Doing a little house cleaning in the garage today post-engine-transplant in the Black Car and as I was cleaning things to list on here I pulled my old, dirty, spare Q-Jet carb off the shelf to get at the other boxes. I figured I'd shine it up a little while I had the cleaning gear out and I noticed some etchings for the first time on the rear drivers side of the main body. The etchings, hand done, read "Built for Len By SK(T or I) Racing" below that a second series of hand etchings read: "Pri 70 73", "Sec Rods RY 10-1-91" The Q-Jet it's self has a casting number of "7045240" followed by a "W9" Julian date of "0305" (Jan 30th, '75). This carb, while not being original to my 1970 Buick GS Stage 1, is what was on the engine when I purchased the car a couple years back from a guy who'd inherited it from his father after his father passed. I admittedly don't have much of the history on the car past the Sloan documentation and Stage 1 registry. I'd ask the seller but I never actually met the guy as I was overseas at the time and my father drove out to chicago and handled the business end for me (and dragged it home, shined it up, tinkered, etc... couldn't thank him enough). The Car is from just outside of Chicago, IL. If anyone knew a "Len" from the area I'd love to know the history and/or what exactly I've got sitting on my shelf waiting for me to get bored enough to tear apart. Thanks in advance. -Hunter
Interesting carb... could it be a pre-M4M 75 or a service replacement? At any rate, it looks like the builder may have staggered the primary jets, which I've heard people do but doesn't mean much without knowing what primary rods go along with them. He also used AY secondary rods, which I believe are actually leaner that stock Stage 1 rods, interesting choice. Can you take a pic of the overall carb from the top/front?
It does look like staggered jetting. The 7045240 is a one year design and has the altitude compensation and some other unique things. The design was only used one year and ditched. I see different markings from time to time on carbs that come through my shop. Most of time, it is marker with jets/rods info. Probably used when tuning or racing.
Admittedly carburetors and especially Q-jet's are still very much a mystery to me. I've read Cliff Ruggles book front to back and back to front but still can't wrap my head around all the nuances. I've kept this carb intending on using it as a learning aid (I'm a hands on guy and can't understand a thing without taking it apart). Thanks for the input! Attached are a series of pictures I've just taken. I've brought the carb inside to look over with book in hand and while this post is active so if theres anything else I can submit let me know and i'll get it posted asap.
ahhh - I see, Mark's right. It is an M4M with the features he describes. There is a paragraph or two dealing with the 75 only features in Cliffs book. I though all M4M's came through as 1705 numbers.... It should be a good carb, but a little complex compared to 76-79 M4M's ... run it and see!
I've got the book sitting to my left and the carb sitting to my right! I'll head for that section. Like i mentioned, this carb was on my car when I purchased it (along with 2 piggy backed ignition modules a coil and an HEI distributor... huge mystery...) I ended up sending the 800 Q-Jet that was in the trunk off to Mark here to rebuild/tune and used it after having replaced the HEI mess with the original Stage 1 distributor (pertronix installed) and haven't touched this carb since. Gotta love the wealth of knowledge on this site. As a younger guy I'm starting to run out of "good 'ol guys" that know all the in's outs and what-to-do's, especially when it comes to Buicks... One day it'll be a lost art.
Looks like a 1973 carb but a replacement in 75 probably had 70 jets and the sec. rods AY Good carb 800 CFM.
not if more like you with a book in one hand and the carb in another take the time to learn these. then you can command a small fortune from your peers to remedy there problems
