HICKL Posted November 12, 2010 Share Posted November 12, 2010 (edited) Ok you smart guys, please help me figure this out. Basic engine facts, 383, dart sportsman II small chamber heads, roughly 11:1 compression ration, block hugger headers etc etc. Original setup was a performer RPM with a Holley 750 dp carb. Ran consistent 11.51's, Switched to tunnel ram with 2 holley 450's, ran consistent 11.51's (almost identical). I decided to play with a little nos so I purchased a victor jr with the extra 1" of height, stuck a cheater plate on it and the same holley 750 dp. My best run with this setup is 11.80 (not spraying). It feels like it really flattens out at around 5800 rpm's where as with the tunnel ram, if the road was not sticky, it would break the tires loose at 6000 rpm in second gear. I understand this short single plane may not rev like the t-ram, but I think it even ran better up top with the performer RPM. Could I be under carbed or under jetted for this intake? Would the same carb setup work good on one intake and be that lacking on another?? I have looked at timing, curve etc and all looks normal, checked compression and all 8 cylinders up above 180. Any idea where to look to find this missing horse power??? Thanks for any ideas, Jeff Edited November 12, 2010 by HICKL Quote Link to comment Share on other sites More sharing options...
dustin280zx Posted November 13, 2010 Share Posted November 13, 2010 Whats your mph between the performer and vic jr and same track/similar weather conditions? If no adjustments were made to the 750dp from switching intakes check your plugs and you should find the answer. I usually check my tuning with a wideband, but to finalize my tuning I put a new plug in #1 and 8 or 7. I then make a hit and shut the car off immediately and pull the plugs. Check for rich/lean conditions and how fuel distribution. I had a problem with #1 and 2 going a little lean with all other cylinders being spot on hence why I check a front and a back. This should be less of an occurrence in N/A though, but I would still recommend checking a front and back to make sure the carb is performing efficiently. Quote Link to comment Share on other sites More sharing options...
HICKL Posted November 13, 2010 Author Share Posted November 13, 2010 Ran 3-4 mph slower with the Victor jr. Quote Link to comment Share on other sites More sharing options...
dustin280zx Posted November 14, 2010 Share Posted November 14, 2010 Ran 3-4 mph slower with the Victor jr. Thats about 30-35 horse at the flywheel. Have you checked vacuum? Quote Link to comment Share on other sites More sharing options...
HICKL Posted November 16, 2010 Author Share Posted November 16, 2010 Thats about 30-35 horse at the flywheel. Have you checked vacuum? Be more specific, do you mean check for a big leak?? Quote Link to comment Share on other sites More sharing options...
cockerstar Posted November 16, 2010 Share Posted November 16, 2010 Checked with a vacuum gauge off one of your vacuum ports. Quote Link to comment Share on other sites More sharing options...
HICKL Posted November 16, 2010 Author Share Posted November 16, 2010 He He, I understand how to check vacuum, was wanting to know if he is specifically looking for something. I know what my vacuum is at idle and I know what happens to it at WOT, I know it changes with timing etc etc... Jeff Quote Link to comment Share on other sites More sharing options...
dustin280zx Posted November 16, 2010 Share Posted November 16, 2010 He He, I understand how to check vacuum, was wanting to know if he is specifically looking for something. I know what my vacuum is at idle and I know what happens to it at WOT, I know it changes with timing etc etc... Jeff Yes for a leak and if it is within "normal" range for your motor. Did you make any adjustments to your carb when on the single plane? Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 16, 2010 Share Posted November 16, 2010 My guess is you're getting a weaker signal with the VicJr and you're going to have to fatten it up a bit to run as well as the rpm. jt Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted November 18, 2010 Share Posted November 18, 2010 (edited) Ive found the edelbrock, vic jr to be one of the LEAST effective SBC single plane intake designs and the Keith darton wieand , and edelbrock super vic , and rpm air gap intakes to be some of the better designs http://www.summitracing.com/parts/HLY-300-110/ http://www.summitracing.com/parts/HLY-300-110/?rtype=7 http://www.summitracing.com/parts/EDL-7501/ http://www.summitracing.com/parts/EDL-7501/?rtype=7 http://forum.grumpysperformance.com/viewtopic.php?f=44&t=392&p=479#p479 I sure wish you were local, Id be glad to help you sort out the car & engine youll want to get a wide band fuel/air gauge or look at reading plugs a bit, because youll want to be running about a 12.8:1 f/a ratio http://forum.grumpysperformance.com/viewtopic.php?f=70&t=202&p=7854&hilit=+fuel+air+ratio+gauge#p7854 http://forum.grumpysperformance.com/viewtopic.php?f=50&t=1853&p=4848&hilit=+fuel+air+ratio+gauge#p4848 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=109 http://forum.grumpysperformance.com/viewtopic.php?f=50&t=1853&p=4848&hilit=+air+fuel+meter#p4848 http://forum.grumpysperformance.com/viewtopic.php?f=50&t=2891&p=9279&hilit=plugs+ratio#p9279 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=109 http://forum.grumpysperformance.com/viewtopic.php?f=44&t=773 http://forum.grumpysperformance.com/viewtopic.php?f=50&t=383&p=2301&hilit=+power+valve+vacuum#p2301 http://forum.grumpysperformance.com/viewtopic.php?f=44&t=777&p=4546&hilit=+power+valve+vacuum#p4546 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1790&p=4544&hilit=+holley+cam+pump#p4544 http://forum.grumpysperformance.com/viewtopic.php?f=55&t=1639&p=4545&hilit=+power+valve+vacuum#p4545 THESE THREADS SHOULD HELP Edited November 19, 2010 by grumpyvette Quote Link to comment Share on other sites More sharing options...
HICKL Posted November 18, 2010 Author Share Posted November 18, 2010 I know you recomended the Keith Darton intake but if memory serves me, I did not have enough clearance for it. I can see losing some hp if not the right match, but I would not expect to loose 30 or 40.. I am still testing my memory to see when it begun to feel flat. Have had a few "mis-haps" since I tried this setup so not sure if I hurt it in another way. I lost 3rd gear while doing a WOT 100 shot of Nitrous one day so of course it pegged straight to redline. Got the trans re-built then had a rocker stud let go at about 6K rpm's a month or so later. Somewhere along the line I had a spring break in my dizzy and fixed that but I "think" I got it back right and my timing curve seems to be the same as it was. She sounds normal, idles fine, no knocks or anything like that. Is it possible that I have cam damage? Can a cam "slightly flatten" or do they only fail miserably? I am open to any ideas on where to look, have been racking my brain over this for months... Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted November 19, 2010 Share Posted November 19, 2010 yes its possible for cam lobes to wear slightly or wear slowly effecting power, its even more common for valve springs to loose tension over time and get into loss of valve control at lower rpms as the springs age and loose tension, or rings to loose a higher percentage of the cylinders compression seal as they wear. the edelbrock vic jr has been a bit restrictive in my experience,as the runner entrance angle and port cross sectional areas, not idea. you can normally gain a few hp with an open 2" spacer but if you had the room for the open 2" spacer you would have more than likely installed the keith darton intake. Quote Link to comment Share on other sites More sharing options...
HICKL Posted November 19, 2010 Author Share Posted November 19, 2010 I went with the 2999 victor jr which has the "built in" 1" spacer and then have the 1/2 cheater plate on top of that. Even this taller vic jr was still about .750 shorter than the Keith Dorton if memory serves me. Quote Link to comment Share on other sites More sharing options...
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