More Tune Up Help Requested

[dm36415]

I have a 1977, mostly stock 2.7, with no documented history. I can tell at some point the car was taken care of (carrera chain tensioner added, tail added), but the last PO neglected it greatly.

The car runs well, but I think it can run great, and I want to get it there.

Here is some background information. I have had to set the idle at 1100, as it "hunts" below that, when both warm and cold. Starts great, both warm and cold. Gets about 18MPG normal daily driving (mix city and Hwy). I'm assuming this is a mixture issue, but I don't have the gauges to verify. I have read on this forum that this engine should run in the 25 MPG range.

I have replaced plugs, points, fuel pump, fuel filter, air filter, 2 oil changes, trans fluid change, fuel line to CIS, fixed CIS boot vacuum leak. Car had previously had the air conditioning removed and air pump removed, and I believe all places needing to be plugged due to air pump removal have been correctly plugged.

About a month ago, I bought a Pertronix ignitor and coil, hoping to eliminate the points. Couldn't get the car to run worth a darn, so I installed a new set of points.

Biggest concern I have, is that when I went to set the timing, I had to set it way off for the car to run smoothly, probably 30 degrees at least.

Before doing this, the timing was close, but the car ran very loud, with quite audible ticking. As I moved the timing further away from normal, the ticking went away, and I had to adjust the idle way down from where it was previously. Previous mileage was more in the 10 MPG range when the timing was set close to where it should be.

Before I checked the timing, I adjusted the valves, and checked that all the head studs were tight (don't know if this has any bearing) as I thought that was the cause of the ticking noise, but that had no effect. Valves seemed to be in close range of where they should have been, and the adjustments I made did not affect the ticking.

One thing I did notice, was that the distributor did have a condenser mounted on it, although the wire was cut and not attached to anything. Could I have a wrong distributor installed? How would I tell?

I would really like to tune this correctly, and enjoy the benefits of a great running car, but as of now the "tune-by-ear" is my best option. I'm afraid I may be masking a potentially much larger issue. Any insight/guidance is greatly appreciated.

[ipacketeer]

Dave,

In order to replace the Chain Tensioners with the Carrera Tensioners, if I remember correctly Distributor has to be removed.
Now i am thinking loudly, is it possible that the PO made a mistake and incorrectly installed the Distributor or missed a chain link or two. This is just another view point should be considered in the analysis of the problem.

[HarryD]

Dave,

If you have no vacuum leaks and your fuel pressures are ok, you may need to get your mixture adjusted. The best way is to put in on an analyzer and ajust as needed. SOUK has a non-analyzer procedure posted (which i never tried) that may help as well. Before you start messing with these adjustments, be darn sure all else is ok or you will be chasing your tail trying to solve the problem.

As far as the condenser, it could be that the PO had the CDI die and whipped up a kettering ignition to get home. My car had the same thing and it was running a Permatune box.

[Walter_Middie]

Dave,

If you fixed an air leak that the PO had, the PO may have set the mixture rich to compensate. The hunting at idle is a sign of running rich - so after you fixed the air leak, you may need to lean out the mixture. Make very small adjustments, and keep track of how much you turned the adjustment so that you can always get back to where you started.

As for your timing...that sounds strange. Have you confirmed if your timing advance is working? As you shine the timing light on the pulley and rev up the engine, do you see the timing advance? It sounds like your advance weights may be stuck, and you aren't getting any advance.

[Walter_Middie]

Oh yea.....you don't need the condenser any more with the pertronix instead of points.

[HarryD]

Originally posted by Walter_Middie
Oh yea.....you don't need the condenser any more with the pertronix instead of points.

Walter,

Actually, if you are using the points to trigger a CDI box, the condenser is not needed at all. The points in this application would last forever if it wasn't for the rubbing block wearing away over time.

The condenser is to help maange the power surge (to keep from burning the points) from the coil with a conventional (i.e. Kettering) ignition system.

[dm36415]

I'm guessing my fisrt course of action should be to check the advance weights. I'll do a search for more information. Is this something that can be repaired via DIY?

Once I get that in line, I'll work on the mixture.

Thanks for the advice!

[HarryD]

Originally posted by dm36415
I'm guessing my fisrt course of action should be to check the advance weights. I'll do a search for more information. Is this something that can be repaired via DIY?

Once I get that in line, I'll work on the mixture.

Thanks for the advice!

If you find you are not advancing, there are some threads on rebuilding your distributor at home. A (upper right hand corner) should turn them up.

[T77911S]

the surging at idle equals too rich. it may even surge enough to cut off.
it could just be the mixture or it could be the WUR.
the only acurate way to check the mixture is with an analyzer. and the only way to check the WUR is with a pressure gauge. i understand j.c. whitney sell a very nice one at a reasonable cost, well worth the money.
with everthing else working, you can get the mixture close, but it tkes time and trial and error.

sounds like you advanced the timing.
the vacuum connection is a retard, check it with a vacuum pump, they are not that much and another good tool to have around.
spec says 0 deg. at idle. i ended up setting mine to the 35 deg mark, which wound up being 5 deg. ATDC at idle. if i set mine at 0 deg. i get spark knock. i dont know why my dist. has 40 deg advance. it was recently rebuilt. anyway, the timing MUST be set before you set the mixture.

your car may also have a TTV, it is a electrical/vacuum device that blocks the vacuum to the WUR when it is cold to make it run rich. follow the vacuum line from the WUR, it will leed to the TTV and then to the throttle body. the TTV should also have 12v applied to it.