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Closed chamber head....
https://slantsix.org/forum/viewtopic.php?t=65770		 Page 9 of 9
Author:  DusterIdiot [ Thu Apr 15, 2021 6:23 am ]
Post subject:  D
D
Author:  Joshie225 [ Thu Apr 15, 2021 9:33 am ]
Post subject:  Re: Closed chamber head....
This is an interesting discussion. With a stock 1967 short block, including the camshaft, 390 Holley on an Offy manifold, single 2.25" exhaust off a lightly ported Chinese exhaust manifold, a ported head with 1.70/1.44" valves, shaved .080" netting a whopping 8.5:1 compression ratio I would run about 17.1 1/4 mile ETs. Did a 16.86 at Woodburn. The transmission was the A903 manual 3-speed and 3.21 axle.
Author:  Dart270 [ Thu Apr 15, 2021 10:54 am ]
Post subject:  Re: Closed chamber head....
Interesting differences. I probably would not run lower than 240 @ 0.050"" with a 10:1 SCR motor. Have run 250@ 0.050" @ 10:1 and it starting making good power around 3000-3200 and revved great to 6000 (as high as I dared w/stock type rods+pistons). Yep, 15 deg initial timing and 27-30 deg at full mech adv. Car ran mid 14s in street trim without fancy tires and w 3400 stall converter and 3.91 gear. High 14s w/3.23 gear.

Lou
Author:  StrokerScamp [ Fri Apr 16, 2021 9:12 am ]
Post subject:  Re: Closed chamber head....
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Actually sounds nastier than I thought it would. This one is right at 10:1 and that's the reason for the big cam so it will be pump gas friendly at 7.9 dynamic. .465 lift, 250 @.050 duration ground on a 108. QFT 450 on an Offenhauser intake with a ported exhaust manifold also opened up to 2.5".
Yeah that overlap event with 250@50 and 10:1 is going to bleed down the cylinders pretty good and provide a noticeable lump...for street I would not go above 235@50 for a 10:1SCR motor...
(currently I have a 250@50 cam at 109 in a 12:1 motor and it runs fine on pump super and a custom timing curve)...Just as an FYI, I ran a 10:1 motor with dutra duals and a hyperpak with a 390 cfm
Holley and it did high 16's on the 1/4-about 190-ish HP... same engine with a 450 holley, offy intake, and single pipe exhaust put the 1/4 back to 17.9 seconds about 160-ish HP...so looking at the build, you are leaving some power and volumetric efficiency on the table...)
At that bleed down and duration its also going to want a lot of initial timing (15 is about right), and your power band is going to sit in the 4000 rpm range...just sayin'... :wink:
and that's just perfect by me. It has 13s and factory 3.55 gears. It's turnin probably tween 3000 and 3500 at 65. The plans are a narrowed to stock width Ford 9" with 235 60 14s and 4.10s so that'll be just right.
Author:  StrokerScamp [ Fri Apr 16, 2021 8:03 pm ]
Post subject:  Re: Closed chamber head....
Here it is after the new exhaust installed and then going down the road to my friend Freddie's house. I must admit, it's really stout and I don't mean "for a slant 6". This car really hauls the mail now. And keep in mind this is with the stock milled head and stock bottom end......sans cam. Very happy with it so far.

https://www.youtube.com/watch?v=T2pyfYeY1IU&t=4s


https://www.youtube.com/watch?v=xjsvAZw-Zn8&t=160s
Author:  StrokerScamp [ Sun Apr 25, 2021 9:34 pm ]
Post subject:  Re: Closed chamber head....
Sneakin up on the tune. Startin to sound really good.

https://www.youtube.com/watch?v=YYcIRxXosa4&t=16s
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