What size header would you run on this combo?

[94guy]

420sbc,11.85comp,M2 Track1 227's,supervic,prosystems1000hp,258-268@.050 on a 112 lobe sep. solid roller. 2sp,3.73,28x10.5W. 2700lbs. w/d. i do spray a 275 shot. but i would like to know a header size for the motor and one for the nos. right now i have a 1 3/4 header.

[Monty Mikho]

The 1 7/8" on motor and 2" on nitrous.. Try www.burnsstainless.com and fill out their spec sheet and fax it in. They seem to have that stuff down pretty good. It's free of charge and they will even draw you a print on the length and step lengths if needed..

[Chris Uratchko]

1 7/8 stepped to 2" on motor... only 1 7/8 for around 6-8 inchs. 1 7/8 straight through is pretty small for a big inch small block.

[94guy]

do you think i would lose some power on motor with straight 2"?

[Chris Uratchko]

Not with a 420" engine. I'm inclined to use a straight 2" over a straight 1 7/8.

[tom_cowle]

Don't let Ego make the decision for you, sure its great seeing them big pipes hanging out of the heads but often times cars have way too big of a header system on the car and they are hurting performance.

Call Stahl and or Hedders by Ed and see what they have to say, these people have been doing this stuff for years and doing it right too.

tom

[94guy]

update. iwent with a straight 2" header. the car ran the same MPH in the 1/8th 111.5 and 138 in the 1/4 @9.88. the biggest diff is the 60ft. is soft. i went from 1.43-145 to 1.52-1.54. any guess what i can do to pick the 60ft. back up?

[tom_cowle]

Mess around with cam timing to produce more bottom end, get your distributor reworked for a different timing curve, put in a different torque convertor to raise starting line rpm, the possibilities are endless

tom cowle

[Jay Allen]

update. iwent with a straight 2" header. the car ran the same MPH in the 1/8th 111.5 and 138 in the 1/4 @9.88. the biggest diff is the 60ft. is soft. i went from 1.43-145 to 1.52-1.54. any guess what i can do to pick the 60ft. back up?
Start off by loosening valve lash HOT. I'd go .002" at a time. Find out what the loosest(?) lash that can be run on that cam core.

But with that big of drop in sixty but it runs the same to the 1/8, the convertor is now wacked out. Think about it.......Almost a tenth slower in sixty but the same at the 1/8? Once she gets rolling its fast! The convertor needs work IMHO.

[94guy]

jay, i'm trying to get some bottomend back because the car has been 112-113mph in the 1/8th and has run better in good weather. the only reason i went to the bigger header is for the nitrous but i kinda want to have my cake and eat it too. jay do you see some improvement in the cam? this is what the cam card says for what i have now. 21btdc 57abdc 70bbdc 18atdc. .631-.631 int.centerline is 108. tell me what you think. i think the cam is on the small side. also the converter is a nitrous conv. and PTC told me to leave it where it's at for the nos? your thoughts on this too please.

[Jay Allen]

jay do you see some improvement in the cam? this is what the cam card says for what i have now. 21btdc 57abdc 70bbdc 18atdc. .631-.631 int.centerline is 108. tell me what you think. i think the cam is on the small side. also the converter is a nitrous conv. and PTC told me to leave it where it's at for the nos? your thoughts on this too please.
I think the convertor is too tight. But making convertor changes BEFORE you make engine changes will cost you double. wait to make convertor changes after you make any other changes.

Can the cam be better? In short, yes. And then you say the cam is small, what is this based off of? Be very careful just to look at duration @ .050" and conclude the cam is small or big. I look at *Lobe Area*. Lobe Area is a function of the entire lobe. Duration is on the "X" axis and lift is on the "Y" axis. 258/268, 631/631, 112+4 is a very mild camshaft.

There is plenty of room for improvement IMHO.