1990 365 hp mag adding 250 blower Help!!

[Smitty]

+3 on head studs. Also have the machine shop polish the combustion chambers so you lessen the chance of detonation with the steel heads.

Don't bother with the MSD crap. Just set max timing at 30 degrees. And go with pullies for max boost of 4-5 lbs, since you have no intercooler.

Smitty

[DMOORE]

I have always heard that on the 250 blower and larger, that dual carbs give a better fuel distribution than a single carb. Anyone know for sure?


Darrell.

[BadCompany]

OK looks like the msd will go back and be swapped for head studs.Looking at the ARP pro series,any better suggestions? Going to try the dual carb set-up for now,can change that easily later.Need more input on the pulley sizes to achieve the 4 to 5 lb. of boost. Should I order the valves or let the machine shop handle this? Thanks for all the input so far. When I start with the teardown I will start the pics.In no real hurry now as boating weather appears to be gone for this year. Thanks Gus

[Griff]

I would let the machine shop order the valves. See if they sell Ferrea valves. If they do get the Super Alloy versions for the exhaust valves. They are comparable to Manley Etreme duty inconels and cost a lot less. Also, get the ARP thread sealer for the head studs.

[BDiggity]

ive got a bm250 & dom 1050 on my 454. Other than that i am clueless & Griff could probably tell you more.

[mrfixxall]

If it were my motor i would pull it and go through the whole motor and do a refresh on it. It wouldnt hurt to know what the bottom end looks like,rings,rod maind and cam bearings wouldnt hurt..

just my 02

[Griff]

Originally Posted by BDiggity

ive got a bm250 & dom 1050 on my 454. Other than that i am clueless & Griff could probably tell you more.

You've got 525 Hawks with upgraded blowers....although I've never actually seen them in person....
maybe I was paying too much attention to Ronda
He is basically building what you have. BD, if you get a chance, measure your upper and lower pulley diameters and post the numbers.

[Strip Poker 388]

if ya go with the dom get the one with a 3 circut. ciruthttp://www.holley.com/data/types/pictures/DOM_IntoZOOM.jpg

Ya might buy one from one of the engine builders that allready calibrated to your combo,I bought the Barry grant with blower cal,its was right on on the dyno and in the boat.

I think Holley has blower cal carbs .

Rob

[tssteph]

516 CI 250 blower 3 inch upper pulley single dominator gives me 5 lbs of boost.

[BadCompany]

Still looking for input on pulley sizes vs boost. Are all bottom pulleys 5.5 and the top is where you change to achieve your desired boost? Will I need a different valve cover with the comp gold roller rockers? Thanks again Gus