Holley 600 4776-5

[Guest kc6wfs]

Hi all,

Question, I just replaced my 750vac sec with a new Holley 600dp and it seems a tad more gutless than with the 750 , It's running hoter but the plugs show fine. The jets are 66H/pri-73/sec. Does this seem too small considering the 750 had 69's for the primary?

I wanted some input before I go and rejet it.

 

Thanks.

Dave

[DavyZ]

Dave, I'm not pretending to be an expert on carbs, but the jets don't seem too small for the amount of hp you are running. The results at the dyno kind of puzzled me, but at least you are over 200 rwhp. Hopefully someone else will chime in too.

 

David

[blueovalz]

I'd say that was just about right. My old 780 has 69's up front and 73's in the rear. IMHO, the DP is more the problem than the jetting. In the VS, the secondaries open when the airflow is sufficiently high to warrant the additonal ventury size. On the DP, the secondaries open almost the same time as the primary, and thus creates the "gutless" feeling (loss of torque until RPMs come up high enough to utilize the already open secondaries). Try opening the throttle in a more sympathetic mode to RPM, and not all at once. Also consider using the 50cc accelerator pump instead of the OEM 25cc. This and even a slightly larger squirter (I think the OEM is a size 25) too. This may help. The center pivot floats are nice for my kind of driving, but I like the "automatic" opening of the VS, so the old 780 is the ideal carb (center pivot and VS) for me. I simply put a little weaker secondary spring to let the secondary open a little quick, and it works great. Also, if you are running unleaded, it's nearly impossible to read the plugs like you could with the old leaded gas, unless you run them for quite a while. I hope this helps.

 

Terry

[Guest kc6wfs]

Hi Dave+Terry,

 

Well I went and rejetted it today at the advice of the local speed shop.

 

It was WAY too lean, I'm now running 69pri/74's sec. and the motor is more alive by far but the water temp is still getting hot too fast. Car still running too lean??

Speed shop thinks so, so do I. There is no smoke at all comming out the tail pipe at WOT and not even a hint of bogging.

I'm going to check vacume tomarrow and see what she is doing at 3000 up a slight hill and probably change the power valves next.

 

But it's comming alive. It's feeling better than the 750 now.

P.S. the air temp has been high 90's and low 100's the last 2 days. Might just need to get a alum rad........

 

Gtech pro said 0-60 6.1 sec. Thats better than with the 750.

 

Dave