Low compression 505

[oldkimmer]

Hi guys, would u build a N/A 8-1 bracket engine with a 270/276 @.050 solid roller cam? 110 cl and .625 lift. Max wedge ported Indy SRs. Super Victor Intake and a 1250 Holley Dominator. Thanks. Kim

 

[RemCharger]

That's a neat question and I would say yes. You can easily calculate how much more you could make with a big compression piston.
If you can live with that difference, then you have a nice pump gas motor.

 

[oldkimmer]

My other option would to 13-1

 

[GTX JOHN]

Everything sound good except I do not understand the
8 to 1 part?
Pistons down 150/175 in the Hole.

We tried to run a 73 440 spec. {.122 down) in our stock
eliminator as it was factored at only 325 HP. However, with
the low compression it would not fall out of a tree.

 

[GTX JOHN]

Is it 030 or 060 bore or some other size?

I will try to find you some pistons that will work
much better as soon as I am well enough to get
to the shop soon!

 

[RemCharger]

Everything sound good except I do not understand the
8 to 1 part?
Pistons down 150/175 in the Hole.

We tried to run a 73 440 spec. {.122 down) in our stock
eliminator as it was factored at only 325 HP. However, with
the low compression it would not fall out of a tree.

What exactly is not fall out of a tree?

 

[GTX JOHN]

It was extremely and disgusting slow
to the point of embarrassment!

Common slang if you are 75+.

 

[RemCharger]

So 5 tenths down?

 

[Kern Dog]

I am far from an expert but this is the cam I have in my 440-495 at 9.8 to 1:

This cam is smaller than yours, I have less cubes than you but almost 2 points more compression.
Mine runs fine but sure was more snappy below 4000 with a smaller cam.
Wouldn't you have to spin yours to the moon to take advantage of that cam?

 

[dvw]

It's a race engine? I'd absolutley go 13-1. At about 1/2 gallon a pass (14 mile) race gas expense is nothing compared to tow fuel to get to the track. Or convert the carb to E85. I'd bet the power difference would be close to 70 hp.
Doug

 

[icetech]

I'm just curious, why are 8:1 or 13:1 the only choices? only pistons available?

 

[33 IMP]

At 8 to 1, I'd hang a blower or turbo or two on it.
At 13 to 1, I'd run E85, and fly it.
Of those two choices, and assuming you have access to E85, I would 100% build it 13 to 1 with that cam.
I'd build it 11 to 1, and run pump gas, if that was a choice.

And John, I knew exactly what "wouldn't fall out of a tree" meant. Same as "won't pull a fat girl off a tricycle".

 

[PROSTOCKTOM]

Unless you are putting this engine in a really lite car that cam has to much duration for a heavy car. I run my 13 to 1 compression 499RB street engine on E85.

Can't say enough about using E85 for a hot street or race engine since the cost benefit ratio is better than anything else.

I like using the KISS method. So NA is where it is for me.

Tom

 

[oldkimmer]

Is it 030 or 060 bore or some other size?

I will try to find you some pistons that will work
much better as soon as I am well enough to get
to the shop soon!

I could use .030 or .060 pistons. Kim

 

[oldkimmer]

I am far from an expert but this is the cam I have in my 440-495 at 9.8 to 1:

View attachment 1655950

This cam is smaller than yours, I have less cubes than you but almost 2 points more compression.
Mine runs fine but sure was more snappy below 4000 with a smaller cam.
Wouldn't you have to spin yours to the moon to take advantage of that cam?

My cam was in my 470. It ran to 7000 no problem.

 

[oldkimmer]

I'm just curious, why are 8:1 or 13:1 the only choices? only pistons available?

Cause that’s what I have for pistons. Kim

 

[oldkimmer]

It's a race engine? I'd absolutley go 13-1. At about 1/2 gallon a pass (14 mile) race gas expense is nothing compared to tow fuel to get to the track. Or convert the carb to E85. I'd bet the power difference would be close to 70 hp.
Doug

Totally a track car

 

[icetech]

Cause that’s what I have for pistons. Kim

ahh that makes sense then

 

[oldkimmer]

Now I feel dumb. The stroker kit I have is 4.25 crank, 6.8 rod and 1.770 cd pistons. .030 4.350 bore. 75cc head and a .040 gasket. 13-1. So then using the .060 over 1.34 cd pistons it comes to 8.0-1. So if I use a 7.100 rod it is 10.2-1. The. It will be a 512. Which is a win. Kim

 

[icetech]

Now I feel dumb. The stroker kit I have is 4.25 crank, 6.8 rod and 1.770 cd pistons. .030 4.350 bore. 75cc head and a .040 gasket. 13-1. So then using the .060 over 1.34 cd pistons it comes to 8.0-1. So if I use a 7.100 rod it is 10.2-1. The. It will be a 512. Which is a win. Kim

Well that's bout perfect