The AMC Forum - Edelbrock shorty headers...horsepower loss??

amx73

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Edelbrock shorty headers...horsepower loss??
03/09/10 at 14:02:00

I have a built 401 in my 73' AMX, and Hooker Super Comp 1 7/8 tube headers, with a 3" side dump exhaust. Ground clearance isn't so hot but, looks and sounds great!!! Want to start messing with the suspention and lowering the car. I want to run a set of the Edelbrock shorty headers(1 5/8 tube) and Nascar boom tubes/flat pipe but, worried about loosing horsepower. The motor is 10.5:1, and has a Comp 280H stick in it, with an Air Gap intake.

Do you think it will be a noticable difference? I'm not drag racing but, I do get her up to 6k rpm regularly!

Any advice/in put would be great!!!

Jake

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73' "Z" code AMX 401/Tremec 5spd, 4 wheel disc brakes, front and rear sway bars, 4:10 gears, posi, 15x8 Mini Lite wheels...
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firecapt321

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Re: Edelbrock shorty headers...horsepower loss??
Reply #1 - 03/09/10 at 14:25:13

I am sure the pros will chime in, but first thing I saw and just throwin this out there, is that with your specs you have a very mild engine with big big exhaust.... How much street friendly torque is this costing you??? Not a race car.... dont worry so much about all out HP....

My engine will gain 15-20 HP on the dyno but lose almost the same in torque going from 1 5/8 up to 1 7/8.... and torque is what you feel push you back in the seat when cruisin and havin fun on the street...

Hopefully the pros will see this thread and give ya some good help...

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Mr Man

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Re: Edelbrock shorty headers...horsepower loss??
Reply #2 - 03/09/10 at 15:53:20

'Til the experts "pipe up" Grin

, I saw some really fascinating ( for a noob on the science of the 4-stroke performance arena ) info on both Headers By Ed's site and Jack Burn's site about header tube size, runner length, and collector diameter and length. Go check 'em out. Everything else being equal, only thing I can see as a power reducer in going from the Hookers to the Edel's is.... Smiley

Really pay attention to what both men say...and the racers on here.

Steve

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amx73

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Re: Edelbrock shorty headers...horsepower loss??
Reply #3 - 03/09/10 at 19:52:18

Quote from Mister Man on 03/09/10 at 15:53:20:

'Til the experts "pipe up" Grin

, I saw some really fascinating ( for a noob on the science of the 4-stroke performance arena ) info on both Headers By Ed's site and Jack Burn's site about header tube size, runner length, and collector diameter and length. Go check 'em out. Everything else being equal, only thing I can see as a power reducer in going from the Hookers to the Edel's is.... Smiley

Really pay attention to what both men say...and the racers on here.

Steve

Read the popular hot rodding article on Jack Burns...primary tube length and diameter! This will make my grunt go away? I had 1 5/8 full length tubes on the car before and didn't feel a difference. I'm not racing the car so, the shorties will serve the purpose I need them for. Ground clearance!!! Where might they suffer...over 6000rpm? I went through this with the decision to put 2.5" ram horns on my 56' Chevy solid roller motor. For the street...it's like trying to hear a dog whistle. HP with ram horns would start to drop off at like 7200rpm according to local Chevy guy sources. In NJ, I couldn't get there if I tried, unless I was at Raceway Park!!! I think with the 280H cam, shorties will be fine.

Jake

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73' "Z" code AMX 401/Tremec 5spd, 4 wheel disc brakes, front and rear sway bars, 4:10 gears, posi, 15x8 Mini Lite wheels...
70' Rebel Machine 401/727 Factory A/C, Cruise, all stock

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Mr Man

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Re: Edelbrock shorty headers...horsepower loss??
Reply #4 - 03/09/10 at 20:16:43

I agree. Only saying that ironically one area would be a possibility for power reduction over what you have now. And that might be a wash when you consider the other difference between what's on there now and what you want to go with. That's why reading what both header builders say on their own sites, not in any magazine article, mostly supports your move. Wink

Steve

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unstable bob gable Forum Junkie REAL AMERICAN BAD AZZ! Posts: 760 Gender: Wastelands of Jersey	Re: Edelbrock shorty headers...horsepower loss?? Reply #5 - 03/10/10 at 03:53:08 Too bad a place like Sanderson headers doesn't make AMC headers. They have all kinds of big tube shorty and mid length headers for the other marques. I think a nice 1 3/4 mid length would work wonders for our street type cars, and give really good ground clearance.
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Red Devil

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Re: Edelbrock shorty headers...horsepower loss??
Reply #6 - 03/10/10 at 04:31:13

My "butt dyno" said the Hooker 1 7/8" gave more push than the Hedman 1 5/8" ... but every combo is different. Don't know how the Edelbrock shorties compare for your combo., but below is a link to the CC Rambler 360 build where they gained torque and hp going from shorties to long tubes (pg.2&3) ... gained a bit more with a bigger carb ... then lost torque but gained hp going to a Torker ... then made the most torque but lowest peak hp with a smaller cam (pg.4). So may not lose much, but sure will gain ground clearance!!
Power is what you feel 'cause that's the acceleration component ... torque is static ... strong low end torque gives you strong low end power. Wink

http://www.carcraft.com/techarticles/ccrp_0601_amc_360_engine_build/index.html

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amx73 AMCrazy American Motors Corporation Posts: 230 Gender: Hillsborough NJ	Re: Edelbrock shorty headers...horsepower loss?? Reply #7 - 03/10/10 at 12:52:39 Heck, if i only loose 12HP at 6000 rpm, I'll be okay with that. I have never had my motor on a dyno but, build wise it's the same as the 370 small cam motor CC built. Mine's 407. Shorties here I come!!!! Jake
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Mr Man

