New Road Demon Running Really Rich...

[Varkwso]

We put a new Road Demon on top of a freshly rebuilt chevy 350 (RPM Air Gap, Comp 280 Cam & Headers) and it is running incredibly rich at idle. I have adjusted the float levels and idle mixture screws. The float level definitely helped - but it is a little past the the last line on the view port already. It has a new Edelbrock fuel pump that is made for a stock pressures.

At idle it will eventually choke itself out.

I hate to keep spinning the idle mixture screws....

Any good suggestions? I have been spoiled by my LS1,2 & 6s and have forgotten the "tuning joys" of carbs....

Thanks

[6'9"Witha69]

The mix screws and float adjustment only do so much. With a 280 cam in a 350 what is the vacuum? I am guessing about 12". You may want to look at the power valve and if it is a vacuum secondary carb the secondary spring as well.

[Shaker455]

Break the carb down and clean the metering blocks for chips or shavings in the passages from when it was machined....

BG's quality rating is poor lately and has been many problems with there machining process.

Check out my post on the PerformanceYears board: http://forums.performanceyears.com/f...d.php?t=482459

Also if your able, measure the size of the Idle Feed Restriction (IFR) and the emulison holes.

[Varkwso]

I have a real vision problem (I do not see myself doing it, actually) breaking down a brand new carb to clean junk out of it .


BG tech told me I bought the "wrong carb"......for my combo....

[Shaker455]

What size road Demon did you buy?

[Zee]

Jeff, what are you doing over here?? Steve here. I just sent you an email re: some good news with the mods you did with my 4150.

[Varkwso]

What size road Demon did you buy?

625

[Shaker455]

Steve,
Got your mail.

Varkwso,
Which Comp 280 cam are you referring to....280H Magnum?....280AH high energy marine?

What are you running for a dist?
Need more complete info on your combo

[Varkwso]

Steve,
Got your mail.

Varkwso,
Which Comp 280 cam are you referring to....280H Magnum?....280AH high energy marine?

What are you running for a dist?
Need more complete info on your combo

Exact Cam Specs

Duration @ .050 204/214

Advertised duration 270/280

Lift .420/.443 Lobe Center 107/117


Running new Mallory Unilite - vacuum advance....


Thanks for all the help....

jeff

[Shaker455]

Good,
Now what's your intinal and total timming with the vac adv disconnected?

When your vac is connected and is it to a full or ported source?

Have you attempted to tune with a vacuum gauge?
Spec chart shows you have 70/78 jets so how many turns is you mix screws out?

[Tech @ BG]

Exact Cam Specs

Duration @ .050 204/214

Advertised duration 270/280

Lift .420/.443 Lobe Center 107/117


Running new Mallory Unilite - vacuum advance....


Thanks for all the help....

jeff

Jeff,

Exactly which cam do you have? The reason you would have been told that is the specs we have from Comp on a 280H are 230/230 @ .050" the idle circuit in the carburetor would been set up for a much milder camshaft.

Where are you at with your initial and total timing at this point?

[Varkwso]

Jeff,

Exactly which cam do you have? The reason you would have been told that is the specs we have from Comp on a 280H are 230/230 @ .050" the idle circuit in the carburetor would been set up for a much milder camshaft.

Where are you at with your initial and total timing at this point?

Exact Cam Specs from the end of the cam box. I cited the adv duration - not the CAM Spec - sorry about that

Duration @ .050 204/214

Advertised duration 270/280

Lift .420/.443 Lobe Center 107/117


12 degrees initial -whatever advance a stock Mallory Unilite comes with.

Have not tuned with a vac guage yet.

I only turned the screws 1/4 - 1/2 and noticed no change - so IQFWI until I had some solid carb advice - it runs horrible.

I had to replace a set of shorty Accel plugs today due to fouling. My son dang near blew up the Flowmaster exhaust system before we swapped plugs.....

[Tech @ BG]

Have you tried increasing the initial timing any further yet? Usually the Air Gap style Intakes like a littke more timing. Probably 15 or 16 degrees initial would make a huge difference.

[Varkwso]

Have you tried increasing the initial timing any further yet? Usually the Air Gap style Intakes like a littke more timing. Probably 15 or 16 degrees initial would make a huge difference.

The thing that helped the most was pulling the darn thing off and putting it in a box. It for sure did not help my brand new engine with all the gas pouring out! The Road Demon carb went through two sets of plugs, drove an oil change (on my new motor) at about 100 miles due to gas fouling in the oil, and leaked all over my new Air Gap . The solution I have at the moment is a 600 CFM Holley I spent way too much for also to get the car on the road to sort out the suspension and brakes. Car runs GREAT with the new carb...

I will be sending the Road Demon to you guys in a box - I really hope when I get it back it works as advertised . It still looks pretty....

[Shaker455]

Varkwso,
the Demon carbs work good once they been gone thru... even a brand new one as I mentioned eariler.

Is that 600 Holley a loaner?....if you like I can build you a great carb for your combo.

[Varkwso]

Varkwso,
the Demon carbs work good once they been gone thru... even a brand new one as I mentioned eariler.

Is that 600 Holley a loaner?....if you like I can build you a great carb for your combo.

I wish - we now have spare carb - when the Demon gets fixed....

I may have you build a carb for my LS-6 for our Chevelle though....

[Shaker455]

Okay,
I'd be happy to help

What can you tell me about the Chevelle's combo?

[Magntik]

Sounds like the same problem I have had for a couple years with that carb on my .040 over Pontiac 350.

BG's tech guys kept telling me to advance the timing.
That must solve everything in their world!!!
Wrong.

When I first got it, I spent alot of time on the phone, then gave up and talked with a local engine builder who told me BG's carbs run extremely rich at idle and just off idle but to be careful b/c he says they tend to lean out at upper RPM's.

I even emailed their tech guys a week or two ago asking if the did a rebuild service like Holley does, figured I'd start from scratch, never even got a response.

Good luck, keep us posted.

[Varkwso]

It just about ruined a brand new motor .

It is on my list of things today to get it shipped to BG for them to fix it.

So far - I am not super impressed with the performance of the carb...

[Magntik]

Like you said the darn thing is pretty,
that's the reason I bought it and the reason it hasn't ended up in a million pieces.