Could use a little carb advice myself... think I got it THANKS!

[BIGSHCLUNK]

NIKKI'S Holley 750 DP w mech secondaries. If I drive her off the line "normal" traffic type driving shes good. If I give her a mouthfull HESITAtION!  Float level good/pump shot good/power valve good/... jets??? I did have an issue with the secondary throtle plates being adjusted all the way closed.  Kind of a PITA cause you got to remove the carb every time you play with it, but I belive I got that handled.  I dont think the former owner ever had this carb dialed in right to begin with. I admit I dont remember what was in there (jet size)when I had it apart last... ok holley guru's what do you think?
Thanks
BIGS

[MEK-Dangerfield]

First off I'll state, What are you doing with a 750 carb on a Hemi?      

All joking aside. Is this when the engine is warmed up? Mine bogs a little the first few minutes some, then it is happy. I don't really think this is a jet problem, but if your spark plugs look whitish, then maybe. I hate to say it, but this does seem like pump shot problem. Do you know what size squirter you are using in the primaries?

[72cudamaan]

I gotta agree with Mike, but what do you mean about the secondaries adjusted "all the way closed" ? Is this a vacuum/idle problem?

[jimynick]

Don't forget the different accelerator pump cams and the adjustable linkage on them. 

[BIGSHCLUNK]

All joking aside. Is this when the engine is warmed up? Mine bogs a little the first few minutes some, then it is happy. I don't really think this is a jet problem, but if your spark plugs look whitish, then maybe. I hate to say it, but this does seem like pump shot problem. Do you know what size squirter you are using in the primaries?

This is warmed up, She's been much happier since I added a manual choke (with a cool braket from Brad!). I got no idea what the squrter size is...  are they marked like jets are?

I gotta agree with Mike, but what do you mean about the secondaries adjusted "all the way closed" ? Is this a vacuum/idle problem?

Maybe I'm using the wrong terminology here. There is an adjustment on the rt side for the rear throttle plates. I forget what the spec is but the screw on mine was backed all the way out. You have to take off the carb to turn this srcew to adjust. If you go to far she'll spit up threw the top. After 3 tries I think I got it pretty well and it did make an improvement. It was a very slight adjustment. I was shown this by a friend of a friend who seems to know a bit about it (I know its a holley)  She's got a good idle and a healthy thumpa thumpa thumpa.... last time (last year) I checked vac it was around 11 or 12 as I recall.   

BTW- the more I read up on this stuff the conflicting info I seem to get. I'm confused enough on my own! 

[72cudamaan]

I was asking about the vacuum because I have seen people adjust the blades to compensate for a vacuum leak that they didn't know existed.
And I assume that the secondaries do work after the hesitation? any distributor advance issues? Any binding in the secondary linkage?

[Strawdawg]

on a dp, this is usually too small a pump shot.  Be sure the pump is adjusted so that it sprays as soon as the blades begin to move.  And, as suggested, check the pump size.  Holley should have some good instructions online with regard to the sizes available.

[MEK-Dangerfield]

on a dp, this is usually too small a pump shot.  Be sure the pump is adjusted so that it sprays as soon as the blades begin to move.  And, as suggested, check the pump size.  Holley should have some good instructions online with regard to the sizes available.

   

The size of the squirter will be stamped in to it, but unfortunately, you can't see it until you take the squirter out. I know it looks easy as it's held on with one screw, but you don't want the little O-ring to fall down into the carb. What makes it even more difficult is you have a choke plate to get it the way. Play it safe and do this with the carb removed.     You probably have a size 31 and need around a 35.

Now we need you to rub Miracle Grow on that carb.   

[brads70]

I agree try a bigger squirter. Put a rag down the carb if your worried about dropping something. Really, it's not hard. Cheap too.  There are also different cams on the side of the carb that affect the duration of the squirter too. Each cam has two positions that it can be installed in. The cams come in different colours to distinguish different profiles.  I've never tried a 750CFM carb on any big block before, mine are 850?

[BIGSHCLUNK]

I agree try a bigger squirter. Put a rag down the carb if your worried about dropping something. Really, it's not hard. Cheap too.  There are also different cams on the side of the carb that affect the duration of the squirter too. Each cam has two positions that it can be installed in. The cams come in different colours to distinguish different profiles.  I've never tried a 750CFM carb on any big block before, mine are 850?

Over a year ago online somewhere (maybe promax) I did a carb vs motor conversion chart thing... I think it recomeneded 834 CFM or something close to that. The 750 was on her when I got her and being the inherent cheap ba$tard that I am (can you say this with a HEMI??  ) I've left it on. I have read about the cams but am very reluctant to open a new can of worms!

So do I try squirters first of go the cam route. Should I go one up (squirt size??) as a start? 31 to 35 is that the next jump up??

Something tells me I'll be sneaking back to the home base today....

I'm going to start playing tomorrow after work.. this give me a little time to round up some parts.
Thanks

[MEK-Dangerfield]

The cams are an easy swap too, but I would start with the squirter size. My old Holley(800 CFM) had a size 31 in the primary, but it took a 35 to get rid of the bog. Squirters aren't real cheap, so you don't want to guess wrong too often.

[BIGSHCLUNK]

I snuck outa here for a little bit, (no worries they can't fire me!). I had to know what squirter I had. So I run over to the speed shop, I thought pick up bigger ones and be done. NOT! out of 31's and 35's    So I ordered one of each, they will be in tomorrow. I also learned there are 2 types mine was the less expensive, on $15 each  woohoo   

[Chryco Psycho]

with DP if you can snap the throttle 25% with no bog leave the front squirter alone concentrate on the rear squirter .
 the squrter controls the speed that the fuel is delivered , the cam controls the volume of fuel so if the bog is instantanious the squirter is too small , if it starts to go & sags for a second the cam is not delivering enough fuel .
there are 3 types of squirter , the tube type  worst as the air flow can draw in fuel @WOT , the type you have which is marginally better , & the box type best as no fuel can be drawn in with air flow past it

[bandt]

Had a very similar problem with my 650 dp. Bad bog off idle.

If you can look right in the carb as you operate your throttle linkage you should be getting squirter shot as soon as the linkage is moved. If not look for a cam profile that will deliver fuel sooner. Worked for me.

Brian

[BIGSHCLUNK]

Niel, the hesitation is imedeate unless I'm real conservative.

Brian, I'm with you on that. But shes adjusted to pump right away! and does....

I plan  on working on it tomorrow night.......