Timing Setup

**MegatronUK** · 22-08-2014, 21:49

Stripping down the engine after having it sat in the car for what seems like years (actually, it *is* years) to mock up the work needed to fit it. We're now ready to paint the engine bay and interior and finally fit it for *good*.

Anyway, as we were degreasing it and generally taking all the parts off, we noticed that the timing wasn't lining up. With the crank set to the TDC mark, the exhaust cam was set correctly (arrow pointing towards the inlet) but the inlet cam and distributor/oil pump drive wasn't lined up either.

The inlet cam was one full tooth out (retarded compared to exhaust), we've corrected it and the distributor gear now (again, one tooth out), so that all the timing marks line up.... Hand turning the crank it's turning over fine now (though it did before!), and with all 3 marks on TDC it's ready to fire on no. 1 and rocking on no. 4 so it looks to be set spot on.
But my question is, could it have run with the inlet one tooth back? Would there be any reason to do this deliberately?

**Erikmex** · 22-08-2014, 22:22

It would run with the inlet cam advanced one tooth. You say retarded but then one tooth back? If the cam is one tooth back in the anti clockwise direction it's advanced.

**MegatronUK** · 22-08-2014, 22:40

Sorry, I was confusing myself by that as well. Looking at the engine from no.1 piston end, with exhaust and crank at TDC, the inlet was one tooth further round clockwise. To confirm, by setting the inlet to the correct timing mark, it made the exhaust and crank go 1 tooth back anti-clockwise.

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The marks were as shown in the attached image - both the inlet and distributor drive out compared to the exhaust and crank.

**MegatronUK** · 24-08-2014, 17:46

Well, I guess this is what happens when you don't set the timing right....

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With the timing belt not having been fitted correctly we just didn't trust it, so have started to strip the engine down. Good job we did.....

Apart from the marks, miraculously, it seems ok. Valves appear straight, though very highly carboned. Crank has been reground and bottom end bearings are all +0.25mm oversize (though most would appear worn - I can't say whether through wear or standing for a number of years while we built the Escort up around it). Pistons are Mahle and other than heavy carbon on the crown (cleaned, in the above image), are very clean with nice bores, good rings with no evidence of blow-by.

It doesn't look like it's been together very long, by the looks of it.

**MegatronUK** · 24-08-2014, 19:49

So I think I'm now even more confused than before!

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I'm just looking back at the pictures I took and didn't realise at first, but the 4 valve marks are actually 2 old marks and 2 new marks. I think the two new marks were caused when we reset the inlet cam to the correct timing mark with the rest of the gears at TDC, as they should be. It's only been turned over by hand, so it shouldn't have damaged anything... but that means that the inlet cam was one tooth out and was not hitting the piston. But the exhaust cam was set right and at some point the exhaust valves were hitting the piston.

I'm now really confused as to why either set of valves should ever be hitting the pistons when the timing is set to what it's supposed to be.

What are the potential causes of this? When setting the cam timing results in valve to piston contact?

**Graham** · 24-08-2014, 20:00

What are the potential causes of this?

its common to see on yb's, even totally standard unmodified ones that havnt been apart or incorrectly assembled, they are short on valve piston clearance from the factory. modified pistons with cutouts is a good idea at any spec of engine

**MegatronUK** · 24-08-2014, 20:06

Thanks for the information, it's reassuring (I think!) to know. So would you recommend any particular remedies or course of action when we re-assemble the engine? I was hoping to re-use the pistons, as other than the valve contact marks, they look remarkably new and unworn.

**Graham** · 24-08-2014, 20:17

no reason why you couldnt reuse them. its still a good idea to have some cut outs put in them though, the dings will make it easy to position them for cutting.

**Erikmex** · 24-08-2014, 20:33

Common on XE's too, I once missed a gear shift on my old XE and pinged it to 8500rpm, lost all compression, lifted the head and the valves looked ok but tiny marks on pistons, 15 valves were bent but visually when fitted they looked like they seated ok.

**Graham** · 24-08-2014, 20:34

http://www.turbosport.co.uk/showthre...=1#post1956629

daves pistons, with a heavily skimmed head and a skimmed block on an engine that will go racing the cutouts are deeper than you will need.

**terry2** · 30-08-2014, 19:22

be carefull on the crank pulley the timing mark for tdc is the crank sensor peg and not the v in pully

**stevieturbo** · 30-08-2014, 22:14

If the engine has been running for a while with the valves hitting...might be worth replacing the valves anyway even if they appear to be straight ?

A broken valve really does some serious damage.

**MegatronUK** · 05-09-2014, 21:12

Well it's now at the engineering company. I want the crank, pistons and valves checking. I just don't trust that it's been put together properly by the previous owner.

**MegatronUK** · 05-09-2014, 21:16

Originally Posted by terry2

be carefull on the crank pulley the timing mark for tdc is the crank sensor peg and not the v in pully

Yep. Spotted that quite early on. The odd thing was the inlet bank one tooth out - everything else was lined up correctly with the crank (peg) at TDC. Should have been a warning sign, I guess!