Cross bolting

shanecl · Apr 4, 2014

Looking at my 4.2 block and notice it has the casting for cross bolting. Would it be worth cross bolting it. Doesn't look to much work. Would be going to a fully equipped machine shop.

jamesmartin · Apr 4, 2014

if its built for it but not then why not

shanecl · Apr 4, 2014

Just thinking while I have it apart should I get it done. No better time. Also where the 4.2 a V belt engine. I have got a 3.9 serp and want to change the parts over but will the 4.2 crank be long enough to drive the oil pump on the 3.9 serp cover

griffman · Apr 5, 2014

Shane

you do not really need to cross-bolt that block.......................

It is a small-journal main so the Serpentine(intermediate) front cover will bolt straight on - you may have to do a bit of machining if you want to fit the cam-retaining plate though.

You will now have a crank-driven oil pump rather than distributor-driven - just make sure the dizzy keyway is the correct one from the serp engine.

I think we need some photos from you

shanecl · Apr 8, 2014

Thanks lads,

Will skip it so

Another question. Which heads should I put on it. The 4.6 or the 3.9 ones

Vic, plenty of pics up shortly

Dr_evil · Apr 8, 2014

marccleave · Apr 8, 2014

You want heads that have a casting numbers of HRC 2479. So yes, 4.6 heads basically.

These heads have larger ports and the combustion chamber volume is 28cc not 36cc. So if you want to keep the compression ratio the same, use composite gaskets. If you want to increase the compression ratio then use tin gaskets.

shanecl · Apr 8, 2014

Thanks folks. Gonna make my shopping list up

listerdiesel · Apr 9, 2014

Are we giving the correct information here?

HRC2479 is a casting number, and comes up on all of our 4.0 heads, plus on checking Microcat, both 4.6 and 4.0 head assemblies are the same part number as well.

I've just physically checked my two spare heads and they are HRC2479 and the pictures of the engine rebuild show the same casting number as well.

Might be missing something, but I have always understood that the Thor engines at least had the same heads for all versions?

Peter

Iann · Apr 9, 2014

As we are talking heads
Do 3.9 heads have bigger vales ,better oil ways better cooling galleries etc
than heads off a 3.5 EFI
and can they be fitted to a 3.5
Or is there point getting my spanners out

Its probably been asked before but I thought Id ask

marccleave · Apr 9, 2014

listerdiesel said:
Are we giving the correct information here?

HRC2479 is a casting number, and comes up on all of our 4.0 heads, plus on checking Microcat, both 4.6 and 4.0 head assemblies are the same part number as well.

I've just physically checked my two spare heads and they are HRC2479 and the pictures of the engine rebuild show the same casting number as well.

Might be missing something, but I have always understood that the Thor engines at least had the same heads for all versions?

Peter

I was waiting for someone to mention this.

I can't find the page now, which I'm really annoyed about. But it went into detail about quite possibly every detail and difference in the Rover V8 timeline, going through variations in blocks, cylinder heads, serp/nonserp, etc.

But other than that some information on cylinder heads can be found here.

As far as I am aware, 4.0 and 4.6 heads are the same. But I can't find the big lot of information to confirm so someone else will have to confirm or shame me completely.

shanecl · Apr 12, 2014

Thanks for the info lads.

Cross bolting

shanecl

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jamesmartin

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shanecl

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Dr_evil

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Iann

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