engine and drivetrain Tii running a little rough after re-build

[SBriggs]

Hi. After the purchace of my 1973 Tii (US spec) I decided to re-paint. Took the opportunity of having a look inside the engine. Re-built with Schrick 292 cam, gas flowed head, JB Racing aluminium fly wheel and fully balanced bottom end. It has raised grand piano pistons and the compression ratio is 10:1. The other parts are just fine as it must have had an engine re-build in the last 5,000 miles or so. There is clearly lots more power, it starts easily enough, accelerates just fine, but is lumpy and the revs vary on the idle. Whilst it does not feel "camy", it runs badly at any constant level of revs when driving. I noticed some comment on other links about the vacum advance, could this be the problem? Any help would be appreciated. To be fair to my mechanic, I took the car away before he had time to properly have a go at setting it up, couldn't wait to drive it again. Anyway, before I give it back I would like to be able to give him some help, we are both new to 02's.

Regards

SB

[ChuckinNC]

Congratulations on getting your motor running again. First, there is no vacuum advance for the 1973 Tii distributor. I would check and double check the lengths of the throttle linkages. My rebuilt Tii motor ran awful, until I went through the linkages very carefully. The factory specifications for length of each rod are critical. I would also verify that you have the correct fuel pressure at the inlet to the Kugelfishcher. I think it should be around 30 psi.

The Tii experts may question the use of the 292 cam, without modifications to the Kugelfischer, but I don't think this is the source of your current problem. Let us know what you find out. Listen to what the real experts suggest. There are a number of them on this board who are more knowlegable than I.

Chuck in NC

[TobyB]

yeah, check the mechanical advance on the dizzy...

t

[BillWilliams]

the 292. A wide-band 02 sensor and gauge could answer that. If the motor was made bigger, i.e. stroker motor, the pump may suffer a bit.

With these mods, an 02 sensor and gauge should have been a requirement.

Moving a tii off of dead stock is tricky and provides little power to dollars spent, Yes, I can say that.

However, you just need to sneak up on things, ignition (timing, spark plug gap, advance issues, etc) then turn to fuel and air. Maybe you will get lucky.

I took the motor out of one car, put it in another, only difference a header, and the motor ran like crap and still struggling with a high idle. Go figure.

I think the 292 is going to give you some lump and the motor may want to run lean on you giving you that "lean hunt" like a vacuum leak. Again, the 02 sensor will tell you that.

[Ray-2002tii]

I know if the shaft that controls the butterfly is worn, the engine will have a tendency to run lean at times, rich at others, making for unstable performance. Some get so bad that the only good fix is to have he shaft machined and bushed, making it tight again. Also, like the earlier comment, if your car has a vacuum advance on it, it is the wrong distributor. That was only used on 1974 tii's.

Good luck, it will work out.

[ibjettin]

I would start with your timing and make sure your K-pump is set properly (TDC to the notch on the pump pully). If your firing is not timed with fuel delivery it will run very poorly.

Check the tii registry for a ton of info

http://www.thetiiregister.com/phpmyfaq/index.php

[ColinK]

the 292. A wide-band 02 sensor and gauge could answer that. ....

Moving a tii off of dead stock is tricky and provides little power to dollars spent, Yes, I can say that.

However, you just need to sneak up on things, ignition (timing, spark plug gap, advance issues, etc) then turn to fuel and air. Maybe you will get lucky......

I think the 292 is going to give you some lump and the motor may want to run lean on you giving you that "lean hunt" like a vacuum leak. Again, the 02 sensor will tell you that.

My experiences say the same thing.

[SBriggs]

Thanks for all of your comments, I shall translate to Polish and go through them with my mechanic. I should have added that before the engine was dismantled it ran like clockwork so the only major changes are the new cam and flywheel. What surprises me now though is how deceptively quick it is compared to modern traffic.

