Hi all, new to these vehicles...been a German car guy all my life. But now I'm trying to help my stepson with his Skylark which just doesn't want to act right. He leaves for the Navy in a couple of months and instead of fighting with the Rochester, I got him a shiny new Holley 4 barrel 600cfm. From what I've been able to find, this 260 has a 4 barrel intake and the Rochester(DualJet 165) is a 4 barrel body...so this should be easy, right? So with that background in mind, here's what I need to really nail down...what vacuum lines on this car matter? Got a diagram? Any advice? Apparently these 260's were a unicorn engine...can't find anything about them. If you've done this swap and have some advice, throw it my way...I'm pretty good with fuel injection but carbs are a little new to me. Thanks in advance, Brad
Well, first, the Quadrajet was a spread bore carburetor, and the Holley is a square bore carburetor. Those are two different bolt patterns. The dualjet was a 2 barrel carburetor, so the intake manifold is probably a 2 barrel. Bottom line, that Holley won't fit on to the intake without some sort of adapter, and if the manifold has 2 openings and not 4, bolting on a 4 barrel carburetor will do no good at all. I suggest you rethink your plan. The 260 is an Oldsmobile engine, and does not have much performance potential. see here: http://www.hotrod.com/articles/hot-rodding-the-260-olds-v8/ Being this is V-8 Buick, I suggest a 350 or 455 Buick engine swap if you want some performance and fun. We have a separate Forum for the 73 and later X body cars (like a Nova) http://www.v8buick.com/forumdisplay.php?98-The-X-bodies
Getting a Holley 600 was a HUGE step backwards in just about every direction. It will require considerable "hacking" to effectively use I that application, and even once it's in place it will never work as good anyplace as the factory carburetor it replaced. I would completely/correctly rebuild the original unit. It's a perfect fit, choke, linkage, fuel line air cleaner, etc. "Cobbling" everything up to put a 600 square flange Holley carb in that application will be a lesson I humility....IMHO....Cliff
the half a Quadra jet it a unique 2 barrel flange. a 2 barrel holley will not fit it. it's certainly not a 4 barrel intake.
Another option to consider is replacing that unicorn 260 with a similar vintage Olds 350, if you have the time, skills, tools and space. :TU: My brother did this swap last spring on his wife's 76 Ventura which was born with that same unicorn. I'm pretty certain it was virtually a bolt in swap, but could ask him for more details.
I had the 260 in a 80 Olds Cutlass. 140 hp rated. About the best that can be said about the 260 is that yes, it will make the driveshaft turn as compared to ........ not turning, but that is about it. Very little to nothing on the aftermarket available when I tried to massage it back in the mid 80's. At the least, have the original 2V sent out to a good carburetor shop for a rebuild / renew. I may be mistaken, but I do think that yes the Olds 350 is externally identical, dimension wise. Hope this helps. Good luck with it. Dadrider
Send the Dual Jet to Ken or Mark here on the board. For a driver, that's the easiest/cheapest way to go. If your stepson loves the car, then swap an Olds 350 in it, cheapest way of the engine swaps
