KNOT-RIGHT

Ok,
after a long winter we are ready to fire the first engine on a makeshift stand. One of the engines is going to dyno. I want to catch any mistakes leaks or god knows what while the engines are on the floor.

These engines were normally asperated last year.
We installed Blower pistons
Reworked ported merlin heads Iconel valves.
cams are crane 139741,s
lower ends are Sonny bryant cranks with corrilo
rods.
Bowtie 540,s
Cometic head gaskets

10-71 Mooneyhams
Richard lee intercoolers Cupranicheal cores
8-10 lbs boost (will see at Dyno) 49 top pulley 52 bottom
Demon 850,s

Ok I set static timing its locked at 30 degrees.
Filled carbs with fuel.
Hook up fuel pump to Can of fresh gas.
Stuffed a garden hose in the cross over. No Tstats
goes write out the headers.

Installed Oil presure gauge
Hooked battery
wired a lawnmower ignition switch to MSD box and starter .

Started write up.
Sounds Killer!!!
Hooked up Mac Timing light
Its Idling at 1500 rpm.

Anyone have any pointers on getting good Idle with
there blown setups.
I turn down the Idle stops then go to the fourcorner
Idle circuits and the engine goes from 800 too 1100
surging. Any procedures or suggestions?

Welcome to the blower world!!
Sorry I am so dam long winded


Thanks in advance
Gerry

Strip Poker 388

iTrader: (6)

Looks like BG carbs.They come with a pretty good instructions.Did you boost reference the carbs?.what power valves?. What is the vacuum going down to on the surge it may be opening the power valve? make sure the butterfly's are open the same. measurement look at the transfer slot on the bottom,When you adjust the front idle screw turn the rear the same ,that way the transfer slots will stay the same .The idle screws should be 1-2 turns out . any more or less you can change the idle air bleeds in the top.to get the calibration rite.the engine Water temp will change the idle also. When we dynoed my motor I was able to run more timing 35 dr. When you run it on the dyno watch the exhaust temp with it at 30.Most dyno shops that I have used they want or can not run the motor cold like it would be running on the lake .Remember on the inner cooler not to run water thru it at idle in the boat .it makes the fuel puddle .

At the dyno room we ran a water hose to the inner cooler and on the exit hook up a set up like on the alcohol motors with a shut off valve and a jet in the end of it the set the water pressure. its worked out pretty good that way.

On my blower motor I set the idle to surge to be able to shift the bravo on the down cycle.it surged all the way up to 2800 rpm but it was on 12pd of boost.My idle surge was 600-1500rpm.It was a little rich at idle . Had a prob with being lean at midrange.
I like the surging

KNOT-RIGHT

Thanks for the response.

The carbs are 850 demons. I was thinking the same with the power valves opening aggrivating the surge.
So before I left the shop I fired it again with two vacuum gauges installed. One under the carbs read
18 to 19 hg at Idle Then the other gauge under blower
12 to 13 hg also at idle. Thats not opening the P/V.

Plugs are black within a minute

The power valves are on the primarys and they are 6.5
the jets are 86 primary 96 secondarys. The power valve is not referenced.

I removed one of the carbs on the motor that is not yet been fired. I was trying to figurie where the demon carb gets its vacuum signal from. I notice it gets it under the base.
Pluging this hole and drilling the side to accept a brass
hose I would think would be the procedure to reference
the PV. However I dont beleave this would cure the surge.

One more thing I noticed it appears the throttle plates on the carb have been bent slightly (upward approx .020) allowing more air to flow this appears on all 4 carbs, but only two throttle plates each carb.

Any procedure known to adjust these carbs?

thanks again
Gerry

marinetrans

When in doubt, call Nickerson Performance in PA. Dean will help you and may suggest you send all 4 carbs to him so he can set them up for the blowers properly. He is the best marine blower carb guy. Might cost you some coin and down time but its worth it.

RLW

Nickerson dialed in my Blower Carb and all I had to do is set the idle stop screw. No transom soot either.
Best money I spent on that engine.

KNOT-RIGHT

Not bad advise
That would take all the fun out of this.

Whaz up Pete???
Today when I had that motor running. I notice even when I whacked the throttle. (Dam thing set all the car alarms at the dealership) the flange on the borg warna didnt even move. Then at idle I checked the forward. Then went back to neutral. Flange came to a nice stop. then hit reverse real nice. before I sent them to you That flange would have been spinning like a skill saw in neutral. Nice Job!!

will see how they stand up.

Thanks Again pete for your help.
Gerry

Turbojack

I have same cam, & timing in 540 with procharger. Last 2 years with carbs motor idled smoothly (best it can with that cam) at 800 in neutral & 600 in gear.

I remember reading where you need to make sure the intercooler is not getting any water while motor is idleing because it causes the fuel to puddle thus surging. I had a twin turbo setup that had intercooler after carbs & never had surge so not sure that is answer.

aero-offshore

Another real good source for holleys is Pro systems out of Michigan in Sping lake, these guys set my 1050 dom. on my Whippled charged GM and all I did was bolt it on, even the idle was set. They do most of the NASCAR carbs,WWW.pro-system.com
Buck,

aero-offshore

I ment to write NHRA instead of NASCAR but can't edit my own posts?.What's up with that Jeff.

KNOT-RIGHT

The float levels are at the very top of the sight glass.
You actually have to shake it to see the level.

I will lower them a tad see if it helps.


Gerry