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Jeff's Headers using Grace Billet

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jtsllc1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jtsllc1 Quote  Post ReplyReply Direct Link To This Post Posted: Nov/12/2019 at 8:33am
Originally posted by klvn8r klvn8r wrote:

FWIW....I have the underhood pictures of the Paschal Javelin and the 'weird' "headers", along with the GM style front stub.  There's a fair chance that they've been posted before, or someone made copies.


Warren Prout made the headers for Jim Paschal as you can see in the pictures you have the headers were made with 1 5/8 primary pipe. The original set of Paschal's headers were for sale on Ebay sometime ago.

Yep with out a doubt I believe they figure out a winning combo between the Crossram and the primary pipe size. Winning 7 out of 8 races speaks for itself and knowing they need the engine to finish the race to win the race was priceless for them.

I.M.O. Warren Prout's headers are opposite in size compared to Penske or Ronnie Kaplan and so is the number of wins and engine failure's.

As far as the Grace Billet they can be considered similar but they are different. All the Grace Billet are identical for each cylinder and flow exactly the same even with the tightest 90 deg. stub cut from what they refer to as doughnut cut into 4 pieces. During flow bench testing rotating the tightest 90 deg. only varied 1 CFM.

The Grace Billet's also can be machined to use the venturi effect allowing a smaller dia. I.D. to out flow a 2 1/4 pipe with a tight 2" I.D. 90 deg attached to the Grace Billet. The 750 carb which uses an 850 throttle plate to produce 950 CFM would be a good example of the results a venturi effect has.  I stopped at just the 1 5/8 Grace Billet with a 1.5" I.D. because it turned out to be the right size for my combo to produce 500+ HP. I felt going bigger would have hurt my numbers in the lower RPM range. I ended up with 1 5/8 stepped to 1 3/4 because I need to cover the 3500 to 6800 RPM range and I also used Big's carb with a 1.440 dia.  opening up to a 1.750 throttle bore flow tested at 950 CFM for the Engine Masters Challenge.

If you were to look at the Paschal headers each port is not the same. I.M.O. they probably did some testing and found out the cast exhaust manifold when cut into a stub has a flow rating within 1 CFM as a cut 1 7/8 header primary pipe. Allot of shops who flow heads use a straight cheater pipe when they flow your exhaust. Coil Racing was surprised when we attached the Grace Billet on the exhaust port with the next tightest 90 deg. pipe  and the Grace Billet surpassed his straight cheater pipe by 10 CFM. He could not believe it and then I asked him if his straight cheater pipe would fit in the engine compartment? My last comment was since your cheater pipe can not you do not have real world exhaust numbers to give to the cam grinder and most likely if you were to have attached a cheater pipe with a bend your flow numbers would be even less.

In the end I always believe seeing is believing so I entered in the Engine Masters Challenge. Even though I had to run a 360 with out our good heads because of the exhaust valve size I decided to enter with the under par set of heads which even turned out to be more problematic with the oil passing the valve seals. We were able to qualify and beat several engines with only 256 CFM iron heads. 

If you were to look up the video you can clearly see for yourself the un ported Pro Flo 2 and the Grace Billet with the 1 5/8 stepped to 1 3/4 and Super Scavenger collectors with a 3 inch hat had not problems running to 6900 RPM and making over 500 HP @ 5890 RPM. I see no problems producing the same wide power range but with higher numbers reaching 550 peak, I will also be going smaller with a 2.5" hat for the collector and shorter primary pipes.

After running the same set of headers from the challenge on my AMX now with my 401  I really do not see the need to run big primary pipe headers in order to make 500 + HP. No Theory's just reality I.M.O. the same reality Jim Pascahl and Warren Prout figured out back in the day....

Since I found no need to run bigger soon Jeff will be the first to shed some light on running the next size up Grace Billet and like I said before seeing is believing. I look forward to see the results with Jeff's new intake and headers. Hopefully he will also be under index like the SS290 and Adkins. 

Edited by jtsllc1 - Nov/12/2019 at 8:41am
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i6cj7 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote i6cj7 Quote  Post ReplyReply Direct Link To This Post Posted: Nov/22/2019 at 10:06pm
Where can these Grace billet flanges be found/bought? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcenthusiast Quote  Post ReplyReply Direct Link To This Post Posted: Mar/29/2020 at 2:21pm
Thanks JTSLLC1 for your better explanations.
443 XRV8 Gremlin YouTube video:
XRV8 Race Parts website:
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