When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Long story short, i got scratches on irons and dont have enough money left to buy rebuild kit AND resurface so my friend is selling me a stock 12a with a holley carb, what difference will this make? i stripped a nikki while planning the engine job and it may or may not work as i had to jb weld a float back together and everyone says it wont work right now. what could i expect from this swap?
Find used or new floats for the nikki. That holley will cause you no end of grief trying to get it tuned to run right.You have enough unknowns here, use the nikki with some better floats and be confident in getting this running. The problem with the JBWeld is it doesn't like fuel a lot and it will unbalance the floats.
My vote would be on the Nikki as well. Get it fixed up and you won't be disappointing - plenty of room to modify it if you're into that sort of thing as well. I have never had any personal experience with a Holley on these engines, but like tg_farrell mentioned, from what I've heard they are rather difficult to get running properly. Now, I have talked to and seen a few people who have been really happy with them, but I have no clue what it took them to get there. To me the Holley only seems like a good option if you don't want to deal with the more in-depth mods required for power on a Nikki and don't care so much about cornering. The best thing about the Nikki is that it just works.
Last edited by Benjamin4456; 03-13-20 at 11:52 AM.
yea im sticking with the ole nikki because i already spent the time to strip it, and if you know how to modify the rats nest to work with a stripped nikki let me know because i dont even know how to put it back together with a stock carb lol
In 30 words or less for a novice, what is it to "hog a nikki". which part is expanded? given the inticacies of laminar/turbulent flow, vortexes, and all that other fluid mass tranfer, it sounds like opening a can of worms to me.
To "hog a Nikki" is to enlarge the diameter of the venturi's, usually the primaries, while also performing other required mods (namely mech secondaries and the AP mod). <-- there's the basic definition; 28 words .
In doing so you really have to move to mechanical secondaries as well due the factory vacuum signal no longer being calibrated correctly, which is another relatively common mod (my knowledge of "common" comes from research and seeing what other people have done on the web). With mechanical secondaries also come the "AP mod" where you cut an extension arm (1.25" hole spacing center to center) to bolt to the existing AP lever arm. Multiple gaskets are then stacked on each side of the AP diaphragm to increase its volume. You can also trim the outer support arms off the booster venturis, reducing one more obstruction to airflow. Additionally, there is also the "airfoil mod" which one applies to the remaining booster support arm in which material is removed to streamline their shape. With hogging a Nikki a jet change is required. With a 24mm primary, and 120 No.2 air bleeds with otherwise stock jetting, a 120 primary fuel jet is a good starting place. This also assume there is no longer a choke, altitude compensator, or any carb related smog equipment (richer solenoid, etc), although I am unsure how exactly those being present would affect things. I should note by now that most of this info is thanks to all the work Jeff20B has done, I have simply applied it to my own carburetor which at the moment is under construction again.
There are a good number of other smaller mods to help things work correctly internally, although in most cases they simply involve blocking off a few passages. That level of detail, or just getting into the specifics of the aforementioned, would likely warrant a thread of its (for those curious, check out the nikki/intake thread in my sig. It's not a how-to, but more so an 'in-progress' learning thread).
Did that make anything clearer?
Edit: I was just reading through my Nikki thread and noticed I used 1 1/8" spacing on the AP extension. Perhaps I am wrong about the 'standard' 1 1/4" spacing; if I am, someone please correct me. I might have also changed the spacing on my carb later down the road, although my thread is so gosh darn long it's taking me a while to figure that out.
Last edited by Benjamin4456; 03-14-20 at 02:08 PM.
no doubt the nikki is a great carb for stock port & street port ...alot of members bash the holley like the racing beat 465 or 600 cfm just because you can't do it doesn't mean it can't be done... RB kit is decent for someone who's goin to use it as a daily.. 600 to much cfm's = no fun sure u can make it work... for rotorhead like myself who do not use the car as a daily just looking for performance and fun.... the holley 390 hp 4150 i build wil out perform any nikki in a straight line or around corners.... if u ever get your hand on some cash its a great option.. nice to hav choices...
03-13-20, 01:54 AM
.
