Unleaded ok for Nord?

Me again,

The gtj is having burnt valves rectified and the head is off.

Question is, do I need to upgrade the valve seats to run on unleaded or are the original items ok?

Thanks again.
Henk

All OK as is.
Make sure they check valve seats and guides are OK while they are "in there".

I agree with RicksAlfas. My Series 3 Spider had one of the exhaust valve seats come loose in the head, so wise to check these thoroughly. I was relatively lucky though, because despite the problem, the valve didn't get hit by the piston, despite being held slightly open. My valve guides were also pretty bad, so these were done at the same time as having the new valve inserts fitted. Hopefully this will now stop it smoking after ticking over for a few minutes......

The valves and seats are OK for unleaded, but ignision set at factory setting you need 98 octane fuel. With 95 you need to advance ignision 2-3 degrees.
Erik

Yes, as the guys have already said. Good tip by Erik.

Thanks all, much appreciated.

Shurely shome mishtake. With the lower octane fuel you would have to retard the ignition. However, that may cause slow running/spitting back problems. Much better to keep the ignition advanced and run on a good 98/99 octane such as Optimax. This will also give more power.

OK, now I'm a bit confushed. As a newbie owner of a '79 116 GTV, I was told by the previous owner (PO) that she had run it on regular unleaded and had been using a lead substitute additive, 'Valve Master' I think it's called. I had a suspicion that it would have brass seats which I understand are OK for unleaded, so I wondered whether I needed the additive after all. Can you tell me if it does have brass seats or not? And, is it better to continue as advised by PO or should I up the octane rating and advance the timing? What benefits are there to each scenario? Thanks in advance. Chris

I was definitely under the impression that these engines had cast iron valve seats...hence the need for a lead subsitute.....

Originally Posted by Stori

I was definitely under the impression that these engines had cast iron valve seats...hence the need for a lead subsitute.....

Ok. I am very far from being an expert but for what it's worth this is my experience. Fistly the valve seats are sintered cast iron not brass (which would be much too soft). All alloy-headed engines such as our Nord 105s have to have iron valve seats and only cast iron headed engines (such as old pushrod crossflows) can run the valves directly in the heads. From what I have read our seats do not need replacing since they are of sufficiently good quality to run unleaded fuel without too much risk of valve seat recession (ie wear). The lead in fuel acts as a sort of cushion and protects valve seats. HOWEVER our engines do need plenty of octane (so use RON 98or 99 not regular RON95). This is particularly important if you have a rebuilt engine and the head has been skimmed (to make it flat), which will further increase the compression ratio. Another reason to use the highest octane fuel you can get is because the advance curve on our old 105s seems to be such that in order to get enough advance to get a good tickover there will be more advance than the manuals recommend when the dizzy weights are "full out" -- ie at high revs. Personally I do not favour Castrol Valvemaster and other such non-lead additives, though they may be ok. I use stuff called "Tetraboost" in my Alfa (Junior) and historic racing car -- this is a genuine Tetra Ethyl lead additive which boots octane (considerably depending on mixing ratio) and does wonders for valve guide and seat wear. It is not available over the counter but has to come in boxes by special delivery (like shotgun ammo). Here is the detail (no! I have no connection with this company except as a customer):TetraBOOST is not a substitute, but is the only additive that makes real leaded fuel from the unleaded pump. It has now come to be recognised as the de-facto standard for fuel additives and is specified by National Motor Museums in the UK, France and The Netherlands, acknowledged marque experts, restoration companies, engine builders and vintage and classic race teams. Indeed most of the most famous and irreplacable vintage and classic cars and bikes now run and race on TetraBOOST additive.

Finally, within reason, compression+advance allied to octane means POWER.
cheers

That's a great post griffo.

Thanks to all, as I've learned something that will be a big help, I'm sure, just regards using the 98RON fuel instead of regular.

I'm glad I drained out the tank now as part of the cleaning out process.

BTW - did you forget the link to Tetraboost?

Yes, sorry. Try: TetraBOOST
By the way this stuff is highly toxic. Be sure to carefully follow the safety instructions on the can.

Hi Griffo, GTVJim and all,
Very good detailed discription, but for all you every day users in 105 and spiders, just put in the highest octane you can get at the station and drive, As long as the engine does not 'pink', cough or run on when you stop, all will be fine. If it does any of those then retard the timing slightly so it doesnt.