URGENT - CARBURETOR ONE LAP

[raycycl]

SOS - We're in the middle on One Lap of America at NCM right now and we're missing the top cap of a side draft, we're running DCOEs. Is anyone near Bowling Green who can help?

[raycycl]

This is a pic of what's missing

 

[visionaut]

That’s the jet inspection cover. On the earlier DCOE it was vented, on the later ones not.

 

As long as your slow-running and idle jet stacks are tightened down, I think it won’t hurt performance if it’s missing, except for some possible fuel splash, but you could try to seal it up with tape/plastic/etc. to prevent dirt getting in there until you can get or fab a cover.

 

You can quickly fab a simple cover from a round piece of plastic with a hole in the center and a nut…

 

[raycycl]

Yep that is what we are doing for now.  We're on track and it got super lean

[tzei]

Seal the substitute cap with something perhaps?

[raycycl]

Yes thinking some coolant hose washers and a nut from home Depot should do it.  Does anyone happen to know the threading on the cap's wing nut?

[AceAndrew]

M5.

Going off of readily available stuff .... I was going to recommend a milk cap.  Could heat up something round with a lighter and punch a hole through the middle.

[raycycl]

This is what we have put together for now... Brake cleaner cap and gorilla tape.  Will go to home Depot after this run

[raycycl]

Got a cap from a gallon jug of water, washer, o-ring and wing nut.  Thank you for the suggestions.  Also has a loose spark plug wire which was adding the the bad running.

 

We found a replacement part in Cincinnati that we will pick up on tonight's transit to Pittsburgh.

 

I really appreciate everyone's suggestions and support.

 

So far we have done about 3500 miles. We drove from Virginia to the start in South Bend and have done/will do the below legs:

May 4: South Bend, IN to Motorsports Park - Hastings, NE

May 5: High Plains - Dear Tail, CO

May 6: Hedge Hollow - Adrian, MO

May 7: National Corvette Museum - Bowling Green, KY

May 8: Pitt Race - Wampum PA

May 9: Putnam Park - Greencastle, IN

May 10: Tire Rack HQ - South Bend, IN

 

Edited May 8 by raycycl

[Leucadian]

I love this forum.  

[Mike Self]

Go to the hardware store armed with the cap from the other carb to get the right sizes.  Find

• a "fender washer" (large OD, small center hole) that's the proper size.  
• get either a wing nut or regular nut with the proper threads, and an appropriately sized flat and lock washer
• get an O-ring that matches the OD of the fender washer, and a second one to go under the flat washer.

Assemble on the stud:  big o-ring; fender washer, small o-ring, small flat washer, lock washer, wing nut or nut.  Tighten appropriately.

 

in an emergency you can substitute cut up polyethylene lids for the two O-rings. 

 

mike

[AceAndrew]

@raycycl  You posting updates anywhere?  Good luck!

[raycycl]

@AceAndrew

 

We are almost done with our transit to Pittsburgh for Pitt Race tomorrow.

 

We have a Facebook page for our car and the charity that we are raising awareness for as well as a live tracker on the car that is live when we are moving.

 

The car is running strong and cruising easily with all of the C8s and GT3s in the highspeed transits but Hal Boyles and I have been on the phone a bunch today trying to debug a few issues that we are managing:

1) Car is not idling well and we need to keep it running with the pedal - idle screws have no effect.  Coming down from speed the engine will idle nicely at about 1200 and slowly fall to about 400 and sound like a cammed American v8

2) We have a slight stumble / misfire in the 3.4-3.7k rpm range under load and then it is as smooth as glass when cruising at 4k+ in 5th (3.9 LSD... Everyone here can do the math on cruise speed)

 

We think that it is a vacuum leak causing the above as we did a rotor, cap, and wire change mid transit with no impact and mixtures are okay.  Curious if you have different thoughts?

 

Engine specs: 10:1 TII Pistons, 121 head with light work, 292 cam, Spanish 40 DCOEs, Ireland intake manifold, late e21 distributor run on a MSD box, shorty header and full exhaust.

 

Facebook: https://www.facebook.com/profile.php?id=61558476563660

 

Live tracker:

Silvercloud - OneLap 2024 - Keepsake Farm Racing

PORTAL.GPS-TRACKING.COM

 

Edited May 9 by raycycl

[resra]

7 hours ago, raycycl said:

@AceAndrew

 

We are almost done with our transit to Pittsburgh for Pitt Race tomorrow.

 

We have a Facebook page for our car and the charity that we are raising awareness for as well as a live tracker on the car that is live when we are moving.

 

The car is running strong and cruising easily with all of the C8s and GT3s in the highspeed transits but Hal Boyles and I have been on the phone a bunch today trying to debug a few issues that we are managing:

1) Car is not idling well and we need to keep it running with the pedal - idle screws have no effect.  Coming down from speed the engine will idle nicely at about 1200 and slowly fall to about 400 and sound like a cammed American v8

2) We have a slight stumble / misfire in the 3.4-3.7k rpm range under load and then it is as smooth as glass when cruising at 4k+ in 5th (3.9 LSD... Everyone here can do the math on cruise speed)

 

We think that it is a vacuum leak causing the above as we did a rotor, cap, and wire change mid transit with no impact and mixtures are okay.  Curious if you have different thoughts?

 

Engine specs: 10:1 TII Pistons, 121 head with light work, 292 cam, Spanish 40 DCOEs, Ireland intake manifold, late e21 distributor run on a MSD box, shorty header and full exhaust.

 

Facebook: https://www.facebook.com/profile.php?id=61558476563660

 

Live tracker:

Silvercloud - OneLap 2024 - Keepsake Farm Racing

PORTAL.GPS-TRACKING.COM

 

Do you have a spare distributor? if so, give that a try.

[Mike Self]

Funky idle with no change when messing with the mixture screws is almost always a vacuum leak somewhere.  Check all the usual suspects including the vacuum line to the dizzy if it has vacuum advance.  

 

Also check the power brake booster hose--esp the little short one between the manifold and the one way valve.  It doesn't take much of a leak to upset the idle.  

 

You can use a can of carb cleaner or starting fluid sprayed around suspected leaks (be CAREFUL doing this) to see if that affects the idle.

 

And keep flying the 02 flag for the rest of us!

 

mike