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CHESTNUTXE

CLEVELAND ENGINE TALK

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Regarding line boring the block... I don't have a clevo and a 400 block to compare, to know if the main cap bolts are the same distance apart for each but if the 400 is wider, then boring the clevo out to suit 3.0" mains might have the tunnel bore too close to the bolt holes and end up with cracking issues or ripping them out altogether.

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I know they used the ground down crank in a 351w block but I have never seen anyone try it in a 351c block but I guess in the USA someone would have had a go at it ,when did the clevo stroker cranks start to be available 90s ? Or later

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I know they used the ground down crank in a 351w block but I have never seen anyone try it in a 351c block but I guess in the USA someone would have had a go at it ,when did the clevo stroker cranks start to be available 90s ? Or later

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In Oz, they used to take the 351 crank and offset grind to a chev rod size and make it a 377. I think Eagle and Scat were the big brand kits to get in the day, and they didn't really come along till the late 90s? The US aftermarket didn't really tool up for clevos like they did for 5.0s as they only built them for 5 years or so there.

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im thinking of taking my beefy 400 block to get it sonic tested ,just to see how much meat is really on it,olm8 at the machine shop said it has almost siamese bores ,about half way down the walls its as if its joined together compard to normal blocks,well thats what it looks like anyway,i wonder how much it would cost to do that,maybe $200 ?.

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im thinking of taking my beefy 400 block to get it sonic tested ,just to see how much meat is really on it,olm8 at the machine shop said it has almost siamese bores ,about half way down the walls its as if its joined together compard to normal blocks,well thats what it looks like anyway,i wonder how much it would cost to do that,maybe $200 ?.
I have never used a machine shop, let alone recently so I couldn't tell you how much a sonic check would cost. Best place to find out would be to ask your old mate, I'm sure he's got connections somewhere.

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On 12/25/2021 at 8:48 AM, CHESTNUTXE said:

hey why cant the 400 crank mains be ground down to 2.749 and fit in a normal cleveland block ? is that too much meat to be taken off ? or line bore the block to 3.000 ? 

Funny you asked that, I've sold a 400 crank & rods last Thursday to a guy who wants to build a Boss 302 type stroker engine. Reckons it's achievable, who am I to argue? Lucky for him he has his own lathe.

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Funny you asked that, I've sold a 400 crank & rods last Thursday to a guy who wants to build a Boss 302 type stroker engine. Reckons it's achievable, who am I to argue? Lucky for him he has his own lathe.

I think he's going to carve up a perfectly good 400 crank for nothing. The biggest feasible stroke an 8.2 deck Windsor can handle is 3.4", which with an overbore gives you 347, and already these don't have a great rod/stroke length. The pistons are very short to clear the crank weights, oil consumption and piston wear becomes a problem due to piston rocking and ring stability.

 

The ideal 302 stroker is the 331 with a 3.25 stroke, this having a much better rod/stroke ratio.

 

Any longer stroke than 3.4 and your rods need to be impossibly short, and I don't think the bottom of the bores will clear the crank or the rods.

 

If he's using a 351W block, that is a whole different story. That deck is 9.5", taller than a clevo at 9.2". The mains are the same size as a 400, and with an offset grind and a bore, you can go beyond 408 cubes to say around 427, etc.

 

With a 4.125 bore, you can go right out to 454 and beyond.

 

Maybe if he's talking about a "Boss 302" type engine, he really means a 351W with clevo heads? That's what they call a "Clevor".

 

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I think he's going to carve up a perfectly good 400 crank for nothing. The biggest feasible stroke an 8.2 deck Windsor can handle is 3.4", which with an overbore gives you 347, and already these don't have a great rod/stroke length. The pistons are very short to clear the crank weights, oil consumption and piston wear becomes a problem due to piston rocking and ring stability.
 
The ideal 302 stroker is the 331 with a 3.25 stroke, this having a much better rod/stroke ratio.
 
Any longer stroke than 3.4 and your rods need to be impossibly short, and I don't think the bottom of the bores will clear the crank or the rods.
 
If he's using a 351W block, that is a whole different story. That deck is 9.5", taller than a clevo at 9.2". The mains are the same size as a 400, and with an offset grind and a bore, you can go beyond 408 cubes to say around 427, etc.
 
With a 4.125 bore, you can go right out to 454 and beyond.
 
Maybe if he's talking about a "Boss 302" type engine, he really means a 351W with clevo heads? That's what they call a "Clevor".
 
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I think he is building a 302m

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4 hours ago, gerg said:

Maybe if he's talking about a "Boss 302" type engine, he really means a 351W with clevo heads?

That's what I thought first, but he said 302. He does know a couple of machinists so they might set him straight unless they can work some magic.

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That's what I thought first, but he said 302. He does know a couple of machinists so they might set him straight unless they can work some magic.
These days, machine work like that is as expensive as a brand new stroker kit, with a steel crank and H-beam rods

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These days, machine work like that is as expensive as a brand new stroker kit, with a steel crank and H-beam rods

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Gerg with that offset job do they take meat off these sides or something like that also check how big that 4" stroke is14f61ae60beed0d5059d7653294c8e0b.jpg9373ac66a1e3e5b5623988159a0029df.jpg52e90d444c151374683d69430df6e527.jpg

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Gerg with that offset job do they take meat off these sides or something like that also check how big that 4" stroke is14f61ae60beed0d5059d7653294c8e0b.jpg9373ac66a1e3e5b5623988159a0029df.jpg52e90d444c151374683d69430df6e527.jpg

 

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Offset grinding means you take down the diameter of the rod journal but the centre of that diameter is ground into it further out in the throw from original, so when first grinding/turning it down, the journal will be wobbling in the grinder/lathe and more material is removed from the inside than out. The theoretical maximum you can increase the stroke by is double whatever the difference in pin diameter is. So a Clevo/400m is 2.311, the usual chev pin is 2.100, difference is 0.211, so is the maximum throw. Double that and you get stroke increase - 0.422.

 

There is a limit to how much throw you can grind into it, determined by main/rod journal overlap (strength), rod to block and camshaft clearance, rod angle and thus rod/stroke ratio.

 

As far as taking meat off the counterweight goes, crank balancers only like to drill them for some reason. It's easier to work out the amount of metal to be removed when it's directly opposite the crank throw so I guess that's why. It would be more beneficial to remove metal from either end of the counterweight as you would be able to remove heaps more to get the same result (reducing rotating mass in the crank), but calculating that wouldn't be easy.

 

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Sorry, my basic math is wrong there. Difference in diameter is halved to get the throw increase, so basically you halve it, then double it to get stroke.

So:
Journal diameters:
2.311-2.100 = 0.211 difference

Difference in pin centreline (throw)
0.211/2 = 0.1055

Difference in stroke:
0.1055 X 2 = 0.211

Total stroke:
0.211 + 4 = 4.211"

So on a standard bore 400 with an offset ground 400 crank, the maximum theoretical displacement would be 423 ci

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Just use these and build any combo you like
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Are you kidding? I can't believe they don't have a shock absorber on that design. That would have some really terrible harmonics, which I imagine would require a balance shaft, and kids we all know that balance shafts make baby Jesus cry

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Gunnar take a month to get the piston set plus cam n lifters and other stuff from the USA,I got 030 pistons

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New pointer and ring compressor lobbed up,about time I used a better one than the one I have been battling for years.716315bdc6809566833271f08c980c45.jpg5a20c68210c7f03a186f258cd295e344.jpg74133b9b893421ff92c4e1c1133c44ed.jpg

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