? about that 3.65” crank

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greymouser7 said:
What fuel (octane) did you run with that build? Thanks!!
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Pump 93. We tried it with 1/2 race gas (110) but it really didn't make any difference. The cam was the PurplePlus Comp cam which is long on duration and lots of overlap. I actually used Rhoads V-Max lifters and 273 rockers, to pump up the bottom end (cylinder pressure). That one build sold me on the V-Max's! Broadest powerband ever and would touch the rev limiter at 7K with ease. The driver kissed 7K every burnout, religiously.
 
Bighead440 said:
Pump 93. We tried it with 1/2 race gas (110) but it really didn't make any difference. The cam was the PurplePlus Comp cam which is long on duration and lots of overlap. I actually used Rhoads V-Max lifters and 273 rockers, to pump up the bottom end (cylinder pressure). That one build sold me on the V-Max's! Broadest powerband ever and would touch the rev limiter at 7K with ease. The driver kissed 7K every burnout, religiously.
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Heck yeah! Which car was that?
 
RustyRatRod said:
Heck yeah! Which car was that?
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I started the build (milling/porting/decking/etc.) for Picone when he had the '68 Dart. When he flew the coup to Florida and I repo'd the car, I had a 365" already ready to go so I stuck it in there and sold the Magnum 318, so there went the top-end for that shortblock. I had Jerry work my old 360 heads from Red-N-White (after I put the original 318 back in with "302's") and used them on the 367. Before I could try it in the Dart, we stuck it in Chapman's Daytona "Pro Street" conversion chassis. It weighed 2700 race weight, so not the lightest Daytona, but still 300# lighter than your avearge Duster/Dart. Ran 7.0@96mph with stupid big tires and a 650 carb. We could have got it in the 6's with 28" tires but these were 31s.
 
Bighead440 said:
I started the build (milling/porting/decking/etc.) for Picone when he had the '68 Dart. When he flew the coup to Florida and I repo'd the car, I had a 365" already ready to go so I stuck it in there and sold the Magnum 318, so there went the top-end for that shortblock. I had Jerry work my old 360 heads from Red-N-White (after I put the original 318 back in with "302's") and used them on the 367. Before I could try it in the Dart, we stuck it in Chapman's Daytona "Pro Street" conversion chassis. It weighed 2700 race weight, so not the lightest Daytona, but still 300# lighter than your avearge Duster/Dart. Ran 7.0@96mph with stupid big tires and a 650 carb. We could have got it in the 6's with 28" tires but these were 31s.
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I remember that car. The blue one, right? Chapman...lol He's ok. Have you heard from him lately?
 
RustyRatRod said:
I remember that car. The blue one, right? Chapman...lol He's ok. Have you heard from him lately?
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This car is white with rainbow MoPar graphics. He did have a black Dart Sport with a 440 I worked on some. His dad is suffering with dementia and that keeps him tied up lately.
 
Bighead440 said:
This car is white with rainbow MoPar graphics. He did have a black Dart Sport with a 440 I worked on some. His dad is suffering with dementia and that keeps him tied up lately.
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Next time you see him remind him who I am and tell him I am thinkin about him.
 
Nice work detective! Let me ask you a question, what piston could I get/use for a 340 main, 3.45 stroke crank in a 340 block?

Bighead440 said:
The CHEAPEST thing to do with it would be to use negative deck 360 pistons. The stroke increase is minimal (.070"ish), so many pistons with a .984" pin and compatible height exist. One that comes to mind with generous valve reliefs (4) is the H405CP, with a 1.637" height. I used these (with head milling and block decking) to make a 367" (.040" over) 360 with a stock crankshaft. Got 10.5:1 with J-heads and ran 96mph in the 1/8mi with a .508" cam and unported RPM intake. You'd have similar compression without expensive decking/milling, even more with smaller chamber heads. Of course all the forged TRWs would work, but no valve reliefs unless you ($$$) have them cut. You'd have to get the small end of the Chevy 6.125" rods honed (after removing the bushing) for a press-fit .984" pin. I have a set of those rods myself, no big deal. Speed-Pro Hypereutectic Pistons H405CP
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rumblefish360 said:
Nice work detective! Let me ask you a question, what piston could I get/use for a 340 main, 3.45 stroke crank in a 340 block?
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Is it SB Chevy rod pins? If so, they make a 6.200" rod that would work with 1.67" CH 360 pistons using a .927" pin or press fit with the small end modified for the .984" pin. The rods are cheap enough and longer than stock, so the benefits (geometry plus lighter .927" pin) might justify the cost of a custom piston or at least a modified (by the mfgr.) shelf piston (still cheaper than a full custom set).
 
