The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 10-17-2019, 06:19 PM   #1
dmjlambert
Senior Member
 
dmjlambert's Avatar
 
Join Date: Apr 2016
Location: Cypress, TX
Posts: 1,899
French locks for exhaust manifolds

Who uses french locks on their exhaust manifolds? Any opinions on them? Supposedly they allow the outer bolts to have less torque and the manifold will be less prone to cracking. Some discussion of them here:
https://www.camaros.net/forums/18-en...all-bolts.html
Attached Images
 
dmjlambert is offline   Reply With Quote
Old 10-17-2019, 07:29 PM   #2
randy500
Senior Member
 
Join Date: Jul 2016
Location: Tacoma, WA
Posts: 7,903
Re: French locks for exhaust manifolds

They are mandatory of you want the manifolds to be leak and trouble free. Dont use manifold gaskets with them either. Usually the manifold needs to be surfaced for a tight seal.
randy500 is offline   Reply With Quote
Old 10-17-2019, 09:27 PM   #3
Andy4639
Orignal Goof member
 
Andy4639's Avatar
 
Join Date: Jan 2002
Location: Liberty, & Garden City S.C. , U.S.
Posts: 18,823
Thumbs up Re: French locks for exhaust manifolds

Quote:
Originally Posted by randy500 View Post
They are mandatory of you want the manifolds to be leak and trouble free. Dont use manifold gaskets with them either. Usually the manifold needs to be surfaced for a tight seal.
They where factory installed on all the Ram horns I have ever seen. X2 on not using a gasket on them too!
__________________
1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver
Seeing the USA in a 71


Upstate SC GM Truck Club
2013,14 and 2016 Hot Rod Pour Tour


http://upstategmtrucks.com/



Get out and drive the truck this summer and have some fun!
It sucks not being able to hear!

LWB trucks rule, if you don't think so measure your SWB!
After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.
Andy4639 is offline   Reply With Quote
Old 10-17-2019, 09:46 PM   #4
FirstOwner69
Senior Member
 
FirstOwner69's Avatar
 
Join Date: May 2010
Location: Wisconsin & Arizona
Posts: 4,377
Re: French locks for exhaust manifolds

I have them on my truck, primarily because they were original to the truck. However, they should eliminate the possibility of the bolts loosening.
FirstOwner69 is offline   Reply With Quote
Old 10-17-2019, 10:02 PM   #5
truckster
Senior Member
 
truckster's Avatar
 
Join Date: Jan 2001
Location: Orem, Utah
Posts: 5,610
Re: French locks for exhaust manifolds

I use them but I never knew they were called French locks.
__________________
If I didn't build it or fix it, it's probably not mine.
truckster is offline   Reply With Quote
Old 10-17-2019, 10:08 PM   #6
rechinca
Senior Member
 
rechinca's Avatar
 
Join Date: Jul 2018
Location: Vacaville, CA
Posts: 269
Re: French locks for exhaust manifolds

There were still on mine, had manifolds resurfaced and threw out the stupid gaskets. Reinstalled the French Locks after.
__________________
1971 Custom/10 - 350/3 speed, Orange/White roof
rechinca is offline   Reply With Quote
Old 10-18-2019, 10:18 AM   #7
toolboxchev
Registered User
 
Join Date: Jul 2015
Location: 2nd left past the stump on a dirt road.
Posts: 2,363
Re: French locks for exhaust manifolds

Those are a good idea, most just rip em off when installing new gaskets or working on the exhaust.

I have gaskets on mine, no locks, no issues, Mileage and opinion will vary. Oh I go thru and tighten them about every 6 months, needed or not.
toolboxchev is offline   Reply With Quote
Old 10-18-2019, 10:35 AM   #8
dmjlambert
Senior Member
 
dmjlambert's Avatar
 
Join Date: Apr 2016
Location: Cypress, TX
Posts: 1,899
Re: French locks for exhaust manifolds

Do you torque the middle bolts to 30-35 ftlb and end-pairs to 15-20 ftlb, to reduce cracking of the exhaust manifold? That is supposedly what the french locks allow you to do.
dmjlambert is offline   Reply With Quote
Old 10-18-2019, 01:00 PM   #9
jaros44sr
Senior Member
 
jaros44sr's Avatar
 
Join Date: May 2006
Location: Philadelphia, Pa. 19454
Posts: 8,715
Re: French locks for exhaust manifolds

Quote:
Originally Posted by truckster View Post
I use them but I never knew they were called French locks.
x2, thats why I opened this thread, I have them on my jimmy and just use copper coat on the block and manifold

curious as to the torque numbers
__________________
Semper Fi...Uncle Sam, you da man

All parts offered to help are free, unless otherwise noted

Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training
SAFETY FIRST

AS usual, off topic

They say your mind goes second, can't remember the first


Jim
jaros44sr is offline   Reply With Quote
Reply

Bookmarks

Tags
exhaust manifold, french locks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 09:08 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com