Unleaded heads

[ISELLHH]

I currently own two Travelers 1961 & 1971. I also have a extra 1098 engine and gear box. My question is, what's the best way to check if any of the 3 engines have been fitted with harden valves and seats to run unleaded fuel. How does everyone feel about running lead subsitute? Since these cars are being restored I'm leaning towards redoing the heads.

[Neil MG]

My opinion: Not really necessary unless you already need or plan cylinder head work. No additive necessary either, just fill up with unleaded and enjoy! More important to make sure the car timing and tuning is spot on and to check your valve clearances regularly. Annually as part of a full service or when you change the oil if you do a high mileage.

[aupickup]

i do about 15000 miles a year motorway and town driving and had no need for an unleaded head or any additives

[mike.perry]

Why change a good head, wait until it is knackered then change it

[bmcecosse]

Exactly - the 'unleaded' story is a huge con trick..... These heads are so common and cheap that you really don't need to do anything - although I do advise 15 thou for the exhaust valve gaps and check/reset them every 3000 miles.

[linearaudio]

And another one!!
I thrash mine around doing about 10000miles a year, and haven't had any valve problems-and that is running a higher compression ratio than standard!

Get the feeling we are trying to make a point?

[ISELLHH]

Thanks for the advice, To much hipe about unleaded fuels. The question that this brings me to is my cars are from New Zealand. How do I know if they are high or low compression heads?

[bmcecosse]

The heads never changed - the low compression was only for 'commercials' and was done with pistons with deeper dish.

[jonjeans]

Hullo All
Is there a significant difference between a 1098 head and 948 head? By significant, bores spacing difference? Any problems fitting a 1098 head to a 948 that |I should be aware of?
Thanks
jj

[bmcecosse]

Bigger inlet valves - and better flowed ports. However the chambers are also bigger - so the 1098 (12 G 202) head needs a 60 thou skim before fitting to a 948. That done - it's a straight swap.

[jonjeans]

Many Thanks for that useful info.

[bmcecosse]

It's effectively then a 'Stage II' head and worth about 4 to 5 bhp extra. If you also fit the 1098 camshaft - that would be worth another 4 to 5 bhp when used with that head - but at ~ 12 % higher revs than before.