Engine tuning options

[bombapinoy]

Hi guys. I have myself a TE72 with a 3tc engine in it. Right now the engine is pretty much stock other than dual mikuni 44s and custom exhaust. So ever since I put on the exhaust I noticed I have lost a whole ton of torque. I know about exhausts and that if you go too big you can start to lose back pressure and basically thats what happened to my car. So I just wanted to ask how one would approach the situation. I would like to add some more oomph for the car. Now this wont be a daily car. In fact this car is just for pure enjoyment. I dont want anything that pure race though as I would be taking the car out once in a while around the backroads and to shows or just for a plain nice ride around the country. However I would still want the car to put some power down for when I do decide to take it out to the track.

So what are some of the options that I should consider. I know I am considering a camshaft. If so can you guys help me out in the selection process? I would greatly appreciate that. Also I was thinking about considering new pistons and boring the engine out. Would this help out with my performance goals? And if so should I consider getting a higher compression? Would I have to consider rods? New valve springs and such? And would an engine overhaul be a good idea since I would be doing all this work? Any advice is helpful. (This is just for a general idea as I wont be doing this for another year or two before I actually pull the trigger and get this done.

[73GTV]

well I would start with the carburetors themselves, by rechecking the jetting. The fact that you have made a modification from your old tuning setup and have not mentioned retuning or re-jetting the carburetors. Recheck your timing again. does your distributor have a Octane selector? That requires adjustment to take advantage of your new exhaust system. I will let everybody else fill in the rest of what you should do to bring back the performance. Start from scratch!
http://www.mikunipower.com/PHH01.htm

[bombapinoy]

forgot to mention that I already checked the timing and got the right jets. Would our cars have an octane selector on the dizzy? If so where would I be able to find out?

[bubbajohnson]

http://3tcgarage.com/viewtopic.php?f=57&t=142

Read my weber jetting post to get you started . The stockish cars with 32/36's on this list all got/get between 18-23mpg city and up towards 30mpg highway. I never tuned them for pure economy, more for all around driving and power, but find the set up closest to your engine specs and start from there. It should get you off on the right foot, I compiled this list because there are many, many posts around the internet about general tuning for Webers, but very few lists of "what jets worked for what car/engine".

[7t5-27]

try these settings for the 3tc with 44mm mikunis 145 mains, 170 air, 52.5 idle, 37mm venturi, 45 pump, accelerator pump in the #3 position. this should get you started Good luck
Greg

[skunk1]

just my expirience but, i think those carbs on a stock engine are too big, you could spend the time rejetting and all that but then you would have to go through all of it again when you actually decide to "use" them. swap out for some 40's or equivilent. basically you are over "airing" (running lean) you engine with those carbs, thats why the power loss. but like with all engines, too big a carb means more air and fuel usually, so more spark is needed (in your case sounds like your jetting is too lean). also when installing any weber static timing can usually be bumped a bit, i would advance till ping and back off a bit. just remember no matter what you jet for regulate fuel for load not static pressure, i personally never go more than 3.5 psi on webers, but use high flow low pressure pumps and lines. meaning at static low psi pressure, under load it will lower line pressure, make sure your float seat is big enough to open at almost 0 psi or you will starve the carb for fuel, and dont go too big or will flood at idle. at least with my carbs i can change float needle seat diameters to suit application.