Break in question

[dzlbunny]

Ok, so I rebuilt my 1.6 NA recently, and I am approaching the 1000 mile "break in" I have put two tanks of fuel through it and got 33 the first and 34 the second. My question is, is this fairly normal for it to be low on mileage and slowly increase after a while, or do i have a major pump or injector problem? Or do I just need to run it a few more mile to find out?? I am fairly new at the whole rebuilt engine thing so any help is much appreciated!!!

[theman53]

I would check the timing

[dzlbunny]

Can timing be that far off to effect it that much??? I have no clue??

[Toby]

Yep. You are at least 10 mpg low if it is in a Rabbit. Check the cam timing first, then the pump.

[theman53]

My IP bracket loosened up, not all the way but enough to affect timing. I was getting no more than 39mpg. I have 4 tanks on it now since retightening and I have not had less than 42.15. with 2 tanks being 45.5mpg. IP timing is almost everything. Cam, to IP, to Crank timing is more than critical. The IP set to around 1.00 mm is the next step. Finally, if your injectors are not the correct breaking pressure then that will change the actual timing in the cylinder. So make sure it is all good.