How much increased horses and torque

[Wyatt Tankersley]

So I've got a 350 out of and 85 c20 suburban so it has a 4 bolt main. I have put wieand dual plain intake with an edlebrock 650 cc carb with long tube heads I just put a new cam in it with .443 lift on exhaust and intake with 280 duration and 110 degrees of lobe separation and was wondering if any knew, ball park, how much horse and torque it will make. It's got a m465 4 speed behind it

 

[Bent77]

Depends on how good the compression is on the cylinders still and how well the heads flow

I’d guess about 280 hp, maybe 360 lb/ft

 

[Wyatt Tankersley]

Depends on how good the compression is on the cylinders still and how well the heads flow

I’d guess about 280 hp, maybe 360 lb/ft

They are just the stock heads from 85 and the cylinders all have perfect compression

 

[Bent77]

Keep in mind those heads are some of the worst GM made

84 was the year for the lowest compression on the 350

 

[Wyatt Tankersley]

I cant seem to find the specs on my cylinder head and it wont let me attach a picture but on the front of the heads they have 3 lines pretty much I know the are not like the vortex triangle mountain or whatever you wanna call them

 

[Bent77]

Unless someone put different factory heads on them, they should be open chamber 1.94 valve smog heads

 

[Wyatt Tankersley]

Unless someone put different factory heads on them, they should be open chamber 1.94 valve smog heads

So that's bad right

 

[Bent77]

So that's bad right

they are already paid for. Despite everyone’s desperate love for Vortec heads, the realized power gains aren’t that significant

If one of those heads needed service or replaced, then I’d worry about it

 

[Wyatt Tankersley]

they are already paid for. Despite everyone’s desperate love for Vortec heads, the realized power gains aren’t that significant

If one of those heads needed service or replaced, then I’d worry about it

Well they actually can make just about 380 horse and around the same torque if you mill down the valve spring seats to so you can put larger valve springs in and convert the press in studs to screw in and that is all with a stick bottom end and a mild street cam

 

[tRustyK5]

I'd agree on the power numbers. Might go as high as 300 hp, but 275 is more likely.

 

[Bent77]

Well they actually can make just about 380 horse and around the same torque if you mill down the valve spring seats to so you can put larger valve springs in and convert the press in studs to screw in and that is all with a stick bottom end and a mild street cam

Once you've spent that much on stock heads (if they aren't or don't crack) you'd have spent enough to buy aluminum heads

 

[tRustyK5]

Blueprint crate, stop wasting time with old OE junk from the worst era of the big three...

https://blueprintengines.com/produc...te-engine-small-block-gm-longblock-bp38313ct1

 

[6.2Blazer]

Depends on how good the compression is on the cylinders still and how well the heads flow

I’d guess about 280 hp, maybe 360 lb/ft

I'm not an engine guru but if you started with the completely stock engine from that vehicle it would have been 160-170 HP stock. I really doubt you would get anywhere close to that amount of power out of it with stock heads and pistons. Just using a butt dyno I used to go to USAC Midget races with a guy in a mid-80's Suburban that had a built 350 that had good (for the time) heads and slightly higher compression along with everything else listed by the OP above. It ran much, much stronger than stock......but the next replacement vehicle was a newer Suburban with a 255 HP Vortec 350 and it pulled just as strong.

 

[Bent77]

I'm not an engine guru but if you started with the completely stock engine from that vehicle it would have been 160-170 HP stock. I really doubt you would get anywhere close to that amount of power out of it with stock heads and pistons. Just using a butt dyno I used to go to USAC Midget races with a guy in a mid-80's Suburban that had a built 350 that had good (for the time) heads and slightly higher compression along with everything else listed by the OP above. It ran much, much stronger than stock......but the next replacement vehicle was a newer Suburban with a 255 HP Vortec 350 and it pulled just as strong.

Keep in mind the difference between how they rated power on early engines versus late

I have dyno sheets from and 8.5:1 stock 1.94 cylinder head and cast iron intake, unported, making 426 hp at 6100, 458 lb/ft


It’s there

 

[tRustyK5]

The horsepower rating thing changed in '72 from "Gross hp" to SAE net horsepower. The big thing is the engines were rated with all the accessories, fan, full exhaust, the whole deal it would be saddled with in the car. An example is the Mopar 318 rated at 230 hp gross through the late 60's until 71. No changes made to the engine for '72, but now rated as 150hp SAE net.

When we pay to dyno an engine, there are no accessories, usually dyno headers, no air filter, and coolant and oil temps are in the sweet spot for max power. 135 F. Running the same engine at 195 F can lose you 15-25 hp alone.