Valve Seat Recession vs fuel additives

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rmel
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Valve Seat Recession vs fuel additives

Post by rmel »

Had to have my heads re-conditioned -- leaky valves due to seat recession :(

This spring, while up in the Sierra's noticed sluggishness which progressed to significant power loss.

Seemed like I was running on 3. Pressure check revealed the problem: ZERO pressure on #1, mediocre
on #2 and #3, #4 on the low side. I knew this could not be rings no evidence of blowby -- had to be leaky valves.

Rig trailered to Alex's shop in Vacaville. I had a spare set of heads with hardened seats originally
worked by Valley Head but needed to be re-conditioned. These went straight to the one head shop
in the Bay Area that knows how to do Pinz heads.

Bad boy heads removed and you can see #1, valves significantly worn into the seats, both intake and
exhaust, with the exhaust open hitting the rocker arm -- so why?

I try to limit pushing this 2.7L convert, keeping rev's around 2,800-3,000 while cruising. I do put on miles as
most interesting places for me is a trek. These heads took less than 25,000 miles for this to happen. I don't
have the complete history on these heads from the previous owner. I believe they were used and only had
the valves re-seated. It could be these seats are just lower hardness than the heads now on the truck, or
my running conditions are more severe than most, with 2.7L higher compression and mileage and thus
additional protection may be needed.

For sure with the absence of lead in the gas there will be more valve wear with these older engines. I've
looked into additives and found several. Most lead substitutes are based on the formation of metallic salts
that deposit on the seat; Sodium and Manganese being the more common. These subs claim to boost in Octane.
Miller Oil in the U.K. is based on Manganese (MMT), this is also the basis for Lucas Oil's Booster. Red Line Oil's
booster is based on Sodium. The literature out there on these products is scant, and what is out there tends to be
contradictory. Just after the elimination of lead in gas the industry substituted with MMT, which was later removed from
U.S. gas for health concerns but ran longer in Canada -- so there is more history on MMT than other formulations.
The classic car guys across the pond seem to like Miller's additive. I tend to trust Lucas and Miller in the U.K. has
positive references MMT vs all other additives. I plan on using Lucas booster as a preventive measure, although I'm
thinking of running at ~70% recommended levels.

Well the rig is back and runs strong, I want to keep it that way.

Anyone else have this problem or have a recommendations (short of trailering all the time)?
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idstitch
Posts: 48
Joined: Tue Feb 17, 2015 11:41 am
Location: North Idaho

Re: Valve Seat Recession vs fuel additives

Post by idstitch »

My 2 cents. Not being having a lot of experience with Pinzs I'll fall back on what I know. When our benevolent Government decided what type of fuel we had to use Harley Davidson's fix for their big twin motors was to install hard seats ,bronze, hard vales and soft guides, cast iron with guide seals. Also when you increase engine compression you must increase the octane level of your fuel.
kdiqq
United States of America
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Joined: Tue May 26, 2015 3:30 pm
Location: Houston, TX

Re: Valve Seat Recession vs fuel additives

Post by kdiqq »

Also, sitting for extended periods hurts valve seats. My dad had a boat that sat in storage all winter, with the valve pressed up against the seat in the head. When we fired it up it idled, started idling poorly, then dropped it's seat. Ruined the head, cylinder wall, and piston. Make sure you're turning the motor over often to make sure valves take turns pushed up against their seats.

As far as additive go, I've done loads of research relevant to hot rods and old, air-cooled bikes (of the same age as the Pinz). I will never ever ever add anything except Bell Performance Ethanol Defense in carb'd vehicles. EFI get nothing at all. Had really really great results with this setup. Hope this helps a few folks fighting gov't regulations :(
1977 Austrian 710M
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