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Engine overhaul commences - advice required
Posted: Wed Feb 01, 2017 8:03 pm
by Jimmy
Pistons and cylinders removed (1968 911T). Having made enquires regarding replacement cylinders and pistons, Mahle only appear to have 'S' spec available. Are these suitable for fitment with the remaining components being 'T' spec?
Or, the cylinders can be machined to accept oversized pistons, any recommendations?
Other items required;
Valves
Valve guides
Gasket set
Rod bolts
Flywheel bolts
Oil pump
Bearings
Recommendations to where to purchase said items would be appreciated.
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Jimmy
Re: Engine overhaul commences - advice required
Posted: Wed Feb 01, 2017 9:02 pm
by fetuhoe
I am not a big fan of Cast Iron 911T cylinders and wouldn't be very inclined to bore them to an oversize.
S Pistons will work in a T engine but there will be an increase in dynamic compression compared to an S cam and this could mean that pinking would be more likely.
Not a really big issue but something to consider.
It is possible to find good quality 4032-T6 forged piston with 9.0:1 compression in 80, 80.5 and 81mm diameter.
I would try to find a set of good used Biral Cylinders and bore them to 81mm or you can find them new.
Intervalve make decent standard vales and if you have an old single Valve Spring engine I would suggest buy new dual springs.
We make Colsibro Valve guides for 911s and they a much better than the stock guides which also have quite poor size tolerance.
Why do you want to change rod and flywheel bolts? If they have not been damaged they are good to re-use and it is easy to check.
I would use an Elring Gasket Set or a Wrightwood Racing set which we import from the USA.
The oil pump can be checked by dismantling and looking for signs of wear.
It is important to mark the sear pairs so they are re-assembled in the correct position.
The only issue with pumps is scoring or wear of the bidy or wear in the end faces.
If they don't show wear then the gears themselves rarely show wear and it is relatively simple to bush the hosuing if the shaft supports show any wear.
We use ACL Rod bearings as current Glyco production has som issues.
Glyco mains are generally OK.
I would also suggest you replace chains with new one piece IWIS parts, fit new chain ramps and rebuild the tensioners and install chain savers.
Re: Engine overhaul commences - advice required
Posted: Fri Mar 03, 2017 6:46 am
by Jimmy
Guys - Have purchased the overhaul parts for the chain tensioners, next step is to purchase and install chain savers (safety collar).
Any advice for what type and where to buy from would be appreciated.
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Jimmy
Re: Engine overhaul commences - advice required
Posted: Fri Mar 03, 2017 7:50 am
by Barry
fetuhoe wrote:I am not a big fan of Cast Iron 911T cylinders and wouldn't be very inclined to bore them to an oversize.
S Pistons will work in a T engine but there will be an increase in dynamic compression compared to an S cam and this could mean that pinking would be more likely.
Not a really big issue but something to consider.
It is possible to find good quality 4032-T6 forged piston with 9.0:1 compression in 80, 80.5 and 81mm diameter.
I would try to find a set of good used Biral Cylinders and bore them to 81mm or you can find them new.
Intervalve make decent standard vales and if you have an old single Valve Spring engine I would suggest buy new dual springs.
We make Colsibro Valve guides for 911s and they a much better than the stock guides which also have quite poor size tolerance.
Why do you want to change rod and flywheel bolts? If they have not been damaged they are good to re-use and it is easy to check.
I would use an Elring Gasket Set or a Wrightwood Racing set which we import from the USA.
The oil pump can be checked by dismantling and looking for signs of wear.
It is important to mark the sear pairs so they are re-assembled in the correct position.
The only issue with pumps is scoring or wear of the bidy or wear in the end faces.
If they don't show wear then the gears themselves rarely show wear and it is relatively simple to bush the hosuing if the shaft supports show any wear.
We use ACL Rod bearings as current Glyco production has som issues.
Glyco mains are generally OK.
I would also suggest you replace chains with new one piece IWIS parts, fit new chain ramps and rebuild the tensioners and install chain savers.
A most excellent post, if I may say
.