TR6 Getting frustrated getting my TR to run properly

[gbtr6]

I rebuilt my TR's engine last year. It has a Goodparts S-2 cam, .060 Pistons, higher compression, and I run 2x SU HS 6's. It has been run in but just. The problem is it has no power. The timing at 1,000 rpm is 12 degrees advanced. The carbs have not be redone. I suspect them as when I was brining it out of storage and at one point it started to act normal, good zip. Then, a dog again.

I am no good at diagnostics, unfortunately. I am thinking of removing the carbs and disassembling them and cleaning them thouroughly.

What at does everyone else do in this situation after a rebuild in order to get it back running well again?

Thanks,
Perry

 

[tdskip]

First , hang in there.

Second, let's start by checking one thing at a time. Is there stumbling or erratic running or "just" feeling off power? Let's make sure that it is not electrical before diving into the carbs.

Have you tried advancing it until it just starts pinging and then backing it off (regardless of what the timing says)?

 

[Gliderman8]

Have you checked your fuel pump? Is the fuel filter good?
I agree with Skip.... one thing at a time.

 

[gbtr6]

Thanks guys. I am determined to get it running well soon because I couldn't drive it at all last year. It is frustrating because until last year it was stone reliable.

No stumbling, just no power. I have played with the timing a bit, but will still try that first. In order to get a baseline on the carbs, I dialed the jets all the way up, then 2 turns down. I am also setting the butterflies with the Unisyn to even them up.

Funny thing was, I tried a couple things with the carbs. On the front one, when I put my hand over it, obscuring most of it, the idle went up. I sprayed a little starting fluid into it and no change. On the rear one, sprayed and the idle went up. Partially cover it and it stumbled. The rear one seems normal. Don't know what to make on the front one.

Perry

 

[TR3driver]

One test that might be worth trying is to richen up the carbs by 2 or 3 flats. It will obviously be too fat at idle, but what you want to look at is whether the midrange feels better. If that helps, you may need richer needles to go with the S2 cam.

If it was me, I would suspect that I got the cam timing wrong. Being off by a tooth generally results in an engine that runs smoothly but can't seem to get out of it's own way.

 

[Geo Hahn]

I would also verify that the centrifugal advance is operating correctly - a timing light can easily confirm this.

 

[arcom]

That front carb shouldn't cause an increase in rpms when you partially restrict the air.

 

[glemon]

I seem to recall such things happening to me in the distant past, one carb doing basically nothing. Making sure the plates are in synch is a good start, Since SU's are so easy to break down I would check a couple basics (please don't be insulted, I and many others here that have worked on these cars for years miss simple stuff all the time). Is the suspect carb's throttle plate moving when you goose the throttle (i.e. are the shaft clamps tightened down) Is their fuel in the carb? (pull the dashpot and the piston/needle, should be gas just below the top of the jet hole the needle goes in). Is there a major vacuum leak, maybe, if it is getting too much air it might speed up a little when you cover the intake. Everything tightened down and snug in the carb to intake manifold to motor connection? I know one time I had a loose carb when I thought I had tightened everything down, I actually discovered it by pushing up and down on the carb with the car running, when I pushed a certain way it sounded and ran better. Good luck, once you find it, it will probably be a simple fix, the tricky part is, of course, finding it.

 

[glemon]

arcom, I set the timing per the book like you do, in the distant past I did it that way because I didn't have a timing light, but it always seemed to work well. I now use the timing light to "rough in" the timing and to make sure advance is working, then I fine tune it with a road test.

 

[TR3driver]

In order to get a baseline on the carbs, I dialed the jets all the way up, then 2 turns down.

And that's all ?!?

That initial setting is just a ballpark to get the engine started, you need to adjust them properly once it warms up and you've set the valve lash, etc.

 

[gbtr6]

Thanks again for the great replies. The shop that built the engine told me they advanced the valve timing as indicated in Goodparts instructions. I thought that may be the case, and I would lose compression and not have very good performance. But, as I indicated before, at one light on the way home, it did perk up and seem it's old self for a moment. That's why I suspect carbs, that and the fact it's been a long time since I've rebuilt or even cleaned them. I also thought with the S2 cam and the overbore that it will need more gas. Hence I tried a little starting fluid to gauge response.

The advance works because when the rpms go up, I see the marks moving with the light to more advance. I am inclined to take the carbs off and disassemble and clean them at least. First, I will check for gas in the jet with the piston and needle out.

Also, I take no offense in the responses. I consider myself a bit of a mechanic, but not in the true sense. I am poor at diagnostics. I can do complex tasks, like an engine rebuild or gearbox successfully, but need to have a plan. My only other problem is patience. I tend to shortcut a process sometime in order to get to drive it. I need to be more methodical.

All suggestions welcome.

Thanks Again,
Perry

 

[JimmyBb]

Sounds very similar to a problem I had. Thought it was electrical but the problem turned out to be a sticking float needle in one of the carbs. It was a relatively easy repair. With the carbs off the car, just clean the needles and seats throughly with carb cleaner. If the carbs have not had attention you might want to get a rebuild kit as long as you have gone through the trouble of putting them on the bench.

 

[Geo Hahn]

Just to show off my ignorance of TR6s - does this car have SUs or Strombergs?

 

[M_Pied_Lourd]

Well, if its stock, it should have ZS carbs.

Cheers
Tush

 

[TR3driver]

Very first line of this thread : this particular car has SU HS6 carbs on it. A popular replacement for the original "emissions" carbs.

 

[gbtr6]

Had a chance to take the tops off the carb. Front one had gas present. I cleaned up the inside a bit. When I removed the piston from the rear one, the needle fell out. I put it back, tightening it in this time. Hopefully that may solve the problem. I am having a bit of an issue with the clutch. Doesn't seem to engage enough. Initially, leaky slave cylinder. Got a new one and the adjustable rod. Bled it once and seemed to work briefly. Will try to bleed again in case it was an air bubble. Master does not appear to leak, but has not been rebuilt in forever. May need a rebuild or new one.

Perry

 

[glemon]

Loose needle would do it. Clutch release bearing fork's taper pin can break on these cars, many people drill the shaft and add another bolt. But by all means try the hydraulics first, you don't need to pull the tranny to fix the hydraulics.

 

[gbtr6]

Update: Got the carbs dialed in and she runs well!

Well, last night my wife helped me bleed the clutch again, and that did the trick. I remembered a saying, "when all else fails, read the instructions". So, I got my SU competition manual out, and reset the carbs to zero, undid the balancing mechanism, and started from zero. Then got the two synchronized with my Unisyn. Went for a spin and it made a world of difference. It stumbles a bit at 4000 rpm, so I may need to rich up the carbs, and check timing. Will also read the plugs. The engine still needs to be broken in with some driving. But, everything is on the right track. And it's going to be nice this Friday and weekend.

Also, the clutch pin was replaced by two bolts. It was an interesting fix, but has lasted for 15+years.

Thanks to everyone that contributed here. I appreciate it very much.

Perry