Tee

I installed my intercooler over the weekend. I now have a very pronounced blower surge, just over a 600 rpm swing. I have run the motor for around 30 hours before the intercooler and it didn't surge at all. What causes this? Is this normal? Will it hurt anything? I see it being a hasle during docking!!! Where do I start adjusting to get it smaller, or eliminated? Jetting? Timing?
Thanks--------T

RLW

Tee, very interesting. I have a newly acquired 27' Activator with a intercooler and B&M 250. Single Carb setup.
I am waiting for an answer from Nickerson in regards to the surge.
The fact that it started after the intercooler install is something I haven't heard of before.
I am not even close to being any kind of authority on these setups. Hopefully someone will chime in about your/our problem.

Turbojack

Put a timing lite on it. My guess is the timing is swinging during the surge.

Other possibility would be 2 lean at idle, vacuum leak. Make it smaller, you should not have to put up with it at all.

Please give us some more info. on motor, amount of boost, type of blower, carbs, efi, & etc.

Smitty

iTrader: (1)

How did you guys plumb water to the chillers??? Are they getting water from the seawater pump?? If the answer is yes probably what is happening is that at idle speed the fuel is changing back into a liquid and causing a loading up/surge.

Per Bob Teagues instructions I ran a separate water supply via an offshore pickup to the chiller. It only works once you are moving 20 mph and above, this being the time when the chiller is needed. It runs cool and does not deprive the motor of additional cooling water.

Dave

Brad Perry

Timing coming in early seems to amplify this. Nickerson and Marv have both directed me to lean out the idle mixture until this goes away. It has worked for me.

Brad Perry

It doesn't sound like your issue, but both of the above guys and Teague said that the transision slots being exposed too much on the primaries can cause this. They said it is a lean-rich-lean issue. Cure is to get the secondaries open a little more so that the primaries at idle do not open as much, so the transision slot is exposed the right amount.

Turbojack

Good point Brad, I forgot about that point.

Tee

Turbo: I run a MSD distributor and it is locked at 34 deg. No advance The motor is a 355 sbc with littlefield 6-71 and twin 650 double pumper holleys (boost referenced). Static compression is 8.0:1 and I am currently running 10psi boost. Full roller motor. 1.62 intake and 2.05 (inconel) exhaust valves. The boat is an Advantage 22 Sport Cat.

Big Wavz: I did plumb it from the sea water pump. So that could be an issue, I have a pressure relief valve ordered that will hold it closed until it gets 10psi.

Brad: I will try the leaning out of the idle circuts, I know I have been running rich at idle for awile now.

One last thing. I ran it again on the hose last night for a longer period and it seems once the motor gets some temperature it settles down to only 2 to 3 hundred rpm.

Thanks

Audiofn

Tee my buddy had the same problem with blower roll and the preasure relief valve made it all good When you get that you should be 100%. As has already been stated the fuel will turn back into a liquid and puddle on the intake runners and mostly go to the back of the engine. Once you stop water from going through there except for at higher RPM's you will be fine. Good luck.

Jon

RLW

Gentlemen, Thanks for the replies.

In regards to my setup, it is a 496" (GenIV 454 stroked) with one 1050 Dominator. It is not boost referenced.
As stated above, it is a B&M 250.
The intercooler (Superchiller) has its own transom pickup.
The timing is "locked in" at 29 degrees.
I am running 5 lbs. boost. I have not tried leaning out the idle circuit, but sounds like a good starting point. How many turns out should I start with? Who knows how the last owner had it adjusted?

Brad,
In regards to your topic of transition slots.
Is this visible when looking down the primaries and secondaries or is it on the primary side only?
Is this adjusted with the idle stop screws?
(I am not refering to the idle mixture screws.)

Audiofn and Tee,
Is a pressure relief valve needed on the intercooler? CP Performance suggested that I have 2 discharges for the intercooler opposed to the single discharge I presently have.

Thanks again for the feedback, Russ Withiam