Mercury Cougar Owners banner

1 - 5 of 5 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter #1
I wanted to ask someone who has experiences with Holley carburetors about jet sizing. I have a 351 c 2v, with a Holley carb. It is running extremely rich right now, I rebuilt the carb because the float stuck, I thought this would cure it but it did not, so, now I will change Jets to see if that helps. The question is: I have size 73 jets in this thing right now, at 8,000 feet in elevation, right now this car spews black smoke upon acceleration and bogs a lot, I tried adjusting for less accelerator pump spray, and it helped, but minimally, even cruising it smokes black, so how big of a jet stepdown would make a sizable difference? I do not want to underjet, but I don't want to buy 100's of jets till I get it right. I know this is a trial and error thing, but how big of a difference will say a size 67 make?
thanx in advance,
Justin:confused:
 

·
Registered
Joined
·
1,832 Posts
Lets get this straight before I try this one. Exactly what Holley carb do you have? You said a 351 2v. Are you telling me that you have a Holley 2v or the original 2v or has it been converted to a Holly 4v? mm
 

·
Registered
Joined
·
22 Posts
Discussion Starter #3
oops, sorry

sorry, I forgot some details, It is a a 500 cfm, not original 2v., today I bought some Jets and found I was 6 sizes too big, I settled on a size 67. This carb is still too big though, but it is at least driveable now, thanx
Justin
 

·
Registered
Joined
·
1,832 Posts
OK, you already found out there is not much you can do with the acc pump without changing the pump cam or the squirter sizes itself. You said you went to 67 jets and your probably on the right track. Did you make sure you went to the right # power valve when you rebuilt the carb? If you have too low a # power valve it will be open all the time and give a rich situation. The 4412- 500 cfm holley is a great carb, but there really not a good situation for a street car. They flow too much all the time and your fuel milage will not be very good compared to a nice little 600-700 cfm 4 bbl. I just think if you could swing it a switch to 4v would make you much happier. mm
 

·
Registered
Joined
·
22 Posts
Discussion Starter #5
Thanx mm, I rebuilt the carb with a Napa rebuild kit, the power valve that came in it had no number whatsoever, the old one looked fine, and was not blown, so I left it in, its a 7.5, the one in the kit was actually stiffer feeling.
something funny, I actually took the accelerator pump spring and bolt(actuator) off and the car doesn't miss a beat now and accelerates great!, but I bet that means I am still Jetted too rich huh? a 4v intake is definately in the making but it will be down the road a while, I would love to, but I have to wait till I get the dough, start my new job tomorrow, after a 2 month jobsearching spree.
Thanx
Justin
 
1 - 5 of 5 Posts
Top