L79 owners, step inside
Thread Starter
Race Director
Joined: Dec 2000
Posts: 12,913
Likes: 60
From: Twin Cities, MN
L79 owners, step inside
My L79 is at the engine shop. When it was disassembled, the engine builder said "wow, looks awesome, I don't think the engine has ever been apart". The engine has roughly 70K miles on it since new. My dad bought the car in 73 and I just took over ownership this year.
I'm having the whole thing rebuilt. I'm not doing anything crazy. I'm just doing the stock specs, all around. My question is about heads. Is anyone running hardened valve seats? If so, why? If no, why not?
I'm having the whole thing rebuilt. I'm not doing anything crazy. I'm just doing the stock specs, all around. My question is about heads. Is anyone running hardened valve seats? If so, why? If no, why not?
Safety Car
Joined: Sep 2004
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From: St. Clair Shores MI
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no harden seats here...unless you plan on running the Cannonball Run from coast to coast, you will not see a benefit from the seats......
Pro
Joined: Sep 2005
Posts: 618
Likes: 18
From: scotts mi
I was told by a cylinder head expert, pretty much the same thing Donny said. If you don't do them, and want to run it hard (racing) put some racing gas in it. He said he ran a 68 suburban for 80,000 miles with no problem, towing his race car around.
Instructor
Joined: Dec 2004
Posts: 151
Likes: 0
I did my seats several years ago. I also added screw-in studs, 2.02/1.60 valves, guideplates, and porting. I now have $1400 in my heads. I should have bought AFR or Darts and painted them orange. I will never spend that kind of money on stock heads.
I counldn't tell a difference in the headen seats. But, I was told it is a MUST for todays gas.
I counldn't tell a difference in the headen seats. But, I was told it is a MUST for todays gas.
Melting Slicks
Joined: Jan 2007
Posts: 2,842
Likes: 622
From: Pasco Florida
Unfortunately, many engine builders will tell their customers that hard seats are required with todays fuel. Unless you plan on driving the car on a daily basis for 100,000 miles, don't waste your money.
Burning Brakes
Joined: Nov 2001
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From: Tank sticker? I ain't got no tank sticker! I don't need no tank sticker! I don't have to show any stinking tank sticker!
A friend ran his engine with unleaded AMOCO from new to 100,000 miles and took the heads off for inspection. There was zero damage to the valve area. Put on new head gaskets and re-torqued them to spec. Still running like a champ.
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From: Cape Cod, Mass.
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Last rebuilt my L79 65 in 1987. NO hardened valve seats. I run 93 Octane unleadead with NO additives. NO pinging, no engine problems. It runs clean and cool. The hardened valve seats are unecessary IMO.
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Melting Slicks
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From: DFW
Melting Slicks
Joined: May 2004
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From: Willowbrook IL
St. Jude Donor '13-'14-'15-'16
If the engine wasn't broke, why are you fixing it?
Team Owner
Joined: Oct 2000
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From: Washington Michigan
Forget the seats - best way I know to create instant scrap when a shop puts seats in 2.02 heads and goes through into the water jacket while cutting the recess. You don't need them.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
I would agree with most everyone that says this is probably unnecessary for a street driven car unless it is going to be driven hard. Running too low of an octane gas would be much more detrimental to this engine.
However, if you are planning to remove the heads and have a good 3-angle valve job done as well, I would personally recommend that you have a set of screw in valve studs added. Your engine came with pressed in studs and these things can work loose over time or even snap off. The bottom line is a screw in stud can be replaced in 15 minutes when they are damaged or break. Pressed in studs are a whole different ball game. It may not happen, but if it does, you will wish you had added them now while the heads are off the car.
Do not even consider having them pinned... this was done in the old days, worked reasonably well at holding the studs in, but will cost about the same as having screw in studs added... and as mentioned previously you can replace a screw in stud easily at home.
Good luck... GUSTO
However, if you are planning to remove the heads and have a good 3-angle valve job done as well, I would personally recommend that you have a set of screw in valve studs added. Your engine came with pressed in studs and these things can work loose over time or even snap off. The bottom line is a screw in stud can be replaced in 15 minutes when they are damaged or break. Pressed in studs are a whole different ball game. It may not happen, but if it does, you will wish you had added them now while the heads are off the car.
Do not even consider having them pinned... this was done in the old days, worked reasonably well at holding the studs in, but will cost about the same as having screw in studs added... and as mentioned previously you can replace a screw in stud easily at home.
Good luck... GUSTO
Last edited by GUSTO14; Apr 11, 2007 at 12:23 PM.
Racer
Joined: Nov 2006
Posts: 438
Likes: 1
From: Hunington Beach California
I took my 400 sb down just recently. I built it in 88 and did NOT put hardened seats in the stock "ported" 041 heads. Exhaust seats were perfect. I ran this engine VERY hard on 91 unleaded.
Thread Starter
Race Director
Joined: Dec 2000
Posts: 12,913
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From: Twin Cities, MN
Thanks for all the replies you guys. I appreciate it.
Here's the kicker. I told the engine builder not to put in hardened valve seats. I called him a week later to ask if he had written up an estimate, and he said "Well, I got the hardened valve seats put in for ya." He pressure tested the heads, and they were fine. I was extremely upset.
Here's the kicker. I told the engine builder not to put in hardened valve seats. I called him a week later to ask if he had written up an estimate, and he said "Well, I got the hardened valve seats put in for ya." He pressure tested the heads, and they were fine. I was extremely upset.
Melting Slicks
Joined: May 2004
Posts: 2,510
Likes: 531
From: Willowbrook IL
St. Jude Donor '13-'14-'15-'16
Thanks for all the replies you guys. I appreciate it.
Here's the kicker. I told the engine builder not to put in hardened valve seats. I called him a week later to ask if he had written up an estimate, and he said "Well, I got the hardened valve seats put in for ya." He pressure tested the heads, and they were fine. I was extremely upset.
Here's the kicker. I told the engine builder not to put in hardened valve seats. I called him a week later to ask if he had written up an estimate, and he said "Well, I got the hardened valve seats put in for ya." He pressure tested the heads, and they were fine. I was extremely upset.
Does this jamoke still have your engine?
Do you still trust him to fulfill his half of the contract?
Thread Starter
Race Director
Joined: Dec 2000
Posts: 12,913
Likes: 60
From: Twin Cities, MN
Yes, he still has the engine. Yes he will be completing the job. Yes he will be giving me a monster discount.
He has done (with great success) many engines for a local guy who specializes in 63-67 restorations. This guy's shop just finished up a 435 horse 427 out of a 67 coupe. Original engine. It dynoed at 471 hp with all stock specs.
He knows what he's doing, he's just not good at customer service.
He has done (with great success) many engines for a local guy who specializes in 63-67 restorations. This guy's shop just finished up a 435 horse 427 out of a 67 coupe. Original engine. It dynoed at 471 hp with all stock specs.
He knows what he's doing, he's just not good at customer service.