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pistons burnt cooked.

never seen 845cc pistons with a high compression bulge before are you sure its not 956cc?
 
Off topic: how do you fill up your petrol tank in your R4?!?
 
They are bits missing from the edge of pistons,I had sudden crankcase pressure,leaking from rocker cover,changed gasket then she lost compression on no2 though it was the plug at first.Decided to take the engine out of the 4 that I have started to strip ready to do a ground up resto,and take pressure off.Then I discovered there was no hole for the starting handle on broke engine but is on the engine I am about install from other car,the plot thickens.On a good note I can now tryout my newsoda blaster to clean up the engines,like a dog with 2 tails.Best Alan
 
Sandy,has an anti syphon system to stop the Tauregs nicking the petrol in the middle of a desert night.Its inside?
 
Good thinking! I guess a locking fuel cap just doesn't cut it in the desert! Thanks :)
 
burnt pistons

malcolm said:
Those pistons look OK to me from the photos. Plenty of carbon on them fair enough but that comes from the petrol when it's running rich. You'd need to remove that carbon to see any piston damage. No reason to replace pistons unless I'm missing something - is it melted pistons not carbon I'm seeing?

You get a bit of carbon on top of pistons especially if the engine has been running a bit rich (poorly set up in the past maybe). You could scrape it off but be very careful not to put any force on the liners and definitely don't turn the engine over as the liner seals at the bottom will pop out and will need to be replaced.
Click to expand...

Hi,I have rotatated the engine,liners still in place,now locked down.Angel thinks the engine is a 747cc.Am switching engines from the 68 which I have started a ground up resto,have been stimulated by your efforts<sounds abit rude> I will enjoy rebuilding the engine anyway,can I fit 5 engine and box into the 68 and whats does it entail,changing hubs etc,a word would be great .Best Alan
 
The driveshafts for pre-69 models are said to be shorter (the whole front suspension has different measurements). As you have to fit the "square" gearbox from the R5 engine these need to be changed for the new type, and I am not sure if the inner joints will allow that difference in length. If you are lucky enough to have the short driveshafts with the tripod inner CV joint, it's entirely practical to make two "hybrid" ones by fitting the inner joints from the new ones (to be compatible with the gearbox) to the old "short" shafts.

Putting this aside, you will also need to replace:

-engine mountings on the chassis
-radiator and associated fittings and hoses. Don't forget the electric fan, if your 68 is still 6V.
-you have to find and fit the crossmember for the front gearshift lever bush.
- bonnet,as the radiator will be up front now and there will be no place for the early bonnet struts.
- clutch, speedometer and more than likely throttle cables.
- exhaust, 845 one will fit but too restrictive.

Do you think it's worth it?
 
No I dont.Your right with all the messing around and what result,must be these winter nights setting in having to much time to ponder. You are correct it is an 747 engine,68o-1,so its a set of 747 pistons I will need,there is slight damage to head but I am sure this can be milled out.I am fitting the 850 engine out of my 68 while I sort out the engine,the engine has to come out whilst removing body to refurbish the chassis.Will be soda blasting both engines tommorow with my new toy,will post pics of before n after.Trust all is well with you ,best Al
 
Swap con rods as well?

It seems availability of pistons and liners is better for later engines (16mm gudgeons and 55.8mm piston diameter instead of 14mm and 54.5mm respectively)

Could you change pistons,liners and conrods ? The bigend diameter is the same (38mm). I am sure those more knowledgeable than I could tell you

If you do go down that route, I could help you out with a complete set of pistons/liners/conrods. They came from a perfectly good engine I took to pieces a few years ago because I wanted to see how it worked - I just didn't put it back together again!
 
plot thickens.

simonandjuliet said:
It seems availability of pistons and liners is better for later engines (16mm gudgeons and 55.8mm piston diameter instead of 14mm and 54.5mm respectively)

Could you change pistons,liners and conrods ? The bigend diameter is the same (38mm). I am sure those more knowledgeable than I could tell you

If you do go down that route, I could help you out with a complete set of pistons/liners/conrods. They came from a perfectly good engine I took to pieces a few years ago because I wanted to see how it worked - I just didn't put it back together again!
Click to expand...

Hi just got back from france,without a head gasket? Would you believe my local renault garage has found me one,hurrah. Thanks for the offer,but liners look good and are undisturbed I have found a firm that will make me some 747 pistons,just got to strip engine and send sample piston sounds quite promising everyone wants to include liners so we will wait and see in the meantime I will fit the 850 I have,will keep you posted.Best Alan
 
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