The V8 Owners Forum -

The composite gaskets are usually 40 thou and the tins 20thou so -20thou.

You did use composites specifically for a 3.5 engine?

20thou x 1.6 (rocker ratio) = 32thou. less lifter preload.

So either have 20 thou off the heads or have 20thou machined off the rocker pillars.

The drop in compression from using the composite gaskets 10.5/1 to 10/1 will be beneficial but still marginal with 95 RON unleaded.

The valve seats on P6 engines are not hard enough for unleaded petrol but will probably last a while if mileage is relatively low.

Kevin.

CastleMGBV8 wrote:You did use composites specifically for a 3.5 engine?

Yes, as supplied by RPI engineering.

CastleMGBV8 wrote:The valve seats on P6 engines are not hard enough for unleaded petrol but will probably last a while if mileage is relatively low.

Mileage will be fairly low - can't afford the petrol to use this for the daily commute! I do that in my classic Minis - all of which I run on unleaded, and I have yet to have any valve seat issues with any of them. None, to my knowledge, have been converted. When it happens I'll grab one of my spare heads from the shed, get nephew to put hardened inserts in, and swap it over.

off topic, how well has your davies craig water pump worked? by the sounds of it your heaters dont work without another booster pump? was it a 80 or 110?

i ask as i have fitted one to my car due to space restrictions, rads not plumbed in yet so not tested the pump.


Ralph

The pump seems to work fine - not sure what model it is as it came with the conversion, but there is an electronic controller and temperature sensor, and that does what it's supposed to.

The reason the heater doesn't work is the way it's connected; the electric pump is in the main radiator hose about a foot from the original, while the heater take-off is on the mechanical water pump which isn't driven. I suppose the alternative would be to fabricate a t-piece in the radiator hose (not hard, I did one for the expansion tank) and re-route the heater pipes.

If you take the dizzy cap off first, you might be able to get it out without dropping the block?

No, shaft's too long. And I wouldn't get access for the drill anyway, not even the cordless.

It's only four bolts for the crossmember, and I should be able to leave the bumper in place. There's enough flex in the pipes and cables, as long as I separate the air ducting from the filter box.

ON the subject of unleaded running in engines with soft seats, i ran my 1959 landrover for about 6 years as my daily driver on unleaded with no issues with valve seats. I have been told that all should be fine as long as you avoid continuous high revs like you would get with motorway running...

My Dads 101 has short reach plugs- so i guess it has P6 spec heads and this has been running on unleaded and LPG for some time now with no problems, but then it doesn't do much mileage at all.

I have heard of several people running engines designed for leaded petrol on unleaded. I guess it's possible for two reasons.

Firstly, lead memory which is when you run an engine on leaded petrol for a long time, and somehow it becomes engrained in the seat, and so it survives on unleaded for quite a while afterwards or something, don't know much about this but I have heard of it.

Secondly, as quagmire says if the seats are kept cool it minimises damage. I know my dad's lotus seven replica with a 2L pinto engine didn't have hardened seats, but when he put LRP in it, which used to compensate for the lack of lead to an extent but was certainly no replacement for leaded petrol, he always used to take it steady. Put four star in it and he'd let rip and he'd scare the crap out of me with it, but that's another matter

Well I've located the problem, and it's bizarre - at least it seems that way to me.

I took the dizzy out - I could see an immediate problem there - metal filings round the drive dog, which turned out to be shagged as the drive has worn away. Tried to turn the oil pump - seized solid.

Dismantled it, and there is a small crack in the pump body behind the secondary gear - as if it's had a good whack from the outside, which it hasn't. That was stopping the gear from turning.

I really can't understand how that's happened. Need to source some parts now.