just back from our local 'heartbreaker' dyno. enjoy

I have been fooling with timing/jetting/plugs for quite a while now and needed to see my results on what I suspected to still be slightly lean upper rpm condition. At last I had the time to get it to one of the dyno places this morning. This dyno facility houses the local 'heartbreaker' dyno. All the locals know this place and know this Mustang dyno reads at least 2%+ lower than all other Dynojet dynos in town (dynojets software is generous!). Still, I am very pleased with the results but still a bit lean up top.

Bear with me. Trying to post the sheets but for some reason the system is not allowing it. Probably a problem with my firewall. Here are the results explained:

The rpm was calibrated while holding the engine in 4th gear at 2k rpm although rpm on the sheet showing a tad bit low compared to actual. We suspect this is due to not spending enough time calibrating the car rpm to the dyno exactly dead on at 2k rpm. No biggie as this meter is independent to systems which effect the numbers or a/f calculations.

This test was performed with 55 idles, 200 a/c, 140 mains with NGK BP7ES plugs gapped at .042, Crane XR700 optical ignition firing two Mallory 3rli ignition boxes. Idle sits nicely at 13.2:1 ish. We tested cruising speeds in various gears and found that nothing really goes over 14:1 below 5krpm. All other partial throttle resides around 13.5:1 to 13:1. Very satisfied with cruising a/f ratios.

Pulls were made in 4th gear. Elevation is about 2k ft in 77 degree weather here in the desert. Weather correction factor for the day was 1.049. Best pull of 3 pulls was 185.4bhp at the rear wheels @ around 6400rpm. Worst pull was 181.2. I am using US spec intake opening specs at 34btdc. What I am most excited about though is the torque figure of 172.1 made at around 3600rpm. I have my distributors set up to European ignition advance curves so I have about 13 degrees at idle and I am advancing to 30 degrees advance at 2500rpm slowing moving to 40 degrees max advance later at 6krpm. After advancing and retarding the distributor a bit we found that 40 degrees advance at 6k is best. WOT throttle a/f ratio showed 2k-4k was at 13.3:1. 4k-6k was about 13:8:1 and 6k-max power at about 6.5k was 14.1:1 with the lean condition continuing to 15:1 at 7krpm.

I am going to put in either 185 or 190 air correctors with the 140 mains to hopefully correct the lean condition on top and collect at least a few more ponies on the top end. I am leaning towards using 185s due to how quickly it got lean anywhere over 6500rpm. I tried 170/135 but that was too rich. Overall I am completely satisfied, especially with this evil dyno (lol) that has a bad rap.

I have noticed a few '78-'79 cars going way too rich with this jet setting which is probably due to the cams, yet they will make good power. My next run is going to be after I replace my belts and change to Euro intake timing specs which will raise peak power rpm a few hundred rpm due to that extra 4 degrees overlap. Can't wait. Will keep everyone posted on that one! Probably not going to dig into the belts until after our move. Gosh I need to figure out a new screen name since I wont be in Vegas any longer. Hm

-John

 

http://i795.photobucket.com/albums/yy239/lvferraripilot/dynoOct1002.gif

http://i795.photobucket.com/albums/yy239/lvferraripilot/dynoOct1001.gif


this should have it up for us. Should someone like to post them into the actual post, feel free.

One item of note as well. I pulled a couple plugs directly after a run, per the plug reading chart here on fchat, the plugs are a bit rich. The insulator is bone white, the heat on the ground strap is just right showing color change to the apex, the ring has a 7/8 turn of light soot, but the inside of the insulator does not have the blackened ring where it is supposed to be on many engines. The ring is a tiny bit higher than that of where, say, a Chevy WOT run would want to be. I guess a lean Ferrari plugs read a bit rich for other types of engines.

 

BP7ES after WOT dyno run.

http://i795.photobucket.com/albums/yy239/lvferraripilot/plugafterdyno.jpg

 

This is a stock '76 engine with stock '76 cams/compression. Now that I think of it a bit more, I am sure I am going to swap for 185 a/c. It seems the engine begins to sharply become lean right after peak power becoming *really* lean over 7k. I am sure there is another good 5+rwbhp in there once power peaks at a little higher rev range. With this dyno, I was shooting for 180rwbhp just because I know what a nasty piece of work it is lol.

Surprisingly, the car was just not nearly as drivable with 34mm chokes so I never put the car on the dyno with them. This pull was done with stock 32mm chokes. If 185/140 does not do the trick, I am going to try F24 e tubes with 200/135 and see how that goes. Top end gets uncomfortably lean.

 

I scanned the docs to pdf. They are a bit more clear for those who are interested.
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