valve size

[poo slinger]

what size valves can i put ina rover v8 cylinder head without changing the valve seats?

[CastleMGBV8]

what size valves can i put ina rover v8 cylinder head without changing the valve seats?

1.63" Inlet 1.4" Exhaust. Seats will obviously need recutting and you need to have the seats opened up to seat size, the throats opened to match and blended into the bowls otherwise there will be little benefit from the big valves.

Depending on the cam you may also require valve cut outs in the pistons for clearance.

Kevin.

[poo slinger]

is that the biggest size that will go in?

how much do new valve seats cost?

[CastleMGBV8]

If 94mm. or larger bore then you can go for larger, I think ultra big valves are normally 1.76" Inlet and 1.5" exhaust but that would warrant extensive headwork to justify the valve sizes.

Note there can be a negative effect by going larger than necessary.

What spec is the engine? Cam, induction system? Road or race use?

Kevin.

[poo slinger]

3.9, +20, piper 270 cam, weber 500 carb.

its just a toy, trackdays and road use

[CastleMGBV8]

I would have thought stage 3 normal big valve heads would be fine with what you have. If you have standard heads at the moment it will make a big difference as you cam will very resticted by the heads.


Check out V8 Tuner, JE Developments, V8 Developments etc for prices.

http://v8tuner.co.uk/product.php?id=21

Kevin.

[poo slinger]

i found a pair of cylinder heads, owner said it has probably done only a few hundred miles.

41.11mm inlet valves
35.45mm exhaust valves
inlet pots are 25.5mm by 41.34mm
exhaust ports are 25.5mm by 37.4mm

bulleted guides and 30cc ocmbustion chambres.


are they worth £500? and what are bulleted guides?

[sidecar]

i found a pair of cylinder heads, owner said it has probably done only a few hundred miles.

41.11mm inlet valves
35.45mm exhaust valves
inlet pots are 25.5mm by 41.34mm
exhaust ports are 25.5mm by 37.4mm

bulleted guides and 30cc ocmbustion chambres.


are they worth £500? and what are bulleted guides?

Dunno about whether the spec is what you want but bulleted guides are guides that have had the ends machined into a sort of "bullet" point. They occupy less space in the inlet and exhaust tracks and therefore aid gas flow.

Pete

[CastleMGBV8]

Depends on who did the work on them, does he know where they came from and are they waisted stem valves?

The fact that some body went to the troulble of fitting bulleted guides is a good sign but the headwork itself is important. I'm a cheapskate and just have my existing ones machined down.

Kevin.

[poo slinger]

he bought them 2nd hand but they hadn't been used and the original owner paid £1100 but had to sell them due to a divorce.

[CastleMGBV8]

Sounds like they should work fine with the 270 cam and your carb and manifold. they are what are normally described as stage 3 although varies as to who did them, £500 sounds a good price if the port work is well done.

Kevin.