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Talk about engine building here. New products, tricky questions or showcase your work - If it's engine building related it's welcome here.
Hello all, forgive me if my question may come off as somewhat ignorant and somewhat longwinded, but nonetheless I would like input from the wise people here on the matter. I have a 65 Galaxie 500 with the 390Cui FE big block motor that needs to be rebuilt as the compression on some cylinders is cooked (70 psi or thereabout on two of the cylinders). I am fairly sure its the rings as putting a bit of oil in the cylinder resulted in compression skyrocketing up to 150 psi or so, however that is not my concern, my concern is that these engines were designed to use leaded gasoline as was available at the time which if I'm not mistaken functions as an anti detonation additive, and of course as we all know, we no longer have leaded fuel (outside of airports that provide it for GA aircraft), which means I will obviously have to continue running non leaded fuel.
I have heard that running non leaded fuel in these motors will significantly reduce the lifespan of these old V8s. I would like to know how valid/factual/significantly this affects the lifespan on the engine. What I heard also is it wears out valve seats a lot faster. Given that information I fear that if this is something to be concerned with and I don't address it during the rebuild, I might have potentially another component failure down the road and I will have to go in and tear it apart again. I want to make sure the engine is as well built and suited for how it will be run as possible.
The engine has the original heads and block, I was curious if maybe going with aftermarket aluminum heads with a fresh valve train with modern alloys would negate this issue IF it is in fact something I should be worried about or if there is possibly some other measures I could take to ensure the engine will be as reliable as possible. I use 89 octane fuel at the moment as looking through the factory manual, Ford recommended for the 390s premium whereas the larger 427, 428, and 429s were recommended Super which I assume is the 60s equivalent of 93.
Thank you for your time
Yes, the lead in the fuel not only acts as a detonation suppressant, but it also lubricated the valve and seat.
The first isn't a problem, with modern refined fuels, but for the valve seat wear there are generally two options for older engines - use an aftermarket seat lubricant that's added to the fuel, to prevent the wear, or have hardened exhaust seats fitted to the heads, possibly with better material exhaust valves. It's called Valve Seat Regression, IIRC, if you want to check it out.
The seat inserts is actually a relatively simple job, but as with most things the trick is finding someone who's actually competent to do the job.
If you fit aftermarket alloy heads, they will be set up for modern fuels, and will give a handy weight saving, but $$$ - cheapest would be the inserts and, maybe, valves - no recommendations, but a DECENT engine specialist should be happy to do it for you.
With the octane, just use what's recommended, maybe up a grade if it's pinking, because higher than required is expensive, and slightly less efficient.
Gord,
Thank-you so much for saying higher octane fuels are less efficient! Higher octane fuels making your car faster is one of these myths it is impossible to get out of people's heads.
Hi Mark,
A modern head is aluminium which also helps alleviate detonation. I don't know how set you are on keeping things original but a modern head would really breathe life into an engine from that era.
But if not, it should be possible to find a shop to make your heads un-leaded-proof.
Regards,
Henrik Morsing
I'm not worried about maintaining it original, the car already has a Sniper EFi system, and a top loader swapped in so that bus left the station a long time ago. I was looking at some of the pre assembled heads from Edelbrock and Trickflow, however what initially swayed me away from it was I heard speak that the aluminum heads being more susceptible to wear than the iron heads as aluminum is a softer metal. I always doubted the significance of this however as many cars have used aluminum heads with no real reliability issues, and they are especially common on modern engine designs, maybe this is just more wives tales from people stuck in their ways, after all there's still people that think back pressure is good because they don't understand exhaust scavenging and Bernoulli's principle . I really would like to switch to the aluminum heads for the aforementioned benefits, performance and compatibility. I am however also curious as to whether the differing metals would possibly cause some form of galvanic corrosion, I am not super educated on the subject of metal alloys and chemistry so I'd like to know if that something I should worry about?
ALL alloy heads use valve seat inserts, about the only thing that you might worry about is corrosion in the water jackets, and that's easily avoided with any of the dozens of products available to prevent that, such as any anti-freeze.
Okay, one more question which is a point that I heard on the Iron vs Aluminum head matter was that the aluminum head will be more susceptible to heat warping, which we of course leads to bad sealing of the deck, and we know where it goes from there. What is your opinion on that claim?
It's only going to be a problem if the engine is over-heated, basically boiled dry. Under normal conditions, with it actually looked after, there should be no issues.
If some damn-fool thinks that's actually a problem, they shouldn't be allowed to own a vehicle.
Look at AFR heads as well, not that I'm an expert, but I think they're pretty good.
Regards,
Henrik Morsing
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