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I have a 69 nova,406 sbc I in the process of building. Some experts say 1 3/4" primary tubes,and some say I'm better off with 1 5/8"headers.The heads are alum. angle plugs,compression is in the 10s.The cam is a sollid roller,Ultradyne dur @ 050 is 242 & 249,lift is .556 on both.LSA is 108 & int. cL is 103,and the gears are 3.70. The desk top dyno shows peak hp @ 5500 & peak [email protected] 4000. I was asking the sales guy at Summitt about a pair of Hedman #66003,with 1 3/4 primary tubes,he said they were a little large considering I wasn't taking it over 6000 RPM. ???What are your thoughts ?
What is a Saginaw Quick ratio steering gearbox look like? a bubble buster on some headers. My box has a logo of a large box shape with a S in it.as in Saginaw. The car curantly has a pair of 1 5/8 tube Hedman
 

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Will this be a street car or full race car? Street car you will probably get a better low end torque and loose a little HP on top, they will work on a race engine if you are only gone to pull the motor to 6,000 rpm's, they will actually scavenge your air flow better to 6,500 rpm, any more than that and you are loosing HP on top. If you motor makes peak HP at 5,500, you want to shift it at 5,700-5,800 rpm's.
 

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Discussion Starter #3
a street car

Will this be a street car or full race car? Street car you will probably get a better low end torque and loose a little HP on top, they will work on a race engine if you are only gone to pull the motor to 6,000 rpm's, they will actually scavenge your air flow better to 6,500 rpm, any more than that and you are loosing HP on top. If you motor makes peak HP at 5,500, you want to shift it at 5,700-5,800 rpm's.
Thanks, I also read a very good build on a 406 in a magazine,they had alum. dart heads,with a comp. solid xe284 making 455 hp and said the eng. made more usable hp with the 1 5/8 tube headers. J. V.
 

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Running Dynatech stepped 1 3/4" x 1 7/8" stepped headers on my street-strip 383 - 72 Nova.
Ceramic coated and the fit is excellent with my power steering.
 

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Running Dynatech stepped 1 3/4" x 1 7/8" stepped headers on my street-strip 383 - 72 Nova.
Ceramic coated and the fit is excellent with my power steering.

Sounds good,our cams are very similar, I was wondering about how high you go on the RPM s. Did anyone recommend those headers? I'm glad to know they fit. Thanks
 

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I have the 1 3/4" hedman 65003 on my 72 with power steering and I still had to clearance one tube for the gear box they were supposed to fit. the 65003 should be the same as the 66003 only difference is they are painted instead of ceramic coated
 

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Sounds good,our cams are very similar, I was wondering about how high you go on the RPM s. Did anyone recommend those headers? I'm glad to know they fit. Thanks
Mine is hydraulic and has a 110 LSA. I have run mine up to 6700 a few times, but mainly I run it to 6500 rpms. Haven't had it to the track, but it pulls to 6500 without any problems. Have upgraded spring package and Morel lifters(the cheaper ones-:D)

Nobody recommended the headers, I just started seeing the name thrown around here. Used to be a sponsor on this forum and for $349 shipped to my door for a set of coated and very well made headers I couldn't resist at the time.
 

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Discussion Starter #8
headers

I have the 1 3/4" hedman 65003 on my 72 with power steering and I still had to clearance one tube for the gear box they were supposed to fit. the 65003 should be the same as the 66003 only difference is they are painted instead of ceramic coated
Thanks, thats good to know
 

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You are making peak power under 6000 rpm's so IMO the need for 1 3/4" primary tubes is not there. The 1 5/8" will flow enough, make plug changes easier and fit around the steering gear better.
My 406 makes 400+ hp and close to 500 lb ft of torque running through the 1 5/8" headers and 2 1/2" exhaust.
 

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You are making peak power under 6000 rpm's so IMO the need for 1 3/4" primary tubes is not there. The 1 5/8" will flow enough, make plug changes easier and fit around the steering gear better.
My 406 makes 400+ hp and close to 500 lb ft of torque running through the 1 5/8" headers and 2 1/2" exhaust.
exactly what he said!
 
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