I'm going help a friend install bosch +40 4 hole injectors and I need to know what washers I need to use. The kit came with some thin ones, some really thick ones, and the injectors already come with an in between size on them.He is looking for fuel mileage so which ones would be good to use?
Thanks everyone.

 

I was always told to use the same thickness as what came out.

 

When I got my 190's it said on the website to use the thinner washers. So we did.

 

The thinner you go the deeper the spray pattern is in the bowl. This is especially important if you are running more timing then stock. Id use the thinnest ones provided.

 

The truck has the 1/8" timing bump.Will the thin washers have any negative affects like less power or mileage?

 

No sir, if anything they will improve mileage and idle quality, also gives a slight/minute timing advance due to position of the injector tip. But it is minute, very minute, almost unmeasurable/unnoticeable esp with just 40hp injectors and 1/8th timing bump.

By having the spray deeper in the bowl, you'll get a more complete burn, also should help bottom end power a little. You really have to be used to your truck to notice the difference.