Thread:

BBC 454 timing help please

Hello Alexi or other helpers I have a twin engine offshore style boat with twin 454's they have 781 large oval port heads, junk stock flat top cast pistons so I think I'm in the 8ish to 1 ratio, nice size hydralic flat tappet cams, 750 edelbrock carbs... ok here's my question since i can only afford to run the garbage 87 octane regular fuel sold here in California what should I set my total timing advance to? I want my most performance but don't want to detonate with my weak cast piston strength, is 33 degrees good? more? less? thanks so much for your help

No more than 36

I would think 34 would keep it safe. What you should really do is Google spark plug reading and print it out. Take it with you on the water and run up to where you run (RPM), shut it down and read some plugs.
You will see it there if your off on fuel or timing.
Just my humble opinion.

If your really running 87, I would set it at 30 total. This will be safe and likely not much less power vs. The SAFTEY margin. Maybe you can try out some octane boost and run it up a bit. Make sure the timing marks are legit as if they are not- your timing may seem correct but surly be off .
We use Lucas octane boost as a crutch if your in a place were 87 is available. Thanks

ya the problem I have is this is a twin engine offshore style boat and it eats the gas, so I want to continue to run the regular fuel if possible, but I think I'll do the half regular half premium idea and run it at 34 just to be safe... thanks again ronnie

If you do, keep do keep plug gaps at .035 or less

Timing is always based on how efficient the head design is, and piston. Your factory head is good casting for the oval ports. BBC really likes 32-34, 36 is safe on good fuel. Any more it just builds heat and prob ping. Degree the balancer and it should have all the timing in around 2500. Good base to start with. I'm not a fan of vacuum advance so mechanical advance gets my vote. As does MSD billet distributor.