Visit The Dirt Forum for More Information

Author Topic:   KP HELP ON A 7448
jammin james
Member
posted May 13, 2003 05:45 PM
7448 on a 79 MONZA 4 Cyln. had a leak between carb and intake when we got the car. when we fixed the air leak it really started to stumble all over itself. float was adjusted a little low when we corrected it it got worse. in the pits at about 2500 rpms it was pussing fuel out of vent and was sitting there trying to drown itself. tore carb apart last night everything looked alright,changing power valve tonight and putting it back together. carb has 8.5 power valve, 30 accl. pump, 31 squirters and 61 h jets{seems low}. the car has always seemed like the carb was messed up but were new to the holley. how bought a price on a rebuild kit and any suggestions 1/2 mile high banked.sorry so long. thanks


KPLugnut
Member
posted May 13, 2003 07:58 PM
Firstly, let's start at the beginning. Can you verify that your fuel pressure isn't sky high? It shouldn't need more than 6lbs at idle. Next, if you have a nitrophyl float, it could be saturated and causing most, if not all of those symptoms.
A rebuild kit may or may not fix all this, so before we go there, let's go thru all the basic stuff first.
The idle circuit needs to be set properly, the power valve needs to be 1-2" rating less than what the motor has for an idle vacuum reading (in inches of Hg). So if you have 10 or more " of vac at idle, then an 8.5 PV will work.
The jets are fine for that carb on that motor for now.
Also, I'm assuming nobody else has previously modified this carb for any other uses (for example, altering air bleed sizes, etc) as that will totally change whether or not the carb will do what it should when set up for you in this way.
Next, for a 30cc accelerator pump on a 4cyl motor like that, a black pump cam and a SMALL squirter size will suffice. Probably no more than a .028 or .025 is necessary, and due to the pullover sometimes caused by harmonics, an anti-pullover squirter is something to think about.
In a nutshell, an off-the-shelf 7448 is in no way set up for the typical 4cyl racer.

OK, as for rebuild kits....the 7448 kit comes in 2 flavors - regular and the pro kit. the regular kit runs about $20, and the pro kit which includes all fasteners, bolts and the whole works will run $40.

Hope all this helps, and let me know if I can be of further service.

Dayton Umholtz, owner
Kinetic Performance


jammin james
Member
posted May 13, 2003 08:19 PM
man, do you have a carb head on your shoulders or what. bought a vacuam gauge and a fuel pressure gauge today but we ran it out of gas pulling it into the shop today, will have #s tommorrow as far as being modified, it probably is we found some dandy doings deeper in the engine that said someone had some knowledge on what they were doing but have no idea to what extent or right or wrong,brass float, have the bergandy cam on there thanks,thanks,thanks!!!


rico 08
Member
posted May 14, 2003 04:03 PM
One thing you need to consider is did the original owner try to adjust the carb without knowing there was a vacuum leak and when you fixed it now you are way too rich?


jammin james
Member
posted May 18, 2003 11:32 AM
checked fuel pressure 9# got a regulater ,will be in mon am,should the regulator be at the carb or can we mount it at fuel pump in the trunk, when we get the thing running i'm sure i'll have more questions thanks


KPLugnut
Member
posted May 21, 2003 01:07 PM
Sorry, I missed this one....
Mount the regulator as the LAST thing before the carb. It doesn't have to be absolutely close to the carb, but there shouldn't be things like inline filters etc between it and the carb.

Hope that helps..

KP


Back to the Archives