I had a problem similar to many of the posts on here with a bog / stumble under hard acceleration in 1st to 2nd or sometimes 2nd to 3rd. I've rectified a few small problems I found with but with no success. Today I replaced the fuel pump with a stock replacement unit but without return line. The bog seems to have disappeared but now the car is blowing significant block clouds upon initial throttle opening.

I rekitted the carb recently to try to eliminate the aforementioned bog, so most parts are new. I've tried checking the float level but can't find a spec to check against. Carb is a 86 (17086004) and there are no settings for these in Haynes. Rochester book suggests 7.5mm which is about where it was. I've reset the M/C solenoid travel which was quite a bit more than specified.

What should I try next? The plugs for the rich / lean mixtures are missing so I guess these have been played with at some stage. I don't have a tool to adjust them at the moment. Aircleaner is OK and does the same with it off. Initial timing is at 8° and coil is a new Mallory high output HEI version.

All help very much appreciated.


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83 Berlinetta - LG4, Mr Gasket Shorty Headers, Custom Y pipe, 3" pipework, 3" Vortech Muffler, Performer Intake, Open Element, QJet mods. Best 1/4 Et 15.11 @ 90.4 mph, 2.097 60ft.

Put the M/C control setting back to stock. Anytime you have to move something "quite a bit more than specified" it's a good chance you have another problem and are just covering it up with an excessive adjustment like that.


[This message has been edited by Damon (edited November 12, 2001).]

Thanks Damon. The adjustment I made was meant to set the lean mixture screw back to the stock setting, strangely the rich mixture screw was in about the right place (3.2mm travel) so I didn't adjust that. But I think you are right about covering up another problem. My fuel economy has halved since putting the new pump on so i think that the problem is simply that the float or new needle & seat aren't doing their job and the fuel (now under more pressure) is getting through and overfilling the bowl. I guess I'll have to pull the damn thing apart again.

Damon, I have lowered the float level and borrowed a compressor and blew the crap out every little orifice. Things have improved - less soot over the back bumper I still get a bit of black when I mash the gas, and the car bogs a little of the line when warm.

I have the lean stop set at 2 1/4 turns from seated, and set the rich stop so that there is 3.2mm travel on the plunger. Where should I go from here?

Did I mention that since I've had the car (2 years)it has thrown a lean / o2 code intermittently whilst cruising at light throttle. If I apply a bit of gas or back off the light goes out after a few seconds. Is it likely that the O2 sensor is faulty and causing my problem? When I put the headers on it had to be relocated downstream, if I replace it would it pay to get a heated one - any complications? Sorry to get off topic.

Cheers.