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waynegrovs

351 clevo with 302 rods

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I'm pretty sure the pistons in my 302 rodded 351 are ACL, the local engine build supplied them when I had the clevo rebuild a few years back.

 

I've never had any issue with this setup, it seem to make more torque down low compare to similar setups with the 351 rods in them and seems to rev a bit better but other than that it's really just what your engine builder preference would be.

 

I would have been happy with either.

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unfortunately I have been told that ACL are no longer I want to use quality pistons not cheap unknown crap but Im not interested in forged Im going to rev limit it to 6500 to 6800 anyway

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back in the olden days we used a 351 crank ,302 rods short skirt racing pistons ,stage 3 competition cam an 2v heads ,we used to call it a 383 stroker ,in the olden days ,loads of funn.lol

 

 

 

the pistons have the gudgen moved a little closer to the oil ring ,and the skirts are a lot shorter then nomal clevo pistons

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back in the olden days we used a 351 crank ,302 rods short skirt racing pistons ,stage 3 competition cam an 2v heads ,we used to call it a 383 stroker

How does changing rods length give you more ci ? Or is this just something you would just bluff your mate's with ?

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O.o

 

Using 302 rod doesn't make 383 cubes on a 351 crank, the rods might be 6 inches long but the crank still only has a 3.5 inch stroke and with the correct piston still only gives 351 cubes.

 

The crank would need to be offset ground down to about 2 inches to increase the stroke from 3.5 inches to 3.8 inches to give 383 cubes.

 

As my 5 year old says...get off the grass!

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I have been reading up and have heard some horror stories about hypereurtectic piston so I have two questions who makes the best  hyper pistons and if I go forged who make the best mid price forged for my combination I am also worried about the looser clearance with required with the forgies and possible extra ( meaning quicker) wear

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How does changing rods length give you more ci ? Or is this just something you would just bluff your mate's with ?

no bluffing ,I worked in an engine shop for yrs ,this was a combination that's been used for yrs ,measure the height with a 302 rod on a 51 crank ,then we used a short skirt racing piston with the gudeon moved closer to the top of the piston ,hey I only fitted what the boss told me ,always was told 383 ,

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no bluffing ,I worked in an engine shop for yrs ,this was a combination that's been used for yrs ,measure the height with a 302 rod on a 51 crank ,then we used a short skirt racing piston with the gudeon moved closer to the top of the piston ,hey I only fitted what the boss told me ,always was told 383 ,

What did you do offset the 351 crank too ? If its just a std 3.5" crank well its not a 383ci.

 

Only way possible for 383ci with 3.5 stroke is with a dart or arrow block with a big bore at 4.170 which in your case you say its been done for years, as mentioned by another member on here it doesnt matter what rod or pistion length or comp height you have it won't change the cid. Only stroke and bore side changes things.

Hope that clears it up.

Sorry to say mate but all that has been happening is your boss has been bluffing yourself.

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^^^^ This

 

If the crank hasn't has an offset grind and hence retains the stock 3.5 inch stroke there is now way in hell using 302 rods will make 383 cubes it is physically impossible to do with the stock crank stroke and stock bore.

 

All that using the longer conrods does is slows the piston down during rotation and hence alters the power/torque characteristics when compared to the stock crank/ stock rod combo, the Piston still travels the same distance up and down.

 

In the couple of 351's that I've built I've found the long rod combo's give better torque in the lower and mid range compared to the stock rod combos and are smoother revving, they don't seem to rev as hard as the short rod setups and tend to run out of puff 500 rpm lower, but that really does depend on the cam/carb specs as well.

 

I think your old boss may have spent WAY too much time on the grass however, my current long rod 20 thou over 351 in my XD might be worth a total of 354-355 cubes maybe, If all you needed was 302 rods on a 351 crank to make 383 cubes, I think every bloke packin a 351 would have a 383 instead.

 

Now pass it along now so the rest of us can have a toke :P

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Rod length does absolutely nothing to change capacity, you could have 3 foot long rods on a 351 crank and it will still be 351ci ( provided the block was tall enough)

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If I was building from scratch id fit the forged slugs as well. 6800rpm out of a cast piston is decent revs and it would always be in the back of my mind its would kill pistons. But in saying that im turning 2 cast piston clevos that hard so im a hypocrite :D but ive smashed my pistons in one of them

My mates got a 6inch rod clevo in his F100 he is forever telling me its a stroker HAHA it also goes like stink to "even more HAHA" I drove it looking for a problem some time ago id be keen to go in what he thinks is slow

Shhhhhhh don't telling him im talking about him :D

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I have been reading up and have heard some horror stories about hypereurtectic piston so I have two questions who makes the best  hyper pistons and if I go forged who make the best mid price forged for my combination I am also worried about the looser clearance with required with the forgies and possible extra ( meaning quicker) wear

 

 

If you use a quality piston like a Wiseco JE CP or Diamond it will be fine.When you use shit pistons and Ross fall into that category is when you have trouble.Ask Ando about how long his forged Ross pistons lasted and If I remember I'll put a pic of the sunken POS Ross slug sitting on my bench that came out of Gavin Fletchers speedway car.

 

Why not forged . These day they work fine if set up with correct clearances

 

 

As for Hypers the same , correct ring caps and clearance all good .

BUT to the 6500-6800 I'd be using forged

 

Correct bro...I set mine up pretty tight as instructed by Wiseco and there fine.Rings gaps were a bit looser but not as big as many would think,maybe the 3th per inch of bore space rule.It got revved pretty hard for like 28mins straight on the Winton cruise curcuit the other week and if it was gunna die it would have then cos it copped a REAL HARD time lap after lap after lap.Rev's = forgies and I'm suprised no one else has said it but good rods not just stock 302 shit? Why bother with stock shit when a good Scatt H beam with good ARP bolts would be around the same price by the time all the work is done anyway.

 

Shot peened polished honed new bolts balanced any other machine work and you could have got some Scat H beams in any length you want.I use SCB Scat beam's in my xflow cos there cheaper than Spool rods and they are 400,000 times better than any stock rod.

 

Just saying it's not as expensive as you think and it's much cheaper than a rebuild. 

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My first decent engine had ross pistons I never had a issue with them well till it snaped a camshaft and destroyed the engine :( I went back in revs after that as it was engine speed killing my engines. we worked on power with less revs. I went back to low 6000s and did not need to run NOS so I did not need forged slugs, my idea is working so far

I can understand the cast vs forged debate but to say a good brand forged piston vs another good brand and ones shit I don't agree with, The fastest NOS crossy I know of runs ross pistons and its been around a long time even the old ross pistoned engine is still around the bike pistons is just another way of doing it

I never herd that ross make shit pistons but like anything you hear bad storys  

 

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Oh no there a awesome piston...they just do this.Well worth the money if you ask Gavin Fletcher Ando or Marty White LOL

 

20141005_231645_zps6005981d.jpg

 

A forged piston is not spose to look like this BTW :)

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