Hot Rod Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
Hello,
I have a 1969 Nova with a chevy 350 that i built for it. It has a air gap performer intake, 600 cfm Edelbrock, performer plus camshaft, fulie heads off of a 1969 camaro 194 150, 1.6 ratio roller rockers, hei dist with vac advance, long tube headers. I have a turbo 350 transmission with a 2000 stall convertor. I have my timing set around 20 degrees initial. My problem is the car will stumble and sometimes die when i floor it from a stop. If it stumbles it will grab and take off nicely. It is just a problem off of the start. I have read about the accel pump on hollys but i don't know what to do about an edelbrock. Adjusting timing doesn't help and neither does changing from ported to manifold vac. What can i do to fix my problem?
Thanks in advance,
Matt
 

·
Registered
Joined
·
3,925 Posts
Sounds like you need to change the accelerator pump springs. I did this with my 750 and it pretty well curred my bog and backfire problem.

If you didn't get a tuning manual with your carb you can go to the Edelbrock web site and download the manual for your 600. It well tell you how to troubleshoot and fine tune the carb.

Dewey
 

·
Registered
Joined
·
23 Posts
Discussion Starter #3
Thanks for your info. Which color springs did you use? do you want a higher vac or a lower vac rated spring? also what timing did you set your car at initial. thanks for your help.

Matt
 

·
Registered
Joined
·
3,925 Posts
I experimented with all 5 springs and the blue (the weakest spring/lowest vac. setting) was the one that did the trick for me.

I set my initial advance at 8 degrees (this was edelbrock's spec for the cam). But then once the car is running decently I fine tune the timing using a vacuum gauge off the manifold (set to highest vacuum possible and then back it off a couple of degrees of advance). Since I go by vacuum and not degrees - can can't tell you exactly where it ended up of the degree wheel.

One other thing you can fiddle with (if you haven't already) is the pumper rod. There are three or four holes where you can set it in order to get more or less "squirt" when you hit the throttle. BTW, you have to bend the rod a bit to get it in the final hole.
 

·
CLICK ON MY AVATAR
Joined
·
321 Posts
Why is your initial timing set at 20 degrees?Is your motor getting hot?Yor timing should be set between 8-14 degrees..in my opinion. BM
 

·
Registered
Joined
·
23 Posts
Discussion Starter #6
Well thanks a lot you have been a great help. I will try out all of the springs and mess with the rod. Did your stumble go away completely or do you still have a little stumble? Did you have to swap out any of your metering rods or jets? Thanks again!!!!

Matt

My timing is around 20 or so prolly a little less because when it is 12-14 like the cam sheet says it backfires through the carb.
 

·
CLICK ON MY AVATAR
Joined
·
321 Posts
I have almost the same exact motor and setup as you.I have my timing set at 10* with full manifold vacuum.My car flies.If your getting backfiring thru the carb at 12-14* I think something else is going on.You might want to ask a couple of the smart fellas on this forum....killerformula or doc corvetteor ghetto jet.These guys have all the answers.1 more question....what kind of temp do you run at when its hot? bm
 

·
Premium Member
Joined
·
3,519 Posts
I've experienced a bog with that same carburetor on several motors out of the box. Of course, every motor is different, but I've found that generally the problem can be fixed easily. I would first experiment with the length of the pump shot adjusted by the three settings for the throw rod on the front left of the carb (right if you're facing the carb). As illustrated before, a difference in your springs on your metering rods will also affect your transition. Stiffer springs will cause the transition to happen more slowly, causing less of a rush of fuel.

Next time your car bogs, quick and put it in neutral and rap it up a couple of times. If you're seeing a gust of grey or black hazy smoke, you're getting too much fuel on transition. The above will correct it.

K
 

·
Registered
Joined
·
3,925 Posts
bigman,

Are you setting your initial advance with the vacuum advance hose attached to the distributer or do you have the hose detached and plugged? Try it detached (plugged) and then set your timing to 8 degrees.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #10
I set the timing with the advance unplugged and capped off. My car rund about 185-190 when it is hot. The car has good power just not from a stop. I will try the things you have suggested tomorrow and let you know how it goes. But more info would be great. Anything to help me out would be greatly appreciated. Thanks again everyone!!!

Matt
 

·
Registered
Joined
·
23 Posts
Discussion Starter #11
I was also wondering if anyone had experience with changing the jets and metering rods on the edelbrock? If so did it help? and how do i know to go rich or lean?

Thanks,
Matt
 

·
Registered
Joined
·
3,925 Posts
If you are backfiring through the carb - you are lean. If you backfire through the tailpipe or have lots of carbon in your exhaust pipe - you are rich (there are other symptoms as well but these are basic). When I had my bog (actually a bog and then a backfire through the carb and then take off like a bat) I stepped up my primary rods/jets and my secondary jets (richer). Didn't make any difference. The solution was changing the springs as described in earlier post and a slight change in timing based on manifold vacuum. BTW, if you are going to fiddle with your rods and jets I'd recommend getting the complete "kit" from edelbrock. They provide a good assortment of rods and jets which the manual fully explains in terms of troubleshooting.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #13
Well thanks for everyones help. I set my timing at 10* initial and started messing with the carb. I put the pump rod on the lowest setting and used the blue springs on my metering rods and hesitation is almost nothing. It is more like a hesitation and not a bog and die. Thanks a lot for everything. I am gonna try some more spring combos and mess a little with timing and hopefully i will need new tires by the end of the month. Thanks again!!!

Matt
 
1 - 13 of 13 Posts
Top