how do i find out if my heads can run on unleaded fuel?

rousecapri · Post by **rousecapri** » Wed Jan 31, 2007 5:58 pm

i have early heads can i use unleaded fuel?
was told if a magnet sticks to the exhaust valve they are not any good for unleaded fuel is this right
thanks mark

ppyvabw · Post by **ppyvabw** » Sat Feb 03, 2007 1:37 pm

I think the matter is subject to some debate. The official line is that only heads after 1976 SD1 will run on unleaded, but I think some people say it is possible to run any rover heads on unleaded because they all have inserts in.

Who told you about the magnet on the exhaust valve, I dont think thats right somehow.

mikeinatruck · Post by **mikeinatruck** » Tue Feb 06, 2007 8:54 am

Early heads between 1967 and 1982 are not designed for unleaded fuel, ideally you need to use a lead substitute.
Up to this time the inserts where close grain cast iron/mechanite but after 82 they where made from exceptionally hard copper bronze.

Its not too expensive to get them changed if you have the heads off.

EDIT: had 72 not 82 in main body...

ppyvabw · Post by **ppyvabw** » Tue Feb 06, 2007 12:12 pm

I thought it was up to 76 with the introduction of the SD1

mikeinatruck · Post by **mikeinatruck** » Tue Feb 06, 2007 4:31 pm

76 saw the intro of the SD1 and they increased the size of the inlet and exhaust valves 40.0mm and 34.3 respectively. But the valve seats remained the same. until 82. This also marked the change to single valve springs. (you cant interchange valve springs either without machining)

Post by **katanaman** » Tue Feb 06, 2007 5:50 pm

mikeinatruck wrote:76 saw the intro of the SD1 and they increased the size of the inlet and exhaust valves 40.0mm and 34.3 respectively. But the valve seats remained the same. until 82. This also marked the change to single valve springs. (you cant interchange valve springs either without machining)

Not quite right but I know where your coming from. From 76 on land/range rover said the heads can run unleaded but rover didn't on the SD1. Given they are the same heads from the same factory heads from 76 on will run unleaded quite happy.

mikeinatruck · Post by **mikeinatruck** » Fri Feb 09, 2007 8:48 am

Its not that you cant run unleaded its the fact you needed an additive to prevent VSR.

Austin Rover as they where at the time and Land Rover where run as seperate entities so never agreed with each other.

I expect its been mentioned before but the best lead substitute is Tetraboost, its not cheap though.