C1 & C2 Corvettes General C1 Corvette & C2 Corvette Discussion, Technical Info, Performance Upgrades, Project Builds, Restorations

L71 Head Issues

Thread Tools
 
Search this Thread
 
Old Aug 14, 2015 | 05:50 PM
  #1  
427435's Avatar
427435
Thread Starter
Drifting
10 Year Member
 
Joined: Nov 2001
Posts: 1,658
Likes: 25
From: Rochester Minnesota
Default L71 Head Issues

As part of my restoration, I wanted new crank seals on the engine. I let the engine guy talk me into taking the heads off (engine was running fine and had been rebuilt about 15 years and 1000 miles ago). He found one piston pretty much free of carbon and suspected the valve guide was leaking water. He then pressure check the heads and found both heads showing leakage around the exhaust valve seat on one end of heads (same valve on both heads).

At the time of the rebuild, I had inserts put in to avoid problems with non-leaded fuel. Maybe a bad decision.

The current engine guy has found a pair of correct heads (without inserts) that supposedly have been magnafluxed and pressure tested for $3000!!!!!!!!!!!!!!!!

I wonder if putting new inserts in with some high temp sealant might solve the problem. That of course assumes a little water is a problem (I won't be driving car more than 500 miles a year when it's back together).

I'm looking at using:

http://http://www.northernautoparts.com/ProductDetail.cfm?ProductId=3569

Or

http://https://www.fastenal.com/products/details/0608689


Has anyone got a better idea other than spending another $3000?
Reply
Old Aug 14, 2015 | 06:00 PM
  #2  
Nowhere Man's Avatar
Nowhere Man
Team Owner
20 Year Member
Liked
Loved
Community Favorite
 
Joined: Feb 2003
Posts: 54,180
Likes: 9,474
From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
2015 C2 of Year Finalist
Default

What does your engine builder suggest. My history with engine builders and going the cheap way out never works out to well. I am no head expert but why can't they be fixed without using the inserts?
Reply
Old Aug 14, 2015 | 07:36 PM
  #3  
427435's Avatar
427435
Thread Starter
Drifting
10 Year Member
 
Joined: Nov 2001
Posts: 1,658
Likes: 25
From: Rochester Minnesota
Default

To put in hardened inserts for un-leaded gas, a machine cut was needed. Evidently, the water passage is close to the exhaust valve and the machine cut got too close to the water passage-------------thus the leak.
Reply
Old Aug 14, 2015 | 08:08 PM
  #4  
JohnZ's Avatar
JohnZ
Team Owner
Supporting Lifetime Gold
20 Year Member
Veteran: Army
 
Joined: Oct 2000
Posts: 38,897
Likes: 1,927
From: Washington Michigan
Default

Originally Posted by 427435
To put in hardened inserts for un-leaded gas, a machine cut was needed. Evidently, the water passage is close to the exhaust valve and the machine cut got too close to the water passage-------------thus the leak.
Which is why it has been posted here hundreds of times NOT to risk ruining perfectly good cylinder heads by having them machined for unnecessary installation of valve seat inserts.
Reply
Old Aug 14, 2015 | 08:27 PM
  #5  
jrm5657's Avatar
jrm5657
Melting Slicks
25 Year Member
Active Streak: 30 Days
Liked
Top Answer: 1
 
Joined: Jun 2001
Posts: 2,751
Likes: 725
From: Fountain Hills Arizona
2022 C2 of the Year Finalist - Modified
Default

I have a set of 3904391 heads dated late 66 which is the head you should have on a 435hp car. I will sell mine for $2000.
Jim
Reply
Old Aug 14, 2015 | 10:33 PM
  #6  
427435's Avatar
427435
Thread Starter
Drifting
10 Year Member
 
Joined: Nov 2001
Posts: 1,658
Likes: 25
From: Rochester Minnesota
Default

Originally Posted by JohnZ
Which is why it has been posted here hundreds of times NOT to risk ruining perfectly good cylinder heads by having them machined for unnecessary installation of valve seat inserts.

Unfortunately, 15 years ago, that wasn't common knowledge.
Reply
Old Aug 14, 2015 | 10:35 PM
  #7  
427435's Avatar
427435
Thread Starter
Drifting
10 Year Member
 
Joined: Nov 2001
Posts: 1,658
Likes: 25
From: Rochester Minnesota
Default

Originally Posted by jrm5657
I have a set of 3904391 heads dated late 66 which is the head you should have on a 435hp car. I will sell mine for $2000.
Jim

Have they been magnafluxed and pressure tested?
Reply

Get notified of new replies

To L71 Head Issues





All times are GMT -4. The time now is 09:10 AM.

story-0
2027 Chevrolet Silverado 1500 First Look: Everything You NEED to Know!

Slideshow: Is the 2027 Chevrolet Silverado 1500 the best Silverado yet?

By Michael S. Palmer | 2026-06-16 08:01:12


VIEW MORE
story-1
5 Best & 5 Worst Corvette Daily Drivers

Slideshow: 5 best and 5 worst Corvette daily drivers

By Joe Kucinski | 2026-06-15 10:32:13


VIEW MORE
story-2
The Headlights of Every Corvette Generation Explained

Slideshow: The headlights of every Corvette generation explained

By Joe Kucinski | 2026-06-15 10:17:14


VIEW MORE
story-3
5 Best & 5 Most Overrated Corvette Track Packages of All Time!

Slideshow: The 5 best and 5 most overrated Corvette track packages ever.

By Joe Kucinski | 2026-06-09 12:46:45


VIEW MORE
story-4
Every 2027 Corvette Engine Explained

Slideshow: Every 2027 Corvette engine explained

By Joe Kucinski | 2026-06-09 12:16:31


VIEW MORE
story-5
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette

Slideshow: A Jaguar designer's personal project imagines what a modern front-engined Corvette might look like if Chevrolet revisited the golden age of the Stingray.

By Verdad Gallardo | 2026-06-08 19:53:43


VIEW MORE
story-6
10 Ugly Corvettes That We Still Kinda Love

Slideshow: 10 ugly Corvettes that we still kinda love.

By Joe Kucinski | 2026-06-03 10:34:17


VIEW MORE
story-7
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer

A lot of money has changed hands at the online auction house over the years.

By Brett Foote | 2026-06-03 10:21:50


VIEW MORE
story-8
10 Things Every Corvette Owner Needs (2026 Edition)

Slideshow: 10 great gifts Corvette enthusiasts actually want for Father's Day!

By Michael S. Palmer | 2026-06-03 15:43:40


VIEW MORE
story-9
8 Most "Only Corvette Owners Understand" Quirks and Problems

Slideshow: These are the quirks, annoyances, and oddly lovable problems that every Corvette owner eventually learns to live with.

By Pouria Savadkouei | 2026-05-28 09:31:39


VIEW MORE