A BV Question.......

[Hoover.]

As some of you are aware there is a strong possobilty of my my car being a bd BV (not given it's name at birth ).

I was wondering if the BV's have a differnt size exhaust manifold ..... as I've just changed my gaskets not paying attention to what was there thinking they're all the same.....

put it on a rolling road at the weekend and lost 25 horses .... obvioulsy not happy and this is the only thing I've changed.....

so I've concluded that BV's must have larger exhaust outlets/manifolds....anyone want to concur before I look to taking the bloomin things off again.

[Barreti]

There are two different sized gaskets for the two flange gaskets Hoov.

[Hoover.]

Barreti said:

There are two different sized gaskets for the two flange gaskets Hoov.

yep.... worked that one out when one set didn't fit.....


it's at the engine end I'm wondering.........and I think I'm right.

[The AJP Griff]

Some unported heads can use the std Landrover 'square' exhaust port gasket.For the ported heads,ie tuned 4.x and 500's you need the rectangular gaskets,so you have a ported head by the sounds of it.

[Hoover.]

The AJP Griff said:

Some unported heads can use the std Landrover 'square' exhaust port gasket.For the ported heads,ie tuned 4.x and 500's you need the rectangular gaskets,so you have a ported head by the sounds of it.

fitted the ACT metallic composite ones....... which were rectangular.

Hmmmmmmmmmm ....... must be more to it I think.

[The AJP Griff]

Hoover. said:

The AJP Griff said:

Some unported heads can use the std Landrover 'square' exhaust port gasket.For the ported heads,ie tuned 4.x and 500's you need the rectangular gaskets,so you have a ported head by the sounds of it.

fitted the ACT metallic composite ones....... which were rectangular.

Hmmmmmmmmmm ....... must be more to it I think.

They should be fine,then.As you say,there might be more to it than the gaskets.The rectangular ones are good even with the very over ported 500 exhausts.

[Hoover.]

..... somewhere along the line i lost 25bhp in less then 2 months..... and the rr aint to blaim as the car on before me had been on the previous road and only droped 2 bhp..... seeeing as we were within 0.??? i expected the same... alas mine -25 even with additional weight over rear wheels

[griffter]

Try as you might, you just can't identify a BV for sure without taking the heads off. My (originally non-BV) 4.3 heads were ported and polished beautifully. Even had Wills rings installed. All that, but no big valves.
If (big if) a specific cam were installed on BVs you might be able to determine that by measuring cam duration and lift at the rockers. If (big if) BVs sound 'different' or have a specific torque/power profile, you might detect or measure that.
You could split the ECU and look at the chip - does it day '4.3' or '4.3 BV'?
At the end of the day though, none of these checks mean anything about the valve sizes themselves, especially if yours is a non-BV that happened to have BV heads fitted.

I've often wondered whether a bore inspection tool (you know - light and camera in miniature) might be used to measure the valve sizes in situ (eg through spark plug hole or exhaust port). I even conjured up a plan to stuff a sponge into the combustion chamber to try to take a carbon 'print' of the valves.

At the end of the day I only found out - and upgraded to BVs - when an exhaust manifold bolt sheared and the heads had to come off for repair.

Afterwards the car was slightly freer revving, cleaner, crisper - edgier - at the very top end. But that could have been down to the heads being cc'd at the same time as the BVs were done. I certainly wouldn't claim to be able to tell by driving.

Nope...heads off is the only way I think.

[Hoover.]

After reading peoples posts.... I have concluded that my initial thoughts on my cars poor running are wrong.... absolutly nothing to do with gaskets/BV engine etc....

I thank HarryW for "saying the car sounded asthmatic on the rollers".....

I checked all the induction and found that the small pipe from the plenum to flying saucer had not been reattached/fallen off following the manifold gasket replacement.....

All is back to norm now..... free reving and accellarting upto big numbers quickly