Proper tune up procedures

[IH2LOSE]

Guys what is the proper way to tune a car.

I mean where are you supposed to start first,I am an a/c mecanic and there are specific procedure to properly tune up an a/c system and if you dont follow them you just wount get the system running at its peak performance.Some adjustment should be made before others because the effect the other adjustments.

I know how to tune a car but I guess I am looking to make it the best it can be,I plan on taking the 66 to the track before I replace the rear end and want to see what it will do with the 411's in the 1/4 mile before I install the 336'S So I guess I am looking for a long exspanation on where I should begin,I am looking thru my notes from the other forum from DUKE to make sure I understand how to properley time the car,Right now I have the timing retarded and I am running on sunco 94 gas,I will be tuning and running the car with cam 2 in it for track day.


I also have a set of slick's I am going to borrow.I am going to run the car with the street tires and a good freind of mine is a bracket racer he is going to run it with the slicks.

I get nervous at the stageing line and eather red light or leave up in smoke,My run is to overcome my fears His run will be to get some good time slips I can keep with the car.

 

[JohnZ]

Larry -

1. Plugs - check gap on new plugs (.035") and install
2. Check plug wires - routing, cracks, seated in cap, etc.
3. Distributor - change points, condenser, rotor
4. Fire up, set dwell (before setting timing)
5. Set timing
6. Adjust carb - idle speed, idle mixture screws (adjust for highest steady vacuum), re-adjust idle speed as required.

I'd think twice before hammering it with slicks - street tires are the "safety valve" for the drivetrain, especially with a big-block; when that "safety valve" is gone, the next thing to go is the half-shafts

 

[iron cross]

I presume it`s a BB chevy. 94 is OK for anything below a L88. In otherwords, 11-1 motors can run effectively with 94. Don`t retard the timing, a minimum of 36 total, or as long as it starts when hot.

 

[Corvette-Pilot]

:duh
Ouch !!

 

[IH2LOSE]

John where are these pictures from was it a test on a machine to test how strong they were? Or did a car realley twist these like this? I hope I am not being arogent here but I am doing the rear end over with new haft shafts and are figuring if I twist one no problem I just going to be replacing it anyways.My freind whos going to run the car with the slicks also feels this is a bad idea.He has driven the car when I first got it and the original owner ran cam 2 in it with some hot timing his thought is that if the rear isnt torn out the car he may lift the front end.He not afraid of that just if he does break a shaft he then said the front comes down real fast and hard.
He exsplained with the slicks on the car he can leave the line real hard and he said something may go,

 

[IH2LOSE]

I presume it`s a BB chevy. 94 is OK for anything below a L88. In otherwords, 11-1 motors can run effectively with 94. Don`t retard the timing, a minimum of 36 total, or as long as it starts when hot.

Iron cross I canot find my notes on total timing adjustment could you run throught it please.I do own an ajustable timing light I purchased just for the total timing

 

[IH2LOSE]

[6. Adjust carb - idle speed, idle mixture screws (adjust for highest steady vacuum), re-adjust idle speed as required.

John what effect what
it seems I never really make a difference when adjusting my carb,Is there a starting point with the screws and then say if you cant get a clean idel,(or as you say the highest vacum reading witch I am going to use this method)After says 3 screws out you know the is a different problem,

 

[iron cross]

Do all the things JohnZ recomended. Thats where fine tuning starts. Actually setting the carb idle and timing work together. As you advance the timing the idle will normally get higher as the engine cleans up, then turn the idle back down to 800-850 if its a high compression solid lifter engine. If the engine cannot hold this idle, you may have a vaccum leak. Those so called high RPM idles {1000} are not necessary. All my solid lifter cars in all makes of engines operate in that area. If you are hooked to cable on your computer, go to my site at Http://www.nitroalley.net , across the top of the site are names of pages, go to the Walts Puffer page then select the A990 Cuda page. scroll to the engine and the {start engine} botton, push it and hear a 550hp Race Hemi at idle and a occasional blast. Dial up requires a long loading time however. And good luck at the track. After that, :bar

 

[JohnZ]

Iron cross I canot find my notes on total timing adjustment could you run throught it please.I do own an ajustable timing light I purchased just for the total timing

Connect the timing light, fire up the engine, disconnect the vacuum advance and plug the hose; loosen the distributor hold-down clamp enough so you can move it by tugging on the can. Set the dial on the light at 36 degrees, point it at the timing tab, rev it up gradually until the mark on the balancer stops advancing (probably 3500-4000 rpm), and move the distributor until the mark on the balancer aligns with the "0" at the center of the timing tab. Shut it down and tighten the hold-down bolt. Fire it up again, let it idle (you'll have to adjust idle speed) about 700-800 rpm, point the light again, and turn the dial until the balancer mark again aligns with "0"; the dial reading on the light tells you what the base timing is (you can also set the dial at "0" and read the same thing directly on the timing tab). The difference between the 36 degrees and the setting you now see at idle is how much the centrifugal advance in the distributor is adding. Un-plug and re-connect the vacuum advance hose to the distributor, re-adjust the idle speed screw again, and then start tweaking the idle mixture screws (back and forth from side to side) to achieve highest steady vacuum (you'll also have to tweak the idle speed screw as you go along to maintain your desired idle rpm. You'll probably end up with the idle mixture screws somewhere between 1-1/4 to 2 turns out from lightly seated when you're done. Checking the idle timing again now will show you how much timing the vacuum advance added.

