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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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

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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Recognized by US Federal Courts as a Fuel Economy Expert!

The fans spinning down will generate enough juice to keep the ignition firing if they are direct to the battery.

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Official Cookie and Mater Tormentor.

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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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

I assume you have premium gas in there. If not, try that.

Lou

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Home of Slant6-powered fun machines since 1988

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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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

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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Home of Slant6-powered fun machines since 1988

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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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

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

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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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

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.

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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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

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

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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84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

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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Home of Slant6-powered fun machines since 1988