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> OMG WTF, if it's not one thing it's another
Type 47
post Mar 26 2023, 07:12 PM
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so we've been battling a tuning issue which is being discussed in another thread, so I don't want to muddy the waters with another issue, hence the new post.

So, i'm sneaking up on this carb tuning issue and get the car idling to do the carb tune stuff and I notice this shxt...

I get the car started, rev it to 2-3K for a little bit until it establishes idle at about 1,200.

so I get out to start fooling with the carbs and notice it's not smoking with white smoke like it was the last time. Outside temp was about 50, now outside temp is 64ish.

It's freak'n spitting out oil. There is a spray pattern out the tailpipe about 12' long.

When we filled the oil I instructed 4 qts but not sure if son put in the whole 5 qt Mobil One container in. Also, on initial run he thought it was a little low, on oil, so we put in another 1/2 qt.

Engine has been sticking a (measuring) really high ever since.

Has a piston ring gone south??

Is the oil overfill causing this issue?

Why did this just start happening?
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technicalninja
post Apr 6 2023, 07:53 PM
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I am Jedi-master class when it comes to ITB carb set up.

I briefly toyed with the idea of getting a set of 2bl down draft carbs as an interim step before modifying them to run true port FI with ITBs

SupeHawk advised to run much smaller carbs than I prefer (my experience is mostly DCOE and Mikuni PHH side drafts). I disagreed with him.

A serious dive into multiple IDF threads proved to me that he was RIGHT!

The Weber IDF idle and transition circuits provide so much of your normal running feed that the venturi size really needs to be 75% of what a DCOE or PHH requires.

It was way too much intentional intake pumping loss for me and I will start with aftermarket FI and not try and modify a carb body to make it work.
FI does not require ANY intentional intake restriction.

For 2.0l and smaller it looked like the 40s with a 28 venturi was the least problematic for many, many folks.

40s with 32s needs a 2.2l or larger engine.

It also looked like Dellortos might be a better choice, but I have little experience with Dells and decided I didn't need the exposure.

I will build something 2.2L or larger and for ITBs I need throttle blades 44+ with FI.
This would have made the part throttle BS even worse.
My current thoughts are a single DBW t-body of 60-65mm and a custom plenum.

For a mild 2.0L with IDFs I'd now suggest a venturi of 28 with corresponding main and air correction jets. Probably closing on $200 in cost.

With aftermarket FI I will have every single jet, emulsion tube, accelerator pump cam/nozzle, anything you can imagine, built into my ECU and available with a few strokes of a lightsaber that looks very similar to my index finger.

So, a Jedi-master decided "These are NOT the carbs you are looking for" and walked away...
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Posts in this topic
Type 47   OMG WTF   Mar 26 2023, 07:12 PM
nditiz1   When you say "He thought it was a little low...   Mar 26 2023, 07:29 PM
Van B   :agree: I doubt it’s low on oil… But you can a...   Mar 26 2023, 07:36 PM
mihai914   Why don't you start all over with the car just...   Mar 27 2023, 07:32 AM
VaccaRabite   Put the car level somewhere. Check the oil. If i...   Mar 27 2023, 07:38 AM
Type 47   Put the car level somewhere. Check the oil. If ...   Mar 27 2023, 11:06 AM
Type 47   so we've been battling a tuning issue which i...   Mar 27 2023, 11:04 AM
Van B   see if it smells like gas when you drain it.   Mar 27 2023, 11:17 AM
bossboy302   Man, I feel your frustration. I've peeked at m...   Mar 27 2023, 12:56 PM
Type 47   Man, I feel your frustration. I've peeked at ...   Mar 27 2023, 07:23 PM
Type 47   We are back up and running. Not great but close t...   Apr 6 2023, 05:32 PM
Superhawk996   Good job - making progress. So the 32mm venturis ...   Apr 6 2023, 05:54 PM
Type 47   Good job - making progress. So the 32mm venturis...   Apr 6 2023, 06:47 PM
Superhawk996   How are you doing with the iteration between adjus...   Apr 6 2023, 05:58 PM
nditiz1   You should be running 28 vents. Pick up a set, as...   Apr 6 2023, 07:01 PM
Type 47   You should be running 28 vents. Pick up a set, a...   Apr 6 2023, 09:53 PM
technicalninja   I am Jedi-master class when it comes to ITB carb s...   Apr 6 2023, 07:53 PM
Type 47   I am Jedi-master class when it comes to ITB carb ...   Apr 6 2023, 10:02 PM
technicalninja   Yep, if I was in your shoes, I'd work with tho...   Apr 7 2023, 08:46 AM
VaccaRabite   It only takes about 10 minutes to swap the vents o...   Apr 7 2023, 09:49 AM
Type 47   Guys, my bad. it has 28's   Apr 7 2023, 02:36 PM


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