Engine Rebuild Part 2
Thread Starter
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Moderator
Joined: Dec 2007
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From: Boise, Idaho
However, as far as pistons go, I really don't know the difference. They state they're for heavy duty (another site I saw said "UPS") and not for racing. I don't understand that stuff well enough yet to know why, without someone explaining it.
If you're feeling a little shifty you could order one each of a few 300 pistons, enough to get free shipping from Summit, have them CCed then return them. Just like dusting off and nuking the site from orbit it's the only way to be sure. All you'd be out is the cost of return shipping.
I'd thought about this and am considering it. Kinda sucks to pay to return them, but at least I'd know.
I DID, however, find a site that listed these specifically as 19cc pistons.
Silv-O-Lite Cast Pistons 1170-030 - Free Shipping on Orders Over $99 at Summit Racing
Beck Racing - Silvolite Pistons
What are the thoughts on cast?
FWIW, I measured an H674P pistons and it was 25cc.
Lead Driver
Joined: Dec 2000
Posts: 6,293
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From: South central, Minnesota
I know you are pretty thorough when it comes to the #'s. Just make sure to confirm the compression height on the pistons. There were one or two different pistons I've found used in some of the 70's 300's that were quite a bit shorter then most. It might be the one that was a true flat top with no dish or valve reliefs. I believe it was listed for either a 300 HD engine or a UPS 300. So just make sure the compression height is what you need.
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Moderator
Joined: Dec 2007
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From: Boise, Idaho
I know you are pretty thorough when it comes to the #'s. Just make sure to confirm the compression height on the pistons. There were one or two different pistons I've found used in some of the 70's 300's that were quite a bit shorter then most. It might be the one that was a true flat top with no dish or valve reliefs. I believe it was listed for either a 300 HD engine or a UPS 300. So just make sure the compression height is what you need.
Postmaster
Joined: Mar 2005
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From: Earth
Say, so those h674P pistons I measured have a 25cc D-shaped dish - .310" deep.
Silv-O-Lite Hypereutectic Pistons 3171H-030 - Free Shipping on Orders Over $99 at Summit Racing
Those are basically the same except a .290" dish. Figure maybe 3cc smaller.
Assume you can safely mill a head .060". Mill it .030" and you've got at least two resurfaces in the bank. Another 400,000 miles hopefully.
With a 22cc dish and 72cc chambers you should be really close to 9.0:1 at .005" below.
Silv-O-Lite Hypereutectic Pistons 3171H-030 - Free Shipping on Orders Over $99 at Summit Racing
Those are basically the same except a .290" dish. Figure maybe 3cc smaller.
Assume you can safely mill a head .060". Mill it .030" and you've got at least two resurfaces in the bank. Another 400,000 miles hopefully.
With a 22cc dish and 72cc chambers you should be really close to 9.0:1 at .005" below.
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Joined: Mar 2005
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From: Earth
I just so happen to have a 240 head, a carb 300 head and efi 300 head on hand right now, plus a '96 short block with d-shaped dish hyper pistons. Out of curiosity I used a piece of clear plastic and a head gasket to trace the piston dish so I could see how it matched up to each of the heads. We talk about squish, so what gives?
The plastic was shiny and made getting good pictures a pain. But for what it's worth.
First, the EFI head
Then the 240 head
Finally, the 300 carb head:
Pretty obvious why Ford went to a D-shaped dish. It mates almost perfectly.
The plastic was shiny and made getting good pictures a pain. But for what it's worth.
First, the EFI head
Then the 240 head
Finally, the 300 carb head:
Pretty obvious why Ford went to a D-shaped dish. It mates almost perfectly.
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Joined: Dec 2007
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From: Boise, Idaho
That's a really awesome diagnostics/experiment, thanks for that Baron! That shows a lot, such as why there's the D shape in the pistons.
Is that triangle area that's entering the D shape on the EFI head the "fast burn" edges?
Sometimes you can explain things and explain things, but sometimes, just seeing it makes all the difference.
Is that triangle area that's entering the D shape on the EFI head the "fast burn" edges?
Sometimes you can explain things and explain things, but sometimes, just seeing it makes all the difference.
Lead Driver
Joined: Mar 2008
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From: Near Los Angeles
I'll answer for BVA: No, that is not the ridges of a fast burn chamber. That is simply the shape (heart shape) of an EFI head. A fast burn chamber has ridges around the valves that are meant to direct the gas flow, as in the photo below. The top chamber has the ridges; the bottom chamber has had them removed, and is polished. The top chamber has 1.94 intake valves, while the bottom one has 2.02 intakes.
