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Discussion Starter · #1 ·
Hi guys,
I bought a 327 for rebuilding to put in my truck. While the block was a 327, the rest seems to be a hodge-podge of whatever the guy could get his hands on; for instance: 60cc heads on one side with 70's on the other and a 302 crank.
Right now I need to figure out the pistons, the only marks on them are 740P on the inside. They look fine, but are they for the 327, a 302 or a 350? Did those engines have different heights from the pin to the piston top or was it one size fits all?
The pistons are flat tops with reliefs and look fine; can't really tell if they're cast or forged, but I'm guessing cast. Has anyone ever come across these ones before? Any help would be appreciated before I buy a new set for new reason.
Thanks
Howard
 

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hyarbour said:
Hi guys,
I bought a 327 for rebuilding to put in my truck. While the block was a 327, the rest seems to be a hodge-podge of whatever the guy could get his hands on; for instance: 60cc heads on one side with 70's on the other and a 302 crank.
Right now I need to figure out the pistons, the only marks on them are 740P on the inside. They look fine, but are they for the 327, a 302 or a 350? Did those engines have different heights from the pin to the piston top or was it one size fits all?
The pistons are flat tops with reliefs and look fine; can't really tell if they're cast or forged, but I'm guessing cast. Has anyone ever come across these ones before? Any help would be appreciated before I buy a new set for new reason.
Thanks
Howard
If it is a 302 crank, then it is not a 327 cube engine.

If you intend to use that 3.00 stroke crank you will get a 302 to 310 cubes, and you need 302 parts.
 

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if 327 pistons were used with a 302 crank the pistons would fall short of the top of the bore by quite a distance. I would be certain the crank is a 302, these shafts are rare and many will pay top dollar for them. I would check the crank again by the casting numbers to be sure. If it is a 302 crank and the pistons make it to the top of the bore then 302 pistons were used, but I honestly don`t know of a company that makes a flat top 302 replacement pistons, it`s hard to come by a company that makes these pistons period since it`s a very hard to come by engine only produced 3 years.
 

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Discussion Starter · #5 ·
Pistons

The block was a '66 327, I can tell someone threw a rod at one point because of a nick at the bottom of a cylinder.
I did verify the cranks casting number, Mortec says:
3815822..265,283,302.forged..small journal....3.00" stroke
and I was told that the ones with one notch in the crank flange were used in the 302's.
 

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crank

I have seen the 3" cranks with the notch that were not it factory 302's

If it thas the notch and the snout is drilled and tapped for a bolt then it is a real good chance is was a factory 302... If the snout is not drilled it's not a 302.


Keith
 

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O.K., so it's a small journal 327 block and obviously has a small journal 3" stroke crank; it really does'nt matter it's origin. What I really want to know is what are those "740P" pistons. Any partsmen/machinist have any idea? I'd heard at one time Ford 352 pistons could be used if the wrist pin bore on the Chevrolet rods were opened up to the Ford size and the rotating assembly rebalanced. Any truth there? It would seem if all this is true, then using small chamber heads to get some compression back would make for a fairly cheap 301/302 build. Add a cam, 180 degree intake, and a heavy flywheel and instant back-to-the-60's. Seems everyone wants a 301/302. Anyone? BUTCH.
 

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Discussion Starter · #11 ·
The crank snout is drilled and I've already taken care of the head problem with a set of 041's; 64cc, 1.94 in 1.50 ex. As far as journal sizes; apparently the '67 was the only year for a small journal 302, '68 went to the medium journal size.
 

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Measure the wrist pin bore in the pistons, 0.927" is a small block Chevy, 0.912" is a small block Ford, 0.990 is a big block Chevy, etc. If the pin mikes 0.927", then measure from the crown of the piston at the very edge down to the top of the pin bore. A measurement of 1.332" to 1.337" will be a piston for a 3" stroke small block Chevy.

The diameter of the piston could be 3.875" for a stock bore 283 or 3.905" for a 0.030"-over 283 or 3.935" for a 0.060"-over 283 or whatever. For a 302 it would be 4.000", 4.030", 4.060".

Drag out your dial caliper and have at it. :)
 

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junior stocker said:
That does'nt make sense if it has a 3" stroke crank. The piston must be far below deck height? What are the rods? Deck height? This is'nt making sense to me now. :confused: And can anyone confirm the 352 Ford piston use? BUTCH.
Ford= If it fits the cylinder, then the pin/rod can be made to fit.

