Under performing 357 sbc
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Re: Under performing 357 sbc
Make up port floor tongue inserts to fill the floors of the intake ports to speed up the ports.
Play with the insert contour to get it right.
Play with the insert contour to get it right.
Re: Under performing 357 sbc
Thanks to all!!
Great info here It sounds like I need a smaller intake port to wake up the combo.
Thoughts on the cam with a smaller intake runner?
Great info here It sounds like I need a smaller intake port to wake up the combo.
Thoughts on the cam with a smaller intake runner?
Re: Under performing 357 sbc
256-260 int, will get a 357 in the 72-7500 range with your style of head. the exhaust should be based off of the exhaust system. If your running headers and collecters only, about 5 degrees less exh duration will be pretty stout. If you start adding tail pipe or collecter extensions to it than you need more exhaust duration.
I've had decent luck reverse engineering the exhaust lobe to fit the current exhaust sytem with pipemax.
Obviously giving as many specs as you can to a cam expert could be a good way to go.
I've had decent luck reverse engineering the exhaust lobe to fit the current exhaust sytem with pipemax.
Obviously giving as many specs as you can to a cam expert could be a good way to go.
Mummert Machine and Development 4 stroke hp
Mummert Y-blocks
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Re: Under performing 357 sbc
That cam should work well with smaller heads & better intake.
Mine is 4.040x3.48
264/272 .686 .630. 108 in at 104
A little more compression with Dart 215’s & a SV
750 alky carb on a 2” spacer
Tight 5700 converter with 4.88’s & weighs 300lbs less in an old upright roadster with 14.5x32’s
1.21 3.60 5.65@120 shifted at 7200 & crosses @ 6400 1/8th
Put the right heads on yours & it should fly.
Re: Under performing 357 sbc
I can tell you through several conversations.....larry meaux does not put a lot of stock in ports being too large for the cfm. He said thats a typical trait of the BBC rectangle port.......and that 260 fps is about the slowest fps that still makes the expected horsepower. Even as big as the runner on a 235 is.....it will still be 260+ fps, and honestly shouldn't cost power. For example.....LS3 ports that stock flow 320 cfm. Similar size to cfm. But those 6.0's haul the mail.....period. Too slow is rarely an issue. Too fast is usually it. I'd guess neither in this case. Is the head ideal? Probably not......but I bet a 290 cfm head with a 210 runner wouldn't make much difference.WeingartnerRacing wrote: ↑Tue Oct 15, 2019 11:43 pm The heads stock only move about 290s cfm on my bench and for that size runner it makes them a turd velocity wise. You port them and really wake them up but then they are larger than what you can use. As they are now with your combo the heads are already borderline. The older hurricane intakes are not as nice as the newer ones. However either way they are decent but not great. Porting helps them too.
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Re: Under performing 357 sbc
Get that engine on a dyno, cam timing, tuning, and the resultant graph can help with converter and gear selection. Knee jerk response is you need more converter stall. 350/glide is yawn inspiring. More cubes would definitely help.
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Re: Under performing 357 sbc
Yes but I would rather have 285ft per sec. It will make more power and run better. I’m not arguing for a smaller head but one that moves more air for that size.rewguy wrote: ↑Fri Oct 18, 2019 8:01 pmI can tell you through several conversations.....larry meaux does not put a lot of stock in ports being too large for the cfm. He said thats a typical trait of the BBC rectangle port.......and that 260 fps is about the slowest fps that still makes the expected horsepower. Even as big as the runner on a 235 is.....it will still be 260+ fps, and honestly shouldn't cost power. For example.....LS3 ports that stock flow 320 cfm. Similar size to cfm. But those 6.0's haul the mail.....period. Too slow is rarely an issue. Too fast is usually it. I'd guess neither in this case. Is the head ideal? Probably not......but I bet a 290 cfm head with a 210 runner wouldn't make much difference.WeingartnerRacing wrote: ↑Tue Oct 15, 2019 11:43 pm The heads stock only move about 290s cfm on my bench and for that size runner it makes them a turd velocity wise. You port them and really wake them up but then they are larger than what you can use. As they are now with your combo the heads are already borderline. The older hurricane intakes are not as nice as the newer ones. However either way they are decent but not great. Porting helps them too.
Eric Weingartner
Weingartner Racing LLC
918-520-3480
www.wengines.com
Weingartner Racing LLC
918-520-3480
www.wengines.com
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Re: Under performing 357 sbc
Just for reference my personal 355 12to1 has 241cc head flows 323cfm made 672hp@7500 on methanol. I like a little large with runner.
