Hello again. Just looking for a little advice on headers vs stock manifold. I have a gs 350 engine in my convertible. Looking to add a ta performance stage 1. Keeping stock cam, valve train and qj for now. Any reasonable gains to be had from swapping the cast iron stock exhaust manifolds for a set of hooker headers or ta performance headers? By the way, the car has a 2.5" dual exhaust system installed. I would appreciate a little advice. Will be adding discs, posi, gears. Like to make sure ill be spending money on useful upgrades. Thanks. Chris
Track testing shows that even a stock low compression 350 gains by headers. Have a look at my word document a few posts down: http://www.v8buick.com/showthread.php?120004-Kenne-Bell-350-testing-from-1984
when adding headers will they bolt to the exhaust system that is currently installed on the stock manifolds, or are they longer and require exhaust pipe modifications?
I would pass on both of those mods for a street, low rpm, car like yours. Headers create a lot of heat, some drag speed humps, may require changes in your exhaust pipes etc. Spend your money on having your ignition advance re-curved. This is a $200 or less modification.
X2 I would also spend your money on re-curving your ignition and carb tuning. Even Kenne-Bell tests (which are known for being on the optimistic side) only show about a 15 HP gain with headers on a stock low compression 350. In addition to the ignition and carb mods a good mandrel bent 2 1/2 inch exhaust system with low restriction mufflers will also help. And, the new sound will make you smile as well. :TU: (Just noticed in your OP that you already have the 2 1/2 exhaust system)
In Denver ,on a ALL STOCK low comp 350 with re curved distributor, 3.73 gears, headers were worth 7 tenths over manifolds added to a current 2-1/4 dual system. Real results,not internet BS Carry on
Thanks for the input.. I appreciate it. Now I'll have to decide which set, and whether wraps are worth the hassle. I'd say with a glass hood, they would make a lot of sense, keep things cooler in the engine bay . Any thought on header wraps ? Thanks , Chris
I'd considered the exhaust / collector / pipe issue. Just a matter of matching the reducers up , a little cutting and welding . I expect a little bit of work to get headers to mount up . Should be easier without the ac stuff in the way .. Don't really need ac on a convertible in Colorado !! Probably fab up a couple of heat shields to insulate the floorboards ( maybe use a set from a s10 blazer or 1990's Chevy truck they're curved with a rivet/ spacer that would leave a good air gap . Thanks for the advice everyone . Chris
Nickev , thanks for the real world results post .. Very helpful. I see the manufacturers hp gains as advertising hype. ( what engine / cam / temp, conditions are they operating with ? Drag strip results and real world testing are what matters. Along with a distributor recurve / lightweight wheel/ cheater slick , a set of weight transfer shocks and the battery mounted over the right rear tire , that could make the car about a second quicker ! Any other person to learn to not underestimate a skylark ! Thanks
Was the motor otherwise completely stock or did it have cam, heads, etc.? With respect, while I'm not doubting your statement, I really believe that there must have been something else that changed for you to get a 7 tenths gain. That's about 70 HP and no set of headers ever produced that much gain on a 350 IMO. :grin: Were the short times on the comparison runs the same?
Thanks for the tips . I checked with a local speed shop on Colorado Springs , $65 to recurve the dist. $1200 to install posi and gears if I BRING them the rear axle !! Yeeouch !! Curious about DIY options , I recently talked to an old school muscle car mechanic , I am sure hell be a lot less !! I'll take him the parts/ bearings, etc .. And the axle with the housing bar .. Anyone know if my axles are bolt-in , or c-clip ? It's a stock 72 unit with LKB stamped on the right axle housing ..
Header wrap is a good idea only if in a dry garage... Add moisture to the wrap and they will rust out the headers.
How much driving do you do and under what weather conditions? My chromed T/A headers have held up very nicely now for 20 years. I drive between 1 and 2k per year, and never in weather. The chrome collectors look very cool peaking out just below the frame rail. I have occasional banging on speed bumps if I roll too aggressively over them. Yes you'll have to rig up pipes between the collector and muffs. And if you send this work out, you'll get the pleasure of driving open headers to that destination. That was a FUN!! morning - particularly with a 4-speed car.
$65 seems a little much to me for a ignition recurve. Tell me if im wrong but I though the msd or even the mr.gasket kit was a re curve kit. If it is it could save you a $$ doing it your self.
Seems to me it would be alot easier to do still attached to the car. You can buy all the parts you need in a kit, and installation should not break the bank.
The reason why track performance gains of .7 seconds and dyno's showing a 15 hp gain don't add up is that headers add to the entire torque curve and response of the engine. The 15 hp gain referred to is ONLY at peak hp, and might not be comparing the same rpm. Header's may help tremendously depending on tube lengths, how restricted you are to begin with and what your combination is.
Get quality bearing for rear end. Timkin are good. You should look at the post for Scott Brown cam. I think that cam would perform well in your engine with headers.
