Idle problem on C15 261 CU IN

[Bob Carriere]

Hi Terry

................ Hi Phil

My truck has a GMC civilain rectangular dash. Only the gas gauge and the amp meter are connected and working. I used a voltage reducer on the gas guage and the amp meter as is.

I am using an after market mechanical heat guage with the bulb installed on top of the steam outlet on the original 216. I also have a mechanical oil pressure and a vacuum gauge. I later installed a tachometer......all in the interest of better monitoring the performance of the engine..... they may be removed at a later date not sure when as I now depend on them.

Nice to know you are doing 2000 rpm at 30 some mph even though the engine is screaming and the gears whining all is good. Gets close to 2900 at 44 mph flat out..... with me holding on tight. Nicer to drive at 30 - 35 mph just relaxing.

Really curious to see what kind of readings you get when you have a proper manifold connection.

Phil........ any tips or tricks you want to share....?

On a 248 GMC fire truck engine they actually add a 5 to 6 inch adapter/spacer for clearance purposes with other do-dads installed on the engine. I have read somewhere, from hot rod sources, that increasing the length of the air flow and increasing the size of the vaccum plenum is beneficial to engine performance...... so an extra inch spacer certainly will not hurt. Just make sure that you have a good seal on all joints..... paper gasket smeared very lightly with silicone sealer works great for me. Just apply the silicone to index and thumb and smear the paper...... gets tacky and compresses well with no overkill silicone getting inside parts.

Phil are you using a NOS spacer or a homemade one??? they do come up on Ebay once in a while.

Cheers