DT, i had the same thought today to retard a few degrees. i am going to have the engine out for the trans swap anyway. that just means i have to get the new trans sooner
andy.
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| Author: | akbmotorsports [ Sat Jan 12, 2013 1:27 pm ] |
| Post subject: | long rod |
hello. got the 84 D100 back on the road!!! got the exhaust hung yesterday and have made a few short trips across town. seems to run great so far. the only issue i am having is run-on after ignition turned off. i have tried advancing timing a bit from 7 to around 12 allowing slightly more closed throttle plates, and retarding from 7 to around 4 requiring more open throttle plates. i have gone from NGK BPR5EY to a BPR7EY with little or no effect. idle speed 600 in gear and 1000 in park/neutral. the plug color has been good although i have only put about 25 or so miles on the new engine. electric fans are wired direct to the battery. should i try a non projected tip plug? i am a bit stumped right now. engine build details; 1967 block w/198 rods-wiseco pistons at zero deck big bore head gasket oregon cams 346 grind (262/252) dialed in at 100 icl pertronix ignitor 2, flame thrower 2 coil, DI recurve offy intake w/edelbrock 1404 500cfm engbldr valves/guides/springs, some porting and bowl blending, 60cc chambers 6/1 header w/2.5 inch outlet stock 904 trans thanks, andy. |
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| Author: | mpgmike [ Sat Jan 12, 2013 2:28 pm ] |
| Post subject: | |
If nothing else, the air conditioned cars had a throttle solenoid. You could install one and set it so that it gives good idle when activated. Turn back the normal idle speed screw, and wire the solenoid to key-on. When you turn the key off, the throttle plates will close. No more run-on! Mike |
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| Author: | slantzilla [ Sat Jan 12, 2013 2:38 pm ] |
| Post subject: | |
The fans spinning down will generate enough juice to keep the ignition firing if they are direct to the battery. |
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| Author: | akbmotorsports [ Sun Jan 13, 2013 10:45 am ] |
| Post subject: | |
thanks. fan disconnected has no effect. it did not like the 7 range plugs. am going to tighten the valves a little, have backed them off to .020/.024 to smooth the idle. andy. |
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| Author: | Dart270 [ Mon Jan 14, 2013 2:12 pm ] |
| Post subject: | |
I assume you have premium gas in there. If not, try that. Lou |
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| Author: | akbmotorsports [ Mon Jan 14, 2013 2:46 pm ] |
| Post subject: | |
yes sir, 93 octane. my worst enemy (besides myself) i think is the stock torque converter. too high no load idle to achieve good driveability in gear. hopefully when i do the gm trans swap this issue will go away. maybe the idle stop solenoid would work as well. i need to check the cranking pressures to verify compression ratio calculation were correct. after putting some miles on it this weekend, i am pushing up the trans swap to REAL soon. thanks again, andy. |
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| Author: | Dart270 [ Tue Jan 15, 2013 12:49 am ] |
| Post subject: | |
Cyl pressure readings will be informative. Sorry I did not get the Wilcap plate mailed to you before my 1wk work trip. I will get it out next week for sure. There are tons of GM converter options. Lou |
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| Author: | akbmotorsports [ Wed Jan 16, 2013 11:33 am ] |
| Post subject: | |
the good news is all cylinders are the same, the bad is they are 200 psi. well, there you go. i must have either measured cc's wrong or made an error checking intake closing point. at least now i know what needs to be corrected. i already have the aussie head gasket so i may have to do the double fel-pro head gasket cheat until i can get another head worked over. do you think that would be enough to get me where i should be? how many cc's do you think it will take? should be around 160 psi for 10:1, correct? thanks, andy. |
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| Author: | DadTruck [ Wed Jan 16, 2013 2:03 pm ] |
| Post subject: | |
I have wondered if you could not mill some stock from the top of the piston,,maybe none on one half and .030 on the other, to make a quench shape, using the piston..., can you try retarding the cam a bunch, so the intake closes later,, maybe you won't build as much dynamic compression. here are the numbers from my build.. chambers were 59cc stock, removed .040 and they measured 53cc, pistons are down .160 with the small duration cam I have (IVC 27 ABDC @.050) I measured cranking pressure of 158 getting that with a dynamic compression of 7.6 and static of 8.5 |
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| Author: | akbmotorsports [ Wed Jan 16, 2013 6:47 pm ] |
| Post subject: | |
DT, i had the same thought today to retard a few degrees. i am going to have the engine out for the trans swap anyway. that just means i have to get the new trans sooner andy. |
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| Author: | DadTruck [ Wed Jan 16, 2013 8:15 pm ] |
| Post subject: | |
a few degrees won't be enough to drop the cranking pressure 30 points, and if the cam was retarded enough to get there, that would probably screw the performance up anyway. Your original thought, double gaskets (and maybe some more head combustion chamber polishing) is the best bet. |
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| Author: | akbmotorsports [ Thu Jan 17, 2013 11:23 am ] |
| Post subject: | |
i was somewhat surprised when i got that psi reading. the engine seems "happy" with the cam set where it is, it doesn't ping or show any other symptoms other than the run-on, it accelerates effortlessly. i haven't revved it over 3000 yet so i guess its possible it would start to detonate at higher revs. plugs look good, although #6 is running a bit rich. maybe 10:1 is just too much for this cam in this configuration. andy. |
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| Author: | DusterIdiot [ Thu Jan 17, 2013 5:33 pm ] |
| Post subject: | Hmmm... |
I am also thinking that the throttle solenoid or (dash pot) may be needed. 10:1 and your cam 234/228 @.050 isn't bad and if you set it up with a 106-108 LSA it should be just fine... (the Erson 280/270 is only 230/220). -D.Idiot |
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| Author: | akbmotorsports [ Thu Jan 17, 2013 6:47 pm ] |
| Post subject: | idle stop solenoid |
thanks for the replies, i will see if that works tomorrow, will back off idle speed screw, hold by hand and kill ignition and close throttle simultaneously. it is gonna be decent weather tomorrow. have a great day, andy. |
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| Author: | Dart270 [ Fri Jan 18, 2013 12:57 am ] |
| Post subject: | |
200 psi is a bit high for premium. Retarding cam some will help, and I have run 180-190 psi for long periods on the street. 2 Felpros will drop you at least 0.5 pt of compression. Lou |
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