Thanks, (obviously) I wasn’t thinking out of the box which I normally at least think about that route for a moment or two. I wasn’t thinking about another manufactures piston ether. Weird because this comes up at work every now and again between the motor heads.

No rods yet. The crank was part of a package deal. The pistons were also included. But there a 4.03 bore size and the crank is for the smaller mains. Being that I have a lot on my plate in front of me to do engine wise, I have not bothered to entertain thoughts on the cranks use yet. I still have 2 more 340 blocks to sonic check for Potential use.

I have in front of me a pair of 340 blocks that are reasonable for use. 1 for the 3.58 stroke crank, 1 for the 4 inch (or 4+) arm build.
 
rumblefish360 said:
Thanks, (obviously) I wasn’t thinking out of the box which I normally at least think about that route for a moment or two. I wasn’t thinking about another manufactures piston ether. Weird because this comes up at work every now and again between the motor heads.

No rods yet. The crank was part of a package deal. The pistons were also included. But there a 4.03 bore size and the crank is for the smaller mains. Being that I have a lot on my plate in front of me to do engine wise, I have not bothered to entertain thoughts on the cranks use yet. I still have 2 more 340 blocks to sonic check for Potential use.

I have in front of me a pair of 340 blocks that are reasonable for use. 1 for the 3.58 stroke crank, 1 for the 4 inch (or 4+) arm build.
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I feel your pain! I have a 400" setup (4.100 x 3.79") with oddball (but high end) custom short dished pistons (probably for a long rod boosted application). They use .927" (SBC) pins and 6.200" SCAT rods with a 3.79" crank, so I got a K1 360 main shaft and plan on using it with an (already .060" over) early 360 thick wall block. I paid peanuts for the pistons and rods (both new), so the crank was the hurdle. There's always one big expense or a few smaller ones to complete these "budget" deals, but it's worth it if you are trying to be unique or think outside the box a little. Otherwise we'd take the cheap (SBC) or junky (LS swap) way out. RB
 
"The shorter stroke will have more cycles (suck, squeeze, bang, blow..) per second (because of the shorter distance the piston travels) than a 4.0 arm crank there by creating more available HP."

I'm gonna need you to explain this to me.....if an engine is spinning at a given RPM, let's say 3000RPM, each piston is seeing 1500 combustion events regardless of stroke. The only thing that is really different is piston speed - the longer the stroke, the higher the piston speed. Am I misunderstanding your comment?
 
No, you got it. The shorter stroke does it quicker.
 
gregcon said:
"The shorter stroke will have more cycles (suck, squeeze, bang, blow..) per second (because of the shorter distance the piston travels) than a 4.0 arm crank there by creating more available HP."

I'm gonna need you to explain this to me.....if an engine is spinning at a given RPM, let's say 3000RPM, each piston is seeing 1500 combustion events regardless of stroke. The only thing that is really different is piston speed - the longer the stroke, the higher the piston speed. Am I misunderstanding your comment?
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It’s about the RPM of each engine. A shorter stroke will have more power cycles because it has more RPM. More power cycles means lower ET’s IF you can handle the RPM.

Pro Stock is the best example. They can only be 500 inches. They can run any reasonable bore/stroke they want, and they ALL run the biggest bore they can and the stroke is only as long as it needs to be to make 500 inches and that’s it. And then they turn as many RPM as they can...rumor has it at the time before the ignorant Rev limiter 11,500ish or a skosh more was what they RPM. The Pro Stock builders ain’t stupid. RPM is power.
 
I agree, if an engine turns more RPM it will have more combustion events or 'power cycles' per second than a slower engine. It has to. And I guess an engine with a shorter stroke can spin faster (though that is not a given). I don't like the term 'power cycle' as cycle tends to imply the 4 strokes of a 4 stroke engine and at 3000RPM, an engine has the same number of power cycles per second (or minute) regardless of stroke. The statement as it is written above "The shorter stroke will have more cycles (suck, squeeze, bang, blow..) per second" is just not correct if you make the reasonable assumption that 'per second' is tied to engine speed, i.e. RPM. That's why speed measurement of any sort includes a time reference. You can't say a clock with a shorter second hand goes around more times per second than a clock with a longer hand.

