Marinette Boat Forum

1985 318 manifold vacuum reading is 15. Reading that 15 is normal for some high performance engines. Not sure if the old marine 318s are in that category. The engine is harder to start than my other one.

See this site #3 http://www.secondchancegarage.com/public/186.cfm

Verify the timing and carb adjustments, if that checks out start looking intake leaks. My newly rebuilt stock 318's were around 20 with the correct timing and carbs set to initial settings.

I would like to see some more actual idle vacuum readings for reference.

Lacking a vacuum distributor advance, marine engines tend to have a much lower vacuum at idle.

Jeff

Amazing what a simple vacuum guage will tell you. Need to compare my sbd engine. Timing is at 5*. Carb idle is set for max vacuum. Don't think it's a vacuum leak because the reading would be lower. She holds steady at 15hg. I hooked a vacuum on it about 5yrs ago and I think it was at 20hg. Need to do rapid throttle chop to check for worn rings. Only have about 800 hrs on eng so hopefully that's not it. Will report findings in a month or so. Stay tuned.



Thanks for the input.