Good morning everyone,

I hope you and your families are all doing well in these difficult times.

It is many years since I adjusted the tappets on a Type 4 engine as in my 914 so I want to double check some odd results I am getting.

I checked on Youtube and it is suggested that one way to find TDC etc is to check TDC on No 1 cylinder and the timing mark shows in the timing hole (when both tappets are slightly loose, to confirm) then turn the engine backwards 180º then check cylinder No 2, repeat process for No 3 then again for No 4 cylinder.

The other suggestion in the Brooklands Books Owners Workshop Manual is to remove the distributor cap, line up the rotor arm with the notch on the side of the distributor, with the timing mark showing in the timing hole, then you are ready to adjust cylinder No 1. For No 2 cylinder turn the engine the normal way (clockwise) 90º then you can check Cylinder No 2, repeat again for No 3 then No 4.

I have tried both ways, No 1 OK, then No 2 does not have both valves fully closed. Then when I try No 3 that's OK then No 4 again the two valves are not fully closed.

I have the engine out as I am in the process of checking my "new car" over before I start doing some serious milage, so access to the engine is easy.

Anyone else ever come across this situation. As mentioned, I am no novice but this has me beat!

Any suggestions would be gratefully received.

Hi Tony,

Not familiar with the Brooklands Book method. Do you have the flywheel installed? If so, there should be a notch at the top of the flywheel that aligns with the seam of the engine case when #1 is TDC. That is often more useful because sometimes the timing marks on the cooling fan are confusing.

You can confirm TDC at #1 in various ways. If the distributor is "clocked" properly then yes it should be pointed at spark plug wire #1 (roughly). You can also remove spark plug #1 and very carefully (not with something that will break off!) feel if the piston is at top and going up or down. But the flywheel mark should be correct.

From TDC for #1 rotate flywheel 180 degrees clockwise to get to #4 TDC, then 180 degrees again for #3, and then #2.

There are shortcut methods for finding TDC and picking which valves to adjust (RIP, Krusty), but with engine out and you not having done it in a while it's best to do it very basic I think.

Good luxk.

Very many thanks 'BeatNavy' I will look out the flywheel marking, just in cast someone over the years has fitted an odd fan!

Very many thanks 'BeatNavy'. I double checked the position of the timing mark on the flywheel compared with the mark on the fan. They are both in the correct position. But..... when I checked both of those then checked the distributor the rotor was pointing at No 4!!!! So I can only imagine that whoever built this engine put the off set drive from the crankshaft to the distributor 180º out.


So no wonder I was scratching my head. So I popped the distributor out, knocked out the pin from the off set drive on the bottom of the distributor and turned it 180º. I put the distributor back in and then with all four plugs out checked that I was getting TDC in all the right places on all four cylinders.

So thanks for the heads up, I am in your debt.

Have a good week - Tony

Excellent!

Interesting way of reclocking the distributor. The normal way is to carefully pull that drive gear out of the case and then re-insert at the correct position. But hopefully your way works!

No you're not. That's what this place is here for

I had a chance to visit Normandy about 8 years ago. I believe we stayed at a chateau in Valognes. Wonderful area, and wonderful people

Maybe I’m thinking about it wrong but 180 out from #1 would be #3.
1 4 3 2

If it was pointing to #3, remember that the crank turns twice for every single turn if the distributor, so if it was pointing to #3, i woukd say turn the motor another 360. Being 90 off (or 270?) it seems like your plug wires are off or you need to rotate the distributor 90. Either way, i would use the chopstick down the sparkplug hole technique at this point to find your tdc and go from there.

I'm glad you enjoyed Normandy, it's a good place to live. Did you know Valognes had a V2 rocket site near there during WW2.

Many years ago, while living in England I book a second hand book about WW2 V1 and V2 rocket sites. Years later we moved to Normandy then this old book came into it's own.

Thanks again for your help.

My problem was I was starting from complete unknowns. I had no idea what was where. By going down the flywheel mark at TDC at least I had a datum point.... TDC No1 cylinder. Then I could also check the fan pulley markings.

Then I double checked each cylinder for TDC in turn to prove the theory.

Then my thinking was, if I set this up per the factory any pour soul in the future would be able to do the tappets per the book without re-thinking everything.

But thanks for your comments - Tony

Remember that the crankshaft rotates twice for every full cycle of the engine. So having the TDC mark at #1 will mean either #1 or #3 is at TDC. That's why you check the distributor rotor or the rocker arms on the valves, to see which one it is.

Likewise, turning the flywheel 180 degrees will only turn the distributor rotor by 90 degrees. If your instructions don't specify what is being measured saying "turn 90 degrees" more than likely means the distributor rotor. "Turn 180 degrees" could be either...

--DD

Thanks Dave, just to make sure I tried setting the tappets as suggested, then turned the motor several times. Each time I checked the tappets and all seems to be in order now.

So hopefully that should be all OK. But I will certainly run the engine then recheck the tappets again.

Thanks everyone for all your help and advice. Tony