Lead replacement fuel additives

#1
Been advised my standard reconditioned 302 Windsor needs to run with a leaded fuel additive... My bssic understanding is that you get VSR Valuve seat regression in soft Cast iron cylinder hesds without additives when using unleaded. ..
Has anyone any views on the subject....? Ie is it possible/worth looking to convert the CH in order to run straight unleaded...? Is the additive really necessary...?...Amount of additive to add....
I am a bit new to GT40 ownership with only a basic 302 in a early humble KCC I'm bring back from South Africa so any advice most welcome....
Cheers Marcus
 
#2
What year are the cyl heads, later 80's heads had a factory hardening process applied in the exh valve seat area, however it is reduced if you cut original valve seats by much. You can fit hardened seats, but IMHO that money would be better spent buying some performance heads with hardened seats already fitted. One thing you can do to reduce seat wear is to remove any rotator type valve spring retainers etc and actually fit stronger valve springs along with single piece retainers. As this cuts down on the valve seat wear by preventing valve rotation ( with valve rotation the valve actually skids to a halt each time it closes and tries to friction weld itself to the seat which is what actually erodes the seat material ).
 
#3
Hi Marcus,

You'll probably get a lot of different opinions here. I'm a bit surprised that the reconditioned heads have not been converted with hardened valve seats. I have had valve seat regression using leaded petrol in the past, so hardened seats is the way to go if it's not too late for this build. Otherwise, it's cheaper to use Castrol Valvemaster or similar rather than rebuild again at this stage. Some believe that seat regression is solely due to less-than-optimum ignition timing or fuel mixture. With the loss of lead in pump fuel and also the introduction of ethanol into fuels, I would certainly take the advice and use the additive. For the limited annual mileage of my MGB, the cost of additive is a drop in the bucket. In the GT40 I also add fuel preserver to prevent the modern fuel mixes going stale, as well as an octane booster. Also consider an Ethanol neutraliser if your car is more than 20 years old. Unless you have easy access to a racing-quality fuel !
 
#4
Once again Tony and awesome response and very helpful.....the KVA engine was restored on a budget clearly....!!! Yes it have made sense to have put in hardened seats but what's done is done for the time being..... the seller gave me the additive and said it should be used so I will comply as I believe the engine to be an early/mid 70's and I will get the engine umber off the bottom of the block tomorrow when its on the ramp to verify year. I do fully intend to do some miles in her so would you recommend 95 or 97 unleaded with the additive...?
Once again huge thanks.....:)
 
#5
Sorry Mac fogot to thank you also for taking the time to respond...….this new 40 ownership thing is a bit daunting for a newbie so if great you guys take the time to respond....:)
 

Howard Jones

Member
GT40s Supporter
#6
Need to know what you think the compression ratio and timing is and less importantly the cam specs. However if you think that your engine is "basic" and "humble" and it makes what feels like less than 250-260hp my guess would be about 9 to 1 or even a bit less. I think you would be fine trying the regular unleaded. I have run my 302 @ 10 to 1 on regular (87) in a pinch and it was OK. Kept the revs down and simply drove the speed limit home down the freeway. By the way in California the good stuff is 92 which is what I used all the time without problems. Here in Texas we have 93 and that as good as it gets.

Given you choice of 95 or 97 regular or high test why now just use the good stuff (97). For a multi hour drive down the highway at legal speeds you could run the 95 to save a bit of money I guess. By the way, is there a different octane rating system in SA than in the USA given the much higher numbers?
 

Ian Anderson

Member
Lifetime Supporter
#9
Need to know what you think the compression ratio and timing is and less importantly the cam specs. However if you think that your engine is "basic" and "humble" and it makes what feels like less than 250-260hp my guess would be about 9 to 1 or even a bit less. I think you would be fine trying the regular unleaded. I have run my 302 @ 10 to 1 on regular (87) in a pinch and it was OK. Kept the revs down and simply drove the speed limit home down the freeway. By the way in California the good stuff is 92 which is what I used all the time without problems. Here in Texas we have 93 and that as good as it gets.

Given you choice of 95 or 97 regular or high test why now just use the good stuff (97). For a multi hour drive down the highway at legal speeds you could run the 95 to save a bit of money I guess. By the way, is there a different octane rating system in SA than in the USA given the much higher numbers?
Yes there is a different number system UK to USA
USA uses an average of RON and MON and in the U.K. we only use RON so you tend to need to add between 5 and 6 to the USA number to cross reference to the U.K.

Just something I read up a long time ago!

Ian
 
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