hardened valves 71 383
- Thread starter pjm8047
- Start date
Kernel Sanders
Well-Known Member
- Local time
- 5:35 PM
- Joined
- Dec 13, 2008
- Messages
- 816
- Reaction score
- 241
- Location
- Ottawa, Ontario, Canada
Not likely as the hardened seats were started and ended with the factory induction hardened exhaust seats on the 452 heads for 76 - 78 I do beleive. Here is a link I found on the subject for your reading pleasure; http://www.moparmusclemagazine.com/techarticles/5115_cylinder_heads/
- - - Updated - - -
as an additional note... I wouldnt bother with the lead additive unless you are putting some serious milage on the engine and even if you are planning on it and you have a 'stock' setup you can add some 'rotator' spring retainers (found on truck/mobile home engines) on the exhaust valves though most people chuck them out at the first opportunity.
- - - Updated - - -
as an additional note... I wouldnt bother with the lead additive unless you are putting some serious milage on the engine and even if you are planning on it and you have a 'stock' setup you can add some 'rotator' spring retainers (found on truck/mobile home engines) on the exhaust valves though most people chuck them out at the first opportunity.
- Local time
- 4:35 PM
- Joined
- Dec 4, 2009
- Messages
- 34,101
- Reaction score
- 41,932
- Location
- Pasadena, Texas
I've seen 346 heads with hardened seats too....they started in 71. Unleaded gas was out before the 452 heads came out. After all, cat converters were out in 75. Chrysler was gearing up for it and knew that unleaded would be out within a few years and started the hardened seat heads early knowing that their cars would still be on the road when the gas would be mandatory.
71airgrabberRR
Well-Known Member
Flame Hardened Seats
Your 71 model year 383 may have 906 heads or 346 heads depending on when it was built. Like mentioned above, unless your really going to hammer on it, or are planning on putting some serious miles on it, I wouldn't bother with the lead additives.
The gasoline we have today is crap, compared to "the good old days". But things change............
When I worked in the machine shop, you could tell when the heads were clean if they had hardened seats or not. Chrysler used a "Flame Induction" system to harden around the exhaust valve seat area. This area around the exhaust seat would have a slight bluish tinged color to it.
Cranky is 100% correct.
However if you do start having a problem with the exhaust valves sinking into your head, there is a very easy way to do a quick check. Pull the valve covers and rocker arm shafts. Then simply lay a straight edge across the tips of the valve stems where the rocker arms would normally be. It should be a straight line across the tips. If you start noticing daylight between any of the intake valve stems and straight edge, you are starting to develop a problem. A very slight gap is acceptable. Especially if you are running a hydraulic lifter camshaft.
What happens is the exhaust valve starts to "sink" into the head when wear starts due to little or no lead lubricant. This in turn causes the valve stem of said valve to stick up higher than the rest. This causes the gap to appear on the Intake valves. It also reduces seat pressure on the valve spring.
Hope this helps.....
Your 71 model year 383 may have 906 heads or 346 heads depending on when it was built. Like mentioned above, unless your really going to hammer on it, or are planning on putting some serious miles on it, I wouldn't bother with the lead additives.
The gasoline we have today is crap, compared to "the good old days". But things change............
When I worked in the machine shop, you could tell when the heads were clean if they had hardened seats or not. Chrysler used a "Flame Induction" system to harden around the exhaust valve seat area. This area around the exhaust seat would have a slight bluish tinged color to it.
Cranky is 100% correct.
However if you do start having a problem with the exhaust valves sinking into your head, there is a very easy way to do a quick check. Pull the valve covers and rocker arm shafts. Then simply lay a straight edge across the tips of the valve stems where the rocker arms would normally be. It should be a straight line across the tips. If you start noticing daylight between any of the intake valve stems and straight edge, you are starting to develop a problem. A very slight gap is acceptable. Especially if you are running a hydraulic lifter camshaft.
What happens is the exhaust valve starts to "sink" into the head when wear starts due to little or no lead lubricant. This in turn causes the valve stem of said valve to stick up higher than the rest. This causes the gap to appear on the Intake valves. It also reduces seat pressure on the valve spring.
Hope this helps.....
Similar threads
