If I try a 1/2 or 1 inch open carb spacer on a 289 4V with the original 4V cast intake and a holley 600cfm will this increase or decrease the torque? Which level will it affect low, mid or high end torque?
Well, I would first guess that your engine is completly stock, and probably the carb is 40 years old???
Stock dizy too...??? Bet we can find some power there for you, just by tuning your timing for you.... different gas between now and 40 years ago....changes the timing requirements
If so, or if you have an aftermarket 600 installed, almost a fair bet that the carb still needs to be tuned or re-tuned to work best with your engine. Vacuum secondary? By looking at your spark plugs after driving a little bit, you can tell if you can increase your gas mixture, and maybe make a little bit more power.
If you not sure how to tell, take out Plug Number 1, take a good close up photo of it, and post it here, and we can tell you if you have room to tune.
A few photos would do. One after driving around in traffic for 20 minutes, stop, pull the plug and take a photo.
One at highway speed... maybe 50 MPH, stop take a photo, and one after you have WOT to 100 MPH, stop and take a photo. Keep a spare spark plug with you incase you break it while 10 miles from your house...(wink)
I would use a 1" 4 hole spacer and forget the open kind. The stock cast intake has a 4 hole plenum, so running an open on top of that won't really do much but confuse the carb. Running a stock manifold, I would also recommend using a heat shield under the spacer and using a Moroso plastic item to keep heat out of the carb. The stock intakes get REALLY hot from the exhaust crossover.
Yes, that manifold does have heat passages and 4 holes..... Get a 1 inch 4 hole spacer... NOT ALLUMINUM, they have some great composite material spacers, should go a long way to reducing the heat in the carb.
They run about $25 - $35
<font size=-1>[ This Message was edited by: Mikes66 on 11/29/06 12:34am ]</font>
If you are talking about a stock 289 or 302, the spacer will not make any differance you can ever feel. It would be in the order od 4 to 5 HP gain, and you cant feel anything less than 12 to 14 before your seat of the pants dyno kicks in