If a 302 used the 5.7 rod, the compression height must be tall enough to make the piston come to the deck. So it would have to be 1/4 inch more than a 350. (.240)

9.0 -1.5 -5.7 = 1.8 compression height. Center of pin to piston top.

Which is .927/2 + 1.337 = 1.8

1.337 is exactly what techie said.
 

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O.K., he says he has a 327 small journal block and a verified 265-283-302 crank by casting #. The Nylen piston # is for a 327.so; he's got an awfully low compression 302 cid motor because that piston has got to be way below deck unless a longer rod has been used; and then what would that rod be from? He's got a lot of mismatched parts that don't add up unless I'm missing something here. I understand the math, just not the parts being used. Where's NAIRB? I think he's the one who mentioned the use of Ford 352 "FE" pistons to make a low buck 301/302 Chevrolet. Anyone else see my point? BUTCH.
 

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junior stocker said:
O.K., he says he has a 327 small journal block and a verified 265-283-302 crank by casting #. The Nylen piston # is for a 327.so; he's got an awfully low compression 302 cid motor because that piston has got to be way below deck unless a longer rod has been used; and then what would that rod be from? He's got a lot of mismatched parts that don't add up unless I'm missing something here. I understand the math, just not the parts being used. Where's NAIRB? I think he's the one who mentioned the use of Ford 352 "FE" pistons to make a low buck 301/302 Chevrolet. Anyone else see my point? BUTCH.
You are correct.

A 327 piston will be waaaaaay down in the hole.... :D
He either needs an odd rod of 5.940 or the 302 pistons. :thumbup:

or a 6.0 rod and the top of the pistons milled to zero deck.... which might be 9.020"
 

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What about 6.000 rods ......that should bring the pistons close to the top of the deck and maybe a little bit above deck.Maybe they did that and used like a .040-.060 thickness head gasket.

Not to highjack this thread but Would it be possible to use a block that will accept oem rollercam use hydraulic rollerlifters and a normal hydraulic cam(I understand that there is about a thousandth of an inch taper fron the crown of the lobe to promote normal lifters to turn)But with the dogbones(I thinkthats what there called)that keep them from turning would that thousandth od an inch varrience be much of an issue.Would it be ok to do this on a low reving mild 350?

Thanks
Shane
 

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So then, "HYARBOUR"-Howard ,you have an EXTREMELY low compression 301/302; unless some special rod lenth was used, and that's doubtful based on the montage of parts used. Are you reassembling the short block the same way and just going to different heads? Or are you going to use the correct crank for the pistons and rods and make it a 327 again (3.25" stroke crank)? How did this engine run? The compression ration would have been something like 4 or 5:1. I'm not trying to tick anyone off here, just trying to settle this in my mind. I know a lot of folks seem hung up on the 301/302 "myth", and with todays smaller, lighter cars a lower compression 301/302 with opened up 305 or Vortec heads would be a real blast to drive. Just my opinion. BUTCH. :cool: NAIRB,CNC,MACHINE SHOP TOM, you're thoughts are needed here.
 

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Chevrolet4x4s said:
What about 6.000 rods ......that should bring the pistons close to the top of the deck and maybe a little bit above deck.Maybe they did that and used like a .040-.060 thickness head gasket.

Not to highjack this thread but Would it be possible to use a block that will accept oem rollercam use hydraulic rollerlifters and a normal hydraulic cam(I understand that there is about a thousandth of an inch taper fron the crown of the lobe to promote normal lifters to turn)But with the dogbones(I thinkthats what there called)that keep them from turning would that thousandth od an inch varrience be much of an issue.Would it be ok to do this on a low reving mild 350?

Thanks
Shane
Roller cams are made of steel, flat tappet cams are cast iron. So NO.
The lobe shapes are totally not compatable for mixed parts. No way shape form or fashion. If you look at a roller lifter from the side, it is round. If you look at a flat tappet lifter from the side it is a rectangle. They cannot be interchanged with the shape of the cam lobe.

You can put flat tappet cams in a roller block,
or vice versa with the roller kit.

Piston height must be kept .040+ from the head. Juggling head gaskets and pistons is possible. Watch that intake manifold fit if you get too thick of head gaskets.
 
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