Valve springs

BanditSid · Post by **BanditSid** » Tue Jun 16, 2009 11:26 am

I have a Rover V8 engine, it's in a factory MGB V8 and has the P6 style dual valve springs. Does anyone know if the SD1 style single springs can be fitted in their place? I have SD1 single spring caps to use, but have read that the springs won't seat properly in the head, but as they are slightly smaller it looks to me like they would be fine. Has anyone tried or done this?

topcatcustom · Post by **topcatcustom** » Tue Jun 16, 2009 11:56 am

They would probably fit, but the idea of the spring seat is that it locates nicely so the bottom of the springs don't wander. I would say no, but someone else may say it is fine for road use or whatever...!

p.s. why not just get a pair of SD1 or RR heads with the correct spring seats, they should be much better castings and have bigger valves so you should see a power improvement too, and you will have to take them off to change the springs anyway!

TC

ged · Post by **ged** » Tue Jun 16, 2009 2:49 pm

topcatproduction wrote:They would probably fit, but the idea of the spring seat is that it locates nicely so the bottom of the springs don't wander. I would say no, but someone else may say it is fine for road use or whatever...!

p.s. why not just get a pair of SD1 or RR heads with the correct spring seats, they should be much better castings and have bigger valves so you should see a power improvement too, and you will have to take them off to change the springs anyway!

TC

Not necessarily tc. I made a bar up for compressing the springs. It locates on the rocker bolts. I also made a fitting that connects to an air line & screws into the spark plug holes, with just 5 psi the valves stay closed & it makes changing the oil seals or springs easy.

Ged.

topcatcustom · Post by **topcatcustom** » Tue Jun 16, 2009 3:36 pm

Thanks Ged, I had heard about changing sping in situ but never given it much thought as to how to do it- and didn't know you only needed a few psi!

TC

sidecar · Post by **sidecar** » Tue Jun 16, 2009 3:43 pm

The other way is to feed some soft rope down the plug hole then carefully crank the piston to TDC. (Leave the end of the rope sticking out of the plug hole!!!

)

Post by **katanaman** » Tue Jun 16, 2009 4:19 pm

Not recommended, there is a boss that fits to the inside of the spring to stop it moving around. P6 bosses will be too small to locate SD1 springs properly so they will move around and wear the spring seat.

ged · Post by **ged** » Tue Jun 16, 2009 6:43 pm

topcatproduction wrote:Thanks Ged, I had heard about changing sping in situ but never given it much thought as to how to do it- and didn't know you only needed a few psi!

TC

Your welcome TC

mgbv8 · Post by **mgbv8** » Tue Jun 16, 2009 9:41 pm

The factory MGB V8 outer springs are about 2mm bigger than the SD1 springs Sid!

They will fit into the old heads spring cups. But they may wander a bit in use and wear the head material!

Is this just a stop gap job ??

ian.stewart · Post by **ian.stewart** » Wed Jun 17, 2009 10:44 am

Im with Katanaman here, the springs do have a location to stop them moving about, if you dont locate them correctly, the springs will rattle about, possibly damaging the head, although they are located by each other, excess friction between the springs will cause early need to replace the springs,
Do you need to fit these springs, I would think they are now probably over 25 years old, and could have taxi miles on them by now,
if your aim is to stop valve bounce I dont think the the factory doubles do a lot, Your lifters would probably limit the engine befors you get bounce, I only run after market singles and use 7k regularly with amechanical cam.,