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#121
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You'll be fine with the 2.25" outlets. My stock 455HO did pretty good on the dyno (430 hp @ 4900 rpm/535 lb-ft @ 3500 rpm) with factory original RA manifolds with 2.0625"/2.125" outlets, so your larger outlet RA manifolds will work fine on your 400.
Dennis |
#122
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The Parts Place had a few sets on eBay. Next morning they were sold out. Not sure you can find 2.25" now either. |
#123
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JLP |
#124
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My first exhaust job and want to do it correctly! |
#125
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Dennis |
The Following User Says Thank You to SD455DJ For This Useful Post: | ||
#126
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RA manifolds on, tailpipes installed. Getting closer.
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#127
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Sounds good with X and 18" Turbo Pros, no drone. RA manifolds do sound kinda like headers. Bad weather/roads/salt coming so probably won't see the road for a while. |
#128
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Dennis |
#129
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Working to dial in the timing a little more, wasn't advanced quick enough. You like 36 degrees at 3200rpm? I've just advanced it more, am at 12 initial now with maybe 33-34 around 3000. Didn't get to test this yesterday. |
#130
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Dennis |
#131
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Just checked it again. Hitting 36 degrees at 34-3500 rpm. I've got 91 non ethanol treated with 104 booster.. |
#132
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Dennis |
The Following User Says Thank You to SD455DJ For This Useful Post: | ||
#133
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I suspect my next focus should be my lousy 2.3-2.4 lousy 60ft time. Launching with my foot on the brake and revved up some.
With the upgraded exhaust the 0-60 improved quite a bit but 60ft stayed about the same. I've got upgraded rear bushings(not rubber) I did in the 90s. Also added a rear sway bar but don't have boxed lower control arms. And have rubber spacers under the springs to raise the rear an inch or so. Probably should ditch these? |
#134
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here's my understanding with a quarter mile bent on them;
stock soft bushing = allows squat, and results in quicker weight transfer - you want as much weight over the drive tries as possible. "upgraded bushings" = read: for autocross/handling; slows weight transfer because it resists movement better than rubber. Rear Sway bar = read: for autocross/handling; prevents weight transfer; I have understood that often quarter mile guys will effectively disable the rear sway bar to permit movement Rubber spacers under the springs = this is a "for looks" modification; this also shifts weight towards the front of the vehicle, and effectively raises ones "cool" quotient, because it makes it easier to do a burnout. There's a reason why older race cars would have their noses in the air... http://www.speedhunters.com/2013/05/...nce-and-style/ This might not be a perfect example, but hopefully you know what I'm getting at.
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
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#135
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KSZR, To add to what Jonny said, by keeping the rear end on a GM A-body lower, you improve the "instant center" geometry between the lower and upper control arms, where the imaginary lines drawn parallel to the upper/lower arms should intersect as close to the rear of the car as possible, ideally closer than the midpoint of the wheelbase. This helps to plant the rear end (causes lift) and control wheel hop more effectively. A rear sway bar doesn't hurt traction on lower hp cars, so keep it. The non-boxed lower arms are OK too if you added sleeves for the bolts to run through to prevent crushing the arms when tightening the nuts. I did the same thing to my '70 Tempest and just sleeved the control arms.
Dennis |
#136
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Thanks guys that is helpful. I'll ditch the spring spacers.
Car looks higher in the picture than stock. Even more than I thought. I do have the sleeves inside the lower arms, can't see them in my picture. |
#137
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Several places make the A-body lower mount that has multiple holes for adjustment of instant center, and the brackets are much beefier:
https://www.umiperformance.com/home/...ckets-bolt-in/ https://www.umiperformance.com/home/...ckets-weld-in/ EDIT: Some also make front mounts too for anti-squat. .
__________________
. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be Last edited by HWYSTR455; 12-19-2022 at 08:36 AM. |
#138
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My front cover gasket is weeping antifreeze so I guess that is a sign to go for the cam swap!
Can I get away with the stock rocker nuts that torque to 20 lbs with the 2802 cam? I'm 99% sure I've got HO racing valve springs cause I ran their HC-01 cam with these #16 heads on the original 350. Are the springs easy to ID? I do remember when I took the 350 apart to swap these heads to the rebuilt 400 there was a bent pushrod. |
#139
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Kent, You'll need to get 7/16" rocker studs and poly-locks for the 2802 cam.
Dennis |
#140
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Kent,
Please start a new thread regarding whatever you’re doing with your car, this focus of this thread should be on what Dennis is doing with his car. Thanks. |
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