In the third photo the chamber is oem and you can see the depth of the chamber opposite the spark plug. The chamber with the ridges has only had .020 removed. Quite a difference. I should mention the photo of the polished chamber was supplied by pmuller9, on the other forum. After he removed the ridges he cc'ed the chambers and came up up a 76cc chamber.
I also wanted to thank BVA for the photos. Your illustration makes me like the 351 SpeedPro piston in your link even more because of the oblong indentation.
My new .912 rods arrived! Hoorah.
In the third photo the chamber is oem and you can see the depth of the chamber opposite the spark plug. The chamber with the ridges has only had .020 removed. Quite a difference. I should mention the photo of the polished chamber was supplied by pmuller9, on the other forum. After he removed the ridges he cc'ed the chambers and came up up a 76cc chamber.
I also wanted to thank BVA for the photos. Your illustration makes me like the 351 SpeedPro piston in your link even more because of the oblong indentation.
My new .912 rods arrived! Hoorah.
Postmaster
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From: Earth
Interesting, the chamber of the 240 head I've got looks pretty much identical to the chamber in that top picture - same ridges on the spark plug side. I'll get another picture in the a.m. without the plastic. I think you've got yourself a 240 head. Have you CCed the chambers?
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Lead Driver
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From: Near Los Angeles
Interesting, the chamber of the 240 head I've got looks pretty much identical to the chamber in that top picture - same ridges on the spark plug side. I'll get another picture in the a.m. without the plastic. I think you've got yourself a 240 head. Have you CCed the chambers?
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If you wish to know more, talk to Mike Johnson at, J.M.S.: R.E., i.e. Johnson Machine Service: Racing Engines, in El Monte, Ca.
JMS Racing ? Since 1973 - Racing Engines and Vehicle Service
Fleet Mechanic
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A fast burn chamber has ridges around the valves that are meant to direct the gas flow, as in the photo below. The top chamber has the ridges; the bottom chamber has had them removed, and is polished. The top chamber has 1.94 intake valves, while the bottom one has 2.02 intakes.
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Flashman, I was making a JOKE, pretending to quibble about a single dimension when you had typed out a whole bunch of dimensions.
Why is it that people take my words seriously only when I'm joking, and at no other time? But really, Flashman, you shouldn't take anything I say without several grains of salt, LOL.
Why is it that people take my words seriously only when I'm joking, and at no other time? But really, Flashman, you shouldn't take anything I say without several grains of salt, LOL.
Lead Driver
Joined: Dec 2000
Posts: 6,293
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From: South central, Minnesota
There was a company that offered oversized valves that were a direct replacement ( length wise ) for the 300. I think the company was SI. But if I remember they discontinued them. But they still offer the SBC length valves.
The ones I'm looking at are some Manley ones. But they are kind of spendy $$$. And they are longer then the stock 300 ones. If you don't want to spend this much I'm pretty sure you can find basically the same thing for less from another brand.
There are two different part #'s for the intake valves. I can not find what the difference is between them. They appear to be the same valve. But one they say is for a Ford and the other is listed for a chevy.
Intake:
Manley Race Series Stainless Steel Valves 11532-1 - Free Shipping on Orders Over $99 at Summit Racing
Manley Race Series Stainless Steel Valves 11522-1 - Free Shipping on Orders Over $99 at Summit Racing
Exhaust:
Manley Severe Duty Series Stainless Steel Valves 11543-1 - Free Shipping on Orders Over $99 at Summit Racing
The ones I'm looking at are some Manley ones. But they are kind of spendy $$$. And they are longer then the stock 300 ones. If you don't want to spend this much I'm pretty sure you can find basically the same thing for less from another brand.
There are two different part #'s for the intake valves. I can not find what the difference is between them. They appear to be the same valve. But one they say is for a Ford and the other is listed for a chevy.
Intake:
Manley Race Series Stainless Steel Valves 11532-1 - Free Shipping on Orders Over $99 at Summit Racing
Manley Race Series Stainless Steel Valves 11522-1 - Free Shipping on Orders Over $99 at Summit Racing
Exhaust:
Manley Severe Duty Series Stainless Steel Valves 11543-1 - Free Shipping on Orders Over $99 at Summit Racing
Thread Starter
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Moderator
Joined: Dec 2007
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From: Boise, Idaho
Thanks for the link to those.
What happens with a longer valve? Would you just get longer push rods and raise the rocker higher up on the stud?
As for SI, I remember a few years ago back when I was looking at valves, they were listed everywhere. No sign of them anymore.
What happens with a longer valve? Would you just get longer push rods and raise the rocker higher up on the stud?
As for SI, I remember a few years ago back when I was looking at valves, they were listed everywhere. No sign of them anymore.