The lost art of engine tuning

I would like to see a good "how to tune your engine" thread posted at this forum. There are many discussions about picking the right camshaft, pistons, heads etc etc. But I havent found any particular post that gathers info about "how to get the most out of your engine". I guess there are people out there who is cussing engines that runs poorly, simply because they werent tuned the right way. Certainly there are many "unrevealed" horsepower out there! So, please c'mon now every experienced engine builder. Share some valuable information how you tune your carbs, ignition, valves, cams, etc etc... Maybe Paul could lead the way?
Matt

that sounds like a great idea for something that could become a stickie. Even starting with the basics, like the order in which to do basic stuff. A simple guide for newbies, could even be hands on FAQ with some pictures. it is hard to learn how to set up a carb with nothing but a haynes manual.

Hey Mike and Paul, here I see an opportunity for you guys to answer the question once, and then move to the best of tech for future reference.


Mike, since you work with a dyno all day, I will bet you have the best tuning tricks.

I'm with the other guys on this one. I have picked up a tidbit here and there on the subject of tuning, but it would be really helpful to have a nice compilation of good methods for proper tuning.

Randy (shutting up to listen now) :shh:

Well, the first step is making sure you have the right parts in the first place.
For example low compression, big cam engines are hard to tune except for wide open throttle and run a like a sick, 3 legged dog on the street.

The second step is to be sure the engine is in good condition.
The difference between a crisp running, tuned engine and a tuned but lazy engine is directly related to pressure/vacuum sealing. Do not underestimate this fundamental concept.


For example these make tuning difficult if not impossible:


Poor ring to bore seal poor valve to seat seal burned valves/sticking valves worn cam/lifters Loose timing chain vacuum leaks slipped balancer ring faulty plugs/wires/cap/rotor loose distributor shaft bushings sticking advance mechanism/ruptured vac advance diaphram


To diagnose and tune it is imperitive you have the correct tools:
Timing light hand held fuel pressure gauge with long enough hose to duct tape to windshield vacuum gauge vacuum hand pump (Mityvac) tach/dwell meter compression gauge leakdown tester


Keep a log book on your engine. Record each and every change. For example I note and date jet, metering rod or timing curve changes. If you make a change or changes that make it worse you can back track by checking the log book. Only change one thing at a time. If you change two things one might help and the other hurts, but you won't know which.

You should also check and record the cranking compression at regular plug changes intervals. The plugs are out and it only takes 15-20 minutes to check all 8 holes. If you are changing the cap and rotor you might as well take 2 minutes to check the timing chain slop. With the plugs out and the cap off you grab the balancer and turn it back and forth with the timing mark at 0. If you get more than a degree or 2 of movement before the distributor rotor moves it's stretched and needs replacing.

I often see people spinning in circles, frustrated from tweaking and adjusting worn out engines. Then they get it so far gone that they decide "it's the carburator" or "engine computer's junk" and start willy nilly replacing parts hoping they'll stumble on the "bad" component. The smart tuner does what a good physician would do. Test and take data before attempting to diagnose the problem

I agree with Paul, to document everything. I am in the process of trying to fine tune A/F after a cam change, and hogging out an RPM Air Gap, and adding a HVH Street Sweeper 1" spacer.
I was pretty much in tune before those changes, now I am starting from scratch.
To give you an idea as to how a small change can affect things, we were on a rear wheel dyno with my new combination, and changed rear jetting 4 sizes and gained 27lbs of TQ. Now 27lbs is something you can actually feel the difference in your pants.
Fine tuning is a lost art, and I can only do so much myself, so once I have the set-up at least where I think it might want to be, I go to a rear wheel dyno to have everything checked.
In the next few weeks I am going back to the rear wheel dyno to do more rear wheel pulls from 2,500 to 4,000 left and right bank A/F, record the data, analyze, change jetting / timming, and start pulling to the power peak in baby steps. At all times, recording what we did for timing etc etc.
I have seen 50HP, and 50TQ " FOUND " on a rear wheel dyno. I sure hope my own home done tuning does not gain me that much, I would be a bit embarrased to say the least.
I don't have the equipment, time, or the garage space to set up a decent shop, so I am spending some loot on the dyno.

I know the first question asked, "Can we have a guide to tuning", or whatever it was, has a long winded answer, but it would be really useful for all of us! If possible, can someone who has the knowledge(and the free time) answer this for us? The information regarding logging information was great, but it didn't get into the details of tuning... If fully answered and laid out in detail for the average gearhead to understand, we would all be in your debt forever!!

Thanks xnovassx, That's just what I was looking for when I started this thread...
It would be great if some could write down experiences when it comes to tuning ignition/distributors, carbs, cams, using the vaccum method, etc etc...
I think lots of people would find it both interesting and helpful.
Matt

I couldn't agree more... Let's have it boys!

check out the stupid timing question post