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Old 10-12-2017, 06:02 PM   #1
71ChevySS(straight6)
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250 is constantly giving me fits... considering something different

I'm getting so fed up with this 250. Now it's acting like its got sticking valves or possibly collapsed lifters. Idles fine, revs great in neutral for whatever reason, but put a load on it and it goes to sputtering and hesitating. Can anyone point me in the right direction here? I poured seafoam into the carb while it was running and put a dash in the crankcase, so we'll see what happens...

In the meantime, I've been considering swapping something else in more and more - at least until I can afford to properly go through and build up the 250 some day in the future.

Was thinking big block... but don't have a big block budget. Max $300.

Then I remembered those undesirable 366 and 427 tall deck engines.

Would any of you happen to be within 150 miles of me (McPherson, KS) with an old grain truck sitting on your back 40 that you don't use, but she'll start with some gas and a fresh battery?

If it's still in a truck I can pull it.

The bellhousings on those are a little different, though, aren't they? I'd have to take the truck 4 or 5-speed with it...

Thanks in advance.
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'71 Custom-10 2wd longbed, 250 inline-6, NP 435 four-speed. Medium Bronze Iridescent. Farm truck deluxe.

Rat rod build: 1949 Crosley Station Wagon body on 1993 Dodge D350 chassis, Cadillac 500 powerplant.
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Old 10-12-2017, 06:21 PM   #2
geezer#99
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Re: 250 is constantly giving me fits... considering something different

Is your motor warmed up completely when you test it?
Is your heat riser working?
What distributor?
What's your initial timing?
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Old 10-12-2017, 08:34 PM   #3
mongocanfly
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Re: 250 is constantly giving me fits... considering something different

$300 budget isn't gonna get you very far...
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Old 10-12-2017, 08:42 PM   #4
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Re: 250 is constantly giving me fits... considering something different

Have you gone through the fuel System? I'm talking from Gas cap to carb. Lines, filter, and pump.
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Old 10-12-2017, 08:46 PM   #5
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Re: 250 is constantly giving me fits... considering something different

A 292 L6 will be an easy swap into a ''CS...'' VIN truck. You will need the 292-only passenger-side motor mount. Otherwise very much the same but nearly 2 inches taller.
Dependable engine. Torque like a big block.
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Old 10-13-2017, 09:28 AM   #6
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Re: 250 is constantly giving me fits... considering something different

I had a 1976 250 a couple years ago giving me fits. It would start and run fine in neutral but could not take any load. I took the Monjet apart several times and tried to figure out the power jet system and finally had to admit defeat. I bought a NOS Holly Economaster for it and it has never run better. Maybe if you could find a Monojet expert he could set you up. Mine had HEI, if you have points then your problems are doubled.

I see 68GMSEE is a Monojet expert. Maybe you can PM him and have him rebuild one for you.
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Old 10-13-2017, 09:47 AM   #7
Alex V.
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Re: 250 is constantly giving me fits... considering something different

The tall-deck big blocks bolt in where any other BBC does... but your symptoms don't sound like your engine is done - sounds like fuel or ignition. Those systems on these engines are far from impossible to master. Methodical troubleshooting and doing what needs done will get you farther than frustration and shotgunning parts.
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Old 10-16-2017, 12:11 AM   #8
71ChevySS(straight6)
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Re: 250 is constantly giving me fits... considering something different

Quote:
Originally Posted by cadillac_al View Post
I had a 1976 250 a couple years ago giving me fits. It would start and run fine in neutral but could not take any load. I took the Monjet apart several times and tried to figure out the power jet system and finally had to admit defeat. I bought a NOS Holly Economaster for it and it has never run better. Maybe if you could find a Monojet expert he could set you up. Mine had HEI, if you have points then your problems are doubled.

I see 68GMSEE is a Monojet expert. Maybe you can PM him and have him rebuild one for you.
I was thinking carb issues as well, possibly, but I've rebuilt that thing four times. Turns out it was the points. Somehow the gap had closed - thinking it may be the road I live on, it's rougher than **** and has knocked the truck out of time before - so I regapped them and it runs like a top now. I went ahead and ordered a cheap eBay HEI distributor, so I'll swap that in when it gets here. hopefully no more issues after that's taken care of.
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'71 Custom-10 2wd longbed, 250 inline-6, NP 435 four-speed. Medium Bronze Iridescent. Farm truck deluxe.

Rat rod build: 1949 Crosley Station Wagon body on 1993 Dodge D350 chassis, Cadillac 500 powerplant.
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Old 10-16-2017, 12:14 AM   #9
71ChevySS(straight6)
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Re: 250 is constantly giving me fits... considering something different

Quote:
Originally Posted by '68OrangeSunshine View Post
A 292 L6 will be an easy swap into a ''CS...'' VIN truck. You will need the 292-only passenger-side motor mount. Otherwise very much the same but nearly 2 inches taller.
Dependable engine. Torque like a big block.
I've heard a lot of good things about 292s. But I can never find any, and have yet to even see one in person
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'71 Custom-10 2wd longbed, 250 inline-6, NP 435 four-speed. Medium Bronze Iridescent. Farm truck deluxe.

Rat rod build: 1949 Crosley Station Wagon body on 1993 Dodge D350 chassis, Cadillac 500 powerplant.
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Old 10-16-2017, 01:20 AM   #10
'68OrangeSunshine
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Re: 250 is constantly giving me fits... considering something different

Quote:
Originally Posted by 71ChevySS(straight6) View Post
I've heard a lot of good things about 292s. But I can never find any, and have yet to even see one in person
Well I was lucky, I bought a truck in 1973, and it had a factory 292. Still have it. Ran it to work today.
I have one runner, rebuilt in 2005 and 2 more cores. One was a kick-out from somebody else's ''barnfind'' and the other I bought in a junkyard in Yuma in 1977, and rebuilt, and ran for 25 years. Many years ago a parts guy at my local Chevy dealers told me that the '' 292 was Chevy's best-kept secret''.
You gotta keep looking, but 50 years after the fact, they are admittedly getting rare.
UPS vans, dump trucks, school buses, K/20s, C/30s seemed to be powered with 292s.
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Old 10-29-2017, 01:04 PM   #11
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Re: 250 is constantly giving me fits... considering something different

there still around just not in your area...............

https://harrisburg.craigslist.org/pt...337220374.html

https://york.craigslist.org/pts/d/gm...337174514.html
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