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Old 03-13-2019, 11:12 PM
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350 Crate with Mods HP estimate?

Just curious if anyone has built there 350 in a similar fashion and have a H.P. estimate? Dyno?
350, Std Bore and Stroke, Flat top hyperuetectic pistons with 4 valve reliefs with stock piston to deck height, Vortec heads with some minor exhaust port clean up and intake bowl clean up not disturbing the Vortec intake shape. 64CC. Shim gasket for around 10.2:1. Comp HE 268 - 454-454 lift, 268 duration - 218/[email protected], Jegs aluminum high rise with a 600 Holley, Headers. HEI ignition.

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Old 03-14-2019, 03:36 AM
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Should make a nice solid 395-410 Hp combination. Nice simple set-up

If you are geared enough to use it a 750 cfm carb will help from midrange on up to add another 15 hp on the dual plane intake, as each cylinder only "see's" 1/2 of the carb flow when on a dual plane intake even though a notched plenum divider helps to alleviate that somewhat.
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Old 03-14-2019, 08:05 AM
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Quote:
Originally Posted by arnoldsel View Post
Just curious if anyone has built there 350 in a similar fashion and have a H.P. estimate? Dyno?
350, Std Bore and Stroke, Flat top hyperuetectic pistons with 4 valve reliefs with stock piston to deck height, Vortec heads with some minor exhaust port clean up and intake bowl clean up not disturbing the Vortec intake shape. 64CC. Shim gasket for around 10.2:1. Comp HE 268 - 454-454 lift, 268 duration - 218/[email protected], Jegs aluminum high rise with a 600 Holley, Headers. HEI ignition.
This is a pretty commonly done recipe that works very well and has a lot of test reporting. The baseline dyno numbers are in the range of 375 to 385 around 5500 RPM with pretty solid torque numbers all the way up. A very good combination for a solid build that makes excellent streetable power.

This can be pushed into the 400's with a 750 CFM carb some people have done it with a 650. That mounted on an Edelbrock RPM or similar well designed intake. 1.6 roller rockers, preferably non self guiding to get some weight off the business end and mounted on 7/16 studs to stiffen up things without having to go to girdles which are hard to fit to L31 heads without going to perimeter bolt adapters and valve covers which is something that can happen with roller rockers as well as some of these interfere with the center bolt covers.

This is a build that is a good choice of components that makes a long lasting reliable motor with muscle car power.

Bogie
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Old 03-14-2019, 08:37 PM
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750 Holley?

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Originally Posted by ericnova72 View Post
Should make a nice solid 395-410 Hp combination. Nice simple set-up

If you are geared enough to use it a 750 cfm carb will help from midrange on up to add another 15 hp on the dual plane intake, as each cylinder only "see's" 1/2 of the carb flow when on a dual plane intake even though a notched plenum divider helps to alleviate that somewhat.
Thanks! It does run well but was not sure on the power. I'll take those numbers! LOL! I was thinking more like the 330hp crate engine but adding 30 with the Vortecs and about 10hp with the C/R from the flat tops. 370hp conservative figure? Just put in 3.73 posi about 200 miles ago. Really can feel a good bump.

So the 750 Holley would wake it up? I do have one and thought about using it. Have any idea on Jetting?
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Old 03-14-2019, 09:54 PM
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Stock jetting should be on the money, maybe a step or two lower in the front but you'll have to drive it and tune it to be sure.

72 jet front, 80 jet rear is stock if it is the no rear power valve version.

Will probably prefer the lighter Purple spring in the vacuum secondary(stock is plain/silver, slow to open) so get a spring assortment kit, 31 pump nozzle(shooter) for the pump shot(stock will be 28, you can try it before to see if it will be enough) and either the stock White pump cam, might need to be the second hole, or the Orange cam in the same second hole(probably want to get the Pump Cam assortment kit too).
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Old 03-15-2019, 09:10 AM
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Carb tuning

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Originally Posted by ericnova72 View Post
Stock jetting should be on the money, maybe a step or two lower in the front but you'll have to drive it and tune it to be sure.

72 jet front, 80 jet rear is stock if it is the no rear power valve version.

Will probably prefer the lighter Purple spring in the vacuum secondary(stock is plain/silver, slow to open) so get a spring assortment kit, 31 pump nozzle(shooter) for the pump shot(stock will be 28, you can try it before to see if it will be enough) and either the stock White pump cam, might need to be the second hole, or the Orange cam in the same second hole(probably want to get the Pump Cam assortment kit too).
Eric, thanks and great info. Always helps to get help with the learning curve. I am always in the pursuit of more power but don't want it to be a stinking pig rich idler! LOL!

I do have the Vacuum Spring kit from tuning the 600. I actually swapped over the components from the 4150 (3310) because a fuel bowl started leaking around the fuel inlet and could not fix it.. So I am using really the main body and throttle plate only. Works really well. So no metering plate on the secondary side. Jets fore an Aft. So it is just a swap back. The guy I bought the 750 from did some jetting tuning for a 351 Ford with some camming. So the jets in it are probably pretty close. almost certain the fronts were the 72 but not sure about the rears.
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Old 03-28-2019, 04:57 PM
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I just purchased a 260HP version of one of these engines.
Had it running now for several years and very happy with it.
It has a low compression ratio but still decent HP and I can run any gas without issues...

https://www.jegs.com/p/Chevrolet-Per...gin|0||P_SKU|0

The only thing that was disappointing to me was the on going problem of oil leaks from front of oil pan.
For Christ sake it is the year 2019 and GM still can not offer an engine without leaks no improvement since the 1950's in that regard...
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