Slant Six Forum :: Hesitation going from cruise to WOT

H'mmm.

It doesn't hesitate at all off the line, only if you're already cruising along and then step on the gas?

Have you checked out what is happening with your accelerator pump shot from part throttle? Are they both pumping a good stream?

Ok testing revealed that my front carb has NO shot at all. Both are set at the very bottom hole on the accelerator pump linkage.
So now I'm confused. Does this basically mean the carb isn't shooting ANY gas at all?

Will it spin the tires yet?

Leaks you describe are common/typical, but won't prevent adequate accel pump pressure buildup. Use TWO correct gaskets at both body casting junctions!

Tried to find one in the stack, but none of the others were an exact match. Some were missing a flange but otherwise correct. Figured trying to make that work would only make it worse. Please correct me if I'm wrong. There must be 5 other variations in the kits I have.

Author:	NewLancerMan [ Fri Jul 29, 2005 9:14 am ]
Post subject:	Hesitation going from cruise to WOT
Hello all, I've been trying to get my Lancer all tuned in after the 225 transplant, and I'm most of the way there. However, I'm still trying to get a few things dialed in. Right now, the main problem I have is when I'm just cruising around town at say 20 mph, then go to WOT, it hesitates and wants to stall out. Sometimes it will power through this and start accelerating, sometimes it just bogs. What would be the likely cause? Is the mixture too rich and flooding the carb on WOT (lack of air flow or the jets too rich?). I'd really appreciate some advice. BTW the setup I have on the dual carbs is: -PCV to a central chamber on the intake that is supposed to distribute to both carbs -Vacuum advance is T'd to both carbs. Thanks! MJ

Author:	SlantSixDan [ Fri Jul 29, 2005 9:27 am ]
Post subject:
Probably a problem in the step-up (power valve) system on one or both carbs. Did you go through both of them?

Author:	NewLancerMan [ Fri Jul 29, 2005 10:36 am ]
Post subject:
yes I rebuilt both of them, but its not like I'm Mr. Carb or anything. Should I tear them back down? Any way I can start testing or looking for issues? Thanks Dan MJ

Author:	SlantSixDan [ Fri Jul 29, 2005 11:03 am ]
Post subject:
H'mmm. It doesn't hesitate at all off the line, only if you're already cruising along and then step on the gas?

Author:	Slant6Ram [ Fri Jul 29, 2005 11:26 am ]
Post subject:	Saw it at Columbus
Really cool car in person! I can't imagine it would be very easy to tune that setup. Have you checked out what is happening with your accelerator pump shot from part throttle? Are they both pumping a good stream? Why not do some trial and error tests by changing the accelerator pump to a richer setting and seeing if it improves or gets worse? Or go in the other direction, too much could be just as bad as too little. Another though is the vacuum advance. Have you hooked up a timing light to watch the reaction during the stumble? You've got your work cut out for you, but the cool factor is in effect! Almost wish I had one.

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Author:	NewLancerMan [ Fri Jul 29, 2005 2:51 pm ]
Post subject:
Quote: H'mmm. It doesn't hesitate at all off the line, only if you're already cruising along and then step on the gas? That is exactly right. I'll do some more road testing tonight and see if I can get more specifics on behaviors. Ram I'll do some testing and post back. Fun fun! MJ

Author:	NewLancerMan [ Sun Jul 31, 2005 5:12 pm ]
Post subject:	Re: Saw it at Columbus
Quote: Have you checked out what is happening with your accelerator pump shot from part throttle? Are they both pumping a good stream? Ok testing revealed that my front carb has NO shot at all. Both are set at the very bottom hole on the accelerator pump linkage. So now I'm confused. Does this basically mean the carb isn't shooting ANY gas at all? Its all further confused by some linkage problems I'm having, but I'd appreciate further troubleshooting on the carb here. I haven't unscrewed the hard line to the carb to make sure gas is flowing there, but that's probably a good check just to be sure my t fitting isn't malfunctioning. Anyway, and help and advice is always appreciated. Thanks! MJ

Author:	Jeb [ Sun Jul 31, 2005 5:58 pm ]
Post subject:
Will it spin the tires yet?

Author:	SlantSixDan [ Sun Jul 31, 2005 7:38 pm ]
Post subject:	Re: Saw it at Columbus
Quote: Ok testing revealed that my front carb has NO shot at all. Both are set at the very bottom hole on the accelerator pump linkage. So now I'm confused. Does this basically mean the carb isn't shooting ANY gas at all? It means the front carb's accelerator pump has a problem. It doesn't mean gas isn't reaching the front carb, or that the front carb isn't working at all (you'd know it if you were only running on three cylinders). These BBS accelerator pumps have to be put together right -- that means soaking the leather pump plunger cup in light oil until the leather is soaked right through, then using a small screwdriver (or your thumbnail) to grab and flare the bottom of the leather cup outward. Really bend it outward, don't be delicate about it! Then you install the plunger into its round well with a twisting motion, making sure the leather cup doesn't fold up on itself. If the cup isn't flared properly, then the fuel in the well will just leak upward past the edges of the cup when the plunger is activated. Also check for presence of the two check balls (one at the bottom of the well, under the plunger. The other in the small round well on the driver's side of the carb. See your service manual for details.). If either is absent, especially the intake check ball under the plunger, the accel pump will not work. Sometimes the intake check ball's seat corrodes and the ball no longer seals properly. To fix this, you place a pin punch firmly atop the inlet check ball and give a sharp rap or two with a hammer, to form a new seat. Then you dig out the old ball, discard it and install a new replacement.

