I bought the 6901s ....im runnin 302 with gt40 heads.t5 tranny....they dont fit my car worth $hit...my car is manual steering ...dropdown arm off the steering h its the.driver sidean.....passenger side header hits.the idler arm...druver side also.hits the steering box...i would not reccomend the 6901s..i kbow they worked.great for some folks but not for me...i hated beating up these brand new headers to fit...very.disappointed
I've been informed by many people to ensure my shock towers haven't sagged, my mounts aren't worn out, and that my engine is riding in the exact appropriate spot prior to installing any headers. I still want to know if the 3" collector is an issue or not more than anything else.
You'll use the appropriate reducer to mate the collectors to the exhaust pipes. I bought Summit's house brand, but the hardware that comes with them are pretty cheesey. A quick trip to Tractor Supply for some grade 8 hardware and we were good to go. Edit: Sorry, I had linked to the stainless version. Try these: http://www.summitracing.com/parts/sum-g4754/overview/
My local auto parts store sells collectorsi bought some hedman 3in to 2.5 collectors from.oreillys...i would also recommend grade 8 bolts...maybe even stainless to ward off the rust
So the 3" won't be to breathy for a bone stock 74 302? Or is it just something that's worth putting up with for a year.
i think this may be the case...the welds look crappy on the flanges and one of the flanges looks alittle warped....idk..ive kinda gotta sour taste in my mouth after the experience i had with them
The 3" collector is a non-issue. The 1-5/8 primary tubes on these headers work perfectly fine with stock engines and actually make a little horsepower.
I disagree somewhat. Those collectors are too big for a smaller displacement lower compression motor like that one. I've personally learned that lesson the hard way many times. They'll easily knock off 12-15 ft lbs of off-idle torque in that combo and soften the average torque up to about 2,500'ish rpm compared to similarly designed headers with smaller 2.5 inch collector. Even on the 350 horse combo down the road.. they will be marginally too large as well.. though not what I would really call bad. 2.5 inch collectors will allow better throttle response(some from more accurate jetting/AF ratio in itself), and a broader power curve without limiting the higher rpm ranges on a smaller moderately built motor. Then again.. sometimes we just have to do with what we have available to us.. and inevitabely get pinched by the law of averages. Lose a little here.. gain a little more there.
So what is really needed to be able to put in any set of headers without a lot of stress. I mean should I notch my shock towers out a bit? I'm completely open to that because I currently can't change my spark plugs without jacking the motor out a bit (really big hands). Or I guess I just go with the Doug Thorley shorties.
The shock towers arent the problem with the 6901's. I didn't have to do anything to make them fit in that area. As others have said it's the idler arm bolts ( cut them off flush with the top of the nuts), the steering box ( a little rounding of the corner with a grinder and dimple the header tube), and the pitman arm on manual steering cars (some major denting of the header). I don't want to cause a big argument here over the collector size but I do have very positive experience with 1-5/8 headers with 3" collectors in a maverick with stock engine (with 4 barrel). In my case the car picked up three tenths in the quarter mile over exhaust manifolds and the rest of the exhaust system being the same. It had super crisp throttle response and low rpm power was definitely up. The headers added power at every rpm. If you don't have good crisp throttle response it's probably the tune.
I'm running a 2 barrel carb. thanks everyone for the advice and opinions. I'll probably be starting a thread later this weekend asking for advice on an entire exhaust.
The 3" collector doesn't have much of an effect when you have a full exhaust system after it. To the engine, the whole exhaust looks like a collector.
