edwinsmith

That sounds like a good plan. Once you get home do a comp. check and if it's not using a lot of oil and compression is reasonably good enough to fire then run it until you're in a better position to do a permanent fix. You could do a major overhaul with a bore job and new pistons/rings inserts etc... All that fun stuff.

Dan s

Her is an update. Head is cracked. Gotta get one on the way asap. Anyone got any suggestions. WhT would be the best route. I have 9mm injectors but I've only found 7mm heads. Should I just bite the bullet and go with the 7mm head

oliver foster

The only way I know to get a 9 MM head is to buy a used one.
All the re man head and injectors I have seen are 7 MM.

Where is the head cracked?

Dan s

3 cracks. All going into injector ports. Machine shop said it's the worst they had seen. Right. NOw I'm thinking just to go with the 7mm head on the 1990 and keep the rest of the injectors as spares for the 93. Of course now I gotta try to figure out what head is worth the money. I don't think I'll ever need a Hamilton head or a fire ring head. The turbo I got is only good up to 50 psi. I'll might see 45 at best. After the lower end is gone through. Any suggests on a after market head would help. I don't like eBay. 285 dollars seems way to cheap for a "new china made head". I only want to do this ounce. Thanks guys

oliver foster

The '90 injectors will not be spares for the '93, if that is what you meant.
The 9 MM heads was factory stuff on the non intercooled motors only.
They have no aftermarket support, that I know of.
The '91.5-'93 motors all came the the different head, and the 7 MM injectors that had the smaller overall spray amount than the earlier NON I/Ced injectors had.
You will need to upgrade the 7 MM injectors from stock to keep up with the flow of the 9 MM NON I/Ced injectors.

Dan s

Thanks for that information. I was way off with my thinking. What would be equivalent to a 9mm injectors in a 7mm

oliver foster

I run a lot of the earlier motors in my trucks, as I like the bigger factory sticks from a tuning and power stand point.
I believe the earlier injectors are about 50% bigger in total area when you do the math of amount of holes and the size of the holes.
I am sure someone that knows more about aftermarket injectors than me will chime in.

Dan s

Thanks Oliver. I gotta pull the trigger on this in the next day or 2. I like the dually but it's not ole red. I like it better��

edwinsmith

Is it possible to ream out the holes in a 7mm injector head to accept 9mm injectors?

deere country

This would completly defeat the entire purpose of the 7mm head. The only reason cummins changed to the 7mm nozzle bore in their head was to rid themselves of the problem of cracking between the valve seats at the nozzle hole. This is why you cannot buy a new 9mm head, why sell something that is problematic down the road.

deere country

As Oliver has said the earlier nozzles are much larger in regards to the amount fuel they are capable of delivering with their 4 larger holes. This has nothing to do with the 9mm size versus the 7mm it is simply the way they were manufactured at the time. The problem with the older 4 hole nozzle is the simple fact they cannot atomize the fuel as well as a 5, 6, or 7 hole nozzle can. Just think of it as old versus new, the technoligy that we have today versus what was available then. With an updated nozzle you get better atomization which creates a more complete burn with less unburned fuel which also makes more power. It also leaves a cleaner combustion process and helps keep your engine oil cleaner longer.

I would ask the machine shop about your head as the cracking between the nozzle holes does not necasarily equate to a leak that would pressurize the coolant system. Make sure you have found the cause of that before you spend a pile on a new head for it.

Dan s

The last time I had the injectors out I noticed that I had 2 that leaked by. I'll ask them to mark the head where it's cracked

bigragu

There you go, then post pics for the sharp guys on here to evaluate( not me, lol)