Cam timing

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ZanettiZA
Posts: 70
Joined: 23 Sep 2009, 23:50

Cam timing

Unread post by ZanettiZA »

Hi everyone, I am looking for some advice on correctly setting up the cam timing, I have a 302 head with vernier cams.
I have read much about the 2.2mm method and understand that this is the best method, but when I set the cams up according to the markings and turned the engine over back to TDC (exhaust) the engine seemed to have correct overlap whereas with the 2.2mm method it did not. The only thing I can think is that I am doing something wrong.

So my question is, could some explain the procedure from beginning to end, as if the cams have just been reinstalled and all the tappets are relaxed...

Thanks
Peter
Posts: 21
Joined: 22 Dec 2008, 17:17

Re: Cam timing

Unread post by Peter »

I'm by no means an expert, but since no-one else has picked this up, here's my understanding:

The 2.2 mm method is based on the timing spec given in the Technical Data sheets. This states that for a valve clearance setting of 2.2 mm, the exhaust valve is just closing and the intake valve is just opening when #1 cylinder is at TDC at the end of the exhaust stroke. At this point in the cycle, the firing cylinder will be #4, and on that cylinder both valves will be fully closed.

So there are 2 ways to check the timing. The first method is to set the valve clearance on #1 to 2.2 mm, then observe that the intake and exhaust valves are just opening and closing as stated above. This can be done with a dial gauge. The second method is to set normal running clearances, and observe that the intake and exhaust valves are open to the extent of 2.2 mm at TDC. Again this can be done with a dial gauge.

Actually, the 2.2 mm for the second method should be corrected for running clearances, but when I did the measurements there was sufficient spread in my dial gauge readings that it didn't make much difference. And in any case, on my S2 engine the camwheels are not adjustable, so all I could do is confirm that cam timing was more-or-less correct, which it was.

Obviously, with either method, there is significant overlap, since by definition the intake and exhaust valves are both somewhat open at TDC.
Andrea Nistri
Posts: 549
Joined: 07 Jan 2009, 14:46

Re: Cam timing

Unread post by Andrea Nistri »

the 302 should have 1 mm; check the manual. Andrea
Andrea N.
ZanettiZA
Posts: 70
Joined: 23 Sep 2009, 23:50

Re: Cam timing

Unread post by ZanettiZA »

Hi Peter, thanks for the reply, basically what I did was to turn the engine till #1 was at TDC (exhaust) then set the clearances to 2.2mm on #1 turn the engine over twice and confirm the 2.2mm clearance at TDC which was 100%.

I then went on to set the running clearances from 4-2-1-3.

Obviously checking first that the piston didn't hit the valves with the new setting.

I also had make a new TDC marking on the flywheel as the existing marking (painted on) was about 50% out... Triple checked that the new marking wad correct by inserting a screw driver through the plug hole (very carefully) and cornfirming the piston position.

I checked yesterday before reassembly and found that there was markings on the cams in red obviously put there by the previous owner and with the setup that I did they line up perfectly so I guess it must be right!

I have another issue now though...

I will make a new thread for that, thanks for confirming the procedure.

Andreas thanks for the reply but I was told specifically that the setting is 2.2mm although I have seen the 1mm setting...
Andrea Nistri
Posts: 549
Joined: 07 Jan 2009, 14:46

Re: Cam timing

Unread post by Andrea Nistri »

Glad to know you sorted out your problem. I can confirm that the 302 engine on my Fulvia GTE is correctly timed with the 1 mm max valve lift. Best regards, Andrea
Andrea N.
Peter
Posts: 21
Joined: 22 Dec 2008, 17:17

Re: Cam timing

Unread post by Peter »

Andrea is of course correct. For the 302 engine it's 1 mm, not 2.2 mm. See attachment.

Peter
Attachments
cam_timing.jpg
cam_timing.jpg (122.7 KiB) Viewed 605 times
ZanettiZA
Posts: 70
Joined: 23 Sep 2009, 23:50

Re: Cam timing

Unread post by ZanettiZA »

Well this where it gets interesting...

At present the car has a 130(1216) block and crankcase, originally she had a 303, a transfer done by the previous owner. The head (302 casting number) however does come from the original 303 engine.

There have been some mods for this to work ie. Spigot bearing, alternator and starter fitment etc...

I have a 303 block and crankcase which I am working on which will be refitted in the car but for now she runs fine.

So I guess the question would then be... For now... Which is best? 1mm or 2.2mm ?

BTW she runs much better/smoother now at 2.2mm
Huib
Site Admin
Posts: 1563
Joined: 17 Dec 2008, 10:12

Re: Cam timing

Unread post by Huib »

Setting the valve clearances (the operational clearance as well as the measurement clearance of 1 resp 2.2 mm) is done with the pad of the rocker facing the base circle of the camshaft. The base circle is more than 180 camshaft degrees thus the exact position is not critical. You can just look at the cam to see if it is roughly pointing the other direction from the pad. The way I do it is look at the opposing valve. If it is open you can set the clearance for the valve you are working on.
If setting 1 then 4 most be open.
If setting 3 then 2 must be open
If setting 4 then 1 must be open
If setting 2 then 3 must be open.

Whether you use the 1mm of 2.2mm for setting the timing depends on the camshaft. The 302 engine does have an 818.100 camshaft which needs 1mm. The 303 engine has a 818.342 camshaft which needs 2.2mm. On the vernier camshafts the number is often engraved on the camshaft.

Using a 1216cc cilinder block to rebuild a 1300 engine was and is often done. Its original bore is 76.00 mm. Boring it to 77.00 gives a "brand new" standard 1300 block. You don't have to buy new pistons. If boring the 1300 block to oversize you have to buy oversize pistons in addition to paying for the boring.

The 1216 cc block has three M8 bolts at the rear while the 1300 blocks have three M10 bolts. Personally I would increase the hole diameter and use the M10 bolts with a 1300 crankcase. I seem to remember there is also an issue with the position of the dowel pins. Others may use the original 1216cc crankcase. The 1300 crankshaft runs well in both crankcases. The 1300 crankcase has more reinforcements though.
ZanettiZA
Posts: 70
Joined: 23 Sep 2009, 23:50

Re: Cam timing

Unread post by ZanettiZA »

Hi Huib, thanks for the reply, I will double check but I'm sure they are 342 cams.

In fact I have a second engine which I will be cleaning up etc... Then taking the 1216cc out and putting that engine in which is a 818.303.

But that's not a bad idea to rebore my 818.130, are there any specific details that I need to know if I were to have that done...?
Huib
Site Admin
Posts: 1563
Joined: 17 Dec 2008, 10:12

Re: Cam timing

Unread post by Huib »

I was assuming that the 1216 block was already bored to 77mm and that pistons, conrods and crankshaft from the 303 were transferred to the 1216 block / crank case but of course it can still have the 1216 crankshaft, conrods and pistons. Did you check?
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