Hey everyone, I am a newbie here. Of all the GS Skylarks (and one RivGS) I have owned, the only one I have held onto is my first one from high school--a 1969 GS400 with a balanced, very-high-compression '69 430 (bored .030 over) full of Kenne-Bell guts and the original Muncie 4-speed. When I bought it in 1977, it had a Holley 650 double pumper that was very responsive but ran out of gas after a few seconds of acceleration. So I tried an 800 Thermo-Quad and didn't really like it. Ditto the Quadrajet. So I am back to trying Holleys. I have a 4781-2 (850 cfm, mech. secondaries) and a 3310-2 (750 cfm, vac. secondaries). Before I rebuild them both, I was hoping those of you with more experience running Holleys on Big Block Buicks could help me decide which of the two will make me happier when I go through the gears on the country roads. I don't race, and I never take the beast over 5000 rpm because that last engine overhaul I did is the last one I ever want to do. What are the drawbacks of 4160 Holleys compared to the dual-metering-block 4150s? Thanks in advance for your ideas! I love this site.
i think the 4 corner idle is best if you have a huge cam and your trying to get vacuum out of it or make it streetable. but im not exactly sure. i would say use the mechanical secondaries 850.
Thanks, Lonnie, I was hoping that would be the right answer because I think this engine can use all the gas it can get. I am running a Window Rattler for a cam, and I don't know that vacuum is a major issue since the car has no power brakes. Nor power anything else, for that matter, except hopefully engine. :grin:
Have you ever considered one of the holley nascar three barrel carbs that were made in 1968 and 1969....???? they came in 950 and 1050 cfm, with vac secondaries.... I am running a 1050 cfm on my nailhead... and have in the past run a 950 cfm on the same engine... the engine runs strong with these carbs... I t is nice to run a carb that will just bolt on and has big performance without multiple carbs or a dominator..... dont forget to modify your air cleaner assembly for more flow.... it amazes me that the factory puts a carb on with 4 holes in it and then has it breathing thru a air cleaner snorkel with one little 1 1/2 in. hole in it...:laugh: :laugh: If you dont already have it, a cold air intake is worth a lot of power, as is my Doc dual plane mod... and recurving the dist.... cheap , perminate , power all......
Thanks for taking the time to post, Doc. Yes, I would love to give the old Holley 3-barrel a try--I have heard great things about them, ditto the Dominators--but for now I am stuck with the carb choices in my "inventory." The intake on my GS is a B4B, ported & polished in the right places along with the rest of the respiratory system of the engine. If I don't like how this 850 works, maybe I will try to get my hands on a 950. I do have another question: I want to put a phenolic spacer under the carb because this motor makes heat like crazy. Should I use the open-pattern spacer, or the 4-hole one? Thanks for all the insights you can share. I want to get this high-school car on the road before I die of old age. It's been in storage over the past 30 years more than it has been in use.
If it is a thin spacer a open one would be ok.... but if it is thicker then you would need the 4 hole type... personally I have the ole Doc dual plane mod done to my intakes so I take a 4 hole and make it into 2 ovals front to back to match the manifold.....
Ah, I see. Your mod sounds like a good idea. What kind of tool do you use to remove material to get it to that shape?