I recently jetted my triple dhla 40s for a standard N42 L28 and the car felt like it was running great. Basically no hesitations and clean acceleration throughout the the rev range. Carbs are all in sync more less and very responsive.

I wanted to do some fine tuning and put on a wideband o2 sensor. The car according to my gauge is running absolutely rich as it gets. I can set it to idle around 14-15afr but as soon as I touch the gas it goes right to 7-9 afr and cruises at 9. The jets/chokes I know are around the proper size. 32 mm chokes, 130 mains, 35 pumps, 7772.5 emulsion. 50 idles, 195 air correctors. 

What would possibly be the cause of it running super rich?? I'm still very new to this so any help would be appreciated.

Thanks!!

Edited May 22, 20204 yr by spoolin4life

20 minutes ago, spoolin4life said:

If I had to guess it's valves as I didn't hear any detonation.

I'm going to do a better inspection tomorrow night. I may just pull the head off and see from there. Hoping it's nothing in the bottom end. 

This isn't a turbo motor correct?

I would agree that I would be surprised if you tore it up. These motors tend to be pretty tough

3 minutes ago, Patcon said:

This isn't a turbo motor correct?

I would agree that I would be surprised if you tore it up. These motors tend to be pretty tough

It's a standard N42 top and bottom. My car went super lean under deacceleration with load still on the motor (roughly 20ish) after a pull. I might have burned the valves. That's my guess. Either that or my builder didn't do the greatest job and it was a matter of time

Burnt valve is surely possible but I would check all the easy stuff before I got drastic, like others have suggested

27 minutes ago, Patcon said:

Burnt valve is surely possible but I would check all the easy stuff before I got drastic, like others have suggested

I'll see what I can check on my own. I'm not the most mechanical savvy person unfortunately. But I'll let you know what I turn up.

Fresh engines should have the valve lash checked often. As the valves wear into the seats, lash will tighten and keep the valves open longer. This can cause rough-running and compression problems. Also do a leak-down check before tossing the engine out of the car. That will tell you where your problem may lie and is a fundamental step in troubleshooting compression issues.

On 6/18/2020 at 8:42 PM, Patcon said:

Burnt valve is surely possible but I would check all the easy stuff before I got drastic, like others have suggested

I checked the basic stuff and valve clearances are good. Do you know how much play should be on the lose side of timing chain?

I've read different information. Seems there's a cm of play on the driver side and the passenger side is very tight.

assuming you have an LHD car, the drivers side is the tight side and the passenger side is on a sprung tensioner so you will feel a bit of slack.

when you tested compression, did you do it with the throttle open?

50 minutes ago, jonbill said:

when you tested compression, did you do it with the throttle wide open?

I did a couple tests wide open and no throttle at all. Numbers were roughly 110, 90, 110, 120, 120 and 130.

We compressed some air into the cylinders and the bottom end seems solid still. I'm guessing valve issues still. 

And oddly enough the driver side seemed slack and the passenger was tight. My car is lhd

Edited June 21, 20204 yr by spoolin4life

On 6/21/2020 at 9:16 AM, spoolin4life said:

I did a couple tests wide open and no throttle at all. Numbers were roughly 110, 90, 110, 120, 120 and 130.

We compressed some air into the cylinders and the bottom end seems solid still. I'm guessing valve issues still. 

And oddly enough the driver side seemed slack and the passenger was tight. My car is lhd

Did you spin the motor by the cam bolt?

You shouldn't have to guess where the problem lies if you've done a leak-down test.

On 6/22/2020 at 8:30 PM, LeonV said:

Did you spin the motor by the cam bolt?

You shouldn't have to guess where the problem lies if you've done a leak-down test.

I pulled that engine. Bottom end was fine. Valves were burnt ?

but I think I know the issue. My car is going super lean after a pull. Runs super rich during cruising and during a pull. But as soon as I lean it out even a bit and then do a quick pull it spikes lean to 22 and stays there for a good 12 seconds. I guess it runs super lean and then burns the valves from being too hot. Almost did the same thing to the engine I just put in today. Any idea what would cause it to starve for fuel after a pull? 

On 6/21/2020 at 12:00 PM, jonbill said:

when you tested compression, did you do it with the throttle open?

Hey Jon refer to my recent reply. Maybe you know what it's not getting fuel. Scared the heck out of me. New engine started misfiring but then did a compression test and it was 150psi across the board