John Burns Posted April 25, 2011 Share Posted April 25, 2011 Have any of you big block guys ever played with staggering the jets in your Holley? My 454 has always pinged a little bit in the upper RPMs (unless I dump a little race fuel in it). I ran across something about factory ZL-1s (in 1969) having staggered jets. I tried it- no pinging and it pulls like a freight train. It also seems to run cooler. Supposedly this is good for dual plane intakes (I have Performer RPM). My 800 doesn't have a power valve in the back, so I went up 10 sizes in the back. Check your shop manual for 69 Chevrolet. In the back under specifications section 6m, it gives the specs for stagger jetting a ZL-1 Holley 4 bbl(primary throttle side #82, choke side #78 and secondary throttle side #80 and choke side #82). Keep in mind that ZL-1 motors came with open dividers on their dual plane manifolds. Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted April 25, 2011 Share Posted April 25, 2011 I've heard of it but it's not commonly done anymore. Typically on a Holley if the rear PV is plugged there should be about 8 sizes between the front and rear (rear higher). If it improved from adding jet it was probably lean in the first place not because of the stagger. The stagger was a fine tune idea to account for the different runner lengths on each side of the manifold. Sounds like you hit on a good thing that really helped the car though. I would even the jets to the highest size front and back and then do some plug reads to see if you need to adjust up and down from there...that is much easier than trying to juggle all 4 corners....JMO.... Quote Link to comment Share on other sites More sharing options...
72 LS5 Posted April 26, 2011 Share Posted April 26, 2011 I've found the staggered jet topic very interesting, but like you noted, it was recommended by Chevy for the open plenum, dual plane manifold only. I was going to do this myself, but my Eddy RPM has a notched divider, but its not open. Those GM dual planes with the open dividers were installed in high rpm solid lifter motors. Here is another guys resuts: http://www.chevelles.com/forums/showthread.php?t=182244 Quote Link to comment Share on other sites More sharing options...
LS65Speed Posted May 7, 2011 Share Posted May 7, 2011 As mentioned by some responders this was done with the open plenum manifolds ...mostly on race cars. A friend of mine (RIP Tony) raced BBC powered dirt track "modified" cars. Modified sure was the word for those old racers...another topic for another time. He was always fussing with the staggard jet idea. His engines we ALL OUT race engines with HUGE cams, aftermarket heads, manifolds and no end of race car engine modifications. I don't know if this staggard jet theory has much value on the street. Something else jumped into my mid. Back in the day there were aftermarket intakes that "twisted the carb" off the centerline of the engine. It looked really funny but I think it had something to do with trying to solve unequal fuel distribution in BBC engines under high RPM race conditions. I thing the staggard jetting was an attempt to get the same results as the "twisted" manifolds. Quote Link to comment Share on other sites More sharing options...
71monteme Posted May 7, 2011 Share Posted May 7, 2011 As mentioned by some responders this was done with the open plenum manifolds ...mostly on race cars. A friend of mine (RIP Tony) raced BBC powered dirt track "modified" cars. Modified sure was the word for those old racers...another topic for another time. He was always fussing with the staggard jet idea. His engines we ALL OUT race engines with HUGE cams, aftermarket heads, manifolds and no end of race car engine modifications. I don't know if this staggard jet theory has much value on the street. Something else jumped into my mid. Back in the day there were aftermarket intakes that "twisted the carb" off the centerline of the engine. It looked really funny but I think it had something to do with trying to solve unequal fuel distribution in BBC engines under high RPM race conditions. I thing the staggard jetting was an attempt to get the same results as the "twisted" manifolds. like this one? Quote Link to comment Share on other sites More sharing options...
LS65Speed Posted May 8, 2011 Share Posted May 8, 2011 UNIONVILLE CT!!!!!!!!!!!!!!! I grew up in Litchfield and lived in Glastonbury before I moved to Atlanta. The racer I mentioned was from Burlington!!! Wow small world!! Just the other day I read that Marcus Dairy in Danbury folded up. That was a great cruise for Sat nights in the summer. Sad to see it go. I also recall Main Street in Bristol back in the day. That was pretty cool also!!! Do they still have that Sat night cruise on the west side of Bristol?? Out toward Thomaston..just off some large two lane blvd that ran more or less parallel to Rt 6? Yes those are the maniflds I was thinking about. It always seemed a little goofy to me but I suppose the people that make that stuff always needed to have the latest newest "trick" thing to sell more product. Notice that in your picture the mfld has an open plenum. Quote Link to comment Share on other sites More sharing options...
