I'm getting ready to start my motor. I've got some old headers to use until I have it tuned,So my coated ones won't be turning colors.What temperature should I be reading an inch or so from the header flange.Its a sbc 350, 600 holley, mild cam.Thanks for any info Steve
Well, since you've got your old headers on, which by the way is a good idea, don't worry about your exhaust temp yet. Get her to fire up and idle first, get the motor broke in and run the cam in, (at least 30 to 45 minutes), on roller motors, about 10, then check to make sure you have no leaks. Get your timing set, making sure your where it needs to be.
If everything is within reason, a sbc + Small Cam + 600 cfm Holley, your not gonna be too hot. Unless someones been jacking around with the jets usually.
But to answer your question, on normal tuning, with regular headers, 550 to 780 , going down the road, under load, air running past the header tubes.There are alot of variables here, so much so, You won't get a accurate reading. You don't raed your temp at the header flange....if your gonna read cylinder temp, its gonna get the hottest, right before the 1st bend....that is wwhere you want to aim your heat gun.
When we run engines in on the dyno, I can tell you within 5 dergrees what your cylinder temp is, cause I have thermo-couples embedded in the header tubes and collectors so I can tune for optimum power. I'm also reading surfacw temps, which is what I gave you....
Use your heat gun to make sure all the cylinders are running the same heat....go by your coolest cylinder and shoot for that. Stainless headers run at a different heat than chrome headers, that run at a diff. heat than ceramic coated, that run at a diff. heat than plain painted. See what I mean?
If your running chrome headers, theres some old school tricks for keeping your pipes from turning blue. There some products you can put on your pipes and in them to keep this sorta thing from happening. Back in the old days with chrome on the steel, we used to get a big gob of grease, coat the inside of the header. In later years, I preheated them in my pizza oven I had in my shop back then, then put the grease into the tube to burn.
Then we'd put just a little more in there, bolt them on the motor and fire her up.
The Grease burnt coating inside the metal pipe would form like a porcelin sleeve inside that tube, keeping it from turning colors and burning out. But eventually, it would still turn blue later on. I started doing header wrap before header wrap was cool. I'd burn't the piss outta myself on a bunch of exhaust systems....and if I had to be around them, I wrapped them. I'd let the customer take the wrapping off if he wanted.
Now days, they've got white wrapping, gray wrapping, all kinds of diff. colors, and you can even get it in titanium.....
ANYWAY, YOU REALLY NEED TO HEAR WHAT IS HAPPENING INSIDE YOUR ENGINE TO GET IT ALL TIMED CORRECTLY AND ALL THINGS SET PROPERLY... LET RUN LONG ENOUGH TO CHECK YOUR RADIATOR/COOLING SYSTEM ALSO... ONCE YOU ARE SATISFIED THAT THE ENGINE IS RUNNING THE WAY IT SHOULD, NOW YOU CAN SWITCH TO YOUR NEW (LOUDER) HEADER SYSTEM FOR A TEST DRIVE. (THIS PROBABLY WILL CHANGE HOW SHE RUNS, LIKE THE JETTING MAY NOW HAVE TO BE CHANGED IF SHE RUNS HOTTER WITH THE HEADERS... KEEPING A FOOT ON EACH PEDAL, (WHOA AND GO) AND THE BIGGEST THING, KEEP THE SHINNY SIDE UP... :spank:
