Jump to content
Sign in to follow this  
Carlucho

73 RRC overacelerated at low MSL

Recommended Posts

Hey,

 

I need your help, I got 73 RRC  3.9-liter petrol with Stromberg carburetors.

 

Currently my house is at 1600 MSL (meters), so when I went to the beach (0 MSL) the last 3 times my RRC got accelerated until I returned home .

The distributor is calibrated to 9 degrees.

Do you know what may be happening?

 

Thank you in advance for your help.

Share this post


Link to post
Share on other sites

I suspect so. There's no altitude compensation on the Stromberg (or most carbs for that matter) so if you've got it right for where you live up high, it'll be rich down low. 

You've got relatively few options for easy adjustment and none that won't involve twiddling stuff with tools when you transition. How bad is it? 

Share this post


Link to post
Share on other sites

Could it be a sign of a split or holed diaphragm ?

Share this post


Link to post
Share on other sites

That shows up as runs terribly all the time. You usually get the opposite problem where its tuned for ~sea level  elevation and gets bad when going up high.

Share this post


Link to post
Share on other sites

@FridgeFreezer maybe it's too rich, I don't know it properly because at 1600 MSL is working good at 850 RPM, but I supose that is rich for altitud reason. 

1 hour ago, lo-fi said:

I suspect so. There's no altitude compensation on the Stromberg (or most carbs for that matter) so if you've got it right for where you live up high, it'll be rich down low. 

You've got relatively few options for easy adjustment and none that won't involve twiddling stuff with tools when you transition. How bad is it? 

It's not that bad, maybe make some settings to keep it in an intermediate range.

 

1 hour ago, smallfry said:

Could it be a sign of a split or holed diaphragm ?

I replaced them already twice, also all carb gaskets as well once.

 

57 minutes ago, lo-fi said:

That shows up as runs terribly all the time. You usually get the opposite problem where its tuned for ~sea level  elevation and gets bad when going up high.

It's true, for that reason it was not common, I didn't know if I was lacking any knowledge about it.

 

Thank you for your help.

 

Any other idea?

Share this post


Link to post
Share on other sites

Ah, wait. You mean the engine is idling faster when at sea level? That's because for a given throttle opening, more air is entering because its denser. More air, more fuel, more power.

You could make some removable shims for the throttle stops. Just remove at low altitude and replace when you go back up. A piece of sheet brass cleverly cut, folded and soldered ought to do it. 

Share this post


Link to post
Share on other sites
18 hours ago, Carlucho said:

Any other idea?

Well, my idea would be to fit Megasquirt EFi with a 2nd MAP sensor for altitude compensation and have it running right everywhere automatically, but that's just me talking crazy :lol:

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy