SBC temp question

Just got done firing up the 350 SBC in my 53 BelAir, when I noticed the paint burning off one of the manifolds. I hit it with an infrared therm. and it shows up about 100 degrees HOTTER than the rest...Hmmm, somethings wrong here folks...Anybody got any ideas?

 

is it a center or outer cylinder?

 

Drivers or pass manifold? Are they both open or does one have the thermostatic spring/plate? Intake=single or dual? Too tight valves? Any shaking/missing? Fill us in.

 

Sorry, should have put some more info it...It's number 5, it has an Edelbrock aluminum intake with Holley 4412 2-barrel. Timing is at about 10 degrees advanced before vac. advance is hooked up. Has Dart Sportsman heads and domed pistons, moderate circle track cam.

 

possible lean condition....

 

I just checked the timing, the mark on the damper is at the 12 o'clock position with the advance hooked up, so it's waaaaaaay advanced, gonna try to turn it back, see if that helps, and more ideas?

Of, btw, the idle mix screws are BOTH out 1 and a 1/2 turns, so I don't think it's running lean, plugs look fine too...

 

I think you found your primary cause....

Please remember......

Your firing order (1,8,4,3,6,5,7,2) fires #5 and then #7 cylinders and thus these two are always somewhat hotter exhaust temps (especially at idle w/low water movement) than the other individual cylinders. Most racing cams are 4-7 swaps for this primary reason along with a modest HP increase and better cooling of the #7 hole but I'm getting way OT......

 

I'd turn it back to 4 degrees advance and put a vacuum gage on it and tune
the carb to max vacuum.
See how that works for ya.

 

At 4 degrees advance it BARELY runs...I turned it down to just under 16 degrees and it runs much much better. I also replaced the water pump and flushed entire system...

The other thing I'm thinking is I need a bigger fan. I'm running 2-10" fans pulling over a aluminum radiator... I'm gonna try 1 15" fan and see what that does...

BTW, according to the temp gauge. water temp was normally around 200, but that was while moving...Wend almost to 250 when idiling in traffic...

 

What kind of water pump does it have now? If it's a hi-flow that may be the problem............try an OEM pump.

The 200 at cruise isn't terrible, but the 250 is pretty hot. Make sure your temp gauge is accurate. If it's truly in the 250 range it should sound hot (snap, crackle & pop) and won't restart easily. Try using a infrared temp gun on one of the freeze-out plugs to verify the 250 reading on the gauge.

I had a situation where the temp gauge read 250 while driving and my temp gun at the freeze-out plug read 176. I tried everything and finally replaced the second brand-new hi-flo pump with OEM. It's been perfect ever since.

 

Lets look at the obvious.

First off you should be running 12 degrees min. @ idle.

Fast timing will not burn your exhaust slow timing burns your manifolds as it is firing closer to the exhaust event.

Whether you run headers or cast manifolds the paint is going to burn off of them. That's just the nature of the beast and as has been mentioned the 5 and 7 will burn off first as a rule.

I would double check the spark plug wires and make damned sure that they are correct.

I would also make sure I didn't have any tight valves. If you are running a hydraulic cam you should be running between 1/4 and 1/2 turn past no play. Other wise you should have your valve lash set to the recommendations on the cam card.

One thing that is common with hydraulics is that the lifters are not pumped up yet when someone sets up a new engine when they pump up you get tight valves.

That should get you started. If there is still a problem it may well just be that there is no problem at all.

oh and maybe you should take a look at your cooling system. 250 is just a little on the hot side.

 

It is a stock water pump, I used a IR temp gauge, and the readings were pretty accurate.

 

Is the stock water pump in good working order and is it OEM new, used, rebuilt or aftermarket?

Did you shoot both the top and bottom of the radiator with the IR temp gauge? Where else did you shoot it? At 250 did you notice the heat coming off it, was it crackling and hard to start? Did it smell hot?

Do you have a fan shroud that may not allow enough air to pass through it when moving (ie: no rubber flappers)?

 

higher compression,higher combustion tempertures,maybe have a look at your thermostat,antifreeze mixture,stuff like that.i would definetly change out the thermostat to maybe 160?