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Teknon |
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#1
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The more I learn the dumber i think I am ![]() ![]() Group: Members Posts: 357 Joined: 10-August 04 From: Denver, Colorado Member No.: 2,505 Region Association: Rocky Mountains ![]() |
Ok Motorheads,
Senerio: New 2056, Slightly more aggressive than stock Isky VP-228 cam, ported 5pt heads with '74 2.0 D-Jetronics. Crane xr700 009 dizzy. Burch exhaust through SSI HX'ers Question: What would be some tricks and tips to make this engine more efficient. (IMG:style_emoticons/default/cool_shades.gif) I thought of having the MPS adjusted for a 2056, read that somewhere. Would like to put an oil cooler in most likely. What else would be things to concider. The engine is in boxes ready to assemble. Please chime in Joe D |
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jk76.914 |
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#2
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Senior Member ![]() ![]() ![]() Group: Members Posts: 809 Joined: 12-April 05 From: Massachusetts Member No.: 3,925 Region Association: North East States ![]() |
I'm running an Isky 229 with D-Jet. Though there isn't much overlap (12 degrees at .050" lift, just like your VP228), I saw a significant reduction in vacuum at idle, though my idle was still pretty smooth and quiet. I experimented with advancing the timing at idle, and it improved significantly, which makes sense if overlap is indeed the issue. I'm in the process of modifying a spare distributor to reduce the total centrifugal advance, so I can run more advance at idle but not exceed 32 degrees (plus or minus) total at 3500 RPM. I'll know later this season.
The second thing I noticed was a lean miss at about 3000-3500 RPM at part throttle cruise. I "fixed" it by installing slightly higher flowing injectors, but I think the real solution (not proven yet!) is to tweak the MPS for richer running. Trouble is, I'm convincing myself that the problem is that the diaphram transitions off the part throttle stop too late, because if I open the throttle more (reducing the vacuum, and thereby starting the transition) the miss goes away. Unfortunately, this isn't one of the adjustments available. I hope to get a better handle on this this season as well.... There have been a number of posts from other folks having this problem as well...... I have no regrets in going with Isky. Good luck with the engine... Jim |
Bleyseng |
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#3
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Aircooled Baby! ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 13,036 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest ![]() |
I'm running an Isky 229 with D-Jet. Though there isn't much overlap (12 degrees at .050" lift, just like your VP228), I saw a significant reduction in vacuum at idle, though my idle was still pretty smooth and quiet. I experimented with advancing the timing at idle, and it improved significantly, which makes sense if overlap is indeed the issue. I'm in the process of modifying a spare distributor to reduce the total centrifugal advance, so I can run more advance at idle but not exceed 32 degrees (plus or minus) total at 3500 RPM. I'll know later this season. The second thing I noticed was a lean miss at about 3000-3500 RPM at part throttle cruise. I "fixed" it by installing slightly higher flowing injectors, but I think the real solution (not proven yet!) is to tweak the MPS for richer running. Trouble is, I'm convincing myself that the problem is that the diaphram transitions off the part throttle stop too late, because if I open the throttle more (reducing the vacuum, and thereby starting the transition) the miss goes away. Unfortunately, this isn't one of the adjustments available. I hope to get a better handle on this this season as well.... There have been a number of posts from other folks having this problem as well...... I have no regrets in going with Isky. Good luck with the engine... Jim Its much easier to adjust the MPS for the correct AFR using the inner, outer screw and the WOT end plug. The stock injectors have plenty of fuel flow to handle it. The 2270 might be tough be still doeable depending on the cam. I have never used the Isky cams, I just know how much research was done by Raby to perfect his cam and lifter face grinds to stop the excessive wear and early death caused by the changing of the oil formula's. |
Teknon |
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#4
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The more I learn the dumber i think I am ![]() ![]() Group: Members Posts: 357 Joined: 10-August 04 From: Denver, Colorado Member No.: 2,505 Region Association: Rocky Mountains ![]() |
[quote name='Bleyseng' date='Mar 19 2007, 12:18 AM' post='876619']
[quote name='jk76.914' post='876526' date='Mar 18 2007, 09:04 PM'] I'm running an Isky 229 with D-Jet. Though there isn't much overlap (12 degrees at .050" lift, just like your VP228), I saw a significant reduction in vacuum at idle, though my idle was still pretty smooth and quiet. I experimented with advancing the timing at idle, and it improved significantly, which makes sense if overlap is indeed the issue. I'm in the process of modifying a spare distributor to reduce the total centrifugal advance, so I can run more advance at idle but not exceed 32 degrees (plus or minus) total at 3500 RPM. I'll know later this season. The second thing I noticed was a lean miss at about 3000-3500 RPM at part throttle cruise. I "fixed" it by installing slightly higher flowing injectors, but I think the real solution (not proven yet!) is to tweak the MPS for richer running. Trouble is, I'm convincing myself that the problem is that the diaphram transitions off the part throttle stop too late, because if I open the throttle more (reducing the vacuum, and thereby starting the transition) the miss goes away. Unfortunately, this isn't one of the adjustments available. I hope to get a better handle on this this season as well.... There have been a number of posts from other folks having this problem as well...... I have no regrets in going with Isky. Good luck with the engine... Jim [/quote] Its much easier to adjust the MPS for the correct AFR using the inner, outer screw and the WOT end plug. The stock injectors have plenty of fuel flow to handle it. The 2270 might be tough be still doeable depending on the cam. I have never used the Isky cams, I just know how much research was done by Raby to perfect his cam and lifter face grinds to stop the excessive wear and early death caused by the changing of the oil formula's. [/quote] [/quote] Its much easier to adjust the MPS for the correct AFR using the inner, outer screw and the WOT end plug. The stock injectors have plenty of fuel flow to handle it. The 2270 might be tough be still doable depending on the cam. I have never used the Isky cams, I just know how much research was done by Raby to perfect his cam and lifter face grinds to stop the excessive wear and early death caused by the changing of the oil formula's. [/quote] I thought I saw a post somewhere that you have to put constant WC pressure on it turn on screw than a nut. I'll have to find that again. Sounds like lots of tool bench preparation. But worth it, if I don't fkit it up. Nice to know the adventurous geniuses out there already figured these things out. Thanx Geoff Do we posses the 914 or does the 914 posses us????????....LOL |
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