Q-jet and Holley
 

Chevy small block 350,make 597 hp with holley 750, and drop to 562 with Q-Jet .What can I do?

Any input Thank,

Re: Q-jet and Holley
 

Whos q jet is it why did you take the 750 off??

Re: Q-jet and Holley
 

The air valve was probably not working properly.--- open all the way.
Or most likely you were trying to dyno it with the turbine installed on the carb.
I have experienced problems with some q-jets and the turbine. I think ours causes some air currents that the q-jet boosters/bleeds dont like. Look at your EGT's. I bet they were haywire from the Holley pulls. You might also check the fuel flow from the q-jet to the Holley. It could have been the N/S in the Q-jet not flowing enough fuel. Had that problem before, too. There are some hi-flow N/S available. Good luck

Re: Q-jet and Holley
 

I agree with Adger. I just did a test on dyno 2 weeks ago and we removed a Holley and installed a Qjet with the dyno top hat and saw a significant drop in power. Air flow way down. Removed hat and power much closer.
reed

Re: Q-jet and Holley
 

Thank every body for the input!

Adger,What do mean by NS?

Ex. temp cyl . 1 2 3 4 5 6 7 8
Holley 1319,1295,1335,1315,1406,1263,1360,1314,

Q-JET 1318,1247,1346,1259,1359,1288,1261,1253,

Re: Q-jet and Holley
 

4-7 swap cam?

Re: Q-jet and Holley
 

I think it is an abbreavation for needle & seat valve. EXCUSE, I dont mean to steal any ones thunder. ed:)

Re: Q-jet and Holley
 

Cam is Bullet Standart firing order 18436572

Thank!

Re: Q-jet and Holley
 

Yes, N/S = Needle and Seat
Put a stock curved bottom Air filter on the Q-jet to test it. Use o2's instead of the hat to tune. Don't run the fuel pressure too high. The q-jets I've delt with don't like high fuel pressure because of the float. The bigger the N/S the harder it is for the float to overcome pressure (W/added N/S area)and maintain proper float level. Thanks, No thunder here, Ed :~0
Sorry didn't see the temps. Look how the numbers changed. You had cool get hotter and hot get cooler and I looked at it the temps a little differently. Actual firing order.
Cyl # 1 #8 #4 #3
-1 -60 -55 +11

Cyl #6 #5 #7 #2
+23 -18 -55 -48
Notice 3 & 6 got hotter. Is it a coincidence they are in the center of the engine and on opposite banks? Look at the manifold design.
With just a carb change you were down on power and the temp changes were significant
leads me to believe there is an air / fuel problems. It is either the hat distrubing the air or the carb is way off.

Re: Q-jet and Holley
 

Thank for your help!
Adger, With the turbine on the Q-jet,the engine pif,paf,like loosing cylinder,Engine won"t pull . Q-jet is hedwork with DA metering rod.