Labour Time To Change Rings And Bearings

[Guest toby7]

Hi there,

 

This is my first post to this great forum. I'm not a mechanical wiz yet (Office worker) but am learning as I go. So here goes . . .

 

My compression is between 145 and 155psi on my 1988 series 1 205gti with the 1.9 D6b engine. Engine at this stage is completedly standard including intake and exhaust) To restore compression to the correct values (What should they be for the D6b engine in psi) rings and bearings and head need doing. Standard compression I think is 9.6 to 1. Would a skim of 0.028 thou (.7mm) raise comp ratio to 10.1 ?

Does the engine have to be removed to do this work or can the rings bearings be done in the car. If It can be done am I saving costs in labour or is it better to completely remove the engine.

Finally . .If I do the rings, bearings + Rotate the liners 180 degrees, 3 angel valve job, skim head and blending only porting ( Not bigger ports as I want to retain gas speed for torque), port exhaust manifold and maybe intake manifold and Enlarge the throttle body by 5mm diameter will the standar Jetronic injection cope and run the correct fuel air ratio ?

 

Thankyou for your time and any helpful advice / experience you have to offer

 

Thanks

Pete

[PsychoSimon 0]

I would say it would be easier to have the engine out of the car in my opinion, as the bores would have to be re-honed/glaze busted for the new rings to bed in properly, and this is best left to a machine shop.

in regards to the compression ratio, i really have very little experience and knwledge on the size of the combustion cambers in the pistons and head so could not avise you solidly on what the compression ratio would be, but as a rule of thumb i generally never go more than 0.5mm off a head as it starts to mess with other things. for example it can alter the cam timing quite a lot if the engine only has one cam belt tensioner, and also you may get pinking if the standard distributor gives too much advance for the compression ratio.

I am 99% sure the standard injection system would cope with above setup, just double check with somebody more experienced than me with the compression ratio.

if you port the exhaust manifold DO NOT match it to the ports on the head. there needs to be a slight mismatch between the two so that the "pulse" effect can take place.

hope this helps you on your way,

regards,

Simon

[pugrallye 0]

10 psi isnt catastophic between cylinders, obviously could be bettered with rebuilding. yes skimming would raise compression ratio, assuming your cylinder head hasnt been taken to within tolerance already???

Engine out job is the only real way of doing such jobs you are requesting. bearings can be done in car , but if you are planning major rework removal is th e easiest option, fuel is easily adjusted if you decided to port throttle housing

Edited January 11, 2006 by pugrallye

[j_turnell 134 3 Cars]

Probably be cheaper and better for you in the long run to get the whole engine rebuilt.

[geoffmslater 0]

Hi there,

 

This is my first post to this great forum. I'm not a mechanical wiz yet (Office worker) but am learning as I go. So here goes . . .

 

My compression is between 145 and 155psi on my 1988 series 1 205gti with the 1.9 D6b engine. Engine at this stage is completedly standard including intake and exhaust) To restore compression to the correct values (What should they be for the D6b engine in psi) rings and bearings and head need doing. Standard compression I think is 9.6 to 1. Would a skim of 0.028 thou (.7mm) raise comp ratio to 10.1 ?

Does the engine have to be removed to do this work or can the rings bearings be done in the car. If It can be done am I saving costs in labour or is it better to completely remove the engine.

Finally . .If I do the rings, bearings + Rotate the liners 180 degrees, 3 angel valve job, skim head and blending only porting ( Not bigger ports as I want to retain gas speed for torque), port exhaust manifold and maybe intake manifold and Enlarge the throttle body by 5mm diameter will the standar Jetronic injection cope and run the correct fuel air ratio ?

 

Thankyou for your time and any helpful advice / experience you have to offer

 

Thanks

Pete

 

Hey Pete

 

I rebuilt my mi16 engine "in place" it is possible. Of course better to do out of car. I am doing one out of the car at the moment, Give me a ring if you need anything 03 352 9310

 

Good to see fellow kiwi Pug enthuasast

 

Cheers Geoff

[pug_ham 242 3 Cars]

Far easier out of the car as the head has to come off to do them with it fitted still to get the rods & pistons out.

 

Graham.