A/F Ratios and EGT's

[lun40119]

After some recent dyno testing to establish a baseline for a head swap on my sbc, it was brought to my attention that I may be running a little lean. I am at 12:1 with 64cc chambers. A/F's range from 12.7 at 3800 to 13.2 at 7000. There was a small spot between 5600-5700 where they hit 14.3. The EGT's range from 1200ish at 3500 to 1550ish at 7000. Total time is at 40*. That is where it made its best power. The exhaust valves, runners and the headers were a really light brown. I am running 110 octane fuel. Any input would be appreciated. Thanks for your help in advance.

[Awesome Bill]

anything over 1350 with gas, is considered warm, I would not run any egt over 1475 with gas and 40° timing. your most likely lean, but it does make good power with a low bsfc. What was it?

[lun40119]

Between .445 and .585. The combo was way down on power, I think there was alot of exhaust contamination on the intake side. Will be going back with a new set of pro 1's. I am pretty sure the valve job on the old heads was due to get freshened up. They are old :D

[Awesome Bill]

.44 is not bad, but how down was the power? .58 sucks and will cause high egt because of burning fuel in the header tube. Carb is everything, get a bad one and you'll suffer.

[lun40119]

Ok.........the EGTS went down with a secondary jet change(up 2). All between 1214 and 1372 at 7000rpm. On the first testing day with the World heads the average BSFC was .445 and the Peak was .585. With the Dart heads, the jet change and at 38 total the Average BSFC was .470 and Peak was .591. The A/F ratios on day 1 were between 12.7 @3800 and 13.2 at 7000 with a small 200rpm at 14.3. On Day 2 A/F was between 13.2 at 3500 and 12.3 at 7000. And at 4400-4600 a short little bit at 11.9. The way it was explained to me was that inorder to bring that peak down..........it won't be as simple as just turning a screwdriver. Any ideas.....

[Awesome Bill]

air bleeds!

[lun40119]

Thats all I get............................................... ............