Another Header issue.

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Casper393W
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Another Header issue.

Post by Casper393W »

Hey folks,. I know we have a topic going on headers but I have a different problem... I'm building a 393w with David Vizard and I am putting it in a 71 F100. My question is...what is the most power you guys have seen 1.625 headers support? There isn't a company out there that manufacturers a 1 3/4 or 1 7/8 header for a Windsor engine in a F100... So I'm stuck with a set of Hedman street headers until I can get some custom made.

Here is a pic of the engine
Let me know what you guys think!
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cgarb
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Re: Another Header issue.

Post by cgarb »

A 1.60 exhaust valve right? If the air makes it through there it will make it through the 1.625 tube, provided there are no mismatches at the port. I wouldn't pick it for a 1st choice, but if you weld up the outside and grind the flages to match the ports and taper it back in, it would work.
cjperformance
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Re: Another Header issue.

Post by cjperformance »

^^ 1.6" valve? Port face CSA?
End use of vehicle ? Full exhaust?
1.625"x.062"wall tube can make over 700hp when everything else is a correct match.
Your engine HP /estimate/goal?
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Re: Another Header issue.

Post by groberts101 »

I know less than squat about that chassis/header availability.. but just had to tell you I think.. AWESOME JOB!

Plus.. I really wanted to know what brand/model valve covers those are?! :mrgreen:
Casper393W
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Re: Another Header issue.

Post by Casper393W »

It is going to be a street/strip type deal. It does have 1.60 exhaust valves the exhaust flowed 215ish with no pipe... We should be on the Dyno here in the next few weeks... We are thinking it will make 600hp/ 540lbft
Time will tell... You would think they would make a header for a F100 with a 351w but since it was never offered from the factory that is why....

The rest of the combo is a Dynamic Racing built C4 trans M2 Fully Rollerized, with a 9.5 in 4000 stall converter, built 9in rear with 4.33 gears with CalTrac bars

A race weight around 3850lbs!!!!
Casper393W
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Re: Another Header issue.

Post by Casper393W »

Those are "C9" original Holman Moody valve covers I got from a guy at my work...I had to have them so I had to pay for them!!! Lol they were NOS in the box! $300
cjperformance
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Re: Another Header issue.

Post by cjperformance »

Yeah nice valve covers! I recon $300 is cheap for something with some history.
Yse the headers you have at 1-5/8" they will work great. 2.75" collector if using a straight collector with no time to try different sizes.
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Casper393W
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Re: Another Header issue.

Post by Casper393W »

Thanks guys for the kind comments! I hated paying that much for them, but I had never seen a set in person! I had to get them and the boxes they came In were pretty awesome too.

I hope they work well....I know they will prolly give up a few numbers compared to a 1.75 tube. But what is the old saying???? Beggers can't be Choosers!
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Re: Another Header issue.

Post by 427dart »

Is that the Weiand 302 tunnel ram with Price Motorsport adapters? What carbs?
I had a pair of those valve covers on my 302 back in the 90's !
GARY C
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Re: Another Header issue.

Post by GARY C »

400 ci SBC with T. Ram, header test, 1.5/8 vs 1.3/4.
https://www.youtube.com/watch?v=rTlHEOE ... HutSOu7srE
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Casper393W
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Re: Another Header issue.

Post by Casper393W »

427dart wrote: Thu Mar 15, 2018 9:00 pm Is that the Weiand 302 tunnel ram with Price Motorsport adapters? What carbs?
I had a pair of those valve covers on my 302 back in the 90's !
Yup you got it! The carbs are 1850's that BLP modified for me they have machine stepped boosters... The throttle shafts have been slabbed. I am so ready to see and hear this baby run!
cjperformance
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Re: Another Header issue.

Post by cjperformance »

GARY C wrote: Thu Mar 15, 2018 9:18 pm 400 ci SBC with T. Ram, header test, 1.5/8 vs 1.3/4.
https://www.youtube.com/watch?v=rTlHEOE ... HutSOu7srE
They are always interesting tests to watch but it only really shows (and they say this in the vid) that the 1-3/4" set out of the 3 options available were the best option on that combo and tune.
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Casper393W
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Re: Another Header issue.

Post by Casper393W »

I was really surprised that there was only about 10 HP difference..between the 1 5/8's and 1 3/4's. Given this was a 530 HP engine. I would say the numbers would diverge more as the power increases. So at a 600hp level you would might see a 20-25hp difference?? I'm guessing

I'm sure also if the engine had a tighter LSA camshaft the gains would be even greater???

If you have been watching that show the very first show they made nearly 560 HP with the same engine but without mufflers!
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Re: Another Header issue.

Post by groberts101 »

Casper393W wrote: Fri Mar 16, 2018 6:49 am I was really surprised that there was only about 10 HP difference..between the 1 5/8's and 1 3/4's. Given this was a 530 HP engine. I would say the numbers would diverge more as the power increases. So at a 600hp level you would might see a 20-25hp difference?? I'm guessing

I'm sure also if the engine had a tighter LSA camshaft the gains would be even greater???

If you have been watching that show the very first show they made nearly 560 HP with the same engine but without mufflers!
Guessing yours is very similar to that build used in the test and would also like the 1.75" pipe to take better advantage of that induction system. Maybe run these for now and look at mod'ing a set of cleveland/351M/400M headers with new stubbed flanges?

What they DON'T show you in that video is.. and is typical for inertia dyno's in general.. is the transient throttle response and low rpm acceleration rate differences that a smaller header will give in an actual running driving vehicle. Does your engine really accelerate at 600rpm/sec in 1st gear? I also find it kind of ridiculous to assume that 1 tune fits all and not take the time to at least TRY to redial the tune to find further gains/losses. Hell, we often have to redial the fuel curve, even spark curve, slightly just by changing out an air cleaner and or replumbing on an induction system.. so seems rather silly to assume that an engine would not need slight recal for different header sizes too.

And don't even get me started about running standardized AFR's! Assuming that a specific AFR is best for all motors and combinations of parts is very misleading to say the least! I've tuned dozens of engines that have come out reputable chassis dyno shops through the years and found power, sometimes LOTS, below the rpm parameters used on the dyno. Most of it can be found under peak torque because the dyno operator(or equipment) couldn't or simply didn't care, or customer was too damned cheap, to simulate road loads the engine actually encounters. Starting the pull from 3,000 rpm saves time and money and just fluffs the numbers for people who like to brag and frame the printout on their walls.

Sorry for the rant.. cool video but in the end not fully comprehensive and same old typical magazine/video BS as usual.
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Re: Another Header issue.

Post by jasonn »

I have a 70 mach with a 408 windsor stroker. vic jr heads, dual plane perf rpm intake. 750 holley with a small hyd roller. 1 5/8 headers. Dyno'd at 525hp. Tons of torque. I am sure it could pick up a bit with bigger headers (among other things) But It's a blast to drive and I am happy.
1970 mach with mild 351w
11.40's@117
1970 prostreet fastback with pump gas 427
8.58@157 2nd place pro street p/a 2021 drag week
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