77 140 INTO A 71?

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77 140 INTO A 71?

Postby sportriderok » Fri Apr 10, 2015 1:44 pm

Does anyone know if a stock 1977 140ci will work in a 1971 Vega with a 2 spd auto? I have a super clean 71 Hatch that has had it's engine removed, and a running 77 engine in a crap car. Both are automatics, the 71 a Powerglide and the 77 looks like a M200? I know the HEI will have to be addressed, is there anything else I need to look out for?
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Re: 77 140 INTO A 71?

Postby hammerdown7 » Fri Apr 10, 2015 2:13 pm

Should be a pretty straight forward swap. The '77 HEI is self-contained except for the coil.

Dick
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Re: 77 140 INTO A 71?

Postby sportriderok » Fri Apr 10, 2015 2:44 pm

Perfect, thanks for the quick response. I know what I'm doing this weekend!
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Re: 77 140 INTO A 71?

Postby spencerforhire » Fri Apr 10, 2015 3:40 pm

I see you're aware of the problem with using an HEI distributor in an older vehicle. The HEI will not run properly on the 71's existing points ignition coil + supply(yellow). Instead, hook the HEI coil power to the large pink on the oil pressure/fuel pump switch.
The "fleet"-
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
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Note- the very act of listing all of these has made me realize I have some kind of problem.....

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Re: 77 140 INTO A 71?

Postby sportriderok » Fri Apr 17, 2015 3:37 pm

I am now! I usually run a bigger gauge wire for an HEI conversion, but I forgot about the oil pressure switch. Thanks for the tip.
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Re: 77 140 INTO A 71?

Postby cammerjeff » Sat Apr 18, 2015 12:04 am

Just make sure you have a full 12V from the switch for the HEI (you should) HEI's do some strange things with low Voltage.
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Re: 77 140 INTO A 71?

Postby 74_Vega_GT » Tue Jul 26, 2016 8:45 am

I couldn't help replying to this old thread, I was not aware of this issue with the HEI swap. Can you tell us what problems are cropping up as a result of the low voltage/amperage wire? I will be addressing this issue when we reinstall the 140 on my project. Thanks for posting.
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Re: 77 140 INTO A 71?

Postby Monza Harry » Tue Jul 26, 2016 6:15 pm

The HEI will [probably] run at the 9 volts or less supplied by the GM installed resistor wire, but your secondary voltage output will be less than the old points system [I would expect a lot for most]. So expect a lack or complete absence of power at full throttle as the Rev's go up, for starters and/or probably some scattered misses as well. I would also expect hard starting issues, especially hot as you will have even less power when you need it most. Those are the ones that come to mind I am sure others will chime in with their experiences. Harry
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