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

[LightNFast]

............................

[blykins]

Originally Posted by xb-60

But logic tells me that stroking to 331 or 347 would produce an engine that's less happy at higher revs. But more powerful, yes.
Cheers,
Glen

That's a pretty common misconception....a longer stroked engine can pull the rpms just like a short stroke engine. I have 4.100" stroke 445W's pulling over 6500, as well as 4.300" stroke Boss 9 engines pulling 6500 rpms.

I have a customer that runs the 7.50 1/8th mile class. The 347 that I did for him gets shifted at 7000.

[xb-60]

Originally Posted by blykins

That's a pretty common misconception....a longer stroked engine can pull the rpms just like a short stroke engine. I have 4.100" stroke 445W's pulling over 6500, as well as 4.300" stroke Boss 9 engines pulling 6500 rpms.

I have a customer that runs the 7.50 1/8th mile class. The 347 that I did for him gets shifted at 7000.

Let me re-phrase the question...logic tells me that stroking a 302 to 331 or 347, or a 351W out to 445 would require significant spend on the rotating assembly to make them as happy at 6500 as a standard stroke engine, yes?
Re-phrasing further, what spend would be required to make a 347 safe at 7000, and a 445W safe at 6500?
I like this friendly banter, Brent. Keep it coming!
Cheers,
Glen

[Jerry Clayton]

if you buid it with sbc or honda rod journal sizes you could turn it 9000 for hours

[xb-60]

Originally Posted by LightNFast

....Lifters - Ford Racing rollers with Keith Craft "High Rev option".....

.....I wish you the very best with your project. Keep us posted…

Kurt, are the lifters solid rollers or hydraulic rollers?

And thanks. As soon as I have something actually happening,I'll report

Cheers,
Glen

[xb-60]

Originally Posted by zrayr

love the story of your truck, but lets's keep in mind that we are talking about a 2,100 lb Cobra here, not a 3,500 lb truck, or even a 2,900 lb. Mustang like I have, etc. A 289 or 302 will have plenty of torque for the fun factor desired.....

and...

.....There's a lot of enjoyment to be had by staying close to the original spirit & experience of the car by not going "modern" in the drivetrain department. Z.

Z, that's two very valid observations there....

Yes, surely I can get away with a higher diff ratio in a lightweight Cobra replica than I could with a truck or a Mustang!

And no, I don't want to go modern. Example...head says Tremec five speed trans, heart says 4-speed Toploader. I could keep going, but you get the drift. I want to replicate a Cobra (as closely as the budget allows), so if something from the period is still reasonably easily available, I'll use it.

Cheers,
Glen

[blykins]

"Re-phrasing further, what spend would be required to make a 347 safe at 7000, and a 445W safe at 6500?"

The same parts that would make a 289/302 safe at 7000.

Just because it's a shorter stroke, like a factory 289 or 302, it doesn't mean that it will automatically live endlessly at 7000 rpm. I wouldn't build a 302 to make power at those rpm levels without a quality aftermarket crank, rods, light forged pistons, shaft mounted rockers (or at least stud rockers with a girdle), etc, etc. The 445W automatically gets most of those parts as the SVO blocks use the 2.750" forged crankshafts, aftermarket rods, etc.

But there again, we're losing sight of the original agenda....a 7000 rpm engine doesn't match to a 3.07 rearend gear in a street car.

[zrayr]

Originally Posted by xb-60

Z, that's two very valid observations there....

Yes, surely I can get away with a higher diff ratio in a lightweight Cobra replica than I could with a truck or a Mustang!

And no, I don't want to go modern. Example...head says Tremec five speed trans, heart says 4-speed Toploader. I could keep going, but you get the drift. I want to replicate a Cobra (as closely as the budget allows), so if something from the period is still reasonably easily available, I'll use it.

Cheers,
Glen

exactly ! my dream Cobra is a 289, but the FIA body style ( more curves, not slab sided), IDA webers, 4 speed, etc. If, and only if, I became dissatisfied with the "all period correct" approach would I go to more modern components.

Not saying my method is right for anyone but me.

Z.

[zrayr]

Originally Posted by blykins

That's a pretty common misconception....a longer stroked engine can pull the rpms just like a short stroke engine. I have 4.100" stroke 445W's pulling over 6500, as well as 4.300" stroke Boss 9 engines pulling 6500 rpms.

I have a customer that runs the 7.50 1/8th mile class. The 347 that I did for him gets shifted at 7000.

in the narrow scope of this discussion, using stroked SBF engines as examples, you are essentially correct. As you say, a 289 stroked to 331, etc, will rev to 7,000 or more. Bit I still maintain that shorter stoke engines will hit the red line quicker if the overall displacement is more or less equal.

In the long run, long stroke engines just can't compete with over-square engines in a maximum rpm context. Valve size is the one major limitation in small bore/long stroke engines, but excessive piston speed (measured in ft traved per minute at maximum rpm) cannot be ignored.

That said, for example I am much more happy riding the long stroke 650cc Triumph vs. the short stroke 650cc BSA.

Z.

[xb-60]

Originally Posted by zrayr

exactly ! my dream Cobra is a 289, but the FIA body style ( more curves, not slab sided), IDA webers, 4 speed, etc. If, and only if, I became dissatisfied with the "all period correct" approach would I go to more modern components.

Not saying my method is right for anyone but me.

Z.

I like the way you're thinking, Z

[blykins]

Originally Posted by zrayr

to the degree we are talking about, stroked SBF engines, you are correct. However long stroke engines just can't compete with over-square engines. Valve size is the one major limitation in small bore engines, but excessive piston speed (measured in ft traved per minute at maximum rpm) cannot be ignored.

Z.