Ideally, you want all your distributor's centrifugal advance (usually 20-24 degrees) "in" by 2600-3000 rpm; that, plus your initial timing, is "total timing" (vacuum advance disconnected). You should end up with base idle timing (no vacuum) of around 10-14 degrees, and when you connect the vacuum advance it should jump up to around 25-30 degrees at idle (with the vacuum advance connected to full manifold vacuum, not "ported" vacuum). That will give you a solid, stable idle and good idle cooling, assuming your vacuum advance can is calibrated so it's fully deployed at least 2" Hg. below what you see for manifold vacuum at idle.

 

[JohnZ]

John where are these pictures from was it a test on a machine to test how strong they were? Or did a car realley twist these like this?
He exsplained with the slicks on the car he can leave the line real hard and he said something may go,

Nope, no test machine - it was an L-71 with slicks (first time on slicks); What you don't see is all the damage the flailing half-shafts did to the underbody and chassis after they broke. If I were you, I'd re-evaluate your plan.

 

[IH2LOSE]

Thanks again John I will do my best with your procedure you have outlined.And will post my results.I allways feel Im leaving the car too rich BURNING eyes and I stink like I was running a weed whacker.But when I read my plugs they are perfect?

 

[IH2LOSE]

PS I almost feel as thought my freind might have contacted you to encorage me not to use the slicks.I just may not do the slick thing My freind made me sign a waiver that he is not responcible for tearing my pride and joy apart with a 3800rpm launch.I really wanted to see what the old girl would do before the 411's came out

 

[JohnZ]

PS I almost feel as thought my freind might have contacted you to encorage me not to use the slicks.I just may not do the slick thing My freind made me sign a waiver that he is not responcible for tearing my pride and joy apart with a 3800rpm launch.I really wanted to see what the old girl would do before the 411's came out

I wouldn't take the chance - the half-shafts may "come out" before the 4.11's come out.:cry

 

[allcoupedup]

You might want to consider the carbon fiber half shafts. There's a group purchase going on at corvetteforum. They're supposed to be very rugged.
http://forums.corvetteforum.com/zerothread?id=561927

brian

 

[youwish2bme]

John,
Well since I'm new to V-8 Carb engines please bear with me. I don't have an adjustable timing light so what should I do different that what you have already posted??? I'm also replacing my condensor, points, cap, and rotor. If I remember correct new points are to be set to a .019 gap. Well this is all well and good but where do I make this measurement??? To preface all this the reason that I'm doing this is that I've developed a nasty miss around 2500 to 3000 under load. I believe that I burnt the points when I was working on the dash lights last week. It never did this before and now it does... Thanks for your help and IH2LOSE I hope I'm not hijacking your thread to much... It seems that we have some of the same questions.. Dave...

 

[JohnZ]

Dave - You don't need a dial-back light to do the same thing; just measure the circumference of your balancer, divide by 10, and measure that distance clockwise on the balancer from the existing timing index line and make a mark - that will be 36 degrees advance when it lines up with the "0" mark on the timing tab, and you can further subdivide it into finer gradations if you like.

Set the points at about .018"-.019" when you first install them (with the rubbing block on a high point on the distributor shaft cam); that will let it start and run. That measurement is taken inbetween the two tiny contacts at the end of the spring-loaded arm that pivots. Then you need a dwell meter and a 1/8" allen wrench to adjust the dwell (through the metal window in the cap) with the engine running. Dwell spec is 28-32 degrees; set new points at 28-29 degrees to compensate for initial break-in wear of the rubbing block. Always set dwell first, before you set timing, as dwell directly affects timing; changing timing doesn't affect the dwell.

If you're working on something in the car that requires power, use the "Accessory" position - that powers up everything except the ignition, so you don't burn the points or fry the coil.

 

[JohnZ]

Here's a photo of a distributor with the cap off - the contact points where you measure the initial gap are at the right end of the copper-colored portion of the white plastic pivoting arm. The screw in front of it adjusts the point gap, and takes a 1/8" allen wrench.

 

[youwish2bme]

John, Thanks for the info man. I have set the points previously and I thought that I knew what I was doing with the timing. But the way you explained it was different so I wanted to do it the way you explained to see if it makes a difference. I got everything in that I planned tonight. I think that the hardest part of it all was getting the vacuum can back in. Well at least getting it screwed back down. Is there a trick or do you just have to do as I did and have three hands to rotate the base and place the screws in the vacuum can?
After bumping it around a couple of times I got it on one of the high spots and it was already at .019 so I was good to go. At least for the initial setting. It was 2200 when I got done so not to wake the neighbors or at least not for to long anyway all I did was make sure it would start. Tomorrow I will set the dwell and timing.
As for using ACC I was working on the turn signals and I didn't think they would work on ACC???? Needless to say the points did have one pit right in the center on one side and a dimple on the other side. I also think that the vacuum can was not up to snuff so we'll see tomorrow. Now I need to start a diifferent thread for another issue...Once again thanks.. Dave...

 

[JohnZ]

I think that the hardest part of it all was getting the vacuum can back in. Well at least getting it screwed back down. Is there a trick or do you just have to do as I did and have three hands to rotate the base and place the screws in the vacuum can?
Once again thanks.. Dave...

Three hands helps, to hold the breaker plate fully advanced so you can get the screws in; I use a Mity-Vac connected to the can to hold it fully advanced while I install the screws.

 

[youwish2bme]

That sounds like it would have done the trick. I guess next time...