Are there differences in stock 1st Gen injectors??

[BushWakr - RIP]

Are there any differences in the injectors used in the 1st Generation trucks and if so, what are they?



Yes, there are differences, not only in the injectors but in the head they fit into.

On the very early 1st Gen trucks 1989-1991. 5 model year the injectors were a 9mm injector.

These injectors ran richer (flow more fuel) than the stock injectors used in the 1991. 5-1993 model years.

The larger 9mm bodied injectors flowed more fuel and in the process the larger body of the injector made the cylinder head more prone to developing cracks due to the smaller amount of metal in and around the injector bore and the valve seats.

This problem/issue was addressed in the later 1991. 5 and up trucks by going to a smaller 7mm body and this resulted in much less cracking potential.



Pastor Bob.

 

[dpuckett]

One hair to split here- dont assume that the earlier injectors with the 9mm tips flowed more fuel because of the 9mm vs 7mm tips. It is beacuse of the size and of the holes in the tips that they flowed more fuel. The so-called POD injectors flow more fuel than either stock injector, yet have 7mm tips.



In my experience, the 9mm tips have 4 holes, not quite evenly spaced; the 7mm stock tips have 6 holes, evenly spaced. Both injector tips have the pattern offset in relation to the injector body to maximize the spray angle into the combustion chamber, and make up for the uncentered protrusion of the injector tip into the cylinder.



Daniel



I'll add some info here.....

The later 7mm diameter body injectors will fit into the older heads with the 9 mm holes by using an adapter that is readily available. This is important to know because all of the standard aftermarket upgrade injectors have 7 mm tips.

Jay