Yellow Bullet Forums banner

21 - 40 of 66 Posts

·
Registered
Joined
·
1,859 Posts
Discussion Starter #21
So hydraulic cam? You may have said that. Just wanted to make sure you didn't have a mechanical cam.
You can get almost 1 compression number out of a thicker gasket. Cometic MLS gaskets are available in thicker sizes at Summit. maybe even for Fords!
yes hydraulic.

entering all my information into a "compression ratio calculator" and changing the gasket thickness doesn't do much of anything. going from .041 gasket to .060 gasket changes compression from 11.73 to 11.16:1 in my instance.

unless i'm overlooking something.
 

·
Registered
Joined
·
4,088 Posts
If you have the piston part number, you can use that to find the specs including compression height which along with the deck height, piston height to the deck,and stroke will let you go to a Wallace calculator table and find the rod length. With a thicker head gasket, will you have enough valve to piston clearance? Need a solid lifter to check piston to valve clearance. I have taped off an engine and removed enough material for radial clearance without disassembly..
 

·
Registered
Joined
·
3,726 Posts
If you have to drop the compression that much, you're looking at moving to a dish piston (with the proper valve reliefs) and having it re-balanced before reassembly, if it was ever balanced to begin with. Do you have a build sheet or itemized bill?
 

·
Registered
Joined
·
1,119 Posts
Seems an odd situation and maybe I'm missing something but the engine sat for 12 years since completed?

If so my first thought is, if it did in fact sit that long it did for what reason? Do you already have the supercharger or something you just planned to do?

If you don't have the supercharger on hand and it's just something you plan to do my first thought would be just machine the pistons for valve clearance (though baffling how the wrong pistons are in it) and run it naturally aspirated.

If you are absolutely going to do the supercharger I would start over with new pistons but at least 10-1 compression.
 

·
Long Live The King
Joined
·
98,197 Posts
If you have to drop the compression that much, you're looking at moving to a dish piston (with the proper valve reliefs) and having it re-balanced before reassembly, if it was ever balanced to begin with. Do you have a build sheet or itemized bill?
And if the guy who built it screwed this part up that much would you trust the rest of his assembly work ? Pull the pistons and get the right ones and Go from there.... even if that includes having it checked out and reassembled by someone who knows what they are doing
 

·
Registered
Joined
·
1,859 Posts
Discussion Starter #27
If you have to drop the compression that much, you're looking at moving to a dish piston (with the proper valve reliefs) and having it re-balanced before reassembly, if it was ever balanced to begin with. Do you have a build sheet or itemized bill?
It is a dished piston, but only 12cc. It was neutral balanced. Build sheet was lost in the boating accident that also lost my guns.

Seems an odd situation and maybe I'm missing something but the engine sat for 12 years since completed?

If so my first thought is, if it did in fact sit that long it did for what reason? Do you already have the supercharger or something you just planned to do?

If you don't have the supercharger on hand and it's just something you plan to do my first thought would be just machine the pistons for valve clearance (though baffling how the wrong pistons are in it) and run it naturally aspirated.

If you are absolutely going to do the supercharger I would start over with new pistons but at least 10-1 compression.
Sat for 12 years because of life getting in the way, and I had no idea how to build a car.

No supercharger yet but I could swing the money to buy it right now. Single guy no kids and no mortgage.

10:1 is higher than recommended by procharger. 8.5 or 9:1 is recommended
 

·
Registered
Joined
·
25,088 Posts
You can have those pistons machined for not alot of money and they will be fine. Why waste money on new pistons (and a new balance job) when you dont have to? I cant remember the name, but there is a specialty shop that just does piston machining, they can do it in no time. I think is Rebco or something like that.
It is Rebco, but they may say send us the right pistons first.
 

·
Long Live The King
Joined
·
98,197 Posts
I know that you didn't know, but that is the type of thing that separates the "real" guys.

