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Turning the engine

PostPosted: 29 Aug 2017 18:06
by Martin Cridford
Whilst checking the timing on my RV8 I found I couldn't see the timing marking on the crankshaft pulley/vibration damper. This was because they are very lightly engraved and the pulley surface was rusty. I obviously needed to get the markings cleaned up and some white paint rubbed into the engravings.

It's impossible to access the markings from above so the only way to get to them is from underneath. This required a lifted car which was easy to solve but the markings were never in a position that they could be cleaned and painted.

I know turning the engine has been mentioned before but there is no way a spanner can be put on the crankshaft pulley. After struggling to turn the engine for some time I hit upon the idea of slipping a socket on an extension bar through the hole in the radiator cowling in front of the alternator and putting it onto the alternator pulley nut. By pushing the fan belt to provide more grip around the pulleys I was able to turn the engine little by little with my socket spanner ratchet until the timing markings were in a good position for cleaning.

Having done that checking the timing was easy. However, I would suggest that a special 'cranked' distributor spanner for the V8 is invaluable as is a good quality adjustable timing light.

And the timing? Well I found it was 10 deg AFTER TDC when it should be around 5 deg (static) BEFORE TDC! No wonder it popped and stuttered along! Adjustment to the correct BTDC was then easily carried out with the above mentioned spanner and timing light.

Re: Turning the engine

PostPosted: 01 Sep 2017 14:12
by Nic Houslip
Martin. A V8 is pretty tough to turn, and as you say getting anything on the crankshaft pulley is nigh on impossible. Your scheme works well, but an old trick I learned from my Dad was to engage top gear and using your knees, push the car backwards until the marker was slightly past where you wanted it, then nudge it to its correct position by pulling the car toward you. There is enough slack in the transmission so that you can move the car a little to nudge the engine. The nudging forward is important, it takes up any slack in the timing chain and gears that might otherwise skew the adjustment. Of course this must be done with the Ignition Off and preferably with the plugs out. The Crow's foot cranked spanner [Clive Wheatley has them in stock] makes the job easy. Timing is critical and the fact that yours was after TDC by 10 degrees it is surprising that it would go at all. If you have the opportunity, get the car on a rolling rod dyno and have the timing set for optimum power, as there are minor variations between engines.

Re: Turning the engine

PostPosted: 01 Sep 2017 16:57
by Martin Cridford
Thanks Nic,

I have done as you suggest before but my problem was having got the car up on stands so as to safely dive underneath to get at the timing marks and be able to clean and mark them, I couldn't roll the car! Neither did I want to lift one rear wheel and turn the other whilst in gear as I'm not sure what a LSD does in that situation and I didn't want to find out!

I also didn't want to have to take out and then replace 8 spark plugs either, especially as the engine was hot.

I was just pleased to find a simple and effective way of turning the engine from the top.

Much as I like the idea of a dynamic RR set up, as a mechanical engineer I have never liked the idea of the process the engine goes through and have a friend who spent all winter preparing his Caterham engine for the next season on track only to wreck it on the RR setting it up! He was not a happy man.

Re: Turning the engine

PostPosted: 08 Sep 2017 10:30
by Nic Houslip
Martin
Understand, didn't realise it was on stand, so your precautions are right. Ultimately if you want to get to the exact timing that takes into account wear in the distributor drive gears, timing chains and distributor A&R bob weights, an RR session is vital.
Sad to hear about the Caterham, but the consolation is that it didn't happen on track when he was pushing hard. It would be interesting to know what had happened inside the engine [i.e. what let go?] What engine was he running?
I agree the process of running the car at almost max RPM on the RR in a shed, with all the fans running sounds distressing, but mostly because you normally aren't that close to a car when it being driven at max rpm.
Nic