offroadrolls
Well-known member
SBC 400 with an aluminum intake and Edelbrock 750 4 barrel. The engine's got about 14,000 since rebuild. I've known for a while something was not right at about 4,000 rpm and above. To me it felt like the A/F mixture was too lean. Recently I had some time to check it out. I have a new in the box Edelbrock 850, so I decided to bolt in on and take it for a spin.......Man did it run nice. So I popped the metering rods and main jets out of the 750 and took a look see. Come to find out the guy that owned the car and did the engine before I bought it had gone 18% leaner on the primaries and had gone about 8 steps leaner on the secondaries which totally explained why it ran like crap above 4,000 WOT. So I re-jetted the primaries to 4% leaner and went 1 step richer on the secondaries to make up for it @ WOT. The car runs much better..... not perfect but a lot better.
So here's my question. What if any damage will a super lean mixture do to the engine. This thing is using 1 quart of oil per 500 miles and will oil foul #3 plug every 2000 miles. #1 plug also shows signs of oil consumption but not as bad as #3. All the other plugs are fine and the V seals and guides are all new. So for sure it's rings. Did the lean mixture cause it?
So here's my question. What if any damage will a super lean mixture do to the engine. This thing is using 1 quart of oil per 500 miles and will oil foul #3 plug every 2000 miles. #1 plug also shows signs of oil consumption but not as bad as #3. All the other plugs are fine and the V seals and guides are all new. So for sure it's rings. Did the lean mixture cause it?