z ya Posted April 5, 2002 Share Posted April 5, 2002 I cant figure out if they are coming in or not? I car is very fast but it almost feels like they sec's never open up or are not fully. The carb is a 3310 holley out of the box. I am thinking I might need to get the quick change kit to play with the sucker. I feel like I am in the same boat as BLK MGK now! Quote Link to comment Share on other sites More sharing options...
Guest tom sixbey Posted April 5, 2002 Share Posted April 5, 2002 im not familiar with the 3310. If its a vac secondary, play with the 2ndary diaphram springs - they sell several different springrates, and you'll have to custom set it for your engine's airflow capacity and transmission type. If its a mechanical linkage, it'll open while its running just about the same as it opens when it's off the car. in either case, just take the air cleaner off for a minute, operate the throttle by hand, and watch. If it is straight out of the box as you say, it should be set up to operate fairly normally, but check anyway and ajust for performance... hope i havent insulted your intelligence! - have fun with it. Tom Quote Link to comment Share on other sites More sharing options...
blueovalz Posted April 5, 2002 Share Posted April 5, 2002 This is a tough problem to diagnose with your pants seat. A properly operating secondary system will not be felt. It may be the the diapham may be ruptured, thus the vacuum signal is not "sealed". A quick, but strong blip of the throttle while the engine is running can many times just barely get the secondary to start to open. But you have to get some real air moving to do this, so don't expect to see the secondary move unless you get to a high rpm to see this. Also a plugged circuit to the diapham, and lastly, and very commonly, a too large a carb will be a cause of no secondary action. Is the 3310 one of the old 780 designs? Quote Link to comment Share on other sites More sharing options...
Guest tom sixbey Posted April 5, 2002 Share Posted April 5, 2002 i thought the 3310 was one of their fuel economy carbs... i cant remember though. Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 5, 2002 Share Posted April 5, 2002 the 3310 is the 750 vac secondary carb. Not ecomony at all. Quote Link to comment Share on other sites More sharing options...
Peternell Posted April 5, 2002 Share Posted April 5, 2002 Like BlueOval said the secondary's should not be felt. Typically if your FEEL them opening, you are FEELING the bog cause by them opening to fast (I believe). The secondaries shouldn't open with the car in park/neutral by just revving the engine (a no load-vacuum sorta thing) You've got two options to check if the secondaries are opening. A) Put a paper clip on the secondary shaft just below the vacuum pod, take it out for a drive and check the location of the paper clip. If its in the middle of the shaft (between the base plate and the vacuum pod) then they have opened. If its still in the same position, well you get the idea. OR Get a friend, brother-in-law or neighbor to ride under the hood and watch the secondaries as you race the car through the neighborhood. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 5, 2002 Share Posted April 5, 2002 I usually hear mine more than feel it. Its a delayed Baaaaawwwaaaaahhhhhh sound in the intake. Of course the scenery goes by a bit faster too I've noticed... Regards, Lone Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted April 5, 2002 Share Posted April 5, 2002 Yup, same boat as me and I'm still carbed it seems. 750 same as me too, not sure on the model #. Try the clip trick with something like a bread tie but don't cinch it too tight. My secondaries are NOT opening near as I can tell - 300RWHP on the primaries only (grr). Figure out if they're NOT working first, then monkey with them otherwise you might screw it up worse. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted April 5, 2002 Share Posted April 5, 2002 I've always been a Holley man, but my 2 x 4 set-up uses a couple of 500 AFBs. I really like the secondary system on them, (it's kinda like points vs electronic ignition), the AFB secondary is too simple for anything to go wrong, and you can actually see them pivot slightly with WOT blips. Quote Link to comment Share on other sites More sharing options...
z ya Posted April 6, 2002 Author Share Posted April 6, 2002 Thanks for the info guys. I will play with it and see how it goes. Quote Link to comment Share on other sites More sharing options...
Guest kc6wfs Posted April 6, 2002 Share Posted April 6, 2002 I switched from the 3310 to a 600DP and made a world of differance with my car. I played with springs and everything, but could not get it to open good. Hope this helps.. Dave Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted April 6, 2002 Share Posted April 6, 2002 I had a 750 edelbrock on my 355 and it was ok but some of the local sbc power freaks said I was losing serious power by staying with the edelbrock. They all said Holley 700 or 750 double pumper if you are into serious power. Tried the Holley 750 double pumper with factory deleted choke and four corner idle. It was hard to get just right and am still making final adjustments but WOW!! Power seems to really come on when mechanical secondaries come open. Now gas mileage does suck but hey I didnt build it for a daily commuter..HE! HE! Anyway my swap so they say is worth 20 plus horses but who really knows? zfan..Mike Quote Link to comment Share on other sites More sharing options...
z ya Posted April 6, 2002 Author Share Posted April 6, 2002 I play with it for a while but i have a feeling that a 750 dp will be on here soon Quote Link to comment Share on other sites More sharing options...
blueovalz Posted April 6, 2002 Share Posted April 6, 2002 Many times I hear where folks say the DP works better than the VS. This has always confused me because in theory, the VS should only operate when the additional mixture it provides is needed. And thus it should be able to maintain the vacuum signal and carb "size" at a more optimum level than my foot ever could using a DP. Any comments? Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted April 6, 2002 Share Posted April 6, 2002 It has always seemed to me that VC carbs are better suited for heavy cars. Our cars are light enough that when we mash the throttle, they just go. Heavy cars can't move from a stop like our cars can(even heavy cars that are faster). VC carbs are great for big block Chevelles, but our cars run better with DP's. V8Z's can take advantage of the DP throttle response. Quote Link to comment Share on other sites More sharing options...
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