Niuhi

What are your thoughts on fuel delivery for one of these systems.

I'm looking to possibly add a 177 or 250 to a stock 454 mag and run it until the motor dies (currently has around 225 hours). I was thinking about going larger and not using the intercooler (finances kinda dictating) and going with a low boost. Do you think that a single carb setup works or do you think 2 are better? I am leaning towards single, but am a bit concerned about leaning out the end cylinders. Got opinions, throw them out.

mcollinstn

two smaller carbs are always preferred on a roots blower setup. The blower is more efficient that way, and the fuel charge is distributed more evenly that way. In fact, the most effective way to setup dual carbs on a roots is to turn them sideways. Sideways carbs will allow the most even distribution of fuel thru a roots. You got 4 primary barrels spaced from one end of the rotors to the other. When the secondaries open, its just more of th same...

Not an issue with Whipple, since it pulls from one end and out the other.

I guess it could be a helpful thing in a Procharger carb application, but I haven't heard it being a priority.

Gary Anderson

For low boost on a stack motor, I would go with the 177 and a single 1050 Holley. The 177 is the blower used on the Merc 525SC motor (454cid). I dont think it's even capable of being set up for twin carbs. I personally think the 525SC is an excellent setup. Bolt on the 177, a 1050 dominator set up for a blower application, and replace your Tbolt ignition with a V6 module. You should be good with 3-4 lbs boost with total advance under 30 degrees and premium gas.
An oil temp guage and maybe a larger oil cooler would also be good additions.
My $0.02
Gary

Niuhi

Thanks for the input guys.

mopower

Les, you going to blow the Liberator

Cal(mopower)

Niuhi

Cal I'm thinking about it. I have to blame (OOOps thank) you for that idea . Still mulling it over though.

mopower

Les,
For what I've seen and done personally and what I've read here and other place , actually that's probably the cheapest and easiest way to go as long as you have a relatively low hour (and compression) engine. I know one guy locally has a 1984 30' Formula who ran B&M blowers on his 330's with TRS drives for 17 years.
I don't know how many hours but I DO know he didn't use it a whole lot . The end of summer 2001 he broke a rod , put a "window" in the block right on the pan rail , broke the cam and some lifters , and of course messed up the pan too
But use some sense and you can get the most for your $ and longevity too.
Oh yeah , those 2 330's pushed a 30' Formula a little over 80

Cal (mopower)

blown1500

Hi, Niuhi,
I agree with Mr. Anderson except the carb choice. I have had better results with a carb more in the 850cfm range, blower ready carb than the Dominators. Fuel economy is better, fuel atomization is better, cost is less, power the same or better.
Mcollinstn is right on every count.
Mopower has a good point about rods. If you can replace the pistons and rods before they break, you can use your block and crank to make 550+HP pretty reliably. If you break, you spent a LOT more money. Chain is only as strong as the weakest link, strong enough is all you need........

VP

Been reading your post. I just submitted one yesterday about a pulley change on a 575 SCi.

I mentioned there that I built a 540 CID using a 177 blower. The 177 came with my original 468 motor that came in the boat. The 177 worked OK on the 540, but I had to spin the blower near its speed limit to try and fill those big cylinders at 4 psi. That in turn generated a lot of heat and oil temp. I had to add a second oil cooler.

The 468 did not require the second cooler. The 177 blower on the 468 worked a whole lot better. I think it is was a perfect match for that cubic inch. It origanally came with a 850 carb which worked OK. I changed to a 1050 however. As stated above, that is the way to go I think.

I would recommend however that you buy a carb (no matter what size) already modified to reference the intake manifold. I modified my own and installed a 1/8 plastic line from the carb to the intake, to operate the primary power valve (i removed the secondary power valve). On the 540 CID, my jets were 81 pri. with a 5.5 power valve, and 93 secondaries - do not take this as the "proper setup" but it may get you started.

To rework your own carb to convert to referencing the intake manifold takes a little thought. In my mind, referencing the intake is a must, because that is the only place you get a true reading of engine vacuum. The blower is constantly sucking and gives you a different reading at the base of the carb, which is bolted directly above the blower. To rework your own carb, you have to block the vacuum port running from the power valve chamber to the open area in the base of the carb (where it normally sees vacuum), and mill a small passage to a spot in the side of your valve body where you can then cross drill to it and tap for the plastic hose fitting. Sounds complicated, but if you study the carb and the passages and the power valve, it all makes sense.


Anyhow - i liked the 177 - it is a very simple package with near zero maintenance (just check oil at both ends).

good luck
gary

VP

P.S.

forgot - your initial question about the fuel system.


I ran an electric fuel pump in series with the chevy mechanical fuel pump (after the mechanical), then through a regulator, to maintain 6 to 7 psi all the time.

I also increased my hose sizes from the tank to the filter to the pumps, etc. to #8 (1/2)

gary