80SG in the Philippines again, mileage?

[hanger10]

Well, after going through hell trying to find the miss, finding it was the valves, we shimmed the valves, all are now within specs. But, we had messed with the mixtures before checking the valves, so went through the process of adjusting them again through checking spark plug burn, which is how we always did before. After shimming, the best we can get is 26 mpg, and thats on the hiway driving nice and easy!!! Before the shimming, used to get between 30-35. According the the plugs, we have good burn on all cylinders, but the mileage has gone to hell!!!! Any ideas guys???? Thanx fellas.


Randy

[Ken Talbot]

Have you sync'd the carbs?

[CaptonZap]

Well, after going through hell trying to find the miss, finding it was the valves, we shimmed the valves, all are now within specs. But, we had messed with the mixtures before checking the valves, so went through the process of adjusting them again through checking spark plug burn, which is how we always did before. After shimming, the best we can get is 26 mpg, and thats on the hiway driving nice and easy!!! Before the shimming, used to get between 30-35. According the the plugs, we have good burn on all cylinders, but the mileage has gone to hell!!!! Any ideas guys???? Thanx fellas.


Randy

Did you use the tool for depressing the lifter cups, or did you take the cams loose when you adjusted the lifters?
CZ

[hanger10]

Mileage

The carbs havent been synced since we shimmed it, and, we used a homeade tool to do the shimming, we did not take the camshaft loose!!


Randy

[TopCatGr58]

Hey Randy,

When you changed the valve SHIMS, you changed the intake vacuum specs and all, so you need to Re-Vac Sync the carbs. You may also need to play with the float height, but do the Sync first and see what you get.

T.C.

[hanger10]

Thanx!!!!

Hey Randy,

When you changed the valve SHIMS, you changed the intake vacuum specs and all, so you need to Re-Vac Sync the carbs. You may also need to play with the float height, but do the Sync first and see what you get.

T.C.

Ok Bro, thanx!!! Will do it this week!!!

Randy

[DGXSER]

I know you did alot of playing with the carbs when you had that miss. Now that you resolved it with the valves, the carbs should be right at factory settings unless you are running PODS or 4-1 exhaust or the like.

Also, check your plug gap. I went for a cruise with a local XSsive once, we filled our tanks before heading out and he made it 54 miles and ran out of gas. (Both specials). He was having issues with a miss and stumble and he opened up his plug gap to try to compensate. He corrected the plug gap before the return trip home, and he made the entire 100 mile trip on one tank.

[hanger10]

Mileage

Hey guys, thanx so much for the ideas!!! Will sync the carbs this week, check the gaps, I havent gapped a spark plug in 3 yrs here!!!! Without this forum, the ole 80SG would be a smoking pile of scrap by now!!! Im not quite so worried about this problem with the mileage though, Im thinking we will be able to take care of it fairly easily! Thanks again!!!

Randy