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| Super Six problems at idle https://slantsix.org/forum/viewtopic.php?t=35390 |
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| Author: | dartslantsix [ Sun May 17, 2009 8:57 pm ] |
| Post subject: | Super Six problems at idle |
Hi, new to the forum. I've got a question about my slant six, I just swapped to a super six with a carter BBD. I'm having some problems. First, I'll give the specs. It's a 1966 225, bone stock except for electronic ignition. Before the swap it was a stock 1bbl and ran fine. I picked up the proper manifolds and carb-which came off a running truck. I mounted the manifolds as shown on this website-using hylomar on both sides of the gasket. I rebuilt the carb following the specs in the factory service manual (1974 edition). (This is the first time I've rebuilt one of these carbs, so the problem may be there) Now, the car runs fine on high idle. Timing was set to 15 degrees BTDC, but the engine idled better with a bit more advance than that. Idle mixture screws were seated then backed out 2 1/2 turns. When the engine is warm, and I kick off the choke, the engine runs rough and surges. It bounces between 800 and 1000 rpm. Where should I start checking? My gut says the carb, but I don't really know where to start. Thanks! |
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| Author: | SlantSixDan [ Sun May 17, 2009 9:38 pm ] |
| Post subject: | |
Welcome on the board. If you have to run more than 15° base advance to get the engine to run well, something's the matter. It should run well at 5° to 8° BTDC. There is no magic number of turns for the idle mixture screws — they need to be adjusted to meet the needs of the engine. Carburetor operation and repair manuals, some training movies, and adjustment instructions are posted here for free download. Depending on your present library and your general level of knowledge, you may want to buy some or all of these three books. |
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| Author: | Reed [ Sun May 17, 2009 10:02 pm ] |
| Post subject: | |
I would start by doing everything Dan recommends, but in the intetrim check for a vacuum leak and make sure the metering rods are adjusted correctly. |
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| Author: | dartslantsix [ Sun May 24, 2009 8:19 pm ] |
| Post subject: | |
Okay, more info. I've read the required reading as posted above. I've checked for vacuum leaks and fixed my EGR block off plate. (I just gooped silicone on the perimeter, but exhaust was still allowed in the intake. I put a gasket under the plate to prevent that.) The car is running better now, but not very good. It doesn't want to idle well and the power is down from the 1bbl. When I first stomp the gas, the car leaves hard, but then slows. I'm suspecting that the car is still lean because the accelerater pump richens it and it jumps, but after that it's lean again. Okay, now for the next question. The vacuum step up piston adjustment screw. I was using a 1974 Factory manual for a 318, it said to adjust the gap on the piston/rod assembly to .030". It didn't say anything about counting the turns to get there. I had to screw it down quite a ways from what the carb had when I took it apart. Now I've read the carb info that was posted above and it says: "Never attempt to change the factory setting of the vacuum step up piston..." Dang it. I'm suspecting that the needles are too far down and are restricting the fuel so the car is lean. Do I need to just start adjusting the metering rod screw until the car is happy? How should I proceed? Thanks for all the info! |
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