Wondering if I will need to get hardened seats installed on my heads pending the answer here.
What year 340 heads got hardened seats?
- Thread starter 340inabbody
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If the heads you want to use do not have hardened seats and the heads will be subject to long term use of unleaded fuel, installation of hardened exhaust valve seats is recommended.
Oh ya... welcome to forabodiesonly.
Oh ya... welcome to forabodiesonly.
I am not sure if any of them did.
Mine received hardened seats in 2003.
Yes, I feel like being a dickhead
Yes, I feel like being a dickhead
What's the deal with needing hardened seats? My dad always mentioned that I would have a hard time with my old cars and today's fuels. Ive never ran leaded fuel or any additives. Ive never had an issue with thousands of miles of daily abuse. Am I just lucky?
I am not sure. A lot of people talk about sunken seats etc. Maybe its not a big deal or maybe you are lucky lol
I am not sure. A lot of people talk about sunken seats etc. Maybe its not a big deal or maybe you are lucky lol
oldmopardude
Well-Known Member
No. I have been running multiple Mopars on unleaded fuels since unleaded came out with no Ill effects. I am just finishing a 69' Cuda with the 383, and I asked my machinist for the umpteenth time: do I need hardened seats? He responded by saying if it was a ford or chevy, yes. He continued to say Mopar used some of the best seats available back in the day, and to this day he would starve if he had to rely on Mopar valve jobs, or rebuilds. They are very well built. I remember reading an article in 1989 in a hotrod magazine documenting a test of Mopar engines by the now defunct racing guys at Chrysler.
I can't remember the name. oh yes, direct connection. They came to the conclusion after extensive testing of all the Mopar engines using unleaded, and came to the conclusion that hardened seats were needed only if you exceeded 90% of the power band 90% of the time. otherwise, don't waste the money.
I keep searching for that article, some day I will find it again.
I had my heads re-done when I built my 273. My machinist said I didn't need hardened seats. If I was abusing it regularly, stainless valves would be a good idea. I only put a couple thousand miles on a year.
Mattax
Just the facts, ma'am
Exhaust valve seats - Maybe '72, probaly '73. see
1973 Imperial and Chrysler Clean Air System Reference Service Repair Book from the Master Technician's Service Conference (Session 302)
1973 Imperial and Chrysler Clean Air System Reference Service Repair Book from the Master Technician's Service Conference (Session 302)
oldmopardude
Well-Known Member
lead is overrated. in 1971 while in the Military I drove a 66' Polara 500 Hardtop with the 383 two Barrel. Fully leaded fuel, 95 octane regular gas. It had it's first valve job at 38,000 miles, and again at 80,000. It was always the same Valve, cylinder #6. Those two barrels ran hot all the time. Upon disassembly the valves were burned up,and looked like
charcoal. Lots of carbon buildup. Today, I have that same 66' Polara 383 model. After twenty years it runs as clean as it did in 1998 when I bought it, if not better. However, periodically I would run seafoam thru it, and some upperlube to be safe. I could get in that car Tomorrow and drive it to California.
charcoal. Lots of carbon buildup. Today, I have that same 66' Polara 383 model. After twenty years it runs as clean as it did in 1998 when I bought it, if not better. However, periodically I would run seafoam thru it, and some upperlube to be safe. I could get in that car Tomorrow and drive it to California.
perfacar
Well-Known Member
if you have same seat and valve angles, 45 deg, and use a stainless valve, you won't have any problems. reason, for seat recession , was interference angles between vale and seat before. also, I've tested many stock exh valves, they are stainless. the int are mild steel. now if this was truck engine, hauling heavy loads, I would install hard exh seats.
harrisonm
Well-Known Member
I know for a fact that at least one 69 340 (mine) got them. OK, seriously, I had them put in mine about 25 years ago because everybody said I had to. Although now I wonder if it is really that necessary. I talk to people all the time who say they did not and have no problems. Modern fuel is better and cleaner than it used to be. I wonder if that helps offset the lack of lead. Remember how dirty and crusty valves and combustion chambers used to be when disassembling an engine? I pulled the heads off my 340 a few years ago to replace a leaky head gasket, and everything was as clean as a whistle. Hmm, exactly how clean is a whistle?Mine received hardened seats in 2003.
