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Topic Review (Newest First)
09-27-2011 08:45 PM
cucumber1949 8.8 CR, 1971 El Camino stock cam, large chamber heads (487 castings with 1.94 intake valves), RPM Air Gap, Edel 1806 carb, running flat top pistons with 4 valve reliefs and steel shim head gaskets, 2000 stall converter. This cam leans toward low end torque.

I originally had 3.36 gears, but when I rebuilt the car I put the current axle in. Now I wonder if I should have stayed with the 3.36. With my current tires the engine turns 2600 rpm at 60 mph. On long trips this thing really needs an overdrive.

I run a 4-row copper/brass radiator with an electric fan on a thermostat, 195 stat. Have never had any issues with cooling. Engine runs consistently at 205 degrees on the highway in the summer.
09-27-2011 06:54 PM
speedball Thanks for the help cucumber

What kind of compression are you running and what intake and cam do you have?

If 3.73 is a little too high what would be the logical step down?

With a stock type engine I would imagine keeping it cool is an added bonus.

Mike
09-27-2011 05:01 PM
cucumber1949 What is it the car will be doing most of the time? Are you planning on regularly racing it? Or will it be a street cruiser most of the time.

There are a lot of details when planning your setup, but from a high level view, consider the following. If your racing, then yes you need to closely match up all your components to get the most performance per run. You will want your torque curve up higher in the RPM band, matching it to shift points and torque converter stall, but choosing the highest ratio in the rear you can without running out of RPM at the end of the run. Lots of variables here.

If it is a street cruiser, then you have other objectives. The car is so light that even a mild street engine will make this car move, and move briskly. The race setup won't be very streetable. A 4.56 gear on the highway with a TH-350 is annoying and not very efficient. You'll want your torque curve lower in the RPM band, good vacuum and idle, and you'll probably want your torque converter to have a lower stall, and you'll want your cruise RPM to be reasonable so a numerically lower rear gear helps out here.

The setup in my T-Bucket is similar to yours and it is a mild street cruiser, good idle, high vacuum, stock cam, but can melt the tires if you want (not very much weight on the back end anyway so the tires are easy to break loose). Sometimes I think the 3.73 gear I run is still too high for long periods of highway cruising. You can still get a lot of power here - mine was timed once when I could keep it hooked up at 3.85 seconds for a 0-60 run - that will outperform 95% of anything else on the street and it still behaves well when you keep it on a leash.
09-27-2011 02:58 PM
speedball
Horsepower vs Torque......ratios?

I posted an earlier question about some double hump heads....and that leads to talking about cams........which leads to talking about compression.......which leads to talking about transmissions.......which leads to rear end ratios.

Holy crap is my brain spent.......

I need to clear my head and rethink this. Lets assume I have only a couple known factors.

1.) 2,000 pound T-Bucket
2.) 350 engine block
3.) Camel hump 1.94 heads
4.) TH-350 transmission

OK, here is what I don't understand. I hear people talk about torque and I hear people talk about horsepower. I looked at some dyno sheets online and I noticed that certain builds have really different ratios as it concerns the two. Some dyno sheets show an engine that produces high torque at low RPM's but low HP numbers until it reaches 5,000 RPM's where it peaks.

Then I noticed where torque was really low until RPM's climbed but HP came in early in the RPM range.

What I read, and what others are telling me, is that I can't pick out a camshaft until I know things like rear end ratio etc.

So here is my question. What is ideal for a light car like a T-bucket? Torque early on in the RPM cycle or HP early on in the RPM cycle?

Once I know that how would that help me to decide on what rear end ratio to use?

Pleas help, this is really confusing for me.

Mike

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