71monteme Posted May 9, 2011 Share Posted May 9, 2011 Ray. small world indeed. our shop is in south glastonbury, Bristol cruise still going strong, did you ever go to the cruise at the mcdonald in glastonbury? the mnfd is a rec. port open plenum. one of these day i'll have to try it out. thanh Quote Link to comment Share on other sites More sharing options...
LS65Speed Posted May 11, 2011 Share Posted May 11, 2011 Actually I lived in South Glastonbury myself!!!! What shop are you talking about? My house was very near the Glastonbury Hills Country Club...on the east side of town near Rt 2. Yes i did stop by the cruise at Mc D's on Main Street a few times. I worked in the office building just down Glast Blv from McD's. The builing is right on the corner by the on ramp to Rt2 and Rt3!!!! I sure miss the N.E. ...sure winter is a pit up there but there is nothing like the fall. Atl. will be hitting high 80's starting soon and the summenr (for me at least) is just a bad as winter is for some folks up North. Quote Link to comment Share on other sites More sharing options...
John Burns Posted July 23, 2011 Author Share Posted July 23, 2011 Hey- y'all hijacked my thread! So I've put some miles and many wot beatings on the Monte since the jet change. Still runs stupid quick, (need a track date when it cools off), no more pinging... and the other BIG plus- it is running easily 10° cooler. Davey, I'd consider your idea with the jets, but it is just too perfect to mess with! Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted July 23, 2011 Share Posted July 23, 2011 hey if it works stay with it!!! Quote Link to comment Share on other sites More sharing options...
680HPStroker Posted July 24, 2011 Share Posted July 24, 2011 With todays carb technology I can't see how that would be necessary if the carb was built right to begin with. Quote Link to comment Share on other sites More sharing options...
John Burns Posted July 25, 2011 Author Share Posted July 25, 2011 A carburetor is a very simple device actually. There is not much new "technology" except for some features that do not add up to a step-change in performance over the 50+ year-old Holley 4150 design. Quote Link to comment Share on other sites More sharing options...
680HPStroker Posted July 25, 2011 Share Posted July 25, 2011 Maybe for the 4150, but there are some significant advancements in 4500 style carbs to make them much more street friendly, but I'm not going to get into a debate about carb technology here. I just know what I've seen, felt, own, and I'll leave it at that. Quote Link to comment Share on other sites More sharing options...
Monteman1971 Posted July 26, 2011 Share Posted July 26, 2011 I'm sort of in the middle of this myself. My carb came from Pro Systems with 78's in the front and 88's in the back and it's only a couple of years old. I increased the fronts to 80's because it was running a little lean. With the head change, Patrick (at Pro Systems) recommended going 82's in the front and 90's in the rear and changing the high air bleeds from 36 to 28. Mike (Mike 57) had also suggested something similar that I tried first. The car seems to be running fine but with my small mishap this weekend I still need to see how the current set up is burning (lean or not). We are talking front to rear or side to side? I'm front to rear... I don't know too much about it but this is what I'm playing with right now. Quote Link to comment Share on other sites More sharing options...
John Burns Posted July 26, 2011 Author Share Posted July 26, 2011 Steve- what I did was stagger side to side (no I wasn't drinking too much!). The car has never run better- runs much cooler, doesn't stink as much, pulls to 6000+ and not even a hint of pinging. It was certainly worth the 20 minutes (with a 5 minute beer break) it took to change the jets! Quote Link to comment Share on other sites More sharing options...
John Burns Posted July 26, 2011 Author Share Posted July 26, 2011 Maybe for the 4150, but there are some significant advancements in 4500 style carbs to make them much more street friendly, but I'm not going to get into a debate about carb technology here. I just know what I've seen, felt, own, and I'll leave it at that. Ok- no debate. And the carb was built right. Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted July 26, 2011 Share Posted July 26, 2011 Clasically, staggering the jets when done right to flatten the torque curve of a hot engine. Not always for wide open driving and race conditions. Mr. Bu used to hit the tires so hard street tires were out of the question (ok, drag radials). Last march I was having fun at a track rental and I noticed that if I dropped two sizes (numerically 4) right front/left rear, Bu really softened up the hit, especially on the convertor launching off the trans brake. Through exhaust on drag radials she bested a 1.49 60 foot. Think all stock style rear suspension before the anti roll bar I put on last month. In essence I problably pulled 20-30 HP out at launch on my AED 1050 HO carb and it was simply a nicer car to race with. And I guess I can drive, my best foot brake launch was a 1.53. Quote Link to comment Share on other sites More sharing options...
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