Cylinder head temp??

mine is 230-240F after I run it for a few passes. I drag race 1/10 mile but I hot lap a lot. im running a mild combo on gas.
 
A properly tuned methanol engine will build head temps over 400 degrees after several laps, you can run less but to run hard on top end , especially the high rpm's you need to get it up there. Jon
 
No problem, I'll share something else with ya, on tight tracks where you drop a lot of rpm, run a little bigger jet and tape up the blower screen to get the heat up. The extra fuel helps them get up off the bottom and the less air going to the fan actually frees up some HP. On a fast track where your only dropping 5 or 600 rpm I'd want the blower screen mostly uncovered and jet it to see 400 to 425.
 
Thanks' Jon.
I made a couple of pulls last night and she got to 295. I pulled the plug and the ground strap was discolored all the way to the threads. I thinking I need to fatten her up on the big end and maybe drop back to a colder plug.
 
I wouldn't fatten it just yet if your only getting to 295, it does take 3 or 4 laps on a track to see how high it will build. If this is about like a Stocker and on alky you should be around a .048 to .050 jet, 1 1/2 turns out on the needle, leave the needle there and change jet .002 at a time to dial in head temp. As far as plug heat range when you run em a little fat you need about a 24 in an ND, that's the range I like to be in. When you go to a colder plug you run the risk of fouling it. In the high summer heat I'll sometimes go with a 28 which is slightly cooler.
 
She's running with a 348e Tilly and a 22 ND. 32* timing.
Slightly more than stock 2.75 bore 3" stroke .400 lift on the intake@108*. Edlbrock head with 1/4" dome piston.
She made 23.15 hp @ 6500 on the dyno last night. I made 2 short pulls at full load and then pulled the plug to take a reading, That's when I found the grd strap was colored all the way to the threads.
 
Ya, I'd go a little colder than that 22, The nice thing about a Tilly is two circuits to work with. Leave the low side rich so it has great throttle response and good bottom end. bring the high side in some to build a little more heat and get it to run hard on top. you have a lot left in that motor, although it made good power at 6500, .400 lift cam can go 9000 rpm, even with that stroke, but if you do, you need more ignition timing , like around 36 degrees to make it work. Since it's an open with a Tilly I'd shoot for about 375 degrees head temp. Jon
 
.048" to .050" is a 8.5% change in area. .050" to .052" is an 8.2% change in area. Those are big changes in jetting, are you sure you want to make that big a change?

Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory. (Al Nunley) oh
 
Yes I am, Al these are flathead 4 strokes, there not very efficient and this is with methanol for fuel, if this was a two stroke on gas changing the area of the jet by 8.5% would be a big change, but on these motors on alky, you would know if you ever tuned one that .002 is not a huge deal, I do have jets for every .001 for fine lining, but usually move .002 to make a real change.
 
Jon Brogden said:
Yes I am, Al these are flathead 4 strokes, there not very efficient and this is with methanol for fuel, if this was a two stroke on gas changing the area of the jet by 8.5% would be a big change, but on these motors on alky, you would know if you ever tuned one that .002 is not a huge deal, I do have jets for every .001 for fine lining, but usually move .002 to make a real change.
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believe what you want, it seems I'll never convince anybody, but if you were running an EGT you would see the huge difference you make with the .002" jet change.
 
What I believe about tuning these engines is based on years of experience with them on the racetrack and the dyno, can you say the same? If you knew anything about these engines you would realize we run headers around .880 ID or less, an EGT probe placed in that small of an exhaust would be a restriction that would kill exhaust flow. EGT is not an option, get it?
 
Jon,
We went to an NGK B8HS plug and changed the header to a longer one with a slight curve and she went up to 23.82 hp @ 7200. I pulled the plug and it was annealed just to the start of the ground strap right where I think it should be. Then just for giggles I added an RLV muffler that I had taken all but one screen out of and twisted her tail again this time she made 24.002 hp @
7200. May be on to something. What ya think?
Were gonna go tomorrow an put her in the dirt and see how she does. Hopefully we have the chassis dialed in to hook it up.
 
Jon Brogden said:
What I believe about tuning these engines is based on years of experience with them on the racetrack and the dyno, can you say the same? If you knew anything about these engines you would realize we run headers around .880 ID or less, an EGT probe placed in that small of an exhaust would be a restriction that would kill exhaust flow. EGT is not an option, get it?
Click to expand...
so what I hear you saying is; it's such a preposterous idea, it's not even worth trying! What ever!

I know one thing; that's a mindset I always strove to avoid.
 
W Lindsey, your finding that the engine definitely hasn't hit it's peak yet, probably got a little left, all you have to do is turn it up some more. Sounds like it' gonna run pretty good. Jon
 
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