advice before job (Henry Schmidt ?)

[philippeF]

Hi all

here are 2 questions :

--1-- I 'll soon start my RS 2.7 replica (72S/911-83 based), the car is in great shape, and i drove 350kms to get it back home : i've noticed a low oil pressure when warm (1.5b/4000rpm), although the engine is running strong without smoke noise ...... P/C are new valve seats too.
Any idea ? btw i'm (almost) decided to rebuild the engine to start with a reliable track car (won't do it if you tell me what could be wrong ) my thoughts are : worn bearings, oil pump (?), bad previous rebuild (?)....

--2-- what should be the rod stretching value to reasonably improve CR (stock 2.7RS engine) and another little improvements (timing mods?, ignition mods ? head polishing (i'll do it !)increase intake diameter?

best regards
thank you for sharing your experience

Philippe

[philippeF]

nobody ?

[BURN-BROS]

What is the mileage?
Oil temp?

I have not heard of anybody resizing rods. What I have seen is shimming the cyl. to establish deck height. Henery or Steve can definitively tell you.

I don't know the quality of euro fuel but if you go past ten, think about twin plugging if you can afford the conversion.

I would go with bearings if the milage is high.

[philippeF]

Engine is down now !
I've checked cams, and things, everything seems to be nice, oil was old and dirty, the engine seems to be rather low mileage .
btw seals are too old, i'm going to change them :

the oil pressure was rather low at operating temp 1.5b/4000rpm/100°c but nice when cold (4b/4000rpm/cold), i noticed the pressure sender was new....

i'l be back when engine is open

Philippe

[Henry Schmidt]

Check the main bearing alignment. Mag engine cases change shape and the bearings loose oil pressure.
There are a couple of things to do that will bring back you pressure. Align bore case, Turbo pump modification, SC/ Carrera oil pump, and cam feed line restrictors.
Updates oil valves with also help ( will not make oil pressure but will control oil flow better.)
You can also loose oil pressure from missing crank plugs. If the crank was repaired and then heat treated the aluminum plugs can fall out if not properly replaced.
You can rebush the rods ( small end ) about .040 to achieve additional compression. I would not go that direction unless no other method was available. I would just order new 9.5 to 1 JE pistons from our host and save the RS spec pistons for some other project. You could also sell the pistons to off set the cost of the JEs.
38 mm ports with help flow if you also change the intake to match.
I would change the cams and you're good to go.
Good luck

[philippeF]

thanks for the helpful answer :

i'll probably stay stock because P/C are only 10000miles from the previous rebuilt, may you post pics about the crank plugs ?

any idea of JE 2.7RS hi comp pistons cost ?

what about the cams : S cams works well don't they ?


best regards

Philippe