I have had a B&M 174 blower now for 10 years or so and never used it. I have a 94 merc 502 motor that has the SQ port iron heads and compression of 8.75. I also have a set of .030 over 454 TRW dished blower pistons and several 454 2and4bolt blocks. Should I put the blower on the 502 or a 454????? Is the small blower a little small for the 502???? I know people who have ran them on 454's with good results but not a 502. This will go in one of my 66/67 street cars. Lately ive been leaning towards the 454 since I recently picked up a set of 10-1 wiescos for the 502. Any help would be greatly apppreciated.........

B&M lists the application of the 174 as 396/427/454/502. However, they do not
recommend it for high boost, high rpm, or most 502's.


Emil DUsek
71 Chevelle SS-502

I have a weiand 177 on my 30 over 454.^-8 lbs boost. KB pistons and have no probs.

The way I figure it, on my about 9.8 to 1, 496" engine, I can only go like 2, maybe 3 pounds of boost before I start getting into trouble fuel-wise..

BUT to each his own b/c boost really builds power!

pdq67

I am about to have my 470 with the Holley PowerCharger 174 test fired at my builder's machine shop. The PowerCharger 174 is basically the same as the B&M 174 (Holley purchased B&M supercharger division). The kit came with 7.9lb pulleys.

My machinist and I agreed upon 8.5 to 1 pistons for this setup; we are using JE custom pistons.

We will see how this runs on the engine stand next week...and let you know the preliminary results.

I am about to have my 470 with the Holley PowerCharger 174 test fired at my builder's machine shop. The PowerCharger 174 is basically the same as the B&M 174 (Holley purchased B&M supercharger division...along with Weiand). The kit came with 7.9lb pulleys. I went with this configuration because this supercharger along with a Holley carb would squeeze under a 4 inch cowl hood. I believe the Weiand is taller...per Holley's web site specs.

My machinist and I agreed upon 8.5 to 1 pistons for this setup; we are using JE custom pistons.

We will see how this runs on the engine stand next week...I will post results.

Other particulars: Merlin oval port heads, ported and polished; Compcam / roller setup.

-stu

If i run the blower on the 502 i have a crane cam i was going to use 296/306 236/246@050 with 553/571 lift with 114 lobe seperation. RPM range should be 2500-6000 in the 502. I have a barry grant 750 that flows 1030cfm for carb. If I run it in the 461 was going to buy a crower cam 302/307 224/234@050 with 529/553 lift lobe seperation 114, 850DP carb. RPM range again 2500-6000RPM. I belive I have seen somewhere that mercrusier runs a little blower on one of there 502's.

my buddy here at work has a Merc 502, bumped compression, added a solid cam and with the bigger B&M 6-71 and he runs it daily, and alot of street usage...runs perfect and ran a best of 10.11 at 133.

Question for you guys running these small blowers. What did you have to do for the power brake unit? I would assume that you could actually draw vaccum through the blower for the brakes and trans by using a tapped spacer plate between the blower and the carb, is this correct?

Also, how is hood clearance with these small units? Does a stock hood work?

I have manual brakes and a large foot. i can upload picture of foot if that would be helpful. my wife has the 142 on her 350 and she has no probs with her power brakes.

Pat, But where do you draw the vaccuum from? Is it from a spacer at the base of the carb or do you have to run a separate vaccuum pump?

On the PowerCharger (Holley version of B&M 174), there is a vacuum port.

graemlins/thumbsup.gif

Hello,

Been running an original style 174 B&M on .060 over 454 for a long time. Crane Commander hyd flat tappet (.553/.571 236/246 @ .050). I installed cam straight up and recall 5 degrees of advance is built into the cam. Vintage Holley 850 DP, square port closed chamber heads, flattop TRW pistons. I file fit the rings for supercharged application. 2 inch Hookers. Stick.

Clearly hear the cam at idle. Runs very smooth around town, stop lights, stop and go, etc. Tons of power and torque whenever you want it. Running smallest top pulley, and getting about 6 pounds of boost.

Car is an SS with orignal power disc brakes and booster. 10+lbs of vacumn idling at 900rpm. Plenty of vacumn to operate the brakes. Never a problem.

Good luck with your hotrod, Joe