MoparMike1974
Well-Known Member
I think it was 72. They did not install hardened seats, the seats were cut into the iron head and then it was induction hardened. I have seen sunken seats on a 318 and a 340.
Lead helped prevent burned valves and seats. Another way to help prevent it is to cut the seat a little wider. The larger surface area helps transfer heat from the valve to the head.
Mopar did tend to use better iron than the other two brand X. Ever pulled down a 100k+ mile 302 ford? Every one I ever pulled apart had a massive ring groove at the top of the bore. I have never seen that on a 340, which they did advertise as having a higher nickle content. Pulled down a 40k mile 318 and it still had the factory crosshatch in the cylinders. So, metallurgy might play a role in why you dont see sunk seats on the mopars very often....but it does happen.
Lead helped prevent burned valves and seats. Another way to help prevent it is to cut the seat a little wider. The larger surface area helps transfer heat from the valve to the head.
Mopar did tend to use better iron than the other two brand X. Ever pulled down a 100k+ mile 302 ford? Every one I ever pulled apart had a massive ring groove at the top of the bore. I have never seen that on a 340, which they did advertise as having a higher nickle content. Pulled down a 40k mile 318 and it still had the factory crosshatch in the cylinders. So, metallurgy might play a role in why you dont see sunk seats on the mopars very often....but it does happen.
famous bob
mopar misfit
Finally , mike got it right. Better metal, and flame hardened. Which could be lost w/ excessive grinding.
I ran my 340 X-head motor 10.000 + miles without hardened seats, I always checked my valve lash at least 2 times a year and never had to adjust them. That was a waste of time but If the exhaust closed up I would know it was burning a seat, The last time I had the motor apart the seats looked like new, In 20 years I had that motor apart many times to check it out and it never needed anything, many 7500 rpm 1/4 mile runs plus street driven. I love my mopars.
valiantwagonguy
Well-Known Member
We had unleaded gas in the early 60's AMACO High Test was unleaded and there were no head problems .I have been running unleaded in my cars for hundreds of thousands of miles with no ill effects .I think this whole valve seat thing is a load of crap unless you are really beating your motor to death constantly. Besides,sll MOPARS have flame hardened seats from the factory so unless you had them ground you are fine.
I sunk some valves in my 68 340 in my Barracuda with less than 10 k on the rebuild... I always have my head guy put hardened seats in the exhaust side...
71 j heads is the earliest I remember with harden ex seats.
I did sink the ex valves in the 318 in my 68, 3/4 ton. Pulled a lot of goose neck trailers with it. It's in my barn, with a m880, 360 in it now. I wore the 318 out at about 350,000 miles. It now has over 500,000 miles on it. That truck has been everywhere from the Big Apple Circus at the Lincoln Center in New York City to Portland Oregon to deliver horses. From Juarez Mexico to Montreal Canada.
I did sink the ex valves in the 318 in my 68, 3/4 ton. Pulled a lot of goose neck trailers with it. It's in my barn, with a m880, 360 in it now. I wore the 318 out at about 350,000 miles. It now has over 500,000 miles on it. That truck has been everywhere from the Big Apple Circus at the Lincoln Center in New York City to Portland Oregon to deliver horses. From Juarez Mexico to Montreal Canada.
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Mattax
Just the facts, ma'am
Except we knew it as American
Premium, or Super premium. lol. Remember the name change? I think they also promoted as 'white' as part of marketing. My folks used it in our 318 powered Belvidere, along with a slightly advanced timing. Probably helped with 21 mpg they got on long trips to the south. We called it Hi Test too. Don't know if that was also what the company's called it, or just slang.
Yup I remember American and I used to get those green dinosaurs from Sunoco too! Dang necks broke off fast in the tub! I think it was life boy but my mom used another brand once when she washed my mouth out. I used to hear this as a kid > filler er up with ethel lol
Be safe and put the hard seats in. Though I've never personally had the seats sink in a passenger car, my trucks are a different matter. I've had many a sunken exhaust seat in my truck engines until I went to hardened exhaust seats.
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