Timing

[JNS]

My spark timing was set to 18 degrees BTDC. This seems excessive after reading Miles Wilkins book, (he recommends 12 degrees)
The car has twin 45 webbers, and slightly larger valves than a standard Twin cam. I've been told by Richard at 'Banks' it has 'Half race' cams.
 Any opinions as to what the timing should be set to?
Thanks
Jeff

[MRN I J]

18° BTDC does sound excessive, however it has 1/2 race cams & 45s, so the effective compression ratio might be low, who set it at that?
I would look to set at 15° BTDC with a good quality timing light & see what happens 

[EuropaTC]

I guess the first question is "how does it run  ?" 

My initial reaction was probably the same as anyone else and "hmm that sounds a lot" but if your engine has had a lot of work with cams & 45's then presumably someone also set it up on a rolling road so that could easily be the optimum setting.

Brian

Or maybe the advance weights are sticking.....   (couldn't resist that one    )

[JR73]

What does it run like? Do you know who built it, where it was set up etc?

*Brian beat me to the same questions, distracted halfway through typing!

[jbcollier]

Initial timing on its own doesn't mean much.  What is your total advance at 5000 rpm?

[Clifton]

Initial timing on its own doesn't mean much.  What is your total advance at 5000 rpm?

What JB said.

 I don't know these motors but most n/a street engines, depending on bore and compression do good with around 27-33 degrees total. Less if the compression is very high.

[kram350kram]

Usually I set the initial timing and the carb(s) with the highest vacuum I can obtain at the idle speed I want. If it idles well, doesn't knock off idle to say 2000 RPM, have good adjustability of the carb mixture screws and the starter can turn the motor over without laboring, 18 BTDC is fine. Could run even better at 15,16, 20 or 22 ? If the motor likes more initial timing because of the cam, combustion chamber shape, valve size, intake, exhaust valve size, intake runner length , etc... the initial timing really doesn't matter.  As JB stated what is the timing at 5000 or better yet at the maximum RPM you would use? It's the total advance that you need to watch. You don't want holes in pistons. Also, if you have vacuum advance you need to watch that total also at cruise, but usually that is not an issue. Find someone with a distributor machine to help limit the total once you get the idle sorted out. Not sure on what total is recommended for your particular engine, but 36-38 BTDC total mechanical advance is usually a safe bet. I run 26 BTDC on a V-8, as the cam I have has a lot of overlap. Make sure your mechanical weights are free, springs not loose and the rotor snaps back when pushed toward advance.

[jbcollier]

36-38 is fine-sh for the stock Europa Renault engine.  Mine is a breathed-upon cross-flow and I've limited it to 32-34.  Twin cams prefer a little less, 28-30 all in.

PS: By "prefer" I mean, "won't blow-up with a long session of full throttle".

[JNS]

Thanks for the replies. I was hoping to have the engine running again this weekend after changing some valve clearances, I was tightening the last cam cover nut and snapped the stud. (18ft lbs). I can't get it out with a stud extractor so I guess its a 'head off' and go cap in hand to the machine shop.
Jeff

[jbcollier]

I remove most studs by drilling them out.

The key is to get the centre punch mark as centred as possible.  Start small and check your centring again.  Lightly mark, check, knock it sideways if you need to.

Now drill out the centre punch slightly with a small bit and check once more.  Again, you can then move it a sideways a bit if you need to.  Use cutting oil and sharp bits.  Get that one straight, centred hole (say 1/8" with a 8mm stud) and go up one size at a time until you just start to see "threads".  Unlikely you're perfect but you should then be able to knock/pick out the remaining bit and you are back in business.

Sharp bits, lube, light/medium pressures means accuracy.

[Kendo]

My son gave me one of these center punches for Christmas. https://www.mcmaster.com/center-punches/easy-view-marking-punches/

It's amazingly accurate.

[BDA]

Very cool!

[JNS]

Thanks guys.
I've checked the torque setting and its only 9 ft lbs not 25. So I've only myself to blame. ( I was reading the cam pully settings not the cam caps.)
 Ive drilled the old bolt and can't get it to shift with a stud extractor. I dont want to go too far and ruin everything.

[jbcollier]

In my experience, stud extractors have limited use.  If the stud is truly stuck, it's more likely the extractor will break off.  If your hole is true, just keep going up a size at a time until you see threads and then pick them out.

[Clifton]

I've had hit or miss luck with broken bolts and studs. Last week I tried one of these extractors. It was a bent and snapped flush third member stud on a Toyota. First battery wouldn't budge it so I used a fully charge 18v Makita 1/4" impact and it actually worked. I had nothing to loose other than pull the axles and remove the diff.