i have a 360 .030 over rv cam, stock heads, exhaust, ect. this engine has always had overheating issues even with alum radiator.

initial tuning was 10deg timing 15in vac at idle.
ran hot 200-220.

after reading a post here about tuning with a vac gauge i went back and retuned it. i ended up with 20in vac and tuned mixture and idle.
now it runs 170-180.

before it would run over 200 with oat of 30
todays current oat is 60 and it was running 180

can someone explain why this would make it run cooler, i thought basically temp went up with timing (sort of).

thanks shane

you were too lean before.

What's your initial timing at now? It's possible (likely?) that the timing mark on the damper slipped, and is now off by a bit.

My 408 likes a little more timing to make it run cool. 15* initial keeps it at 185. Drop it 2* and the temp creeps up to 195.

it was to lean before now you are fatter on the fuel mix which will help cool it some,IIRC

it gets way hotter running lean from comb chamber to the exhast ports and into the header tube...thats why they glow red when lean

setting one with the vac gauge is the best way to see what an engine is doing,rather than listening to it by ear,or light,trusting the marks are correct

dont know how many I have straightend out cause they said they can set it by ear...shadetree falls right on them when the vac gauges does it magic...

just showed some one there burnt up piston cause they could set it be ear...told them it was advanced to much and was not the 93 gas!!!!

said it was built with lots of comp and it pings on the street

they had it so advanced it was bucking like it had a cam

shade tree fell right on them when I showed #4 pist with 1/3 of it gone down to the 2nd ringland

next to a comp check and leakdown test as the best trouble shooters, IMO

so if i understand this right have the timing to slow will lean one out?
i didnt have to move the mixture screws much if at all. i figured this thing was running way fat
having a 750 on it and the M-1 single plane probably isn't doing it any favors either.

but it's what i had laying around.

i'm not sure where the timing ended up, it's off the tab and i dont have a roll back timing light just an old sun timing light.

thanks for the info, i'm just trying to understand whats going on.

shane