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· Young and learning
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46 Posts
Discussion Starter · #1 ·
Evening guys, greenhorn here.

I have a project 1969 corvette with a small block 350 in it. Engine was in the car when I bought it. This detail will become relevant later.

I'm running 461 heads, 2.02/ 1.60 valves. The ports in the heads appear to be unmodified but slag free, but I'll admit it I'm a complete newbie to this stuff, so my eye isn't trained to spot porting. Perhaps they were undercover ported? Vintage holley street dominator single plane manifold, part number 701R1-3001 topped with a 650 cfm holley 4165 carburetor. Solid flat tappet camshaft, idles choppy but not enough to have any issues idling. Stamped rockers, screw-in studs with guide plates, long tube headers. Cranking compression is 140-150 psi per cylinder. Stock bottom end in a 010 block. Finally, it's got long tube, 1 5/8 diameter primary headers. Engine runs on pump gas. Still need to verify base timing.

I'm trying to get an idea for how much horsepower this thing might make before I make the decision to buy more modern speed parts for it, as I suspect that this engine was built in the 80s or the early 90s. My educated guess says low to mid 300s, but I'm too inexperienced to really have an idea. At the same time, I'm fully aware that the rear ends of these cars get squirrely easily if one isn't careful, so I don't want to make too much power with it. If anyone has their own .02 to throw at me, I'm more than happy to hear it.

Eric Nova, if you're reading this, your input is always, especially appreciated.

Thanks, guys!
 

· Young and learning
Joined
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46 Posts
Discussion Starter · #3 ·
Eric, you're making my 23 year old self feel like I might actually know a thing or two, haha. My hat is off to you.

You're correct, the carburetor is a mechanical secondary, spread bore. I'm running 60s jets primary and 62s secondary, with 7.5 power valves on both sides. A little rich but I can fine tune that.

Thanks again for the response.
 

· Registered
Joined
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843 Posts
The number of horses does not really matter, what matters is if this car/engine puts a smile on your face, or if you like your timing slips. This also depends on the way you use/enjoy the car. 300 can be plenty or way too low, depends on you; the numbers are just for bragging rights, and when it comes to bragging, you can say whatever you want, anyway!
Let's see, for instance, is the car too slow off the line? Is it sluggish when passing? Does it run out of air at high RPM?... Then you can work on the specific area that needs improvement.
Also, sometimes the solution to a performance "problem" is not in the engine, but can be elsewhere (for instance an overdrive trans...)
 

· Registered
Joined
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296 Posts
Evening guys, greenhorn here.

I have a project 1969 corvette with a small block 350 in it. Engine was in the car when I bought it. This detail will become relevant later.

I'm running 461 heads, 2.02/ 1.60 valves. The ports in the heads appear to be unmodified but slag free, but I'll admit it I'm a complete newbie to this stuff, so my eye isn't trained to spot porting. Perhaps they were undercover ported? Vintage holley street dominator single plane manifold, part number 701R1-3001 topped with a 650 cfm holley 4165 carburetor. Solid flat tappet camshaft, idles choppy but not enough to have any issues idling. Stamped rockers, screw-in studs with guide plates, long tube headers. Cranking compression is 140-150 psi per cylinder. Stock bottom end in a 010 block. Finally, it's got long tube, 1 5/8 diameter primary headers. Engine runs on pump gas. Still need to verify base timing.

I'm trying to get an idea for how much horsepower this thing might make before I make the decision to buy more modern speed parts for it, as I suspect that this engine was built in the 80s or the early 90s. My educated guess says low to mid 300s, but I'm too inexperienced to really have an idea. At the same time, I'm fully aware that the rear ends of these cars get squirrely easily if one isn't careful, so I don't want to make too much power with it. If anyone has their own .02 to throw at me, I'm more than happy to hear it.

Eric Nova, if you're reading this, your input is always, especially appreciated.

Thanks, guys!
Without porting, maybe ~250-260 Hp at the rear wheels. With heads ported and everything optimized ~300-310 RWHP.
 

· True Hotrodder
Joined
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1,994 Posts
Actually those cars don't get too wild as far as the rear independent suspension. They actually bite a bit better than a solid axle. The problem is that if you do put a lot of power to the rear, the half-shafts will not be with you very long. There were big block shafts that you could get that were beefier and that helped but they too had their limits. Realistically 400-450 is probably a safe limit.
 

· Registered
Joined
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296 Posts
why does he need that if the alternator is already mounted? will it add more hp?
STRENGTH AND STABILITY
Made of 1/4" AMERICAN STEEL, the Header Power Bracket is precision CNC cut on a plasma machine. The brackets' design and increased strength eliminate flex and the associated accessory tweaking and belt squealing. Used without a spacer, the bracket "close mounts" the alternator toward the centerline of the car, reducing polar movement and allowing for use of a shorter belt, reducing whipping.

DESIGN OPTIONS
In addition to both left (driver) and right (passenger) standard brackets, both left and right extended brackets are available that allow for their installation using the #1 and #3 bolt holes, eliminating the difficulty of getting that "tricky" second bolt in-place.

Three styles of billet aluminium spacers, both in satin and polished finishes, are also offered. These work in conjunction with any of the brackets and are available in smooth, ball-milled, and ribbed finishes.

HE PROBLEM
> Big Power Can Strain Parts


f you want to make real power, you need headers on your
Small Block Chevy. And big power creates lots of strain on parts.

Changing to headers requires that you find another way to
mount your alternator. Since about 1969, Chevy and aftermarket heads have all included accessory boltholes on
their forward surfaces providing a convenient place to hang these accessories. But how are you going to mount your alternator if you run vintage '50's or '60's heads with headers?

For the last 55 years, the manufacturers have provided us with
a mass-market produced, thin piece of stamped 3/16" (typically now Chinese or Taiwanese) steel, add the cutout and holes (or even worse, "half holes"), and then stamp angles into it. The process of stamping the plate then distorts both the thickness, leading to varying width across the metal, and the shape of the holes that typically elongate in the process.

While the angles may make it a bit easier to attach the rear mounting bolt for the lower alternator bracket, they compromise the strength and integrity of the header bracket because they induce a flex as the offset bend stretches out like an accordion bellows. Couple that with the flex in the area around the header pipe that actually holds the bracket to the engine, and it is easy to understand why your alternator tweaks out of alignment causing your belt to squeal when you pull up on cruise night and rev your engine.
(How embarrassing!)
 

· Registered
1964 Thunderbird, 390 FE
Joined
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263 Posts
I'm kind of with 59 wagon man. If the OP's current setup works fine with no noticeable flex/alignment issues it'll probably be fine. Now, if I'm building an engine from scratch and am buying an alt bracket, I'd get the better american made one, but if it ain't broke, don't fix it. JMHO.

btw, cool vette. :cool:(y)
 

· Young and learning
Joined
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46 Posts
Discussion Starter · #16 ·
Whoa, I didn't realize how much this thread exploded since I last checked it!

As far as bracketry goes, I'm leaning with T-bird here. If the current setup gives me problems I'll upgrade. I'm very meticulous with my work, and I tend to notice the little details, so I'll be on top of it if I notice anything unusual or about to fail. Also, I just happen to work at a machine shop, so I could make my own bracketry if I really wanted to.

Thanks for all the responses, guys!
 
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