Strange idle problem.. need answers

[KJ]

I was testing out my car before i start the rebuild or engine swap to see an about time i wasn't at the track i could get in the quarter mile. Well i noticed something that maybe is normal but i don't think i ever noticed this before that being said here is the problem. Also i did a few runs to test this out.

Well on run one i was kinda slow i guess even for a stock sohc. But i got about what i thought was right. The next couple times i was doing a little better had a friend timing me. Ok here is where something happened unusual. It dropped in degrees which i know that can help out with the running of the car but i turned the heater on and dropped about a full second of my other times. Now when i set with the car idle it was at 1250 rpm. I stepped on the gas peddle numerous times to see if the choke was stuck and nothing it stayed at 1250. Then i turned off the heater for the last couple runs and it idled at 750 rpm and the full second was back on my times. Does anyone know why this would happen or if it is a problem?


KJ
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