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william1764 |
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Member ![]() ![]() Group: Members Posts: 252 Joined: 11-May 10 From: maryland Member No.: 11,717 Region Association: MidAtlantic Region ![]() |
Just had completed a full engine rebuild of my stock 2.0L (with Webers) to a 2.3L by a small Porsche indy in Maryland (2.256 big bore, 10:2:1 compression, mild cam). Carbs were also rebuilt to accommodate new build. Unfortunately, engine runs like crap with incessant backfire out of exhaust and carbs (during both acceleration and deceleration). Hard to even really tell yet how the increase in displacement feels due to the bucking and backfiring. However, I do know that power seems to peak at mid 4K range. Planned to have dyno'd but until this is resolved no point. Their estimated build time of 2 months took 14 months and still not drivable so I'm a bit frustrated. Indy acknowledges that he doesn't know what the issue is. Said he suspects its carbs but not certain. Wants me to invest in a new set. To be clear, the carbs have worked perfectly for the last 10 years up to the day i dropped off to their shop. Indy acknowledges no issue with carbs when he received. Frankly, I've lost all confidence and contemplating having another shop look at this issue and resolve. In all fairness, this is not a hack shop...very reputable. I don't want to bash/mention names. Requesting recommendation of an indy, ideally in Maryland, that is capable of assessing and hopefully fixing the issue.
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falcor75 |
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Senior Member ![]() ![]() ![]() Group: Members Posts: 1,579 Joined: 22-November 12 From: Sweden Member No.: 15,176 Region Association: Scandinavia ![]() ![]() |
I just got hung up on that it idles fine but doesnt work when driving. I agree with many others. Get yourself a notepad and start checking everything and make carefull notes of what you have checked and what you have measured. No sense in spending money on guesses.
Compression, are all cylinders equal within reason Leakdown, any oddities? Fuel pressure, within spec? Timing, Distributor and ignition leads installed and hooked up correctly How does the spark plugs look, are they wet or sooty etc, make notes Air leaks, both topside and bottom (exhaust side) Carbs and linkage, sync between banks, measure drawn air with a synchrometer Carb jets etc There is no magic ticket, its just systematic fault elimination and keeping notes. |
Superhawk996 |
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914 Guru ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 5,916 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch ![]() ![]() |
There is no magic ticket, its just systematic fault elimination and keeping notes. (IMG:style_emoticons/default/agree.gif) Lots of guessing always happens on posts like these. I need to figure out a way to start some sort of over/under betting pool when these posts pop up. How many guess until the solution for the root cause is properly identified? Placing call to Vegas casinos now to get in on the action . . . . (IMG:style_emoticons/default/laugh.gif) I've always kept a journal style notebook for each of my cars. Maintenance info, engine & suspension tuning info, and troubleshooting info. You'd be amazed how handy it becomes to have that history years later when it's all but long forgotten. |
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