Header Size

[70wayfarer]

last year i built a set of fenderwell headers for a 440 build. that turned into a 493 stroker as they do. any way the tubes are 1 7/8" and 3 1/2" collector. are they now to small for the 493. this is a street strip build, spinning to 7000 rpm. cheers

 

[yellow rose]

How long are the primaries? If they are under 32 inches long I'd run it. IMHO it need a 3.5 inch collector between 18-24 inches long. Don't know how you can get that with a FW header though.

 

[General Disarray]

Primary Header Tube Length and Diameter Calculator

 

[yellow rose]

Primary Header Tube Length and Diameter Calculator

I just ran my combo through that calculator. It shows the primary way too small and too long with a small collector.

Reminds me of carb math.

 

[70wayfarer]

my collector is 3.5" and 14" long with dump pipe and the longest primary is 28". ran my specs through that calculator and seems all is good.

 

[yellow rose]

my collector is 3.5" and 14" long with dump pipe and the longest primary is 28". ran my specs through that calculator and seems all is good.

That's what the Wallace calculator said?

 

[70wayfarer]

That's what the Wallace calculator said?

that's what i have. i'll double check the calculator with my engine builder.

 

[famous bob]

I just ran my combo through that calculator. It shows the primary way too small and too long with a small collector.

Reminds me of carb math.

Big block , or small block ?? THIS was directed at yellow rose, I know the o.p. said 493-----------just trying to clear up my dumb question! LOL

 

[yellow rose]

Big block , or small block ?? THIS was directed at yellow rose, I know the o.p. said 493-----------just trying to clear up my dumb question! LOL

Mine is a SB and I run 1.875 headers 28 inches long with a 3.5 collector 22 inches long.

 

[273]

Id run them for now its always something you can change down the road when looking for better ET's.

 

[famous bob]

Mine is a SB and I run 1.875 headers 28 inches long with a 3.5 collector 22 inches long.

Sounds right , I ran 1 7/8'' on my 406sbc`s, worked well.

 

[oldkimmer]

My buddy’s 511 picked up over 30 hp going from 17/8 to 2 inch. Kim

 

[famous bob]

My buddy’s 511 picked up over 30 hp going from 17/8 to 2 inch. Kim

Lot of diff. between a small block and a stroked big block--------------

 

[oldkimmer]

His post is on a 493 so I assume it is a big block if built off a 440. Kim

 

[70wayfarer]

His post is on a 493 so I assume it is a big block if built off a 440. Kim

correct

 

[RustyRatRod]

Sorta a no brainer. You have them. Run them.

 

[440dartsport]

Big block Mopar’s love big headers and big carbs. If you build another set I would build them 2 1/8” - 2 1/4” primary about 32”-36” long tubes and 3 1/2” - 4” collector for the most power. This is if it’s a healthy 493.
We built a set of 2 3/8” primary 4 1/2” merge collector headers for my 572 and they made a huge difference. All the tubes are equal length also.

 

[oldkimmer]

Those are beautiful. Kim