thebucketslider Posted October 2, 2013 Report Share Posted October 2, 2013 im installing a dual port on my l20. do i need a special gasket for the carb to manifold to seal the primary and secondary throats from each other? i have searched and everything.. some one with a spoon pweeez haaaalp!!! Quote Link to comment
banzai510(hainz) Posted October 2, 2013 Report Share Posted October 2, 2013 i dont think so as I seen photos of the mainfold opened up to just one big hole. Vaccum wise aI dont think the carb knows as inside the manifold the pressure will be the same.On stock manifolds. Dual planes I dont know Quote Link to comment
datzenmike Posted October 2, 2013 Report Share Posted October 2, 2013 In theory they would work if the head ports also kept the primary and secondary seperate but they don't. The smaller passage keeps the air velocity high but as soon as it dumps onto the large open port it slows down again. I think they are wast of time, trust Nissan engineers, they did their homework on the L intake. Quote Link to comment
Stoffregen Motorsports Posted October 2, 2013 Report Share Posted October 2, 2013 I agree with Mike...don't waste your time. The theory sounds good, but an open plenum will atomize the air/fuel better. I usually go the opposite route and open up the plenum by cutting out the wall between the primary and secondary in the manifold and the adapter. I've even made custom manifolds before with large plenums and I always had good results. 1 Quote Link to comment
banzai510(hainz) Posted October 2, 2013 Report Share Posted October 2, 2013 The Taller old style carb adapters have one big hole Quote Link to comment
thebucketslider Posted October 2, 2013 Author Report Share Posted October 2, 2013 Already have the mani, already on motor. Not spending more time finding an l16 mani and hogging it out. Ka swap in the works, any ways,This is just to get by, and I got good deal on it. and offenhauser manifold is a direct bolt on for the 32/36.. No need for adapter. Quote Link to comment
Stoffregen Motorsports Posted October 3, 2013 Report Share Posted October 3, 2013 ^ The gasket set I got had separate barrel ports, but in a pinch - it's easy enough to make a gasket. I think we all know there is a big difference between the racing world and the real world. Your mods sounds like you lean towards the racing motor camp. Larger carb too I'll bet! My application is on a truck that is used for light duty service, mainly driven to work and around town. Staying out of the secondaries for better mileage most of the time ... the "opposite route" of racing :blush: Don't pigeon hole me like that. I cut my teeth on the street just like eveyone else. This mod helps mainly in the bottom to mid range anyway, so your assumption that it's racing inspired is not altogether correct. The best carb I can think to use is the one that y'all are using: a DGV 32/36. Quote Link to comment
LB2 Posted October 3, 2013 Report Share Posted October 3, 2013 Used one of those around `74-`75 and experienced zero change cept for my wallet which got worse when I sold the manifold and put a Crown Turbo kit on :thumbup: :w00t: Quote Link to comment
laotsu Posted October 3, 2013 Report Share Posted October 3, 2013 I run one on my tired L16 and I think I lost 5-10 mph on the top end. Quote Link to comment
Stupid_fast Posted October 3, 2013 Report Share Posted October 3, 2013 Used one of those around `74-`75 and experienced zero change cept for my wallet which got worse when I sold the manifold and put a Crown Turbo kit on :thumbup: :w00t: I run one on my tired L16 and I think I lost 5-10 mph on the top end. Did you guys re-jet the carb after swapping the manifold? I've also heard claims of efficiency and performance with this manifold. It seems like a good design for a street motor, I'm wondering how well it would run with proper jetting. Quote Link to comment
hobbes_the_cat Posted October 3, 2013 Report Share Posted October 3, 2013 I liked how my Offy duel plane ran on an L18. I later swapped on a stock non-smog mani and a newer weber with similar jetting and noticed a loss of power with the stock mani and new carb. Just my .02 Quote Link to comment
thebucketslider Posted October 3, 2013 Author Report Share Posted October 3, 2013 Where in any of my posts did I ask how well it will preform... I simply wanted to know whitch gasket, if there is any I should use. I will make my own if it comes down to it.. But please no opinions, just factual information pretaining to the question asked! Thanks! -mike Quote Link to comment
laotsu Posted October 4, 2013 Report Share Posted October 4, 2013 Where in any of my posts did I ask how well it will preform... I simply wanted to know whitch gasket, if there is any I should use. I will make my own if it comes down to it.. But please no opinions, just factual information pretaining to the question asked! Thanks! -mike WHO the fuck is this guy? Butting in to OUR conversation aboot the benefits of an Offy intake! :sneaky: Turd sandwich for you! :poop: 1 Quote Link to comment
thebucketslider Posted October 4, 2013 Author Report Share Posted October 4, 2013 hahahahaha! that's more like it! Quote Link to comment
thebucketslider Posted October 4, 2013 Author Report Share Posted October 4, 2013 already got the turd sandwitch! its feeding air to my l20! Quote Link to comment
EricJB Posted October 4, 2013 Report Share Posted October 4, 2013 I guess I never really looked at an offy intake before. Strange how they would design it like that while competing with other aftermarket companies. This is the gasket that came with my redline DGV rebuild kit. No, I don't think it will make any noticeable difference which gasket you use. Gotta go with Stoffregen on this one. I have ran a Cannon (open plenum single plain) on L16, L18, and L20. And I have never ran a DGV on a stock mani without creating a plenum beneath it. The DGV is not a very big carb, and doing this tricks the motor into thinking it has a bigger carb on it. This mani is on a bone stock 620/ L20b / auto. It runs way better than it did with the hitachi. Quote Link to comment
LB2 Posted October 4, 2013 Report Share Posted October 4, 2013 Ya, I rejetted my carb just a bit with a jet reaming kit I had and still have though I haven't used it in some 30 years. Because the plane in which the primary intake on the carb is running in is smaller, it's supposed to create better low end because in theory it speeds up the intake charge. This is what I remember Mr. Moon of Moon Equipment in Norwalk Ca telling me when I inquired about the manifold. Plus if running a big cam which typically sucks low-end out of your engine, it restores that feeling and gets the cam to it's sweet spot quicker. Lou Quote Link to comment
thebucketslider Posted October 4, 2013 Author Report Share Posted October 4, 2013 I ended up using the same gasket ^^ and it works good. I dono what is in yalls coffee.. this thing shits n gits now! she pulls from a dead stop all the way to a buck! I also have been running around with an open exhaust manifold :w00t: -mike Quote Link to comment
LB2 Posted October 4, 2013 Report Share Posted October 4, 2013 I'd be careful about the shits :poop: part, but the git part is cool. Maybe your butt dyno is more sensitive :sneaky: Quote Link to comment
620Turbo4X4 Posted October 4, 2013 Report Share Posted October 4, 2013 I ended up using the same gasket ^^ and it works good. I dono what is in yalls coffee.. this thing shits n gits now! she pulls from a dead stop all the way to a buck! I also have been running around with an open exhaust manifold :w00t: -mike Bit late…. But I used a Holley/Weber model 5200 insulated base gasket from a '79 ford pinto 2.3l for my offy intake. Worked perfectly. http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Carburetor-Mounting-Gasket/_/R-FPG60225_0147248624 Quote Link to comment
Stoffregen Motorsports Posted October 5, 2013 Report Share Posted October 5, 2013 Bit late…. But I used a Holley/Weber model 5200 insulated base gasket from a '79 ford pinto 2.3l for my offy intake. Worked perfectly. http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Carburetor-Mounting-Gasket/_/R-FPG60225_0147248624 I like that idea. Give it a litle bit of a cushion. Quote Link to comment
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