vacuum leak and overheating

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Dec 22, 2002 | 05:00 PM

bikerwolfie

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From: usa

vacuum leak and overheating

i finally got my 390 in and started. it has a vacuum leak on the back side of the carb, either between carb and spacer plate or spacer plate and manifold. anyway i'll replace both. its running hot just above 220 deg. could a bad vacuum leak cause it to run hot? the 360 i just pulled ran at 195 deg with a 195 thermostat in it. i used the thermostat, waterpump and intake off the 360 so i can't figure any reason why it would overheat.

Dec 22, 2002 | 05:06 PM

Ratsmoker

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From: Missouri

vacuum leak and overheating

A bad vaccum leak can definitely cause an engine to run hot but you are also breaking it in which will cause more heat. I had to garden hose the radiator on mine for the first 30 minutes while I was initially breaking it in.

Dec 23, 2002 | 06:42 AM

William

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Joined: Feb 2000

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From: Sun River St. George

vacuum leak and overheating

Yup! Garden hose in the radiator until the camshaft is broken in at 1600 RPM for 30 Minutes. The vacuum leak will cause lean condition and definitely cause over heating.
William in Atlanta

Dec 23, 2002 | 09:07 AM

bikerwolfie

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From: usa

vacuum leak and overheating

got the vacuum leak stopped and ran it for 30 min @1500 rpm (per instructions that came with the engine). took it out and ran it at 30 mph with full throttle burst to 50mph. i guess this is to seat the rings. i'm still running at 220 on the water temp. should i be concerned with this? or will it start to drop once the engine is broke in? also i can tell a BIG BIG differance in the power over the worn out 360 it had. how long before i can see what it will do?

Dec 23, 2002 | 02:02 PM

Ratsmoker

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From: Missouri

vacuum leak and overheating

If it is at 220 degrees going down the road what does it do when you are stopped? If it doesn't rise you either have a bad guage or the thermostat got messed up in the swap. Check your timing also. Timing too advanced will cause overheats but it will still get worse at stop signs/lights (whichever the case may be).

Dec 23, 2002 | 02:10 PM

bikerwolfie

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From: usa

vacuum leak and overheating

what should the timing be set at? i have it set at 6 deg. i also think my gauge went bad during the swap. i'm letting it cool down now to see that it drops to zero.

Dec 23, 2002 | 02:18 PM

John72_CS

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vacuum leak and overheating

I think most folks say to start at 12 degrees with an FE. 6 might be a bit far advanced. (That is advanced, right? Don't think I'm losin it but I'm stuck at work behind a desk ;p)