I just bought a used 502 450 hp gm crate motor which I plan to rebuild this winter. I am going to use the 174 blower off of my old 454. I know it might be to small but thats what I have to work with now. My question is should I keep the rectangular port heads that came on it or put my 124cc merlin oval port heads on. Also what would be a good cam choice to make good power in the mid to upper hp range.

your right,that blower is too small.

the 174 is going ot be small. It will work but it won't be as effective as it would be on a 454. I've heard you can use them on a hp500 not the best chioce but it will work.

Agree : 174 charger is 2 small 4 502cu.

Bigger blower, spinning slower with crane hyd roller 139731 cam, You could use the 741 but I think with the little HP you will be looseing at the top end you will need at low end & midrange.


If you existing blower is what you got then go for it, but if you are going to spend money on heads I would keep your existing heads & get a bigger blower. What cam are you using with your existing 454. When you increase cu in. you can go a larger cam & still keep the same torque curve.

I allready have the oval port merlins, so no extra expense there. The cam in my 454 has a 110 cl, so I know it wont work well. The 502 cam is the stock 454hp cam, smaller than I want to use.

If the merlins have inconel valves on exhaust I would deffinently run those. Cam choice? Are you looking to run hyd roller or flat tappet. What C/R do you plan on running. Whith that small blower I would run no lower than 8.5 maybe even 9 with low boost. You will have to scream that blower to get much on a 502 for boost. Any plans on stepping up on blower size later?

The motor has a 8.75 cr with the stock heads. If I use the merlins the cr will drop to about 8.5. It's a gen 6 motor so I think I will have to run a roller cam. I do plan to go to a larger blower later on. I just thought that I could get buy with the 174 for a while since I already have it. Anyone out there got an 871 cheap?

Since you have the parts I would call Crane, Isky, Comp, etc. and see what they recommend. Put it together, run it, and see how happy you are. It's not like you are going to be totally upset with the results anyway considering you aren't dropping a bunch of cash. If its not enough (Which it won't be for long anyway ) Buy an 871 and see how happy you are. Still not happy? Then buy a merlin bowtie with a good stroker crank to get you to atleast 572 (Good starting point) and a 1471. Oh yea, you need atleast a 250 shot on top.

actually,crane makes a roller cam and lifter kit for that blower with the 502 block,call deano out at teague and he'll give you the part #,he should even have it in stock,with the stock pistons you need to put a .020 clearence on the rings and run the 3.23 blower pulley and you should make 6-7 lbs of boost.....MAKE SURE YOU HAVE A WATER PRESSURE GAUGE ON THE BLOCK..20 psi at WOT.......aprrox 900 to 950 cfm carb......