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misfire under load on 1930 large series


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Guest buckfarmer
Posted

Got the 1930 model 64 out for the first time yesterday, since the restoration began. Started out with a misfire when climbing hills. However after a little adjustment of the air screw the engine ran great under all conditions. Then I ran it out of gas and now the misfire has returned and no amount of adjusting timing or airscrew will seem to help. The car runs great at idle and revs nicely. But under a load it misfires like it might be starved of gas? Any thoughts?

Neil

Posted (edited)

Check the tube in your heat riser, make sure it's not rusted out - even pinholes will alter the mixture from the carby.

This may be what you need! This one is for a 1925 Master but I have previously purchased one from this vendor for a 1929/30 master so it may be worth contacting him.

http://www.ebay.com/itm/25-BUICK-MASTER-6-HEAT-RISER-SLEEVE-NEW-/380315658857?pt=Vintage_Car_Truck_Parts_Accessories&hash=item588c946a69&vxp=mtr

Edited by 50jetback (see edit history)
Posted

I agree with Stewart. The heat riser is usually the first thing I check when having fuel issues.

Your symptoms also suggest that your fuel delivery system may be partially clogged with debris. I say this because the probem re-appeared after you ran out of gas.

If your heat riser tests OK, check your gas tank for rust and debris that may intermittently clog the pick up tube.

The fuel pump might also be suspect if it cannot keep up at full load.

Posted

Neil,

If you discover that you are in need of a new heat riser tube, I have already replaced mine and have a second NOS one for your engine (1930 331ci Master) that I would be willing to part with.

Thanks,

Thanks

Posted

The jets on the carb draw fuel off the bottom of the fuel bowl. If you ran it dry, it's possible that you got dirt into the jets. You may need to remove them and check that they are clear. While you have them out, check the jet tubes for hairline cracks. Another common problem on these carbs. The brass age hardens and cracks. They are easy to fix with solder. Just be sure you don't solder the tube shut.

Bob

Guest buckfarmer
Posted

Thanks everyone.

Mark I tried the wd40 and found no leaks. While I was at it I pulled the plug I had in the heat riser cross tube and sprayed in there and found nothing. Next I think I will do a compression test. But that will have to wait until the car gets back from upholstery. Here is a pic of the car loaded to go to the upholsterer.

Neil

post-64154-1431419339_thumb.jpg

Guest buckfarmer
Posted

Mark,

I am planning to attend the 2014 nationals. Hoping to drive the car, my wife, mother inlaw, and children will take turns riding with me while they follow with camper and trailer (in case of mishap andfor trip home)

Neil

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