cold egts #1 and #2 in Top Dragster

hey guys hope you can help.

I have 540 chevy big chief with 1471 Mert high helix, 20% OD, bird catcher with hats and ports flowed by Gorr, msd 10 with 8979 taking 10* for 1.5 s at hit. 28* total timing. leave at 4200 2step with air cylinder opening throttle blades about 4500. Powerglide Trans

Problem is #1 and #2 egts are about 400* and 600* colder than other cylinders which are all pretty tight. This is only the case at idle and while on 2 step. When car leaves they start to warm up. by the gear change they are about 200* and 300* colder and by end of run they are pretty tight.

I have increased #1 and #2 ports by 4 and also decreased by 5 and it makes no change at all??

I run 50/51 in these ports from Gorr.

Did I not make a big enough move, or is it something to do with the 2 step making those cylinders really fat??

Thanks for your help.

 

I have a similar setup with the same problem. I set the blower back and solved the problem. I have also heard of some people using a little bit smaller intake rocker arm ratio on 1 and 2 but I have never tried that. I don't know what effect that would have on the top end EGT

 

Remember that there is a lot of "lag" with thermocouples, the readings are not real time.

 

Hi Casey,
Keep in mind that while idling, and possibly on the two step, you are running on just the hat nozzles. Changing the port nozzles will have no effect at idle, and little or no effect while at part throttle or on the chip.
If you check your fuel pressure at the nozzles during the times in question, and that pressure is below the setting for the port nozzle check valve, then you are definitely only running on the hat.
The fact that they balance out down track says that overall the settings are correct (or very close). If you shrink the front hat nozzles slightly, you should see the idle temps change. However, if you do that, make sure you change the front port nozzles at least the same amount, or possibly more, to keep from leaning out the front under power which, in my opinion, is far more important than idle temps.

Hope this helps.

Kendrick

 

egt

i'd forget the EGT and read the plugs. If they are showing an even burn leave it alone. The plug coloring supposedly happens at the end of the run so if the egt evens out up there they should look good.

We have a motor close to yours but switched to a psi screw and it has cylinders dropping 3-400 degrees early in the run. It evens out on the topend and hauls a$$!
With a converter and timing pulled out on the hit it really doesn't care down low as long as it stays consistent so you can tune around it.

 

Casey, try setting your throttle blades at 3800 while on 2-step. then set your launch rpm to 4000 rpm. This will keep the engine from flooding out while on the 2-step.
And yes, the port nozzles should be working on 2-step. Ours open @ 3000 rpm.
If you have any ?'s, call. 513-543-3097 Glenn

 

thanks

Pete. The blades are set to open at about 4500 if I remove 4200 chip. This way the blades will not be the limiting factor....if I understand the principal correctly.

Kendrick. The ports come in as the rpms go up on the chip.

Overkill. The plugs are all even on the top end as well as the egts. Bottom end is my concern. I tried reading after a half track pass in which the egts show that they are just starting to warm up. This didn't give me a lot of info because my turn up barely gives the top ring "color" on a full pass.

I suppose considering that it is a consistent tuneup that I don't really have a big issue however just trying to make things as I thought they should be.

Just trying to be a tuner like my buddy Kendrick!

 

That;s to high rpm on 2-step. Think about what I said. The engine shouldn't be hitting the rev limiter. Adjust the launch egt's with the barrel valve!

 

launch on 2-step

pete,

I ran a season launching off of air cylinder and thought it was very consistant, but had to be mindful each day of airchanges and adjust setting at the beginning of each day and it would still very slightly.

having it hit the chip takes air changes out of the equation, right?

 

not on ours. If you keep the egt's and tune-up for the weather changes, it should stay very consistant. The key is the barrel valve setting. If you let it go lean when the weather gets better, it will leave more agressively. We run a hemi T/D. My son can cut consistant .010 to .025 lights from morning to dark.

 

I would agree that the rpm will be more consistent on the chip, but I would agree with Pete that the power level can still vary with the air and adjusting the barrel valve while watching the EGT's could help in compensating for the power change a little, but backing off the timing when the air got better might be more effective.
Good food for thought here!

Kendrick