1886 Grand Wagoneer

Loping at idle screams gas tank and carb air vent failure to me.

When the purge valve wears out on the charcoal canister it will cause the engine to lope at idle. If the $2.00 air filter on the bottom of the charcoal canister is blocked, the carb float bowl and gas tank get vacuums on them which can cause loping and a bad loss of top end power tot he point of imitating running out of gas.

To check the air filter, just open the gas cap and see how it runs. I have seen the idle speeds change instantly that way.

The purge can be checked by tracing the PCV system and finding the line that goes to the top of the canister from the intake manifold. It T's off behind the carb on the 258. At idle pinch this line to the canister closed. If the idle changes, the canister is dead. This line will be right below the round valve that sits on top of the canister with the smaller vacuum line going to it.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

Mike, I have no loss of power, it only happens at idle. The filter in the charcoal canister has just been replaced, though it could be the purge valve. Can that be replaced or do I replace the entire canister? Also, what would make the carb whine? It comes and goes but seems to whine more when there is no acceleration, ie. when idling or having reached steady speed.

The valve is part of the canister. Pinching off the purge line at idle tells all. The canister is supposed to be off at idle so pinching the line should make no difference.

The canister, if blown messes with the carb vacuum big time. That could be part of the noise.

Carbs are also very sneaky about coming loose just after a kit... Worth checking.

Mike

It could simply be a vacum leak somewhere as there is a lot of places for it. The AMC 360 when running properly pulls a pretty high vacuum at a idle and even a small leak can cause some problems. You might start by getting a good old vacuum gage and check vacuum at a idle. It should be around 20 inches and steady. One more thing, sometimes the idle mixture can be off and cause these problem. Usually that carb has caps on the idle mixture adjustment that you have to remove to adjust them. I have owned a AMC 360 for over 22 years now in a 79 J20 P/U and I know that engine pretty well.

----------------- TheSnoMan.com

That and a can of good ol reilable carb cleaner to check for leaks. Especially around the base if anyone has ever horked on the bolts to tighten it up a bit more. That tends to bend the ears and leaves a nice gap that you can remove by sanding down the carb base using some sandpaper and a real flat surface like a sheet of glass or very flat workbench. Similar to the procedure here.

Heck, I just want to see what an 1886 Grand Wagoneer looks like... ;)

B