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header size?


dbreese

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Guest 72yellowmc

David your going to lose some low end grunt with 1.75 headers ...... but you might gain some top end also.... it will probably all even out in the end and run the same as the 1.625 headers.... IMO.

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Robyn,

 

I was thinking the same. The headers I run now have primaries that shroud the exhaust port. The ports are larger than stock(Pro Topline heads). This is hurting the exhuast flow for sure.

 

I e-mailed dynatech and asked them if their stepped 1 5/8" to 1 3/4" would fit my app. They show it fitting the 68-72 Chevelle. We will see.

 

David

 

 

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I am no exhaust expert but I would think the torque you would lose you have already lost because of your cam. Also, if you lost any power below 3500 rpms, it wouldn't matter anyway since your converter flashes to that rpm (if I am remembering your converter right)

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I am no exhaust expert but I would think the torque you would lose you have already lost because of your cam. Also, if you lost any power below 3500 rpms, it wouldn't matter anyway since your converter flashes to that rpm (if I am remembering your converter right)

 

Your right Scott the converter flashes to 3600. I'm thinking by unshrouding the exhaust port would have to help. I torn right now. If I can't use the step design from dynatech I'll go with the 1 5/8", more than likely Doug Thorleys.

 

David

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Go over your combo with several header manufactures to come to the correct primary tube size for you. Always mention future mods unless you want to buy another set down the road.

 

Will do Greg. I haven't heard back from dynatech yet about fitment of there step design 1 5/8" to 1 3/4". If the work I'll go with them as this would give me some room if (when grin) I do further mods.

 

David

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  • 8 months later...

So Dave did you get the Dynatechs? I was looking at them too, my exhaust guy says they fit nice, but not sure if the 1 3/4 is too big. I'm running Fastburn heads w/large D ports. If you did what size worked.

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Hey Chris, I think the basic question is, street car or drag car? If it's a street car (occasional track time) then I would stick with the 1 5/8" tubes. I suppose if you ran a 2 3/4" or 3" exhaust all the way back the larger tubes would be okay but IMO unnecessary. The big tubes look nice but all you're doing is adding expense and fit problems, the car is not going to go any faster on the street and you'll have better torque with the smaller tubes......Dave grin

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David, remember our phone conversation? I am relocating two tubes on 1&3/4 headers that are for a chevelle(&el camino). The reason those will not fit the Monte is because of "those two tubes, one on each side" hit the lower A-arm mounting point because of the engine placement on the chassis. Once the two tubes are relocated they will fit fine. Headmans has a set of 1&3/4"headers but for chevelle only. Those are the ones I am redoing(one done so far). Once done, off to Jet Hot for coating. Initial cost 190 a pair. - Dave

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