Valve lifters…solid/hydraulic/roller tappet/flat tappet?

[olddog]

Well I very much disagree with the planned gearing, and I personally wouldn't build a 302 for 8000 rpm. With that said, a 8000 rpm 302 is not all that radical. The SB Ford, likely the shortest deck height of all push rod V-8, is well suited to be a high rpm engine. The short deck gives the lightest of valve trains and the lightest rod. Your starting out with an engine that needs the fewest modifications to go more rpm. The only thing lacking is the block and rods. I would recommend good aftermarket rods and block. I would internally (zero) balance it too.

Let's put some things into perspective. Guys are spinning 4.25" stroke FE 6000 rpm. A 3" stroke has to spin 8500 rpm to achieve the same mean piston speed. Then we are talking a 4" bore compared to a 4.23" bore -- a much lighter piston. Now a 6.488" rod length verse a 5.090" (I don't know what the FE stroker rod is). Certainly the FE stroker has a much worse rod ratio. So the FE is turning higher piston speeds with a much heavier piston, rod, and wrist pin, with a worse rod ratio. I say a FE stroker turning 6000 rpm is a much more radical engine than a 302 turning 8000 rpm, from a rotating assembly point of view.

Now the FE has bigger, longer valves and springs. A longer push rod, and larger rocker, too. I do not have the weights nor the formulas to calculate valve geometry. However my gut tells me that 8000 rpm on the 302 will only be a little more challenge than 6000 rpm on the FE, not a huge difference.

I have spun 327 Chevy to 8000 rpm, with a stock bottom end, and aluminum roller rockers. Springs that came in the cam kit with solid lifters. I ran the crap out of it for a year with no problems. Maybe I was lucky. I sure wouldn't do it today. But the point is 8000 rpm on a 302 is not some insane, radical, or stupid idea. I believe NASCAR was turning FE engines 7000-8000 rpm back in the day.

Anyone know what Shelby and the others were turning the 289 in the races with the original SB Cobra? I expect they were getting every bit of 450 hp and turning them 8000 rpm or more.

[xb-60]

So how can a guy like me who doesn’t really know what he’s talking about make sense of all this?
Why are the pro-stroker and the non-stroker (pro-revver?) camps so far apart?
Cheers,
Glen

[blykins]

Originally Posted by olddog

Well I very much disagree with the planned gearing, and I personally wouldn't build a 302 for 8000 rpm. With that said, a 8000 rpm 302 is not all that radical. The SB Ford, likely the shortest deck height of all push rod V-8, is well suited to be a high rpm engine. The short deck gives the lightest of valve trains and the lightest rod. Your starting out with an engine that needs the fewest modifications to go more rpm. The only thing lacking is the block and rods. I would recommend good aftermarket rods and block. I would internally (zero) balance it too.

Let's put some things into perspective. Guys are spinning 4.25" stroke FE 6000 rpm. A 3" stroke has to spin 8500 rpm to achieve the same mean piston speed. Then we are talking a 4" bore compared to a 4.23" bore -- a much lighter piston. Now a 6.488" rod length verse a 5.090" (I don't know what the FE stroker rod is). Certainly the FE stroker has a much worse rod ratio. So the FE is turning higher piston speeds with a much heavier piston, rod, and wrist pin, with a worse rod ratio. I say a FE stroker turning 6000 rpm is a much more radical engine than a 302 turning 8000 rpm, from a rotating assembly point of view.

Now the FE has bigger, longer valves and springs. A longer push rod, and larger rocker, too. I do not have the weights nor the formulas to calculate valve geometry. However my gut tells me that 8000 rpm on the 302 will only be a little more challenge than 6000 rpm on the FE, not a huge difference.

I have spun 327 Chevy to 8000 rpm, with a stock bottom end, and aluminum roller rockers. Springs that came in the cam kit with solid lifters. I ran the crap out of it for a year with no problems. Maybe I was lucky. I sure wouldn't do it today. But the point is 8000 rpm on a 302 is not some insane, radical, or stupid idea. I believe NASCAR was turning FE engines 7000-8000 rpm back in the day.

Anyone know what Shelby and the others were turning the 289 in the races with the original SB Cobra? I expect they were getting every bit of 450 hp and turning them 8000 rpm or more.

What small blocks were turning in full race cars and in NASCAR has zero bearing whatsoever in this situation. This is a street car with a high rearend gear ratio, on pump gas, with low rpm manners required.

There's also one key difference: for the average home builder to say that he's turning 8000 rpm either means that he's got his distributor wired for a 6 cylinder, or he's making peak power at 5000 and he's turning it 3000 extra rpm. You wouldn't believe how many guys I run into that think they are making power at 8000 rpms.... Do you guys know how much head and cam is required to peak at 8000?

We need to get back on track here. Even if I built a 302 to turn 7000 and make peak horsepower there, it's not a good match for XB's application.

XB...

Again, no one is pro-stroker or pro-revver. I'm both. I use both. I cherish both. The point here (and I need to really type this in all caps) is to build the engine for the application!!!!

An engine that makes peak horsepower at 7000-8000 has nothing down low! Especially very small displacement engines!

[Gaz64]

Originally Posted by blykins

What small blocks were turning in full race cars and in NASCAR has zero bearing whatsoever in this situation. This is a street car with a high rearend gear ratio, on pump gas, with low rpm manners required.

There's also one key difference: for the average home builder to say that he's turning 8000 rpm either means that he's got his distributor wired for a 6 cylinder, or he's making peak power at 5000 and he's turning it 3000 extra rpm. You wouldn't believe how many guys I run into that think they are making power at 8000 rpms.... Do you guys know how much head and cam is required to peak at 8000?

We need to get back on track here. Even if I built a 302 to turn 7000 and make peak horsepower there, it's not a good match for XB's application.

XB...

Again, no one is pro-stroker or pro-revver. I'm both. I use both. I cherish both. The point here (and I need to really type this in all caps) is to build the engine for the application!!!!

An engine that makes peak horsepower at 7000-8000 has nothing down low! Especially very small displacement engines!

All very good points.

Some more info for Glen.

When selecting a cam, the quoted power range from the cam grinder is, eg: 3000 - 6000 rpm, not it's min and max but it's best operating range.

No cams are have a range of idle to 7000+ rpm.

And the higher up you go, the narrower the band becomes.