[Guest Anonymous]

Lots of good information here. I know that there are at least a few around that run 292 cams in thier tii's - it is quite a bit more cam than the stock 264. I cant recall whether or not you need to have the pump tweaked to support the cam properly. I had for a very short time a factory 300 in my tii (After I removed the ALPINA A4 injection system), it ran so poorly even with a correct pump until about 4500 rpm and then look out - was a rocket. It is kind of a science I think to make a "tweaked" tii run better than a properly set-up stock tii. There will be some sort of sacrifice (ie., lumpy idle etc.,). Good luck with it. As a resource you could check with Gus Pfister at Pacific Fuel injection in SF (he is a pump rebuilder but knows a lot) and of course the other guy I hear really good things about is Jack Fahuna (JF Pro) in Los Angeles.

[SBriggs]

Hi

Still struggling to get an even idle and smooth running at lower revs. At higher revs its fine, although it feels like I am not getting all of the power out of the engine, if that makes sense?

My feeling is that its the throttle linkages as at idle there is a very even increase and decrease of the revs. Also, before the engine was re-built everything ran just fine, so I suspect it is not a case of worn bushes. By the way, what is a wide-band 02 sensor and gauge?

Regards SB

[jgerock]

Is it possible you need to run thru your valve clearances after the new cam was installed? Tii's seem to be very picky with valve clearance, spark plug selection/gap and ignition timing.

Or maybe one of the hoses that seemed fine before now has a small hole, allowing excessive air to enter the throttle body? The main culprit is the hose that runs from the KF warm-up regulator to the bottom of the intake plenum.

Keep at it, as it sounds like your car is very close to running like a champ.

[ray_]

Is it hunting at idle? That usually points to a lean condition. Or perhaps timing. Your advance springs are ok?

Did you check the CO at idle?

I'm starting to wonder if that light flywheel is exacerbating things.

GL,

Ray

[SBriggs]

Excuse my ignorance but what is "hunting at idle"? I am not sure it is running lean as the mechanic has checked the plugs and they look fine, it's even running slightly cool (just below the half way mark), which I don't think would happen if it was lean. The timing is fine and I assume the springs are fine as it was ok before the re-build. We haven't checked the CO2 yet (the CO2 meter was burnt in the fire) but it's due the road test next month so I shall find out then. With regards the flywheel, I was hoping it would not effect the idle (I have an alluminium flywheel on my Lotus 7, which is 4 cylinders 1,500 cc and that runs fine), but if it is, can it be exchanged without removing the engine?

[ray_]

Tii's are pretty sensitive to CO % at idle. The small screw inside the tuna can is idle CO adjustment. By hunting I meant every few seconds the idle goes to a different level

You've looked around here, right...

http://tiiregister.com/phpmyfaq/index.php?action=artikel&cat=220444&id=12&artlang=en&highlight=throttle%20body

And...

http://tiiregister.com/phpmyfaq/index.php?action=artikel&cat=220444&id=13&artlang=en&highlight=throttle%20body

Also download the manual and video from the site.

What plugs are you running, by the way?

Not sure how easy the flywheel comes off. I guess dropping the gearbox may be enough. But don't go there yet!

Cheers,

Ray

Excuse my ignorance but what is "hunting at idle"? I am not sure it is running lean as the mechanic has checked the plugs and they look fine, it's even running slightly cool (just below the half way mark), which I don't think would happen if it was lean. The timing is fine and I assume the springs are fine as it was ok before the re-build. We haven't checked the CO2 yet (the CO2 meter was burnt in the fire) but it's due the road test next month so I shall find out then. With regards the flywheel, I was hoping it would not effect the idle (I have an alluminium flywheel on my Lotus 7, which is 4 cylinders 1,500 cc and that runs fine), but if it is, can it be exchanged without removing the engine?

[BillWilliams]

The cam and lightened flywheel are working against you.

Ready for Keith's secret sauce?

at idle, set the timing at 8Degrees BTDC. If you are willing, do it and check back