Are BBC engines free spinning or interference engines

[slider701]

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?

[AussieinNC]

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

[Steeveedee]

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.

[lil hoodlum]

Originally Posted by slider701

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/