Good afternoon, y'all - long time creeper, first time poster.

The information I'm able to find about the 250 engine is minimal at best, but I still wonder...
Some people are running what I've heard claimed countless times as a bulletproof engine, and they are furthermore happy with it. I picked up this '79 for damn near a song about six weeks ago and after having done some of the other maintenance that was long overdue, I'm now pondering this engine.

I completely rebuilt and tuned the monojet as best as possible, and the engine otherwise runs without any sort of hitch, exception of the fact that it is a miserable pile of suck. The engine is mated to the good ol' SM465 and rocks true dual long tube headers. All lines, hoses, vacuums, etc. appear to be in good order, yet... this engine runs like a total dog, exception of first and reverse - almost no real pull in second. I'm not expecting a 350 (which is in my garage just BEGGING for me to build and swap), but I wonder if I should be getting just a little more from this engine? Street driving up any sort of gradient is a nightmare - all I can do is drop it into second and pray it makes the climb.

Any thoughts or suggestions would give me great moral support.
Thanks!

 

A 2 barrel intake would increase the engines performance, and when running correctly the engine does well. Have you given it a tune up and checked the timing recently?

 

She's tuned and timed to an eight degree advance. The carb is for the most part on point (although I love tweaking with the AF mixture every chance I get).

What I'm getting at is as follows:

Other drivers suck - plain and simple. One trick they love to pull is stopping/coming to an absolute crawl where it is not warranted - i.e. a slow right hand turn or any other sort of retarded behavior that causes one to slow down.

The SM465, being a tranny with no first gear sync absolutely sucks to pull into first unless at a stop or at a virtual crawl. What seems to be the issue is that I would have expected this I6 to have enough torque to counter one of those situations where you are forced into a 'red zone' - where you are too fast to shift into first and too slow and it pulls like sh*t in second (potentially flirting with a stall/truck lurching/etc.). Having toyed with a 350 on a 465 has proven that these red zones do not exist, as enough power will muscle its way in second like a champ.

Due to my lack of experience with the 250 I6 - is this just the way it is, or am I lacking something... power somewhere maybe?

Situation #2 is the need to ride second up hills at redline.


Basically, second gear on a 465 is imo THE most important gear on the road - and it's quickly becoming the bane of all creation in my setup. lol

 

The 250 and the transmission combo is not right. The engine has a low horsepower and high torque . The engine should pull near 215 ft/lb of torque in the 1600 rpm range.

So you might consider changing tranny to one with synchronized 1st gear.

 

Thanks for the response on this.

A swap to an NV4500 is part of my consideration, but... all things considered, I'm figuring that I'm probably best just yanking that 6 and selling it since I do have a 350 ready to be built in my garage (need to whelp up some funds first). That engine was originally going to go into the wife's '86 K5 until I ran the numbers of her block and found it to be a goodwrench 350 that someone swapped in there (her VIN lied and I convinced the person we bought this from that they had a 305 when THEY thought they had a 350).

Another odd anomaly I discovered with this 6 is that its fuel economy was WAY below what others are reporting - we're talking along the lines of 6MPG. This is completely puzzling: No fuel leaks, drips, tuned, timed, and otherwise running fine.

I'm probably not going to question it much - swap to the 350 first chance I get, keep the 465 with the intent of possibly going to a 4500 later down the road.