V8 Cylinder head interchangeability?

[antichrist]

Am I correct in that cylinder heads from a '95 Defender 3.9 are the same as a '97 D1 4.0?
I have a rebuilt pair from a Defender and it would be nice to not have to wait on getting the ones from the D1 rebuilt.

 

[jafir]

Do they both have 10 head bolts? I'd think the 3.9 would have 14.

 

[antichrist]

Good point, I forgot about the head bolt count (heck, this morning I couldn't even remember my phone number).
But I just checked and the 3.9 heads I have are 10 bolt.

But even so, not that it matters in my case, since 10 bolt heads supersede the 14 bolt, wouldn't you be able to use a 14 bolt head and just leave out the 4 short bolts?
Just asking this part in case someone else is in a similar situation but has good 14 bolt heads.

 

[roverover]

They are the same and will fit except SAI in later Bosch engines

 

[jafir]

But even so, not that it matters in my case, since 10 bolt heads supersede the 14 bolt, wouldn't you be able to use a 14 bolt head and just leave out the 4 short bolts?

Yep, but the 14 bolt heads will yield a little lower compression when used with the composite gaskets, unless they have been planed to make up for it. Supposedly some came from the factory with the extra bolt holes plugged and the heads planed for the new style gaskets.

 

[carlosz]

They are the same and will fit except SAI in later Bosch engines

correct indeed, in mid 90 there was a redesign of the valve stem where on pre 90 the lower stem had a thin part the after 90 valve stem was completely filled, this was redesigned to reduce carbon build up.
other than that you could use 3.5 heads on a later larger liter motor, or even use sai heads on and earlier non sai block, just plug the left over sai ports.
you can retrofit an earlier engine with non composite head gaskets to composite, just resurface the heads to keep the compresion ratio, the left over 4 bolts non existant on newer blocks simply become omited.

 

[jymmiejamz]

Aren't V-belt heads missing one bolt hole or something like that?

 

[D Chapman]

Aren't V-belt heads missing one bolt hole or something like that?

Yep.

 

[bigcheif]

what heads are the best for flow? some say the 3.9 have larger ports or valve size?

 

[antichrist]

Damn.

 

[singingcamel]

The alt bracket and mounting holes are different on the 3.9 I do believe,.

 

[jymmiejamz]

I'm pretty sure you can use serp belt heads on a V-belt truck, assuming you use composite gaskets.

 

[antichrist]

I'm pretty sure you can use serp belt heads on a V-belt truck, assuming you use composite gaskets.

Yeah, they apparently have superseded the older heads. My problem is that I wanted to go the other direction so I could get the job done quicker.
Oh well.

 

[carlosz]

what heads are the best for flow? some say the 3.9 have larger ports or valve size?

according to rover they have the same flow, they never decided to increase valve size as to why... go figure.
the only change they list as far as "larger valve" is the lower stem in the chamber area so to prevent "excessive" carbon build up.
I miss understood the "larger valve" issues when building my motor as I mixed and matched parts... I too thought they meant "larger valve bore" not larger stem until I saw the differences.
I gotta look for the copy, I will post later.

 

[carlosz]

sorry bud, the valve info I gave on prior post is on rave under range rover 4.0- 4.6 but for some reason It wont cut copy and paste, even thou I have done it in the past .
it is on pages 36 and 37 of the engine section.