43 replies to this topic

[[email protected]]

If you can get your engine number, we can tell you if it was originally built for unleaded (hopefully)

[joakwin]

are the valves for a leaded head different from a unleaded head?

my old 84 998 had triple groove valves and i could see the part number on the valve itself
the intake was 1062 and exhaust was 1770
but i dont know if that was the head that came factory or not

i know my 83 metro 1275 engine has the triple groove valves
the valves say 1058/1061 on them

but other then looking at the part numbers on the valves i have not pulled any valves out of the heads

[[email protected]]

The valves aren't different, it's the Exhaust seats that are hardened to suit the unleaded petrol

[twrminisport]

Valves are the same.
Its just the valve seats on the exhaust valve that are hardened to stop them burning out due to the higher burning temperature

Jesus

[DANNYBRYDON]

my mini is marked 99H7916. Is that leaded or unleaded ?

[[email protected]]

my mini is marked 99H7916. Is that leaded or unleaded ?

Thats a mid 70's engine number, unless someone has changed the head, or modified your one, it will be leaded

[mattaebersold]

Newer member and MINI owner here. I understand about the head being leaded or unleaded. If I were to put unleaded into my 77 MINI (unsure if a conversion was done) what would the symptoms be? How would that harm the engine? At the end of the day would it really matter what the exhaust valves do? They are just letting exhaust into the manifold. Why would the valves/head care if it was leaded/unleaded, unless it had to do with the actual material/metal used to make the components?

 

Any advice would help

[patricksouth]

i have just bought a mini unsure if its leaded or unleaded should i just run an additive to be safe or will this damage the head aswell.

[tim-92]

1989 unleaded

Guide to Engine Numbers

Eventually i'll build this into a guide to Mini and Metro engine numbers. Telling you what they mean, how they break down and which mini's and Metro's have equivalent engines.

So far though here's a list of engine number prefix's which are compatible with unleaded petrol. It is only the head that is different, so you can use this information to source unleaded heads from breakers for your mini.

Here is a list of unleaded engine numbers for the 998cc engines. 99HF15, 99HF32, 99HG30, 99HG31, 99HG32, 99HG33, 99HG34, 99HG39, 99H/D81P, 99H/E20, 99H/E21, 99H/E22, 99H/F16. All the post 1990 1275 mini engines are unleaded compatible, many of them have CATs so can only use unleaded. None of the pre 89 engines, or sizes other than 998 and 1275 can use unleaded, with out modification. Information Received from Barrett''s MG-Rover, Folkestone.

Do you know if the 1989 mini racing runs on unleaded or leaded. I've found one that I'm interested in buying. I am presuming unleaded, but was it later in 1989 or all models throughout the year?

Edited by tim-92, 10 October 2013 - 02:09 PM.

[some1158]

 

1989 unleaded

Guide to Engine Numbers

Eventually i'll build this into a guide to Mini and Metro engine numbers. Telling you what they mean, how they break down and which mini's and Metro's have equivalent engines.

So far though here's a list of engine number prefix's which are compatible with unleaded petrol. It is only the head that is different, so you can use this information to source unleaded heads from breakers for your mini.

Here is a list of unleaded engine numbers for the 998cc engines. 99HF15, 99HF32, 99HG30, 99HG31, 99HG32, 99HG33, 99HG34, 99HG39, 99H/D81P, 99H/E20, 99H/E21, 99H/E22, 99H/F16. All the post 1990 1275 mini engines are unleaded compatible, many of them have CATs so can only use unleaded. None of the pre 89 engines, or sizes other than 998 and 1275 can use unleaded, with out modification. Information Received from Barrett''s MG-Rover, Folkestone.

Do you know if the 1989 mini racing runs on unleaded or leaded. I've found one that I'm interested in buying. I am presuming unleaded, but was it later in 1989 or all models throughout the year?

 

I have a 1989 Mini Racing, registered in April '89, and mine has always been unleaded (there's still a sticker under the bonnet to say as much).  This site - http://www.guess-wor...Tech/engine.htm - might help you double-check your engine. 

Edited by some1158, 11 October 2013 - 07:56 AM.

[ACDodd]

Yes definitely, early CAM 4810 head are Leaded. I have few here that I have for converting to Unleaded by fitting the hardened seats into them. You have to remeber there is only about 3 years of production from the factory with Unleaded CAM4180 heads. Where as, the head dates back to the early '80's in metros and minis all leaded.

AC

[Jordan18]

i don't have a engine number on my engine. i bought it an i was told its been rebuilt and bored to a 1380 in the past 9 years, there is a part number on the head but I'm unsure on whether it is leaded or unleaded. It defiantly looks as it has been re built as all of the ports are polished, its just had oil in it.

 

cheers, 

Jordan 

[dyshipfakta]

i don't have a engine number on my engine. i bought it an i was told its been rebuilt and bored to a 1380 in the past 9 years, there is a part number on the head but I'm unsure on whether it is leaded or unleaded. It defiantly looks as it has been re built as all of the ports are polished, its just had oil in it.
 
cheers, 
Jordan 

If you have seen the ports then you should have seen the valve seat. Unfortunately no way of knowing for you without removing the head.

[Deathrow]

This is a five year old thread. Please start a new topic if you're unsure about your cylinder head.