Head Differences
Discussion
According to Robs post, they are from a low compression 4.2 Range Rover -
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
4th paragraph down...
(Why won't this format into a clickable URL properly?!!)
HTH,
Dom
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
4th paragraph down...
(Why won't this format into a clickable URL properly?!!)
HTH,
Dom
domV8 said:
According to Robs post, they are from a low compression 4.2 Range Rover -
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
4th paragraph down...
(Why won't this format into a clickable URL properly?!!)
HTH,
Dom
I think your right... 4.2http://www.pistonheads.com/gassing/topic.asp?h=0&a...
4th paragraph down...
(Why won't this format into a clickable URL properly?!!)
HTH,
Dom
All the porting varies depending on age and 430vs500 ~ seems like they changed 'design / workmanship' reasonably frequently so it's very difficult to give simple answers.
They are early BV heads (as long as the valves are BIG ~ can't really tell from pics) as the guides are bulleted and they originally had o-rings. Bad news is it looks like they have been skimmed to remove the o-rings so that normal gaskets can be used (copper fire ringed composite gaskets became unobtainable and folks weren't prepared to fit solid copper so frequently skimmed off the rings). Good news is that that will increase CR a tad ~ you actually need to measure the volume to see how much. CR can be tweaked using slightly different thickness of head gaskets which are available ~ all depends on what you want it to be.
They are early BV heads (as long as the valves are BIG ~ can't really tell from pics) as the guides are bulleted and they originally had o-rings. Bad news is it looks like they have been skimmed to remove the o-rings so that normal gaskets can be used (copper fire ringed composite gaskets became unobtainable and folks weren't prepared to fit solid copper so frequently skimmed off the rings). Good news is that that will increase CR a tad ~ you actually need to measure the volume to see how much. CR can be tweaked using slightly different thickness of head gaskets which are available ~ all depends on what you want it to be.
Should have them next week, so will measure the valves. What sizes should they be? I am guessing for 'Stage 3' 1.63" and 1.4" is about right - are the BV valves larger than this? Also, is this measured across the face of the valve - do you need to lift them off the seat slightly to accurately measure?
jeboa said:
You have to love 'Google' - but I'm always suspicious that they'er a little bit imperial biased...
Saying that, they'res always one thing that everyone in the UK talks about in inches, but I'm not sure that's appropriate on a car forum.....
Think it may be because Google are AMERICAN. Same in any Microsoft software. Anyway I quite like imperial, even though I was grounded in metric as a student. Being an older git now I can remember pre decimalisation and all the nice 'old money'. Its fun working on the Griff and my Land Rover because they both use metric and imperial. I blame the French for the Metric System, we were fine with the 'English' measurements until the Europeans stuck their nose in................... Saying that, they'res always one thing that everyone in the UK talks about in inches, but I'm not sure that's appropriate on a car forum.....
Normal 430 valves are Vitesse size, whatever size they are. So anything bigger than Vitesse valves will be BV.
Just found this, maybe help a bit.
Cylinder Heads
There are 4 types of factory cylinder heads for the Rover V8. These are the pre-SD1, the SD1, the Vitesse, and the RV8 type. There are probably not many pre-SD1 heads in circulation now. Apart from having more restrictive ports they also had smaller valves. The SD1 and Vitesse heads come from the same casting and are almost identical. The RV8 heads have bigger ports but the same sized valves as the SD1 heads. They also have smaller combustion chambers. This is worth remembering as there are many people selling new 4.6 bottom ends but if these are used with SD1 type heads the CR will only be around 8.5:1 unless some machining is carried out. Standard pre-SD1 valves are 38mm inlet and 33mm exhaust. SD1 valves are 40mm inlet and 34mm exhaust, the Vitesse and RV8 having waisted stems. The commonly used big valves that fit on standard seats are 41.4mm inlet and 35.5mm exhaust. Ultra-big valves are 43mm inlet and 37mm exhaust. Standard valves can give close to 300HP while race engines equipped with ultra-big valves can produce approaching 400HP. To reach these power levels the heads have to be extensively ported.
The other heads available in the UK are special castings from Wildcat Engineering. These are a completely new casting with much larger, higher ports that have a straighter path to the cylinder. These heads can be fitted with 49mm inlets and 41mm exhausts. Power outputs of 400-450HP are easily achievable with these if the rest of the engine is built correctly.
and this;
For the Griffith and Chimaera, TVR Power, a Coventry-based subsidiary of sportscar maker TVR, built a Rover V8-version with a 4,280 cc (261 cu in) displacement using the 77 mm (3.0 in) stroke crankshaft as per the Land Rover 4.2 engine, but with a 94 mm (3.7 in) bore size. The so-called 'pre-cat' versions of the Griffith predominantly used this engine, although a 4.0 litre version was also available. The Chimaera was introduced with choice of 4.0 and 4.3 litre engines. A small number of 'Big Valve' versions, sporting modified cylinder heads with 43 mm (1.7 in) intake and 37 mm (1.5 in) exhaust valves and a more radical camshaft profile, found their way to early Griffiths and Chimaeras.