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Re: Edelbrock shorty headers...horsepower loss??
Reply #8 - 03/10/10 at 14:40:25

Jake, if you can get the shorties uncoated and run 'em in and send the length specs and collector diameter specs to Ed's or Burns they can make recommendations on how to tune 'em based on where the bluing ends. Don't know if you'd have to send them in to them but that's my plan when I get the shorties. I also have some longer tube Blackjack or Cyclones I may experiment with having shortened/ play with collector length/diameter before hand. Wink

Steve

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amx73

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Re: Edelbrock shorty headers...horsepower loss??
Reply #9 - 03/10/10 at 14:54:58

That's a good idea! Unfortunately Edelbrock only sells them coated. I do have a set of 1 5/8 tube Hookers I would cut up/experiment with. If only someone made 3/4 length headers for AMC's. That might solve all these problems???

Now, the other question is do I continue to run a 3" exhaust? Considering running a 2.5"? Need to source some flat/Nascar tubes! Found a guy on Ebay selling Nascar boom tube take off's for around $100.00!!!

Jake

PS- Check out the April 2010 issue of Popular Hot Rodding. There is a nasty 68' Chevelle, and 65' Pontiac Tempest all done up just the way I like it!!!! Left and rights, and straight line in one package!!! Wink

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73' "Z" code AMX 401/Tremec 5spd, 4 wheel disc brakes, front and rear sway bars, 4:10 gears, posi, 15x8 Mini Lite wheels...
70' Rebel Machine 401/727 Factory A/C, Cruise, all stock

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Mr Man Forum Junkie Sweatshop Posts: 1095 Gender: Sisquoc , CA	Re: Edelbrock shorty headers...horsepower loss?? Reply #10 - 03/10/10 at 16:06:54 Talk to Randy Guynn at Performance American, he may have or may have a line on uncoated ones. If not, I'm wondering if the area that gets cut/welded can be coated or if the whole shebang needs strip and recoat... Steve
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javsst

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Re: Edelbrock shorty headers...horsepower loss??
Reply #11 - 03/10/10 at 16:23:39

Jake - If you're not going to run at the track on a regular or semi-regular basis, you probably
will be happier with the shorty's from the clearance perspective. Especially after what this winter
has done to the roads here in NJ!

And get that X onto a dyno would ya! Wink

Curious to see how that 401 performs at the rear
wheels. It'll probably help determine which setup works best with your drivetrain setup. OR
at least give you a baseline.

Also, not sure how accurate they are, but if you know someone with a G-Tech meter, you could
get a baseline using that?

Steve

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1969 AMX BBO 360/TF727 AMC20 4.10 Gears
1970 Javelin SST BSO 360/BW T10 AMC20 3.54 Gears

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anguscj7 AMCrazy American Motors Corporation Posts: 57 Gender: Tracys Landing, MD	Re: Edelbrock shorty headers...horsepower loss?? Reply #12 - 03/10/10 at 17:57:05 Jake, Here is a possible source for oval tube & maybe some info is www.mandrelbendingsolutions.com. Haven't dealt with them yet but located in Maryland. I've been thinking of redoing my exhaust with some stuff from them as they are close to me. Hope it may help...Tom
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amx73

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Re: Edelbrock shorty headers...horsepower loss??
Reply #13 - 03/10/10 at 18:36:32

Quote from javsst on 03/10/10 at 16:23:39:

Jake - If you're not going to run at the track on a regular or semi-regular basis, you probably
will be happier with the shorty's from the clearance perspective. Especially after what this winter
has done to the roads here in NJ!

And get that X onto a dyno would ya! Wink

Curious to see how that 401 performs at the rear
wheels. It'll probably help determine which setup works best with your drivetrain setup. OR
at least give you a baseline.

Also, not sure how accurate they are, but if you know someone with a G-Tech meter, you could
get a baseline using that?

Steve

Where is there a dyno around here? If UBG sells me his wheels I will need some ground clearance for sure!! Grin

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73' "Z" code AMX 401/Tremec 5spd, 4 wheel disc brakes, front and rear sway bars, 4:10 gears, posi, 15x8 Mini Lite wheels...
70' Rebel Machine 401/727 Factory A/C, Cruise, all stock

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javsst Forum Junkie American Motors Corporation Posts: 718 North Brunswick, NJ	Re: Edelbrock shorty headers...horsepower loss?? Reply #14 - 03/10/10 at 18:43:59 Some of the ones in the area are: Crazy Horse Racing 100 Main St Suite E South Amboy, NJ (732) 553-9050 LaRocca Performance 29 Shoshone St. Old Bridge, NJ 732-723-1111 Power Trip Performance 276 RT. 513 Glen Gardner, NJ 908-638-1194 Steve
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