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TVR 2500M Triple Weber 40 DCOEs

DrEntropy

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Rocky_LC

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True, but then the fuel wouldn’t come out of the velocity stacks.

Anyway - had the car out for a run around the neighborhood…. stayed at low RPM.

I have an airflow “synchrometer”, getting the following at 900 RPM Idle speed.

1: 2.5 kg/h
2: 3.0 kg/h
3: 8.0 kg/h
4: 8.0 kg/h
5: 3.0 kg/h
6: 2.5 kg/h

My reading seems to indicate the two center carburetors are too high, normal range is 1.0 - 2.5 kg/h.

I think this means the throttle plates are open a bit?

Advice on where to start my adjustment?

The Redline guidelines say (step 1) say: “all air bypass screws should be set in the closed position”…. On my carbs, I believe there are hard white plastic caps covering them, and they are non-adjustable?

Thanks -

Rocky
 

DrEntropy

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My guess would be that the throttle shaft on the middle carb is out of sync with the end two rather than bypass screws being mis-adjusted.

Again, a guess.
 

Tybalt

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And I too think that throttle sync is a good guess as the first thing to check. I couldn't remember how you had the linkage set up so I took a look at it this morning (it was too late last night when I saw your post for me to trust my judgement) in one of your pictures. I would go to that turnbuckle link on the middle carb and adjust it. I can't help but feel it is holding the throttle plates open just a bit more than the other two.

As for the air bypass screws, they are indeed the ones under those little plastic caps and they are adjustable, but save that for after you try tweaking that middle carb turnbuckle link.
 

DrEntropy

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Tybalt said:
I can't help but feel it is holding the throttle plates open just a bit more than the other two.

Adjusting the turnbuckle: Can't see the throttle stop/idle adjustment screw on the middle carb but be sure it has no way to interfere with the trurnbuckle adjustment, i.e: keeping the t-shaft from being able to close down the blades further w/turnbuckle.
 

Rocky_LC

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Well - none of the linkage is attached.

I pulled the middle (offending) carb, and adjusted the throttle plates as carefully as I could for full closure. Still the same readings.

Switched the front & middle carbs…. problem moved up front.

I need a flow bench. I might make one with my shop vac. More work to do this week!

Rocky
 

DrEntropy

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hmmm... that both barrels are the same rules out likelihood of bent shaft or plates not seated (since you went back and realigned).

Another thought: is the internal return spring keeping enough tension on the shaft at full closure? Could it somehow have been 'stretched'?
After seeing that air corrector jet in place of a main, my suspicions are raised that it could be possible.
 

Rocky_LC

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I’m going to try a new spring.

I hear I can get 82* throttle plates to have the plates seat on a different part of the throat.

Rocky
 

DrEntropy

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Unless you can see some sort of evidence there's wear at the closure point of the blades to the throats, that two-and-a-bit degrees different angle won't mean much. The plates may be subject to the problem but not the cause, IMO.

Your flow-meter indicated that both barrels are drawing equally, the problem "moved" with that carb, so you've isolated it to that. Something mechanical on that carb is restricting the shaft movement or allowing more volume. It may well BE the bypass screws. But swap out that spring first.
 

Rocky_LC

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Got the car going, took a 6 mile trip yesterday…. Runs pretty good, needs minor “fettling”!

Thanks for all the advice!

Rocky
 

DrEntropy

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Were you able to calm down the "errant child"? If so, what was causing the excess draw?
 

Rocky_LC

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Yes it was just a subtle throttle linkage adjustment interference problem. Got them ALLto within about to kilograms per hour, Most much closer than that.

Fine-tuning to continue!
 

Tybalt

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That is one of the curses of these linkage set ups. They have lots of adjustability in the set up so there are ample opportunities for something to be amiss and cause an issue. Glad to see it was relatively minor fix, and I'm seeing good progress on your project.
 

Rocky_LC

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Out and about!

F23CF69D-78D7-4B10-92BB-EB296A182C13.jpeg
 

Tybalt

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Everything still going along relatively smooth? Glad to see that you're getting the TVR out and about, there's a guy that lives within a few miles of me as near as I can tell with a blue TVR 2500M and I see him out and about in it on occasion.
 

DrEntropy

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Looks great, glad to learn it's running well!
 

Rocky_LC

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Anyone know if it is possible to upload a video?
 

DrEntropy

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Anyone know if it is possible to upload a video?
Only way I know is to upload to YouTube first, then provide a link. Maybe someone else knows a different way.
 
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