Just a bench racing idea I had with the Swagon, so far best time is a 13.99 at 98mph. engine specs: .030 balanced/blueprinted(stock style GS pistons, stock '72 rod, stock crank) 350 10.5:1 comp, hydraulic roller(.230/.237 .525/.531 110lsa), sp3 intake, 1.6 roller rockers, non ported heads but they do have the larger valves, 750hp built by Seibert performance, 1 3/4 tube headers, 2.5" exhaust. car has a Th400 trans with a 3500 stall and 3.73 gears. The reason I ask about the intake because this is in a heavy wagon and wondered if Id be better with the dual plane for more torque. And then I wondered where should I be shifting the thing, I've been shifting to 6000 and it drops to 4500 each gear and then hangs at 4500 in 3rd through the traps.
It's a Neil Chance street performance converter(9.5") that was spec'd for the car it flashes to 3500 out of the hole and then does the 4500 thing I posted about orginally
Ahh,..well I'd leave it alone then,...sounds like you need a little shot,.. Figure the slip on it and send it back for a restall,.. or put a 125 shot thru it
My opinion is that yes, you would be better off with a dual plane intake but I honestly don't know that much about a Buick 350 specifically. The only reason I am posting is simply this: Is this as good as it gets for 350 Buick? I mean, the way it is built sounds like you spent a ton of money on it only to run a 13.99. I would mad as hell with that. Ok, with that said, I am not suggesting you replace it with a 350 Chevy so please don't misunderstand this but I had mildly built 350 Chevy in a 3,800lb car with a 200-4R and a 4.10 gear that ran a 13.50 at 101.18 and I later found that the vacuum secondary diaphragm was stuck on the carb and was only opening about 1/4 of the way. I was very unhappy with that run and I barely had a fraction of the investment in it that you have in yours. So I am just wondering, is this normal for Buick 350? And are you happy with it? I have to believe you have other issues than just the intake. Your car, heavy or not, should be quicker than that. Sorry if my post offends anyone, that is not my intention.
Trust me thats why I'm here. I realize the car is heavy but these wagons arn't that heavy especially next to the B-body full sized car. It just seems the car has at least a 13.20-13.50 in it as is.
I know the SP1 can be worth a good 50 HP with the 455. I'm just not sure about the SP3 yet. It is kinda unproven as of yet, although guys have had good things to say about the seat of the pants feel. I'm curious to see how Mark Demko's 350 runs at Salem. You may gain low end torque with the DP, but lose HP, I don't know. Maybe you should try running through the traps in second gear. The RPM would be 6500 +, but the 350 should be able to handle that and the SP3 should as well.
Ive wondered about the 6500 rpm thing, because I shifted at 6200 2nd-3rd to click off the 13.99. Just wasn't sure if it could handle that rpm with the stock stuff.
Yeah, I'm not sure either. You really need to be running closer to 5500 through the traps. Maybe reducing the gear out back to 3.08 and running through the traps in second gear would help. 3.08 in second gear would be 3.08 X 1.48 = 4.56 Not sure of your tire height, but lets assume 28" 336/28 X 4.56 X 100MPH = 5470 RPM without slip.
I would think that despite the SP3 being a single plane intake, its relatively short runners would not give up that much torque down low. It should outperform the stock intake on everything short of a bone stock 350.
Sounds like you need tuning. The sp3 is probably best for your combo. Stock style gs pistons would require .005 below deck to get 10.5 compression. That’s about.053 off block. Probably cause valve clearance issues with that cam and valve size. Otherwise you are probably closer to 9.3 compression. You don’t mention distributer/timing curve, or if carb has been jetted for your engine. I would suggest an air fuel meter. Find out your timing specs. You may need more fuel pump.
You need ported heads The 350 trans can hold up to 455 power there were 2 guys at D42 that ran it all the time. I ran it with the 125 nitrous shot went 11.81 A 75 shot got me to 12.42 All with a DP intake but I do think the SP3 is your best intake for your combo. 4 speed 2004r will work with a 411 gear. What are your 60ft numbers should be at 1.85, at least less than 1.90 I had 1.75 with the 3500 stall and the 350 trans 1.60 with the 125 shot. Put in a 411 gear and you will turn 5 grand in the traps.
