hay yah everyone ive just finished porting out my exhaust ports includeing removed the chokes and have had the diaginal holes in the port fulled in, now what i was wondering was does any one know what the holes were for ? i thought filling them in would give it better flow ? any help would be great just waiting on advise before putting engine togher thanks https://www.nopistons.com/forums/pub...IR#>/blush.gif

believe the holes were for emission purposes

An air pump used to pressurize the gallery below those ports. A hollow shoulder bolt was in that hole used to carry that air through the bolt into the exhaust stream to burn off HC (unburned Hydrocarbons). You can TIG them shut. Weld the end of the bolt shut and reinstall them, or buy the solid aluminum bolts from Racing Beat and install those.



In any case the holes need to be plugged in some way.



Lynn E. Hanover

so has anybody just welded those holes up in the stock sleeve? If you are running a race engine I really don't see the point in having them either.

Yes welding up the hole hole in the exhaust sleeve has been done for a long time. It is supposed to help air flow. Since I don't have a flow bench I can't say how much it really helps.