Brad Perry

I have 2 of Barry grant's Demon carbs that are factory tuned for blower set ups. They are 975 cfm. I have been told by distributor that they should be very close right out of the box. They are boost reference types.

Anyone out there have experience with these?

Thanks.

Brad Perry

Give me your take...

WETTE VETTE

I know JDNCA1 gave the BG people all of his engine specs and they were pretty close right out of the box. I think some jet changes were made on the dyno but that is to be expected. I think JDNCA's carbs were lean. When making your first runs be sure to keep an eye on the plugs and watch for the formation of a fuel ring before laying into it for a long WOT pass. Better safe than sorry. What plugs are you running? I think some NGK R5671A-9 would be just about the right heat range and will give you accurate readings if viewed after a WOT run. Are you getting pumped?

Brad Perry

Yes, cautiously so.........

I ordered them from the blower shop. Marv gave them the basics (C.I., head type, etc...). I just got off the phone with him. I didn't realize that the race demons were all custom order. Apparently there is a new type that can be ordered blower calibrated without removable venturies that comes off the shelf (non custom). I thought that was the case with these, but Marv says no...

I plan on taking it slow and really watching the plugs. I don't really know the difference between heat rings and color critiquing.

Brad Perry

Those are the plugs I have been running and have a fresh set in.

WETTE VETTE

On my motor I run NGK R5671A-8 and they just leave a gray ring around the base of the porcelins after a WOT pass. On my engine Dean says that ring indicates a slightly rich condition for racing fuel which is good in a marine environment. That is after maybe an hour of running time with minimal idle time. I also did readings at cruising RPM. Do you use a plug magnifier? If so watch out for shiney areas and small beads of aluminum on the procelins. That would indicate pre ignition or detonation. Also make sure the cen electrode isn't "heat blue" after a hard pass. I am sure you already know this but I recite it sometimes to remind myself. Are you running this weekend? JDNCA1 is planning on flying his Stearman up here tomorrow and we hope to put the WETTE VETTE through the paces. It should be fun. Good tuning!!!

jdnca1

Brad;

I run the 775 race demons with the Removable Sleeves, they were dead on out of the box for the TR set-up with the exception of jets. Had to go up 2 sizes all the way around. Two things to watch; first be sure you lock tight the base plate screws in place (wvette and I were lucky and caught mine before a couple got ingested) also periodically check the boosters to be sure they are staying tight (like at every oil change) I've had to tighten mine 1 time in about 60 hrs. You have to buy a special tool from BG to do this.

The tech guys seem to be very good from BG, I thought about changing sleeves to the 975cfm for more power when I started to turn more r's. While they agreed I would likely pick up some on the very top end, they advised against it because idle and mid range would suffer drastically. They basically saved me 600.00 to make the change. Anyway I've been really happy with the Demons...just look at them compared to a holly, put together much better. Good luck

I run the NGK 5672A-10's and the -9's (Projected nose plugs)

RumRunner

Brad:

Those carbs should be safe out of the box, make sure to hook up the vacuum fitting on the side of the carburetor to the base of your intake manifold (it is the boost ref. port for the PV) If you have any problems call our shop (706) 864-8544 or Marv.


Doug

John B

Brad, many times boost referencing doesn"t work on heavier boats. If your mid range is shot, hook it up as stock but read your vacuum under the carb to see where your power valves will open. Just above high cruise speed works best.
JB

Brad Perry

I ran them on the hose this weekend and set the timing. Spent a while working on getting the linkage just right. It had a 400rpm roll on top of a 1200 rpm idle at first. Worked on idle mixture screws and got a stable, 900 rpm idle. I've never got that before with past setup. These carbs seem very sensitive to the least change in setting.

JDNCA; I noticed that the base screws were not that tight out of the box and tightened them before installation!!

It's been still all summer here for the most part and the day I want to go out and test, we had 25mph wind. Drove quite a ways to a lake that had a protected marina and a protected strip of water along north side of freeway. Pulled it off trailer and had no forward gear! If it isn't one thing it's another. Just had the gears put back to 1.5 with new clutch by my most trusted mechanic. I'm sure it can't be much. Hope to try it NEXT weekend.

If I can figure out how to shrink down photos, I'll post a pic of the setup.

Thanks again,
Brad