Try to explain that to the pulling truck guys running 557ci BBF's (4.420" bore, 4.500" stroke) turning 8000 rpms....

There are lots of spoken generalities with engines that are not always the case.

[xb-60]

Originally Posted by zrayr

to the degree we are talking about, stroked SBF engines, you are correct. However long stroke engines just can't compete with over-square engines. Valve size is the one major limitation in small bore engines, but excessive piston speed (measured in ft traved per minute at maximum rpm) cannot be ignored.

Z.

Yes, surely the maximum piston speed on a 347 with a ....3.4"? ...stroke must be a lot higher than a 2.7" or 3" stroke engine? That's got to make a difference in the cost of the bottom end
Cheers,
Glen

[blykins]

Glen, I know you're fighting hard for "short stroke, high rpm" crowd, but you're really making this a lot more difficult than it is.

A Scat cast stroker crankshaft, forged I-beam rods, and forged pistons will hold more horsepower than what a 302 block will withstand. These components are no more special than what I would use for an equally rev-happy 289/302.

If you compare what it would cost to take a factory 302 crankshaft, have it reground, have the rods resized, reconditioned, and fitted with ARP bolts, new pistons, new rings, new bearings, etc., you are not but about $200-250 off from buying a brand new Scat rotating assembly that's not 30-40 years old.

Keep in mind that you have to buy pistons, rings, and bearings no matter what, and those costs are generally about the same, give or take a few bucks. A brand new Scat crank is $250 and the rods are about the same.

Why pass up on 50 cubic inches plus a great amount of horsepower and torque for $250?

I've said earlier that you seem to have already made your mind up, so we may all be wasting our breath here. But building an engine simply around an rpm number can lead to lots of issues and disappointments.

[Gaz64]

Originally Posted by xb-60

Yes, surely the maximum piston speed on a 347 with a ....3.4"? ...stroke must be a lot higher than a 2.7" or 3" stroke engine? That's got to make a difference in the cost of the bottom end
Cheers,
Glen

Very true Glen, and yes you do have to spend money the larger you go, but there are engines out there with 5 1/4 inch strokes or more that spin to 8000 rpm.
For example: John Kaase Racing Engines.

As others have said, if you have a choice, go for a milder package with more cubes, much better combination.

[blykins]

Excellent point Gary....

I was at Jon's shop back in July watching him disassemble a Mountain Motor with about 820ci of displacement. They turn 7000-8000 rpms without issues.

[zrayr]

Originally Posted by blykins

Try to explain that to the pulling truck guys running 557ci BBF's (4.420" bore, 4.500" stroke) turning 8000 rpms....

There are lots of spoken generalities with engines that are not always the case.

I just edited my last post to include, "...That said, for example I am much more happy riding the long stroke 650cc Triumph vs. the short stroke 650cc BSA..."

which is exactly the same as the example you provided. ha ha. Especially on the dirt track , the long stroke, high torque Triumphs ruled. Lower torque, higher rpm machines consistently ate their dust & finished out of the running

Z.

[blykins]

You know, I've never ridden a motorcycle before, but I can see myself getting into them.

I've also never ridden in an all-original GT-350 either....lucky dog.

[DAVID GAGNARD]

Thanks David, for more of the real world comments.
Can you tell me why you decided on flat tappets?
Cheers,

Because back in the mid 90's when I built this engine, it was to be a street cruiser/show car/sunday driver and I was dirt poor and the camshaft with lifters from SUMMIT at that time was about $79.00!!!!!!!!!!!!!!

Every street engine I've built for myself since has gotten a hydraulic roller camshaft....
My race engine uses a solid lifter,roller camshaft.......

The hydraulic roller camshafts just have so much more to offer,it's a no-brainer for me...

David

[zrayr]

Originally Posted by blykins

You know, I've never ridden a motorcycle before, but I can see myself getting into them.

I've also never ridden in an all-original GT-350 either....lucky dog.

My first "real" job was as a motorcycle mechanic in 1969 After a few years I moved on to other endeavors for the next 30 years. I had thought the recession of '09 put me into early retirement, but out of the blue, a job working on motorcycles materialized. So it's a blast back to the past for me these days.

Z.

[xb-60]

Originally Posted by blykins

Glen, I know you're fighting hard for "short stroke, high rpm" crowd, but you're really making this a lot more difficult than it is.

A Scat cast stroker crankshaft, forged I-beam rods, and forged pistons will hold more horsepower than what a 302 block will withstand. These components are no more special than what I would use for an equally rev-happy 289/302.

If you compare what it would cost to take a factory 302 crankshaft, have it reground, have the rods resized, reconditioned, and fitted with ARP bolts, new pistons, new rings, new bearings, etc., you are not but about $200-250 off from buying a brand new Scat rotating assembly that's not 30-40 years old.

Keep in mind that you have to buy pistons, rings, and bearings no matter what, and those costs are generally about the same, give or take a few bucks. A brand new Scat crank is $250 and the rods are about the same.

Why pass up on 50 cubic inches plus a great amount of horsepower and torque for $250?

I've said earlier that you seem to have already made your mind up, so we may all be wasting our breath here. But building an engine simply around an rpm number can lead to lots of issues and disappointments.

Brent, yep, definitely stuck on a non-stroked 302. Not negotiable. Not absolutely authentic, but closer to it than a 302 stroker. It's the heart overriding the head - what more can I say? However, yes, it's a no-brainer to use forged crank/rods/pistons instead of re-conditioned bits. There seems to be overwhelming support for hydraulic roller lifters over solid roller. I will have to consider that advice seriously. I will 'spec' the car as close to what I think will work nicely, based on the advice and information available, but then if I have to change a cam or a diff centre to achieve a degree of 'tuning', then so be it.
Cheers!
Glen