Author:	NewLancerMan [ Sun Jul 31, 2005 8:28 pm ]
Post subject:
Quote: Will it spin the tires yet? lol sadly enough, it does indeed. I had a separate throttle rod problem where the dual carb control set screws came loose, leaving the throttle stuck all the way on. At a stop sign. Both tires started smoking and broke loose from the brakes before I was able to shut the key off. Does that count? Dan--thanks for the tips--I'll check through those and be sure. The front carb was "new" before I used it, and I didn't check to make sure the leather part of the acclerator pump was properly flared. Most likely it dried up and didn't do its job. I'll take a peek at it tomorrow and replace it if necessary. That sounds like the easy fix. I'll also let you know about my throttle rod adventures...stay tuned. Thanks again everyone! MJ

Author:	SlantSixDan [ Sun Jul 31, 2005 9:59 pm ]
Post subject:
With low-miles/shrunk/dried accelerator pumps, you can often save 'em by going ahead and flaring them and reinstalling.

Author:	NewLancerMan [ Mon Aug 01, 2005 7:22 pm ]
Post subject:
ok I reinstalled the accelerator pump and it was just dried up. I put a new one in and flared it out like you described. I checked for both balls and they were present. I didn't see any corrosion at the seat for the accelerator pump ball, so I left it alone. Put the carb back together, primed it (checked to make sure its getting gas and it is), and still no squirt. I've pulled the carb again but I was just curious what else to look for. When the carb was on the car, I did see gas leaking at the gasket between the upper and lower body, as well as a screw that has the second ball bearing sitting in its pocket. Could these leaks prevent the pressure from getting high enought to squirt? I'm just wondering if I should abandon work on this carb and put another together or check something else. Thanks! MJ BTW, I think I am on my way to solving the throttle rod problem. Here's my first try at it. Old linkage: New One: This setup should hopefully stop the tendency of the rod to want to slide towards the firewall, getting the kickdown stuck against a screw end protruding out from the firewall. I dremmeled the opening to make it bigger and reduce the friction and angle the rod previously had. Then I pulled the rod entirely and threaded it for 3/8" coarse thread nuts and tried to make something happen here. I didn't use the sleeve spacer from the old setup because it wouldn't slide over the threads on the rod, but I'd like to get a similar sleeve vs. the nut/lock washer/washers setup I currently have. Once I get it all dialed in, I plan to drill a hole through the linkage sleeve and attach it permanently to the throttle rod so it doesn't slide. I had a problem where it got stuck all the way on and ran the engine up over 5000 rpms while I tried valiantly to hold the brake while I turned the motor off. Needless to say, I don't wish to repeat that. I'd like to get some kind of spacer there, just not sure what to use. I'd have to drill out the offy linkage to thread the throttle rod to put another nut on the firewall side, and without a drill press handy I don't trust myself not to mess it up. Basically, the new locknut on the end of the rod is supposed to prevent the rod from sliding towards the firewall, and the rest of the nuts/washers are there to keep it spaced. Suggestions on improvements are welcome. I'm no engineer, I just had to use what I had in my meager stash in the toolbox. MJ

Author:	SlantSixDan [ Mon Aug 01, 2005 8:55 pm ]
Post subject:
Accelerator pump passages or squirter jet could be clogged. Pry-out the soft white metal plug facing the driver's side of the car, just outboard of the accelerator pump jet (near where that 2nd check ball is located). Unscrew the accel pump jet from the carb body and give it a good backflush with a spray can of carb cleaner. Operate the accel pump plunger with the jet removed to flush out the passages (if still no gasoline pumped up to accel pump jet area when jet's removed, carb's got internal clogging bigtime!). Leaks you describe are common/typical, but won't prevent adequate accel pump pressure buildup. Use TWO correct gaskets at both body casting junctions!

Author:	NewLancerMan [ Mon Aug 01, 2005 10:59 pm ]
Post subject:
Thanks dan, I'll see what I can do tomorrow Quote: Leaks you describe are common/typical, but won't prevent adequate accel pump pressure buildup. Use TWO correct gaskets at both body casting junctions! Laughed at this one. Tried to find one in the stack, but none of the others were an exact match. Some were missing a flange but otherwise correct. Figured trying to make that work would only make it worse. Please correct me if I'm wrong. There must be 5 other variations in the kits I have. MJ

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Author:	SlantSixDan [ Tue Aug 02, 2005 6:34 am ]
Post subject:
Quote: Tried to find one in the stack, but none of the others were an exact match. Some were missing a flange but otherwise correct. Figured trying to make that work would only make it worse. Please correct me if I'm wrong. There must be 5 other variations in the kits I have. Yep, unfortunately, until you've built up a backstash, the only way to get 2ea the correct gaskets...is to buy two kits per carb. Also forgot to mention that you'll need a new replacement soft-metal plug, for they usually get pretty chewed up on removal. NAPA has these in one of those little plastic compartmentalised boxes they keep behind the counter, but I don't have an Echlin fuel system buyer's guide nearby to give you P/Ns!