Fitting alien bearing caps to an engine.

[ian.stewart]

If the block is machined correctly, the crank center line dose not alter, the face of the caps may need to be cleaned up, all mounted in something like a Sunnen boring machine, the block is then positioned correctly on the machine then using the original bore of the bearing is used to line everything up, then a specialised boring bar is fitted to the block and a small amount of metal is removed to bring the bore to the oversize spec of the bearings, then new cutouts are machined to fix the bearings,
I would honestly be trying other places like Tiplers, Harmons, or any of the others to get a price of the machining,
Caps must be easy to find, look for a old leaking engine on Ebay, then pirate that for all the bits you need

[DEVONMAN]

Hi ppyvabw,
As Ian Stewart says it's may be possible to pick up a duff liner engine for a lot less than £400. In fact I have a set of caps from such an engine and am open to offers. Send me a PM if you are interested in the caps.

To clarify, you have a late 3.9 block which has the blank bosses on the outside to facilitate drilling for the crossbolts.
No doubt with alien caps you will need to have the line boring at least checked but it is unlikely that they will be out by anything like 1mm, more like 2-3 thou.
You would need to have the cross bolting done before the line boring work is carried out because on one side of the caps you will find that there will be a gap of about 6-7 thou between the cap and the block for part of the cap height. The caps fit tight in the block near the horizontal mating face but this 6-7 thou gap will pull closed when you tighten the cross bolts and would through out any lining boring checks you have had done.

When I have undertaken cross bolting on an existing engine with matched caps I have introduced shims to prevent the block pulling when the cross bolts are tightened thus preserving the line boring accuracy.

Hope this helps

Regards Denis


,s

[ppyvabw]

Hi ppyvabw,
The caps fit tight in the block near the horizontal mating face but this 6-7 thou gap will pull closed when you tighten the cross bolts and would through out any lining boring checks you have had done.
,s

You mean those little registers at at the mating face? I wondered what was done with those, I thought maybe they were machined off.

In which case your idea of shimming is a good one. I will also have the rebore down after the cross bolt work too.

You have a PM by the way.

[ian.stewart]

I have pondered over the shimming of the block/caps, only because I dont know how the block was machined at the factory, so, if you are using a un drilled block shimming will work and help prevent any distortion when the X bolts are tightened, However, if its a X bolted block with the holes drilled were the X bolts fitted before the block was machined, if they were, the block probably should not be shimmed

[DEVONMAN]

I have pondered over the shimming of the block/caps, only because I dont know how the block was machined at the factory, so, if you are using a un drilled block shimming will work and help prevent any distortion when the X bolts are tightened, However, if its a X bolted block with the holes drilled were the X bolts fitted before the block was machined, if they were, the block probably should not be shimmed

I agree Ian, do not fit shims to a factory block with crossbolts as line boring would have been done with all cap bolts (4 per cap) done up and probably with dummy heads plates fitted also.

I never have liked the fact that the block is distorted on a 4.0/4.6 when the cross bolts are tightened. Seems wrong to introduce bending forces into a casting but maybe the designer liked the idea of some prestressing????

Cheers Den

[topcatcustom]

When I put the caps in my X bolted block I didn't notice any gaps- seemed a perfect fit??

[DEVONMAN]

When I put the caps in my X bolted block I didn't notice any gaps- seemed a perfect fit??

Maybe the gap is less on some blocks but there is always a register lip about 6mm high on one side. Probably 6-7 thou is not noticeable unless you are looking for it.
Maybe Ian S can confirm that there is a gap in his 4.6 block.

Cheers Denis

[ppyvabw]

I got your PM thanks. I'll respond to a it later.

I have those register bits on both sides.

[DEVONMAN]

I have those register bits on both sides.

Has your block definitely got blank bossed on the outside which can be drilled for cross bolting ? Also how much does the block extend up the side of the cap away from the registers bits?

[ppyvabw]

I have those register bits on both sides.

Has your block definitely got blank bossed on the outside which can be drilled for cross bolting ? Also how much does the block extend up the side of the cap away from the registers bits?

Yes it definitely has bosses for cross bolting and the side bits go all the way down, square to the face of the mating surface and level to where the sump goes.

[DEVONMAN]

I have those register bits on both sides.

Has your block definitely got blank bossed on the outside which can be drilled for cross bolting ? Also how much does the block extend up the side of the cap away from the registers bits?

Yes it definitely has bosses for cross bolting and the side bits go all the way down, square to the face of the mating surface and level to where the sump goes.

Ok, If you have registers both side then it looks like in your case you will need shims both sides or have it line bored after cross bolting. The alien caps should fit snug between the registers given that caps will all be machined the same width subject to small tolerance differences of course.
Cheer Denis

[ppyvabw]

Looking at some pictures in David Hardcastle's book and it looks to me like on the cross bolt blocks registers go all the way up to the x bolt hole rather than just 5 mm.

Not sure if there is a discrepancy between cross bolt blocks in that respect but as long as you are confident they caps will fit snug in the small registers and I can shim then that's fine.

I'll PM you again later.

[DEVONMAN]

I think I have a copy somewhere so I will dig it out and have a look.
In DEZHammill's book it shows on page 21 the cap register on one side only.
Cheers Denis

[DEVONMAN]

Looking at some pictures in David Hardcastle's book and it looks to me like on the cross bolt blocks registers go all the way up to the x bolt hole rather than just 5 mm.

Not sure if there is a discrepancy between cross bolt blocks in that respect but as long as you are confident they caps will fit snug in the small registers and I can shim then that's fine.

I'll PM you again later.

In the David Hardcastle book I believe the photos are of the early 3.5 rare crossbolted competiton block. My experience with later 38A casting is that the register is not full height both sides and is usually on one side only. (Starter side.)

To confirm this maybe someone out there with a cross bolted block on the bench can check to see if say a 4 thou feeler gauge can be inserted between the cap and the block with the cross bolts removed.

In fact I believe you said your block (38A type) does not have full height registers. I assume the register is only a few thou proud of the vertical part of the block.

Regards Denis

[ppyvabw]

Yes it's just a few thou, extending about 1/4 in beyond the mating surface. But it is on both sides.

But, whatever, if you think the x-bolt caps will fit in the registers, I may well take you up on your offer in your PM. I'll meditate on it and let you know.