cruiser54

You're good to go. Remember what HO stands for?

salad

The year of the block doesn't matter. The injectors are matched the fuel system, which is to say the ECU.

67 GMC

Thanks-HO? Wasn't that the model train size? I think I had some Marx sets. Guess what HO stood for...Half of O scale.

cruiser54

High Output. As in 4.0.

DFlintstone

Agreed, like said, you're fine with the 746.

Man I cried like a baby when my mom took my Linoel set to the Good Will. (still not happy about it at 55!)I still remember the smell of that oil, and it running under the Christmas tree in 1965. Interesting! Maybe it was "O" sized.

67 GMC

I feel your pain. When I read your post is brought back that same memory of that smell of oil too. I had a flat-bed rail car and I would keep putting more and more weight on it to see how much the train engine could pull. Then you could really smell that oil and a some electric wire burning smells too. I think the Lionels were mostly O scale (with the engines with "smoke" coming out of the stacks too!).

Programbo does have some 746s but not ready to go.

67 GMC

Got the 746s today so this weekend, these nice looking injectors are going in to replace the JY ones. Hope this fixes the problem. Changed the CPS as well a few weeks ago but didn't notice too much of an improvement on the cranking time. Hoping its an injector staying open and causing flood on shut down.

DFlintstone

Bobolink

My 90 runs good, but I'm changing to the Bosch injectors anyway. I put some reconditioned Siemens on there 4-5 years ago, and noticed a difference right away. But they're still single hole, so expect the Bosches will be better. Right now I get about 19 mixed city/hiway. 746s arrive Thursday, and I'll install them on Friday.

67 GMC

I know-Not in yet. This working gets in the way of Jeeping!

Bobolink

746s arrived Wed, put 'em in yesterday. So far they're fine. No big changes in throttle response, but it idles a little smoother maybe. I was incorrect about the injectors that I installed several years ago. They are Nikki MD158484 (aka INP-066). They made a very noticeable difference then. I think the problem lately has been that one has been leaking a bit. I could smell the over-rich exhaust (shades of my hot-rod days of the 60s). No smell in the exhaust at all now, so there's got to be an improvement there. So, as I said, improvements are subtle, but I think the swap is warranted. I'll post my MPG when that time comes. It's been 19 in the past with mixed town/country driving, but lately down to 17-18 with the overly rich problem. Hopefully now back to 19 or a little better.

DFlintstone

Cool. I just got 20 highway carrying darn near 1/2 a ton, 280K on this 90.

Bob, how many holes in the injectors you removed? (4 or 1)

Bobolink

Those Nikkis are single hole.

Bobolink

One other curiosity that I've run across. In looking at injectors lately, I've come across an anomoly concerning the stock OEM injector on the Renix era 4.0L, the 53003956. According to every posting that I can find on all the various Jeep forums, the flow rate for the stock injector is 18.6 lbs/hr @ 39 psi. But on every single refurbisher/seller's chart, both in the US and abroad, the 53003956 flow rating is 21 gal/hr @ 39 psi, which would put the -703 closer in flow specs to the stock injectors than the -746. It's got me wondering which one is correct.

DFlintstone

I had the exact question as I started looking into injectors. I found no definite resolution, except to say it seems agreed that the 703's are within the range of the 02 sensor to trim to the 14-1 ratio. This would mean that anytime the puter was in open loop, running on default settings it would run rich. (assuming the 18.6 is valid). This would allow a seller to say they work, but the closer, (20# 746), seems one of the best current options. I hear they are making 6 hole now....I saw a real improvement over the 703's.

Maybe someone should rattle Bluexj's cage...see what he knows!.....