The presumption is a Pro Stock engine has the biggest bore possible is based in a lot of things....power cycles might be one reason but so are other factors like less valve shrouding and there is not that much need for low end power in a big engine/light car that can be revved high off the line. So what's really being said is (for example) 10,000RPM of weaker combustion events is better than 9,000RPM of stronger events...because the shorter stroke will produce less power per cycle (assuming the engines are both optionally tuned).

I've talked to a few guys who, right or wrong, tell me the R5P7 engines are not as popular in door slammer type drag cars because they make tons of power up high but suffer on power down low. In a NASCAR race no one needs low end because they don't spend much time under 6000RPM , but in a 3000lbs drag car what happens from 3000RPM and up matters more.
 
@gregcon Whops! You are correct! Any engine spinning 3K is spinning at 3K no matter the bore and stroke combo. I was trying to say something else.

How is this? The shorter stroke engine will rev up faster due to the shorter stroke which equals a quicker turn around time for that revolution, thus producing more power in a seconds time because it can complete a revolution quicker. It has less travel distance. Less distance to travel is quicker.

A short stroke engine should be able to rev higher than a longer stroke engine however, with enough money and proper parts researched and developed ......

Arguing that a short stroke engine can not rev as quick as a long stroke engine is an statement with to many holes in it to have an argument on it.

Your 9K vs 10k argument is based on assumption that spark got weaker?
I’d say that if both engines are at a 500 cid, the longer stroke engine will run out or have a lower output against the shorter stroke engine. Not like power fell off a cliff, but less.
 
I've talked to a few guys who, right or wrong, tell me the R5P7 engines are not as popular in door slammer type drag cars because they make tons of power up high but suffer on power down low. In a NASCAR race no one needs low end because they don't spend much time under 6000RPM , but in a 3000lbs drag car what happens from 3000RPM and up matters more

When I read this, it says what I said above. Many guys talk about RPM and doing it, but very few do it. BTDT.

Also, RPM doesn’t always mean a “weaker” combustion cycle. Cylinder head cross section, induction, cam timing, compression ratio all go together to make RPM and make power. I can tell you from experience that any 4 inch crank (as an example of more what we see here) is criminally under headed for much over 5500-5800 unless the cam timing is pretty aggressive. A shorter stroke with the same cylinder head will make more power at a higher RPM an be quicker. Every time. Again, IF you plan for it.

If you are dealing with someone who thinks a 3500 converter is all they can handle and a 3.90 gear is the limit then RPM isn’t for them. Add some stroke and live with it. I’ll take RPM every single time.
 
a chevy piston is for a 23* valve angle, mopar is 18*. new valve notches can be remachined , did it on a set of manley 400 chevy pistons for an x block with 4.125" bore and 3.79" stroke with Oliver rods with .927" pins. This engine ran 41 10 second passes one night at Epping in a street Dart - I sent this to national dragster and they printed it back around 1995- can anyone top this? no response back then
 
I'll confess I'm a short stroke fan and have never quite bought into the stoker fanfare. I have had them, and probably will in the future, but I don't think the payback is all that it's cracked up to be. Does a 526 Hemi make more power than a 426 Hemi? Probably, but not as much as the cubes would suggest. The obstacle to high RPM is usually valvetrain related and can be expensive so that's a real barrier for a lot of guys. Unless it's a BB Chevy in which case they kick rods out first, lol.
 
What's your opinion on 'stroke ability' of heads that flow:

Int
.400 260CFM
.450 283CFM
.550 319CFM
.650 348CFM
.700 353CFM

Exh
.400 215
.450 228
.550 240
.650 249
.700 252
 
gregcon said:
What's your opinion on 'stroke ability' of heads that flow:

Int
.400 260CFM
.450 283CFM
.550 319CFM
.650 348CFM
.700 353CFM

Exh
.400 215
.450 228
.550 240
.650 249
.700 252
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Depends on how much cross section you need and how much cross section it took to get those numbers, as well as the length of the runner.
 
If I did my math right (yall correct me if I'm wrong)
But that would give you a compression height of 1.654 a stock 318 piston is less than that. You could do that build with stock 318 rods and stock 318 pistons correct? I found some elcheapo pistons with a 1.597 height that would put you .057
Under the deck. I'm sure you could find a better piston than that that's just the first one I saw.
 
Iv never really ran the numbers on a 318 before I did all that math when I was planning my 360 build this is the first time I ever done it for a 318 a 318 comes out to a
1.822 compression distance
A stock replacement piston for a 318 has a
1.741 ch
Thats.081 in the hole. That seems like alot no wonder 318 are so low compression. Lol
 
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