vented or non vented distributor cap

Bought a new distributor cap today and it is a non vented,the one on the truck now is a vented one will I make a difference or should I take it back and get a vented one

put the vented cap on and it runs just fine

I put the unvented one on

any difference when starting?....i would think moisture would not be of any issue due to pointless electronic ignition....so it whould not matter which you use. http://ts1.mm.bing.net/th?&id=HN.608...d=1.9&rs=0&p=0not many engines have these anymore.

It shouldn't matter if you use either cap. The most important part is when the cap in placed, you should have absolutely no twist play in cap. It should be locked into place. Some caps come with a slightly larger notch where they lock to distributor and this allows the cap to twist or move on the distributor. Even 1mm can adjust your timing ever so slightly.

I have run them both and as Ragtime posted that image, the vented were mostly used for the points distributors, but vented or not, the distributor doesn't care.

The unvented cap has been on for a week now had have no issue with it starting when I got of work this morning it was negative12 and it fired right up