I'm a Ford guy but even I know that SBC's have different valve reliefs. Any half ass machinist should have known as well.
pretty much seems like the guy had some extra parts in his shop he figured he could charge someone for.
OP needs to figure out C/C on the rods and get the correct pistons to achieve his 9:1 or 9:5:1 target.

20 years ago ( can’t believe it was that long ago) did a major rebuild on the 565 Ford. I was upping the solid roller at the time and bumping the compression, so Danny Crower and I went over the order sheet. We got a piston build sheet from a top piston builder, we decided to not only fax them the build sheet, but we put another build sheet in a box with a piston we were replacing and Fed-Ex it to them. “Copy this piston but make dish “x” cc and valve reliefs this big”

As the engine was going together it was obvious that the first piston was not at zero deck, WTF ? Come to find out the guy responsible for the pistons decided he knew more than we did and made the piston .020 short . (not for an A-460 block) This was discovered on Tuesday and the 3 day Memorial Day weekend at the River was 4 days away. OH Shit.
Dannny Crower calls down to the “BIG Shop” and gets the rod shop on the phone “ Hey, I need a set of rods rebushed with a .020 offset bushing “Rush like yesterday” if you have them in the next hour can we get them back tomorrow morning by 10:00?”
I didn’t know they did that.....
The engine got dyno’d on Friday and put in the boat Friday night.

edit: they were .020 short
 

·
Registered
Joined
·
8,796 Posts
Take the engine to stuska 1 (he's on the board) in W.V. and have him go thru it, tell what you want/need and you will be good to go. He also has a couple of good 460 blocks if you want to go that way. Check out his work below, he's a Cleveland and SBF guy, knows them inside out.
BTW, your valve reliefs are at the wrong angle, they just need to be cut at the right angle, using chevy pistons back then was common.

 

·
Registered
Joined
·
1,859 Posts
Discussion Starter #32
Rods are 6.125.

With this combo I can't accomplish a reasonable compression ratio. That's my uneducated opinion. So please chime in.

Static ratio is 11.64:1 dynamic is 9.69:1

With a .060 head gasket it only brings static to 11.1:1 and dynamic down to 9.25:1
 

·
Registered
Joined
·
406 Posts
you've got too many threads going for the same build . I thought you said 6.2 rod in other thread . either way I think your chevy piston can be cut down to 11:1 and work with your cam head combo na but not with boost . call rebco and see what they say or order a new set with the compression you want .
 

·
Registered
Joined
·
1,859 Posts
Discussion Starter #35
you've got too many threads going for the same build . I thought you said 6.2 rod in other thread . either way I think your chevy piston can be cut down to 11:1 and work with your cam head combo na but not with boost . call rebco and see what they say or order a new set with the compression you want .
I fucked up my math with the rod length. It was not my intention, threads kinda got hijacked.

The dynamic compression ratio is what im concerned about. Worried about detonation but clearly im no expert.

I'd rather not rebalance the motor, which is why im trying to stay away from new pistons and whatnot.

Im trying to keep it simple, believe it or not lol

Either way, boost is out for sure
 

·
Registered
Joined
·
406 Posts
get all your numbers straight and call rebco or somebody like stuska1 to see if it's worth sending them your pistons to cut .
 

·
Registered
Joined
·
542 Posts
If that block is 60 over you've got a 399 rather than 393. Be nice to know the cylinder wall thickness before adding anymore power. Can make 500 Tq and hp with that combo easy enough probably
 

·
FHRITP
Joined
·
49,663 Posts
Rods are 6.125.

With this combo I can't accomplish a reasonable compression ratio. That's my uneducated opinion. So please chime in.

Static ratio is 11.64:1 dynamic is 9.69:1

With a .060 head gasket it only brings static to 11.1:1 and dynamic down to 9.25:1
It’ll run on 93 with aluminum heads like that just fix the pistons. If you’re really concerned run it on E85
 

·
Registered
Joined
·
1,859 Posts
Discussion Starter #40
Besides maybe the torque specs, can I follow this procedure for putting it back together? Start the video at 5:15 ish
 
21 - 40 of 66 Posts
Top