A pal of mine has a T34 .48 fitted to a std 2wd engine with a -31 actuator , the car doesn't make much boost even if you heavily preload the actuator arm , its running an amal valve currently .
Im wondering why , ive read a bit about jetting these to increase held boost , is this the next step or should he dump the amal valve and connect the compressor to the wastegate to control boost , hes looking for 1.4-1.6 bar on greens . ???

 

are you sure the actuator is a -31,, and strong enough?

 

Hi Gareth and happy birthday for tomorrw , lol .

The actuator has the std -31 numbers marked on it , it was very hot yesterday tho and it felt like a normal -31 to pull on .

 

what boost was you seeing?

 

He tells me 10 psi , we wound on a load more turns but it made little or no difference , its a racecar so he didn't watch the gauge all the time but reckoned it peaked at 10psi , didn't seem quick either .

 

i would change the actuator and if that dont work have a look at the exhaust housing

 

I am running the same spec as your friend, I have a small restrictor in one of the amal valve tubes not sure which one though. It was fitted by Mark Shead of M A Developements. Withouit it I was not pulling much boost.

 

make sure your throttle butterfly is opening fully aswell - get a friend to press the accelerator all the way down and then have a look and see if the throttle is open fully. Had this problem on my car, tried new pedals, cables, throttle bodies, couldn;'t work out for the life in me why it wouldn't open fully.


Then I realised that someone had placed a throttle stop under the carpet

 

Tony.....

Remove the return restrictor completely from the Amal valve(pipe stub is marked "R")and then set-up the actuator until you have about half to three quarters of a hole of of pull,this should give you what you are after.....

 

Cheers for the replies , bit confused tho as one says to add a restrictor and another to remove one . Wouldn't it be better all round to remove the amal valve and use the acuator preload to control bleed , sorry ive very little experience with these ?

 

Tony Ryan

you wont get enough boost from a -31 with the compressor piped too the actuator,,, unless you use a bleed valve

 

that set up SHOULD be able to make loads more boost than 10 are you sure there's not got a boost leak ie i/c knackered.

 

Tony, back the preload off to about 6mm and then remove the restrictor from the "R" port and see what happens from there.

 

Thanks Guys, i'll try all these different ideas but i reckon Gareths about on the button with the -31 being too weak for the turbo .
Many thanks Stu , we'll have a mess with the amal but its coming off anyway , i cant trust that it will do its job under these conditions and a twin port maybe on its way .

 

Dont be too hasty with your cash. With std jetting you wont get much boost from a -31 on any turbo. Its only an 8psi spring.