Hi,

I want to purchase cylinder heads to overhaul and put on top of a new block - to change to lot with the 3.9 that is in my RRC at the moment. That way the RRC is kept running.

1) Does it make a difference whether I get heads from a 3.5 (they are easier to get) or from a 3.9 ??
The parts manual has a different part number for them - suggesting that there IS any difference. But which ???

2) BTW: does it make a difference whether the heads are from a carb oder Efi engine ?? I have to keep the Efi-Plenum and intake manifold. If heads from a carburetor engine are missing any fixings or whatever they were of no use.

Thanks in advance !!!!!
Hendrik

Some but not all of the carburetted heads have small threaded ports for an emissions system called Pulsair. The ports can be plugged up so that shouldn't present a major problem. In the mid '70's there were changes to the valves also but aside from where and how brackets for the ancillaries mount up, I think the only real differences came with the 4.0L heads because they are designed for fitment with fewer bolts and the composite gasket (which is useable with the older heads). Where are you located? I have heads from a carbed 3.5, an EFI 3.5L and an EFI 3.9L for sale.

Early heads have different mountings for ancilaries than the later heads.

As far as say a 87 3.5 efi and a 94 EFI both non-serp they appear to be the same heads.

I think the carbed heads lack a notch in the top of the intake ports to clear injectors or injector fuel squirt.
Shouldn't be too hard to replicate with rotary file.

T

I belive valve sizes are also different.

Grem

Check out this site:

http://www.v-8.org.uk/forum/forum.asp?FORUM_ID=19

There are some guys there that really know the older Rover V8's. As I said above, the valves were changed in the 70's when the SD1 was introduced but I'm not sure when any other valve changes were made to the heads before the 4.0L.

In May or june of '95, Rover dropped the lower row of bolts for mounting to the block-not a big deal unless you are married to thte steel gaskets.

As for ancillaries, Ron hit it on the head, the difference is serpentine versus non-serpentine.

AFAIK, heads from an injected 3.5 will be fundamentally similar to those off a 3.9-ie, they'll work! I believe the 3.5 heads may have a slightly smaller combustion chamber, if you are looking for higher compression or have a need to worry about fuel quality.

\PT

In May or june of '95, Rover dropped the lower row of bolts for mounting to the block-not a big deal unless you are married to thte steel gaskets.

As for ancillaries, Ron hit it on the head, the difference is serpentine versus non-serpentine.

AFAIK, heads from an injected 3.5 will be fundamentally similar to those off a 3.9-ie, they'll work! I believe the 3.5 heads may have a slightly smaller combustion chamber, if you are looking for higher compression or have a need to worry about fuel quality.

\PT
I'm still curious about this difference bettween the serpentine / non-serpentine heads. Are we talking about Bosch heads? Recently I've used '93 non-serpentine heads on a 4.0 shortblock on a '95 serpentine Disco and a 4.0 long block, serpentine, for an '88 RRC. I don't recall having any issues.
I think the 3.5 has smaller exhaust valves.
Also, if the motor came with metal gaskets I use ARP's head bolt stud kit and use the metal gaskets without the lower row of bolts, retaining the correct compression ratio and avoiding the unbalanced head bolt tension that causes the metal gaskets to fail prematurely.
Personally I'm running serpentine heads ('95 Disco)with the metal gaskets, '89 RRC V belt set-up, and after 200k + miles the head gaskets are about the only things that don't leak.
That lump will have to come out soon as I'm converting to an oil burner.

Matt Browne
Overland Engineering

Thx so far! That helps.

Somewhere I read that the later valves have a modified stem to prevent carbon build-up. I thought that was the difference that gave them a different part number. But the parts manual says (when closely looked at) even the hardened insert rings have a different part no. for the exhaust valves 3.5<>3.9. Therefore a difference in exhaust valve size (or .. valve seat angle ? unlikely, eh?) seems to be there.

Thx so far! That helps.

Somewhere I read that the later valves have a modified stem to prevent carbon build-up. I thought that was the difference that gave them a different part number. But the parts manual says (when closely looked at) even the hardened insert rings have a different part no. for the exhaust valves 3.5<>3.9. Therefore a difference in exhaust valve size (or .. valve seat angle ? unlikely, eh?) seems to be there.
Dunno, I generally don't use 3.5 heads for anything other than doorstops. Don't even see many of them and I'll be the first to admit that I've never given it much thought as to the difference between them and 3.9 heads.

Matt Browne
Overland Engineering