Jump in Revs / engine question - Vintage Mustang Forums
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post #1 of 3 (permalink) Old 07-18-2019, 12:01 PM Thread Starter
Join Date: Nov 2017
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Jump in Revs / engine question

Hi guys,

So im working through a few things with my 69 and the drive train has been a little - interesting - to say the least. there are a few things i need to work on;

first being the fact that it smells a lot like fuel, more than I'd expect. I'm pretty sure there arent any major leaks anywhere. Is it possible that one or more cylinders aren't firing properly? also could it be a lack of compression? its a fairly powerful 351w with (what should be) 9.1:1 compression.

Next, when i put my foot a bit more on the gas (at around 20-30 mph) there is sometimes a sudden jump in revs until i release and then give it more gas. I think this could be the gear slipping (C4 auto transmission) but I have noticed quite a bit of wheel spin at times. Is there any easy fix for wheel spin? I intend on getting the gearbox looked at in a few weeks.

thanks! all suggestions / comments welcome
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post #2 of 3 (permalink) Old 07-18-2019, 02:54 PM
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Location: JAX
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If it smells like fuel, triple check that you have no leaks.
If no leaks, then carb is probably running rich and needs some tuning. Or it’s flooding and needs a float level adjustment.

The jump in revs could be a slipping trans or something with the torque converter. Impossible for me to know for sure without driving it.

Loss of traction is tires. Or you just need to be easy on the throttle.

1970 Mustang coupe
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post #3 of 3 (permalink) Old 07-18-2019, 03:06 PM
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The jump in revs could be the trans dropping down into the lower gear, normal. Called "passing gear."
Check and make sure your fluid is up, clean reddish and doesn't smell burnt anyway.

Verbose Vocabularian
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