By the way someone recommended a cam not to far off from mine used in this. 252/258
By the way someone recommended a cam not to far off from mine used in this. 252/258
Eric Weingartner
Weingartner Racing LLC
918-520-3480
www.wengines.com
Weingartner Racing LLC
918-520-3480
www.wengines.com
Re: Under performing 357 sbc
What kind of tq at what rpm? It seems the bigger head has a higher peak tq rpm and the op may need to look at an under performing combo as oppose to an under performing 357..WeingartnerRacing wrote: ↑Sat Oct 19, 2019 12:29 am Just for reference my personal 355 12to1 has 241cc head flows 323cfm made 672hp@7500 on methanol. I like a little large with runner.
By the way someone recommended a cam not to far off from mine used in this. 252/258
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!
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!
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Re: Under performing 357 sbc
I would put a 617 gear in it or 630 with that much tire , and 272/280-104 and a 7000 stall ,,, , it's a 350 , wind it
Re: Under performing 357 sbc
On a running 355 cube engine, 44.375 cubes and speed of the piston determine port speed, not the flow bench.
Randy
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Re: Under performing 357 sbc
I agree with Eric. I did a circle track engine with those heads and they suck as cast. Yes they are a little large, but I would still port them and GET THE RIGHT CAM. A large port will be more sensitive to cam selection than a smaller fast port. Just the opinion of a typical garage hack.
Re: Under performing 357 sbc
BBC has "no" valve area per cu/in.. You cannot compare two engines with different curtain areas in a velocity discussion. One has the choke point at the valve and one has it back at the pushrod. When your velocity fall in the tank, you'll suddenly start finding miracles in overly aggressive port textures, kind of like the Ford Boss 302 guys.rewguy wrote: ↑Fri Oct 18, 2019 8:01 pmI can tell you through several conversations.....larry meaux does not put a lot of stock in ports being too large for the cfm. He said thats a typical trait of the BBC rectangle port.......and that 260 fps is about the slowest fps that still makes the expected horsepower. Even as big as the runner on a 235 is.....it will still be 260+ fps, and honestly shouldn't cost power. For example.....LS3 ports that stock flow 320 cfm. Similar size to cfm. But those 6.0's haul the mail.....period. Too slow is rarely an issue. Too fast is usually it. I'd guess neither in this case. Is the head ideal? Probably not......but I bet a 290 cfm head with a 210 runner wouldn't make much difference.WeingartnerRacing wrote: ↑Tue Oct 15, 2019 11:43 pm The heads stock only move about 290s cfm on my bench and for that size runner it makes them a turd velocity wise. You port them and really wake them up but then they are larger than what you can use. As they are now with your combo the heads are already borderline. The older hurricane intakes are not as nice as the newer ones. However either way they are decent but not great. Porting helps them too.
Mummert Machine and Development 4 stroke hp
Mummert Y-blocks
Mummert Y-blocks
Re: Under performing 357 sbc
The tech info these days sounds like it's coming from politicians...
You need a fast slow port with slow fast gental sharp radius's with good cfm that doesn't flow through a big small valve with a critically sized ports right between 150 and 300 cc should get the job done without fail... if you have the correct solid hydrophilic flat tappet roller minimum full travel cam with shaft stud rockers with 0 W 10/15 30/40/50 mineral synthetic used new oil.
Hi, I am Gary C and I approve this message... Maybe.
You need a fast slow port with slow fast gental sharp radius's with good cfm that doesn't flow through a big small valve with a critically sized ports right between 150 and 300 cc should get the job done without fail... if you have the correct solid hydrophilic flat tappet roller minimum full travel cam with shaft stud rockers with 0 W 10/15 30/40/50 mineral synthetic used new oil.
Hi, I am Gary C and I approve this message... Maybe.
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!
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!
Re: Under performing 357 sbc
GARY C wrote: ↑Sat Oct 19, 2019 5:11 pm The tech info these days sounds like it's coming from politicians...
You need a fast slow port with slow fast gental sharp radius's with good cfm that doesn't flow through a big small valve with a critically sized ports right between 150 and 300 cc should get the job done without fail... if you have the correct solid hydrophilic flat tappet roller minimum full travel cam with shaft stud rockers with 0 W 10/15 30/40/50 mineral synthetic used new oil.
Hi, I am Gary C and I approve this message... Maybe.
You're in rare for today Gary.