Gary Lewis Posted July 4, 2022 Share Posted July 4, 2022 The stock 3.08. The high altitude version got 3.55's. There was another thread on this where it seemed the issue is my engine not behaving right by not having enough bottom end. Then again, in OD at 65mph it's only turning 1500 or so... Supposedly I should be doing great there but in reality it struggles. Edit: about to make a 3 hour drive home in it. Gave the TV cable a few additional notches (1/8"?) of tension. 1500 RPM is mighty low. Do you know what your AFR is? And are you sure you got the cam installed on the marks? Link to comment Share on other sites More sharing options...
ratdude747 Posted July 4, 2022 Author Share Posted July 4, 2022 1500 RPM is mighty low. Do you know what your AFR is? And are you sure you got the cam installed on the marks? No idea on the AFR, Cam timing is correct (gear marks lined up when I built the engine). 1500 is too low actually... here's what reality looks like: When down shifting to 3rd, at 70MPH the RPM is around 2700. Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 4, 2022 Share Posted July 4, 2022 No idea on the AFR, Cam timing is correct (gear marks lined up when I built the engine). 1500 is too low actually... here's what reality looks like: When down shifting to 3rd, at 70MPH the RPM is around 2700. Yes, 1500 may be too low. Not sure where you are driving on the 3 hour trip, but if it is through hills there's going to be some shifting going on. But that is quite a jump from 1500 to 2700. If the AFR is too lean you'll have a lack of power until you push the throttle enough to cause the carb to lift the needle. But if that is past the point where you downshift then it is moot. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted July 4, 2022 Share Posted July 4, 2022 No idea on the AFR, Cam timing is correct (gear marks lined up when I built the engine). 1500 is too low actually... here's what reality looks like: https://forum.garysgaragemahal.com/file/n121059/IMG_20220703_204538.jpg When down shifting to 3rd, at 70MPH the RPM is around 2700. That is about where mine runs, 1800 rpm, but I have a NP435 manual trans and the Advance Adapter's over drive IIRC 27% and I have a 2.75 rear gear. I do have a few hills to / from work and it will slow down a little but a little more throttle and I can stay the speed. I also have a AFR gauge and on the flat run about 13.5 - 14.5 and get about 15 - 16 mpg. I want to lean it out a little more to run about 14.5 to 15.5 AFR and hope to bump up the MPG. But I am one of them "if it aint broke dont fix it" It just runs so good I hate to mess with it. Dave ---- Link to comment Share on other sites More sharing options...
ratdude747 Posted July 4, 2022 Author Share Posted July 4, 2022 Yes, 1500 may be too low. Not sure where you are driving on the 3 hour trip, but if it is through hills there's going to be some shifting going on. But that is quite a jump from 1500 to 2700. If the AFR is too lean you'll have a lack of power until you push the throttle enough to cause the carb to lift the needle. But if that is past the point where you downshift then it is moot. I see. I do have a feedback carb. The last tests I ran I didn't get any lean codes. Or rich codes. My O2 sensor is used though (upgraded to a heated unit, same upstream sensor as used on late 90's rangers and explorers) so it's possible that's reading rich and driving the mix lean? One other note: I'm having mixed results driving today... Not as bad if I don't use cruise and allow it to slow down some. Although such doesn't make me any friends behind me though . Also the slight TV adjustment is causing a bit of gear hang when coming out of a valley in cruise... I have to shove the gas, speed up past the cruise set point, and that allows the gas to drop enough to allow the upshift back to overdrive. Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 4, 2022 Share Posted July 4, 2022 I see. I do have a feedback carb. The last tests I ran I didn't get any lean codes. Or rich codes. My O2 sensor is used though (upgraded to a heated unit, same upstream sensor as used on late 90's rangers and explorers) so it's possible that's reading rich and driving the mix lean? One other note: I'm having mixed results driving today... Not as bad if I don't use cruise and allow it to slow down some. Although such doesn't make me any friends behind me though . Also the slight TV adjustment is causing a bit of gear hang when coming out of a valley in cruise... I have to shove the gas, speed up past the cruise set point, and that allows the gas to drop enough to allow the upshift back to overdrive. Typically the ECU will throw a code if the O2 sensor appears to be flakey. So it isn't likely that you are running very lean if the light isn't on. How about ignition timing? You have the SPOUT connector in? What's your base set to? Link to comment Share on other sites More sharing options...
ratdude747 Posted July 4, 2022 Author Share Posted July 4, 2022 Typically the ECU will throw a code if the O2 sensor appears to be flakey. So it isn't likely that you are running very lean if the light isn't on. How about ignition timing? You have the SPOUT connector in? What's your base set to? Base timing at 10 degrees confirmed. Spout is plugged in and working. I don't have a CEL. But the timing is advancing at idle so it's not in limp mode. Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 4, 2022 Share Posted July 4, 2022 Base timing at 10 degrees confirmed. Spout is plugged in and working. I don't have a CEL. But the timing is advancing at idle so it's not in limp mode. You knew where I was going. So I'm at a loss as to why you are seeing what you are seeing. Link to comment Share on other sites More sharing options...
ratdude747 Posted July 5, 2022 Author Share Posted July 5, 2022 You knew where I was going. So I'm at a loss as to why you are seeing what you are seeing. Driving it last night it did better without cruise (and people riding my back bumper). I guess while the 3.08 is good for economy, it's bad for drivability? Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 5, 2022 Share Posted July 5, 2022 Driving it last night it did better without cruise (and people riding my back bumper). I guess while the 3.08 is good for economy, it's bad for drivability? The Bullnose speed control units are way too aggressive in my book. And with your combination of driveline more finesse is needed or you'll be shifting all the time. But yes, 3.08 gears in a truck are quite tall, especially when coupled with an AOD that has a .67:1 OD. That's like having a 2.06 rear end. Link to comment Share on other sites More sharing options...
Recommended Posts