Just found this, maybe help a bit.
Cylinder Heads
There are 4 types of factory cylinder heads for the Rover V8. These are the pre-SD1, the SD1, the Vitesse, and the RV8 type. There are probably not many pre-SD1 heads in circulation now. Apart from having more restrictive ports they also had smaller valves. The SD1 and Vitesse heads come from the same casting and are almost identical. The RV8 heads have bigger ports but the same sized valves as the SD1 heads. They also have smaller combustion chambers. This is worth remembering as there are many people selling new 4.6 bottom ends but if these are used with SD1 type heads the CR will only be around 8.5:1 unless some machining is carried out. Standard pre-SD1 valves are 38mm inlet and 33mm exhaust. SD1 valves are 40mm inlet and 34mm exhaust, the Vitesse and RV8 having waisted stems. The commonly used big valves that fit on standard seats are 41.4mm inlet and 35.5mm exhaust. Ultra-big valves are 43mm inlet and 37mm exhaust. Standard valves can give close to 300HP while race engines equipped with ultra-big valves can produce approaching 400HP. To reach these power levels the heads have to be extensively ported.
The other heads available in the UK are special castings from Wildcat Engineering. These are a completely new casting with much larger, higher ports that have a straighter path to the cylinder. These heads can be fitted with 49mm inlets and 41mm exhausts. Power outputs of 400-450HP are easily achievable with these if the rest of the engine is built correctly.
and this;
For the Griffith and Chimaera, TVR Power, a Coventry-based subsidiary of sportscar maker TVR, built a Rover V8-version with a 4,280 cc (261 cu in) displacement using the 77 mm (3.0 in) stroke crankshaft as per the Land Rover 4.2 engine, but with a 94 mm (3.7 in) bore size. The so-called 'pre-cat' versions of the Griffith predominantly used this engine, although a 4.0 litre version was also available. The Chimaera was introduced with choice of 4.0 and 4.3 litre engines. A small number of 'Big Valve' versions, sporting modified cylinder heads with 43 mm (1.7 in) intake and 37 mm (1.5 in) exhaust valves and a more radical camshaft profile, found their way to early Griffiths and Chimaeras.
Edited by carsy on Saturday 24th August 17:55
Edited by carsy on Saturday 24th August 18:02
Guess that makes sense. From John Eales site:
Stage 2 Ported cylinder heads with 41.4mm inlet 35.6mm exhaust valves & bronze guides (with stem seals). Supplied assembled with double valve springs and steel valve spring caps.
Stage 3 CNC ported cylinder heads with 42.8mm inlet & 36.8mm exhaust valves & bronze guides (with stem seals). Supplied assembled with double valve springs and steel valve springs.
In the BV days, I wouldn't have thought they were 'CNC' ported, but the valve sizes would figure.
Stage 2 Ported cylinder heads with 41.4mm inlet 35.6mm exhaust valves & bronze guides (with stem seals). Supplied assembled with double valve springs and steel valve spring caps.
Stage 3 CNC ported cylinder heads with 42.8mm inlet & 36.8mm exhaust valves & bronze guides (with stem seals). Supplied assembled with double valve springs and steel valve springs.
In the BV days, I wouldn't have thought they were 'CNC' ported, but the valve sizes would figure.
Measured the valves on my 4.3 (4.6) pre-cat recently and they were: 1.69 inches (43 mm) and 1.46 inches (37 mm). Pic here:
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Which ties in with the TVR Power BV head spec as qouted above.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Which ties in with the TVR Power BV head spec as qouted above.
FWIW I have Dom V8s 450 HC BV heads.....if anyone wants them.
I asked Rob to use them when I changed my mind from upgrading my 400 to BV, to having a Rob 500 instead. He said they were not suitable for a 500, only for a 400 or 450. The 450 BV heads are 28 or 28.5 cc combustion chambers, the 500 engine needs 33cc chambers to keep the CR down to 10:1.
Not sure how my BV heads relate to the 430 BV heads. They have double valve springs and have HRC 2479 on the casting.
I asked Rob to use them when I changed my mind from upgrading my 400 to BV, to having a Rob 500 instead. He said they were not suitable for a 500, only for a 400 or 450. The 450 BV heads are 28 or 28.5 cc combustion chambers, the 500 engine needs 33cc chambers to keep the CR down to 10:1.
Not sure how my BV heads relate to the 430 BV heads. They have double valve springs and have HRC 2479 on the casting.
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