Team Camaro Tech banner

1 - 20 of 33 Posts

·
Registered
Joined
·
588 Posts
Discussion Starter #1
i have a 650 dp on my 327, it has a 31 primary shooter and a 35 sec shooter, 6.5 power valve, jetting is 67--77, rear has 50 cc pump kit on it, when i stomp it to the floor i get the bog and then it picks up, so i switched to a 37 shooter on the rear and it still does it, even if i ease into the throttle, i get the hesitation, kinda sounds like valve float sound, then it opens up. i had a 575 demon on here, never had a stumble with it, so far the 650 isnt right yet?
 

·
Registered
Joined
·
2,292 Posts
i have a 650 dp on my 327, it has a 31 primary shooter and a 35 sec shooter, 6.5 power valve, jetting is 67--77, rear has 50 cc pump kit on it, when i stomp it to the floor i get the bog and then it picks up, so i switched to a 37 shooter on the rear and it still does it, even if i ease into the throttle, i get the hesitation, kinda sounds like valve float sound, then it opens up. i had a 575 demon on here, never had a stumble with it, so far the 650 isnt right yet?
You now have a .035 discharge nozzle on the bench.Install it on the primary side for testing.
 

·
Registered
Joined
·
614 Posts
You now have a .035 discharge nozzle on the bench.Install it on the primary side for testing.
Definitely try that first. Most 650s came with a .028 primary shooter, so if the .035 makes it worse you might have to go the other way. Also check the float level.
 

·
Registered
Joined
·
2,864 Posts
67/77 jetting! Why so rich, especially the secondaries? Stock jetting is 60/64-66.
Try going back to stock. If you need your existing jetting to get the engine to run at stoich, you've got the wrong size carb.
 

·
Registered
Joined
·
41 Posts
I had same problem.. pop off the air cleaner and look at the linkage. Not just the one from the throttle lever. Look at the linkage on the carb. If its a DP. theres adjustments on the carb itself. My problem was solved quick with just a adjustment of a nut on the pass side. maybe will help/.
 

·
Registered
Joined
·
588 Posts
Discussion Starter #7
carb revs real nice at idle in park, holley website states stock jetting is 67-76, i will check float level and linkage and try the other shooters i have. if i drive it low gear and give it a kick stab of the throttle i get the bog, then it picks up.
 

·
Registered
Joined
·
588 Posts
Discussion Starter #9
4777 list number
 

·
Registered
Joined
·
588 Posts
Discussion Starter #11
no problem, wish i had kept that demon carb, thought i would try the holley, i think it will be ok, once i get it lined out. frustrating so far, lol
 

·
Registered
Joined
·
1,821 Posts
just for giggles have you check'd your timing?
 

·
Registered
Joined
·
2,292 Posts
I would consider a converter swap with the larger dp holley atop 327 cid and low static cr with that camshaft.Could you find a tight 8" unit that flashes 3800 rpm.With the drag radials and caltracs..your current 2800 stall is more big block friendly.
 

·
Registered
Joined
·
588 Posts
Discussion Starter #15
timing is 36 at 3000 rpm, gives me about 16 initial, with advance hooked to manifold vacuum i have around 30 at idle, earlier today i switched shooters to 33 pri and 37 sec, drove the car around and in low gear creeping along at about 10-15 mph, i stomped it the floor, it bogged then took off like crazy. when i had the 575 demon carb, no bog at all, thats what i cant figure out?
 

·
Premium Member
Joined
·
991 Posts
both shooters are too big. Theres no need for a 50cc shooter supply on the seconday either. my 4776 (600dp) has a .28pri, and .31sec on a ZZ4 350. i would get a stumble and bog when i tried upping the shooters. also check the linkage, you might be pulling the secondarys too soon and pouring too much gas from both (big) shooters when flooring it.

check the linkage (make it progressive), reduce the shooters, get rid of the 50cc acc pump.
 

·
Registered
Joined
·
588 Posts
Discussion Starter #17
i will try a 28---31 squirter, which hole should linkage be on sec?
 

·
Premium Member
Joined
·
991 Posts
which hole should linkage be on sec?
my 4776 has a rod connecting the primary to the secondary (drivers side) that, when bent, is more 1:1 with the primary. Straightening will make it more progressive by allowing more primary before the secondarys start in.

as far as which linkage hole? yours must have a different secondary accuation mechanism than my 4776. my 4776 was mfg in 1975 however.

The 50cc shooter isnt helping you either. its alot of fuel (with a big squirter)and/or for a long time (with a smaller squirter).

the more you get the carb back to baseline, the easier it will be to tune. with a 327, it would not be "over-carbed" if you delay the secondarys for higher rpms/high demand with the proper shooters. You may have to go lower than .28, .31), maybe .25, .28 ? your jetting seems reasonable.

Also, check the secondary idle setting (inverted screw rear passanger on throttle plate). it should be 1/4 turn off fully closed.
 

·
Registered
Joined
·
588 Posts
Discussion Starter #19
i tried the 28----31 shooters and it still bogs, that is the smallest ones i have right now, still have the 50 cc pump on the back, dont have stock one. the 575 demon carb had the same 28---31 shooter and never bogged at all, so far not impressed with the new holley, demon was alot more responsive.
 

·
Registered
Joined
·
138 Posts
Have you tried some alternate pump cams?
how many turns out are the mix screws?
how much transition slot is showing underneath the blades front & rear?
A low dynamic ratio is a bear with DP's--327+xe274+9 to 1=?
I agree that there's NO reason for 50's and rarely over a 31 squirter on a 650 dp
One thing I've found also is that carbs with a leaner front compaired to the rear(common on a LOT of carbs)is to run a bigger squirt in the front than the rear
I like a green cam on hole 1with a 28-33 squirter in the front and a pink or blue on hole one with a 28-31 squirt er in the back on a 4776&4777-On a true square carb(HP's & some DEMONS I make the Fr. % Back the same
 
1 - 20 of 33 Posts
Top