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 02-28-2020, 07:53 PM   #1
slider701
Registered User
 
Join Date: Oct 2016
Location: Dallas, TX
Posts: 21
Are BBC engines free spinning or interference engines

Are the older BBC engines (70 C10 402) free spinning or interference engines?

I’m fearing I broke timing chain. Before tearing into engine I was curious as to what I’m getting into.

Also does anyone know of a good honest reputable engine shop in the Dallas-Fort Worth Texas area.....just in case I need it?
slider701 is offline   Reply With Quote
Old 02-28-2020, 08:29 PM   #2
AussieinNC
Moderator
 
AussieinNC's Avatar
 
Join Date: Jun 2017
Location: Cherryville, NC
Posts: 2,152
Re: Are BBC engines free spinning or interference engines

Sadly, yes they are interference engines....all BBC variants will bend valves and push rods if they break a timing chain.....

Life sometimes throws you a curve, but remember, you are not alone and we are all here to help you out if needed.

After a good nights sleep, a simple one hour diagnosis will tell you where you stand

First off, dont use the starter to turn the engine during these tests....

Pull the dist cap and hand turn the crank and watch the rotor button....if the rotor doesn't move it is most likely a broken timing chain.

Pull the rocker covers and slowly turn the engine by hand...if the valves do not move, this will confirm the broken chain suspicion.

Button it back up and consider next steps...please post your results after you are done with the above.

Good luck


__________________
Family and country before all others...

2006 Chevy Silverado (Daily Driver)
2012 Chevy Equinox


Last edited by AussieinNC; 02-28-2020 at 08:37 PM.
AussieinNC is offline   Reply With Quote
Old 02-28-2020, 10:14 PM   #3
Steeveedee
Who Changed This?
 
Steeveedee's Avatar
 
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,019
Re: Are BBC engines free spinning or interference engines

SBC engines are also interference engines, BTW. Those little crescent moons in the pistons are only there to prevent contact between valves and pistons at high enough speeds. If the timing chain goes, it's going to be a mess of bent valves.
__________________
~Steven

'70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper

Simi Valley, CA
Steeveedee is offline   Reply With Quote
Old 02-29-2020, 01:36 AM   #4
lil hoodlum
Registered User
 
lil hoodlum's Avatar
 
Join Date: Oct 2009
Location: Denton, Texas
Posts: 1,688
Re: Are BBC engines free spinning or interference engines

Quote:
Originally Posted by slider701 View Post

Also does anyone know of a good honest reputable engine shop in the Dallas-Fort Worth Texas area.....just in case I need it?
I had Wayne Calvert Precision engines rebuild a 327 sbc 4 years ago. Rebuild was a long block and I paid $1900 for all machine work and parts plus they broke the engine on their dyno. This was 4 years ago, January 2016. Have not had one single issue with the motor. My truck is my daily driver as well. They are located in Denton, Texas.

https://www.waynecalvertengines.com/

Last edited by lil hoodlum; 02-29-2020 at 01:37 AM. Reason: spelling corrections
lil hoodlum is offline   Reply With Quote
Reply

Bookmarks

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 03:43 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com