Outer Limits 4x4 Board

G`day Adam

Yes , probably that`s what he means .

Tin as i call them are metal so i guess shim steel , which is probably the correct term for them .

Composite are as they say a composition of fibre , steel and what ever else depending on the brand and who makes them .

All Rover V8s can wear either tin or comp but if comp ratios are to be maintained , it`s not always a straight swap.

I know that by fitting a comp gasket where a tin was and doing nothing else economy and performance suffer on any Rover V8 .

I know that some people that sell and/or fit the new short 4.0s and 4.6s say , fit tin gaskets and it will be fine , the ones that are stamped 9.35? won`t be as bad but they don`t give as good economy or performance as they could .

I haven`t got around to working it out for a 4.6 but by putting composite gaskets on a 3.5 and doing nothing else a loss of around 0.70 : 1 ratio is achieved .

This is only a GUIDE .

8.13 : 1 - 0.70 = 7.43 : 1

9.35 : 1 - 0.70 = 8.65 : 1

Depending on which composite gasket is used because there are different thickness gaskets some will be better and some worse .

The margin in a 3.9 which is near enough to the same bore size as a 4.0 or 4.6 will be larger because of the bore size and also they is a larger difference between the tin and comp gaskets for these 3 .

I relise the above won`t seem relevant to what your doing but it`s the best i can explain what is .

For your 4.6 to achieve its 8.13? : 1 ratio it uses a 28cc head and a composite gasket .

What you using depending on your heads could be as much as 38cc and a tin gasket .

The difference between tin and comp is around 0.75mm .
( the 3.5 achieves its loss with a difference of around 0.50mm )

To get a ( 37.4 the one i`ve measured ) 38cc head anywhere near a 28cc head there is a much greater difference than the one of the gaskets .

So for your 4.6 to get its standard 8.13 : 1 ratio with tin gaskets and 38cc heads .......

The difference between the 38cc? and 28cc? chambers has to be worked out ( amount of metal to remove ) . Then the difference between tin and comp gaskets . ( amount of metal not to remove ).

With the two added together and that amount removed from the cylinder heads it should have around 8.13 : 1 Compression ratio .

Some of this i`ve measured , some on paper NONE of it is EXACT .
It`s mostly to give an idea that it`s not as straight forward as some say .

They are different engines and although the physically look similar and bits can be bolted from one to the other they have different ways of making a similar things happen ( compression ratios )

You may have been happy with the initial Yes , if so sorry for the long reply and if it doesn`t make much sense another one .

All the best , peter .

RangingRover wrote: Now, make sure you get your block pressure tested, to make sure it isn't leaking up next to the liners. .

When you say get the block pressure tested, how and who do this. The only pressure testing I have heard of is when all the heads are on ie. compression test, is this what you mean and will this tell me if a liner is cracked?

TRobbo wrote: The 4.4 P76 is a great engine for the rangie with loads of torque and would be my pick. Your problem will be finding a good one.

Isn't that the truth. I was lucky to pick mine up and it's a good one. Std. temp stays on just under half all day (I have a capilary water guage and thay ranges from 75 to 95 deg C pending on conditions).

I've never had a 4.4 before but I am impressed with the torque (probably on par with a 4.6 ) of the engine and acceleration I find on par with my old 3.9 even with a leaky exhaust flange , but fixing that this week with the fitment of EFI manifold and pipe set-up.

Anyway Walker, good luck whichever way you go. Go thr ZF, great unit and you won't regret the conversion, even if it does give you the shits like it did me

Trav