Thread: 260hp 350 crate motor

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i baught a 360hp 350 crate motor and was wondering how much horsepower and torque am i looking at if i add
dual cold air intake
650cfm carbureter
single plane manifold
vortec heads
thumpr cam
hooker headers

It's hard to quantify with only brand names. For instance, are you considering long or short tube headers, what lift/duration on the cam, for starters.

The cfm on the carb sounds conservative, and single plane manifolds are known for poor torque at low end, but the relatively small cfm carb could counter that if you use long tube headers, ultimately the cam runs the show- if you don't match everything as a unit, then you'll have a premium octane dog that can't run with the big boys.

Firebird nailed it! Sounds like you've picked a bunch of name brand parts.... Now some research and good advice on their compatibility with what you now have is in order. Also, been a lot of problems with flat tappet camshafts since the oil changed, hope you're talking hydraulic roller cam!

Welcome to CHR. Instead of jumping to a Thumper cam consider getting the specifics of the heads, manifold, carb and headers that you're planning to get and give the Tech Line at Comp Cams a call. Those guys are knowledgeable about their cam offerings, or can suggest a custom grind for you based on what you want from the engine and what fuel you want to burn. and they may suggest a different intake or header design than you've selected by brand name. The Thumper line is one of those designed as much for a lopey idle as for any true power gains, especially their "Mother Thumper".

i have done research on my parts and i have changed them and i ment 260hp 350 not 360hp
dual cold air induction
700cfm edelbrock carb
stage 3 dual plane vortec manifold
64cc vortec heads
magnum292 cam
hooker long tube headers with 3 inch diameter collector

Too much carb, a 600 is more then adequate especially when using an Edelbrock Carb. Get the calibration kit with it. Too big of a cam, doubt the lift would even work with the heads without coil bind. Try the Comp Cams "Cam Quest" software (it's free on their site), then follow it up with a call to verify with one of their techs.

What car is this going in, what's the transmission, what's the rear gear ratio??? All very important items when selecting your components!

Just a comment from the low end of the HP scale. I marvel that with a 3.55 ratio rear and a 700R4 transmission my SBC350 seldom gets above 2500 rpm in daily driving due to the trans shifting gears. Even though 5500 rpm should be possible I have only seen a max of 4500 rpm by holding the trans in third and not allowing 4th to kick in. My cam is a very mild regrind of the stock 1977 Z28 cam with about 0.010" more lift. The point I am trying to make is that a dual plane intake is better for low rpm torque and I have a Edelbrock Performer RPM rather than the Performer. It seems to me that the Edelbrock Performer RPM is a good compromise between a single plane intake and the more restrictive Performer. I am using the Edelbrock 600 cfm carb and can get 17 mpg with the 3.55 rear and still have a good low gear with the 700R4. I did shave the heads to get about 9:1 CR and had the exhaust ports smoothed out on the 882 heads and opted for a three angle valve job along with a 0.030" overbore cleanup and flat top eyebrow pistons, just a basic 350 rebuild with slight improvements. I had to use shorty hugger exhaust manifolds due to tight frame restrictions but longer headers would be better. I do not have a quarter mile time and can estimate my HP at only about 290 HP but I have to restrain myself at lights in the presence of local patrol cars and I can easily jump ahead of almost any other local cars on the highway accelerating from 50 to 70 mph for passing quickly so I almost never see the tac over 2500 rpm. My roadster weighs 2800 pounds with me in it and including heavy Model A bumpers. Again the point is that unless you are planning to use a 4.11 ratio rear you are better off designing your drive line for low speed torque rather than screaming 5500 rpm. Just my take on the daily driver situation.

Don Shillady
Retired Scientis/teen rodder

Originally Posted by Don Shillady

Just a comment from the low end of the HP scale. I marvel that with a 3.55 ratio rear and a 700R4 transmission my SBC350 seldom gets above 2500 rpm in daily driving due to the trans shifting gears. Even though 5500 rpm should be possible I have only seen a max of 4500 rpm by holding the trans in third and not allowing 4th to kick in. My cam is a very mild regrind of the stock 1977 Z28 cam with about 0.010" more lift. The point I am trying to make is that a dual plane intake is better for low rpm torque and I have a Edelbrock Performer RPM rather than the Performer. It seems to me that the Edelbrock Performer RPM is a good compromise between a single plane intake and the more restrictive Performer. I am using the Edelbrock 600 cfm carb and can get 17 mpg with the 3.55 rear and still have a good low gear with the 700R4. I did shave the heads to get about 9:1 CR and had the exhaust ports smoothed out on the 882 heads and opted for a three angle valve job along with a 0.030" overbore cleanup and flat top eyebrow pistons, just a basic 350 rebuild with slight improvements. I had to use shorty hugger exhaust manifolds due to tight frame restrictions but longer headers would be better. I do not have a quarter mile time and can estimate my HP at only about 290 HP but I have to restrain myself at lights in the presence of local patrol cars and I can easily jump ahead of almost any other local cars on the highway accelerating from 50 to 70 mph for passing quickly so I almost never see the tac over 2500 rpm. My roadster weighs 2800 pounds with me in it and including heavy Model A bumpers. Again the point is that unless you are planning to use a 4.11 ratio rear you are better off designing your drive line for low speed torque rather than screaming 5500 rpm. Just my take on the daily driver situation.

Don Shillady
Retired Scientis/teen rodder

Thanks Don! I was going to jump in with questions, but you just answered them all!! Going to put a 350 with a 4l60 in the wifes 56 chevy and want low end and drive-ability. The car weighs a little more than yours but your set up would work!(I think). Pete