Turned up cool running 425

The early 7fb 425 b models were the hot rods of all the Bs. They had a really good pump cam and could produce more power from turning up the pump.

Your C wont do that well, but should still make around 28 psi . Open it up 2 more turns .
Contrary to other people's input the stock turbo on the C model is plenty big.

 

Your right the screws don't have as much affect as the 7W 3906 pump. But keep in mind at its age anything could be changed.

I agree with big guns if he had much of a pressure leak at all he should see some heat. That said I would test it for my own satisfaction. I have found some minor leaks you wouldn't have thought nothing about make a noticeable difference.

Do you know the serial number and OT spec. If it feels strong just slow to build the timing may be a little retarded. If it is still at factory spec it is in my opinion.

 

I just thought to really look at the exducer wheel, if there is any play I have seen them wear the fins on the edge from contacting the housing. I have seen that really affect one as well

 

If this is a 95 C model its an 8PN...the worst and last of the mechanicals with the highest compression ratio 16.25:1 and lowest degree pump cam 9°! turn the screws out 8 turns past stock and that should pretty well max the rack. it wont deliver enough fuel to make much more power or heat than it did stock because of the nozzles they used and require because of theyre unique shallow bore and engine cam that matches them...they did all this to limit emissions and so their was no easy way make them deliver accessive amounts of fuel and of corse power....only way to make one perform like earlier C's or B's is to build them to older Specs by way of lower compression, nozzles to match, etc. You cant even put a higher flowing nozzle in them cause theyre simply isnt room or time for the amount of air need to go with the extra fuel all because of the way theyre timed. Reason i know this fur a fact is because i battled with one tryna get more out of it with nozzles, different pump cams, and tried alot of different timing specs and in the end i ended up putting the stock 8290 nozzles back in it with the best outcome outta everything else i tried....it now has a 7fb engine cam. Or-1439 14.6:1 cylinder packs, and when i get time ive got to send out the 8789 matching nozzles to get them flow matched and popoffs adjusted. These are from a 587hp industrial C and with the pump and other mods it should be close to 700hp. Without spending a bunch of money your never gonna get much power from a stock 8pn unfortunatly.

 

cant he have the nozzles flowed

 

Yeh he's right, I was gonna say at some point the stock nozzles will limit the fuel.
And gotta be careful with those hi compression pistons.

My '96 8PN is 11 degree time tho... Pulled great from dealer's lot. 435 hp in test cell data!