Cylinder head interchangeability?

[badrover]

Are all P6 V8 heads the same? Can I replace my 1973 car’s near side head with a near side head off a 1970 engine? I think the compression ratios are different on the early engines, will this matter?

 

[harveyp6]

CR is governed by the piston crown. The heads will interchange. Both heads are the same, so it doesn't have to be a nearside head.

 

[badrover]

CR is governed by the piston crown. The heads will interchange. Both heads are the same, so it doesn't have to be a nearside head.

Brilliant, thanks so much!

 

[PeterZRH]

For this exercise it is true. All heads prior to the 4.0/4.6 are 36cc the last ones are 28cc and hence must use the composite gasket to maintain CR.

The simplest P6 engine upgrade is put your P6 heads in the bin and fit the larger valve later ones (SD1 or later). There is absolutely no downside whatsoever. As you can buy a pair in good order for £100 why are you bothering with the originals?

 

[jp928]

I have 2 heads from a 1994 3.9L, and they have 28cc chambers. Casting is hrc2479.

 

[SydneyRoverP6B]

I have 2 heads from a 1994 3.9L, and they have 28cc chambers. Casting is hrc2479.

From memory JP, HRC2479 are the 10 bolt heads that Rover introduced for the P38 4.0 and 4.6 litre Range Rovers. The earlier Range Rovers had 14 bolt heads, but in 1994 the 3.9s also received the 10 bolt heads.

Ron

 

[PeterZRH]

From memory JP, HRC2479 are the 10 bolt heads that Rover introduced for the P38 4.0 and 4.6 litre Range Rovers. The earlier Range Rovers had 14 bolt heads, but in 1994 the 3.9s also received the 10 bolt heads.

Ron

From memory JP, HRC2479 are the 10 bolt heads that Rover introduced for the P38 4.0 and 4.6 litre Range Rovers. The earlier Range Rovers had 14 bolt heads, but in 1994 the 3.9s also received the 10 bolt heads.

Ron

I was going to say it should be obvious from the gasket - but no, a 20 thou skim and the composite version is a common upgrade for earlier heads....

 

[jp928]

This was an 'intermediate' engine - block HRC2411, with bosses for cross bolts (undrilled), and 2.3" crank mains, 10 bolt heads, crank driven oil pump, and a distributor hole. The heads seem to have been shaved 10thou, but it had steel shim head gaskets, where it should have had composite gaskets. Number is a 38D, low compression.