Stock engine or race engine ?

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Tynan918

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You guys know I've been here since last year and I've been playing with this timing and I've been trying to identify things... Especially the parts that are in my engine.

I got to thinking to myself this morning about the parts that were on it when I bought it and started researching some things...

For starters, I believe this car was either used for racing or it was being built to race.

The engine came with a Victor Jr single plane intake... The car ran fine on the highway and all with that Victor Jr single plane intake. My question now is, can you run a stock camshaft with a Victor Jr single plane intake or wouldn't that intake require a bigger cam from stock ?

Wouldn't it cause problems to use a stock camshaft ?
 

ck80

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You guys know I've been here since last year and I've been playing with this timing and I've been trying to identify things... Especially the parts that are in my engine.

I got to thinking to myself this morning about the parts that were on it when I bought it and started researching some things...

For starters, I believe this car was either used for racing or it was being built to race.

The engine came with a Victor Jr single plane intake... The car ran fine on the highway and all with that Victor Jr single plane intake. My question now is, can you run a stock camshaft with a Victor Jr single plane intake or wouldn't that intake require a bigger cam from stock ?

Wouldn't it cause problems to use a stock camshaft ?
To be honest, the condition of that car when you first came on board ranging from the busted parts to the rats nest of horrendous wiring, and add the fact it was a 305, it obviously was being built by a fool who knew nothing about cars.

They literally must've been just throwing either whatever they could lay their hands on into it, or, whatever 'sounded good' in an evert to impress people with no thoughtfulness or planning put into the build.

Well, either that, or had a major crack/meth problem and whatever they were attempting made sense in their own minds, just not in the real world.

Yes, usually a single plane intake is chosen as part of a matched pkg of intake/cam/carb/converter/steep rear gears. However, as I already said, your car was so jacked up I don't see that level of thought having gone into it and think it was a collection of what sounded cool to a crackhead.

As for can you use it with a stock cam? Well, single plane basically robs low end torque and grunt to give more top end and flatten the area under your curve.
 
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Tynan918

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As for can you use it with a stock cam? Well, single plane basically robs low end torque and grunt to give more top end and flatten the area under your curve.
Which means at high speeds on the highway I wouldn't very much power, just at take off ?
 

ck80

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Which means at high speeds on the highway I wouldn't very much power, just at take off ?
No.

First, to even get a proper benefit the whole package needs to be set up to work together.

Second, if properly paired, with a single plane you would see less drop off in power at the high rpm range but the trade off is a lower peak in the lower rpm range.

It comes down to how the a/f mixture moves in the different intakes.

Single plane is a big open space, all runners pulling from a common plenum without mucj bends. So you get the benefits and losses from minimum flow restrictions. Also means smaller carb acts bigger than it is. However, you lose air velocity at the lower end, and, your air fuel charge density becomes lower - think a window fan on low vs high speed.

the other issue in the sbc world is the same problem you see when guys put a 4bbl manufold on an inline 6. Adjacent cylinders in the firing order can rob air/fuel mix volume from eachother, first cylinder to fire out of each pair robs some of the charge from going to the followup cylinder in the order. So, on a 18436572 pattern 5 will rob 7, 8 will rob 4... at least at lower rpm, until the higher velocity of air evens things out a bit at high rpm.

And, if you have numerically low gears, your engine wants to run low rpms as a result of that gearing, and thus, the problem becomes even more pronounced than the higher gears that keep the engine turning higher rpms.

It's an rpm thing, not so much a speed thing, aside from the fact that your gearing and tire size may naturally have you turning higher rpms at highway speeds. It's the rpm that matters.
 
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SSMonteMan

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With what you have your dual plane intake is perfect.

This is your daily/only car, right? Don't turn it into a race car. Don't try to turn it into a race car. Race cars are unreliable money pits. Ask anyone that has one.

And I agree with ck80 on all points. Really hits the nail on the head.
 
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bracketchev1221

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With what you have your dual plane intake is perfect.

This is your daily/only car, right? Don't turn it into a race car. Don't try to turn it into a race car. Race cars are unreliable money pits. Ask anyone that has one.

And I agree with ck80 on all points. Really hits the nail on the head.
I don't know about that. My race car was almost never apart and was dead on consistent.
 

scoti

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With what you have your dual plane intake is perfect.

This is your daily/only car, right? Don't turn it into a race car. Don't try to turn it into a race car. Race cars are unreliable money pits. Ask anyone that has one.

And I agree with ck80 on all points. Really hits the nail on the head.
If one has to ask on a forum about what it is they have..... They need to start from the beginning of how things work so they understand what impact all of the various changes can have.
 
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scoti

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Which means at high speeds on the highway I wouldn't very much power, just at take off ?
You started w/mis-matched parts, The combo of single-plane intake & basically stock 305 wouldn't have much power in either scenario. It will obviously still run but would be far, far from ideal.

Too much intake for a small cam/small displacement motor & non-performance gearing on takeoff.
Too little cam, compression, & displacement for the intake to reach its potential @ high/er speed.
 
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