Racingjunk Forums

Racingjunk Forums (
-   Engine Tech (
-   -   wierd high exaust temps (

hansbuddy70 05-06-2013 07:14 PM

wierd high exaust temps
ok guys I got a weird one, got a motor that runs like a champ, just put it in and it runs great even finished second at a track I normally run mid pack but the exaust temps are crazy hot and i'm goin nuts trying to figure it out, 9to1 350 2brl carb lt1 manifolds running *40 total advance and the plugs look nice and tan so I don't think its a rich/lean condition and water temp stays at 200 all race but the exaust pipes are HOT!!! same pipes with my other bullet temps are all fine? any help would be appreciated!

TheYellaBrick 05-07-2013 05:21 AM

What fuel are you running ?

roadkill2 05-07-2013 07:04 AM

Do you have any idea what your EGT's are? How hot is HOT . . ?

I would caution you about using another or previous engine as a true benchmark. If this engine is running "Better" than a previous one, it could be that the previous one wasn't tuned as precisely as the current one and your EGTs are OK for the tune you have on that engine. That's assuming all your other markers were correct.

You possibly were on the rich side previously, dunno . . .

DRTRCR22 05-07-2013 09:50 AM

What kind of balancer are you running..? Is it possible your timing mark is off...?
It is likely you are not at 40* advance like you think you are, which sounds like way too much anyways...?

I just melted down a fresh new 355 which I [thought] I had 35*, but turns out the timing was wrong and it was more like 42*.
It ran like a cat's butt on fire, but by the time I caught the problem it was too late and burnt several pistons about six laps into the race.

We did a test in the pits one night to settle an argument, and tried four top of the line expensive timing guns from other teams, and we got four different readings...!
We finally settled on the brand new best gun as the most likely accurate reading...?

If you are on alky, and are absolutely sure the timing is dead on, bump your jets up at couple sizes to see if it cools down.

If you are on high quality race gas, and you are sure the jets are right on, I would highly suspect your timing is off...!

I was also told by an expert engine builder it could have been an intake vacuum leak, but I didn't find any evidence of such when I tore it down...?

Scooterz 05-07-2013 03:03 PM

I just saw another post from DD about variance in timing guns/manufacturers.... it echo's what DRTRCR22 is basically saying....

That is scarey when 4 different guns all have different readings!!!

hansbuddy70 05-07-2013 07:06 PM

well for the fuel question 4 gallons of 89 regular to 1 gallon of Sunoco 112 octane which I ran in the last several engines and had good luck. I do agree that one engine against another is not a good benchmark, I guess I should say I've been racing in this same class for 14 years and have been through several motors but never this particular problem and I have no way to measure E.G.T.s as no telemetry besides tach, oil, and water allowed but the pipes actually melted the paint off the floorboard directly above them and burned my foot/leg and have never had that. the timing light is a little older digital MAC light so it could be off? I think I'll try backing off the timing this weekend and see what happens?

hansbuddy70 05-07-2013 07:11 PM

oh and its a proform balancer and I have been through that problem in the past. I double checked the TDC marks after degreeing the camshaft but thank you that's a good suggestion and thanks everyone for the input!!

roadkill2 05-08-2013 07:34 AM

For the fuel you're running, you've got way too much timing . . For the average SBC. 36 to 38 is about average on Gasoline with the Comp ratio you're using. But this is nothing more than a generality. There's all kinds of things guys do with jetting and timing, especially in those roundy round engines with two barrel carbs . .

Any tuning gauge is generally relative, and depending upon the kind and how it's been taken care of, it may or may not give accurate readings. If you have any doubts about the accuracy of the Timing Light (or any other tuning or diagnostic tool) check it against several others.

On the EGT, just check the heat of the header just below the flange or the head right at the flange with a IR handheld temp gauge. Use it across all eight to not only establish mean or average EGT, but it will also tell you which ones are the hottest (Leaner) and which ones are richer or not firing if you have a problem . .

Your exhaust temp is relative to both your measuring instrument and the type of head/cam you're running. That you'll have to figure out, but a place to start would be using your gauge on someone else's combo that's similar to yours and then look at your's in comparison.

markdunlap 05-08-2013 06:28 PM

Pro Comp balancer?

I had an experience with on on a customer's street car. It was off several degrees, just before the outer ring fell off and took off on the floor and dented my tool box.

Might not hurt to recheck the top dead center.

hansbuddy70 05-08-2013 06:40 PM

well normally I run around *36 advance but it made a noticeable difference in power on the dyno at 40, forgot to mention that, but the guy running the dyno said that makes some sense because we aren't allowd to have an alternator and have to run a stock ish HEI ignition and they don't make much spark at 12 volts?? Maby I just need to back down the timing cuz the dyno and the track are two different things

All times are GMT -8. The time now is 05:10 AM.