shouldn't need line boring again although it is a possibility, one way to find out.

If you stray away from anything other than standard when it comes to main cap fasteners than they should arguably be line bored no matter what, even with studs but if it does need line boring then fair enough, at least i'll have piece of mind that i won't have any fretting problems for a long time and the advantage of a cross bolted block which should be a good base to build from whether that be a high revving forged piston'd 3.9 or the 4.8 kit i'm looking at. This is the route i want to take, long winded and expensive it may end becoming but i've thought about it and its the way i'm going.

If you've got the bits already I would go for it!

Especially if it is only a matter of sinking the holes in the block.

If the crossbolt mains are the originals and were used with the engine I wouldn't expect the line hone to be absolutely necessary as the crossblots will pull the block sides in to clamp up with the mains, if already pre machined, but might be worth doing any way while the blocks being machined.

Think I would use a machine shop unless you have all the gear at hope

Good luck with your project

Cheers royston!

If it all goes wrong then at least everyone else knows that it can't be done without a line bore and if it doesn't need a line bore then its a cheap route to a crossbolted block! Let the r&d commence!

ihatesissycars wrote:Cheers royston!

If it all goes wrong then at least everyone else knows that it can't be done without a line bore and if it doesn't need a line bore then its a cheap route to a crossbolted block! Let the r&d commence!

Not every engine will come out the same mate,
where yours may not need boring, someone elses maydo,
so i think if any one else goes this route to get it checked no matter what any one says or thinks,

Please still take advice and ask around before proceeding, I have recently used a local machine shop for the first time on my Range Rover V8 block(having used a couple of others previously) , having top hat liners fitted and the quality of his work convinced me he should complete the rebore/balance on my 1.3 Nova engine.

In each case I discussed in detail what I wanted and what they advised, in conclusion I would rely on Alistair's judgement ultimately, if he said it needed it, it got it!

It was his wealth of experience that convinced me he knew what he was doing e.g. when they finished my V8 block having fitted the liners and he told me they'd left the top hat liners 3 thou proud of the block as "thats what we do with the Lotus BDA's we refurb"

It's very difficult finding a good machine shop you can rely upon so talk to people in your area, before comitting yourself to anyone . guessing you'll be a decent distance from me up North, but can reccomend AMAC at Northallerton

I always try to work with the following statement "Do it once, Do it Right" get it right most of the time

Yes i have someone in ind however i may say sod it and take a trip upto v8 developments and just haev them do it.

Just out of interest royston how much did the relinering cost?

I don't understand how a non crossbolted block has caps with tall sides fitted ie that have the meat in the right place for the crossbolts? Do these caps belong to the block you have or did they come from elsewhere? If from elsewhere then it should be line bored.

You could save yourself a lot of work and expence by just fitting studs and a ladder girdle. Chances are it won't need line boring either. Or, go and buy a crossbolted block. Lots of revving rovers were built using studs alone.

Boosted.

The last of the 3.9 rover blocks, about 95 onwards had the cross bolted caps and the bosses cast into the side of the block for cross bolting, they just weren't drilled to take the bolts.

The caps have not been taken from another engine, they belong to this engine. Its a cheap way to get a cross bolted engine rather than pay a premium price for a 4.0 or 4.6 block.