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#21
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I've always had HEI on my Pontiacs and ran .045 gap on my iron headed 400 with AC plugs. On the engine in my sig I've been running Autolites and they come pre gapped at .025 but need checking. Fuel lately has been 90 octane non ethanol
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Chris D 69 GTO Liberty Blue/dark blue T400, 9" w 3.50s, 3905lbs 461, 850 Holley, T2, KRE 310s, Comp HR288 w 165s, RA manifolds, 11.60@114, 1.58/60 The spare: 467, 850 Holley, T2, Edelbrock Dport 310cfm w RA manifolds, HFT 245/251D .561/.594L, 11.59@ 114, 1.57/ 60' |
#22
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i saw this vid on youtube thats interesting, while its not very scientific & is only showing the spark at very low rpm from him spinning the dist gear by hand & no cylinder pressures, it shows a huge difference in spark with the box vs without, on both a stock coil & a msd one. https://www.youtube.com/watch?v=vMpPtWtTS_s thanks for the replies, i will be reducing the gap on the NGKs in the E heads today to .035. i pulled a couple yesterday & they are at .045-.048, my gap gauge is one of the older style with metal tabs of different sizes & both .045 & .048 will slide in with just a little more resistance on the .048, i will have to find my round ramp type gauge or use a feeler gauge to get more accurate & consistent this time. |
#23
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i have played with fuel psi on the robbmc 1100 pump at 7-8.5 psi for a few runs & also tried a mallory regulator set at ~7.5 & turned the pump up to ~10psi.. no change still happens. next step is to attach a fuel gauge so i can watch the psi on a run & see if its losing psi, but after reading about what too big of a spark gap can cause im wondering if it is ignition related to too big of a gap & a stock hei with a close to stock in cap coil?? that will be added to my list of testing as well as trying out the 6al box i have. |
#24
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Those types of gremlins are exactly why I gave up on HEIs, can't tell you how many coils, caps, rotors, and modules I went thru. I did everything right, too. Boils down to the modules themselves, and no modules worked flawlessly for any length of time, they all failed. Pretty sure I posted here on all that too.
If you just cruise around all the time, you probably will never notice, but once you beat on it more than once or twice a summer, it will rear that ugly head. .
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#25
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im still amazed how easily the car does low 11 sec runs even with its limitations i mentioned, but the gap was definitely too big & im hoping further testing will identify the issue at the track. |
#26
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3 MSD boxes here. 2 of them with billet distributors, one a stock points distributor. All 3 have the zapper MSD coils. One is 11:1 with iron heads. The other 2 are aluminum heads, one with 10.2:1 compression and the other with 10.84:1 compression. They are all gapped at .035. No misfire problems with any. The stock points distributor with a digital 6 box and MSD coil goes to 7000 rpm. The other two see 6000-6500. 2 of them run Autolite plugs and the other one has NGK. |
The Following User Says Thank You to Formulajones For This Useful Post: | ||
#27
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#28
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#29
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Interesting on the .035 gap recommendation by most...something to try
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#30
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what gap do you run & what ignition system do you have? |
#31
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I've ran .045 for years.. The smaller gap has my interest peaked for sure I'm at about 10.8 to 1 for compression. Any slight aid in tuning always helps for sure.
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#32
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i think with the CD box & a bigger coil you are probably ok at .045, my main concern is the stock HEI & close to stock coil i have may not be cutting it with 10.7 comp. |
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