Do I have piston problems?
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 3,791
Likes: 428
From: Aarhus, Denmark
Do I have piston problems?
Hi,
This is one of the pistons from one of my engines.
As you can see, there is some very small and fine "lines" on all the pistons, will this give me problems?, do i have to change all my pistons?
The engine is a L46 1969 engine.
BR,
John
This is one of the pistons from one of my engines.
As you can see, there is some very small and fine "lines" on all the pistons, will this give me problems?, do i have to change all my pistons?
The engine is a L46 1969 engine.
BR,
John
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Those are probably just scratches that were put on the pistons from installing them. But, they could be cracks. You need to clean the surface and look at them with a magnifying glass; then, if you still can't tell for sure, use some dye-penetrant & developer to see if is a crack [or not]. How old are they? Are you wanting to re-use them? If they have many years service on them, you should probably replace them with new pistons.
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 3,791
Likes: 428
From: Aarhus, Denmark
It is the factory 1969 pistons, I am hoping to use them again.
But I don't what to use them, if I have to repair the engine again within a few years.
The scratches is on all 8 pistons.
But I don't what to use them, if I have to repair the engine again within a few years.
The scratches is on all 8 pistons.
Last edited by c3_dk; Mar 14, 2010 at 11:31 AM.
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 3,791
Likes: 428
From: Aarhus, Denmark
What piston must I buy now?
Speed pro dome style?
Keith Black ?
Or ???
Dome or no dome ??
Engine will be like this:
std. 1969 SB 11:1 block
Brodix IK 180
Pro-Flo II
EFI Comp cam.
Roller lifters (Comp cam)
1,6 Rocker arms
Speed pro dome style?
Keith Black ?
Or ???
Dome or no dome ??
Engine will be like this:
std. 1969 SB 11:1 block
Brodix IK 180
Pro-Flo II
EFI Comp cam.
Roller lifters (Comp cam)
1,6 Rocker arms
Last edited by c3_dk; Mar 14, 2010 at 01:51 PM.
Melting Slicks
Joined: Apr 2002
Posts: 2,337
Likes: 14
From: Norfolk VA
Not attempting to hijack the thread but I was thinking about the oem dome pistons from the L46/LT-1 earlier this week. I now see why the L46 was rated at 350 ghp. The domed pistons along with the 64cc heads give it it's 11.0:1 CR. Can these domed pistons be ordered? I'm talking about domed pistons with the EXACT shaped dome. I also understand the cam from the L46 is the same cam Chevy put in the L82 engine in 1973. Btw, were you experiencing detonation while driving?
Last edited by Oldguard 7; Mar 14, 2010 at 04:13 PM.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
You need to check the piston skirt clearance/wear to the cylinder bores. I would bet it is over 0.006" when factory high side specs are around 0.0045" of clearance.
For the $$$ Mahle piston kits are the best bang for the $$$ in todays market. Speed Pro still makes this piston in India with the old USA tooling but, they have earned themselves a bad reputation after initial quality problems, maybe things have gotten better but, I wouldn't spend my money on being a guinea pig for them.
KB, SRP, Weisco and other piston makers still have USA production lines running, that is where I would spend my $$$ for any motor I was building.
For the $$$ Mahle piston kits are the best bang for the $$$ in todays market. Speed Pro still makes this piston in India with the old USA tooling but, they have earned themselves a bad reputation after initial quality problems, maybe things have gotten better but, I wouldn't spend my money on being a guinea pig for them.
KB, SRP, Weisco and other piston makers still have USA production lines running, that is where I would spend my $$$ for any motor I was building.
Safety Car
Joined: Mar 2009
Posts: 3,558
Likes: 4
From: Oakland California
You need to check the piston skirt clearance/wear to the cylinder bores. I would bet it is over 0.006" when factory high side specs are around 0.0045" of clearance.
For the $$$ Mahle piston kits are the best bang for the $$$ in todays market. Speed Pro still makes this piston in India with the old USA tooling but, they have earned themselves a bad reputation after initial quality problems, maybe things have gotten better but, I wouldn't spend my money on being a guinea pig for them.
KB, SRP, Weisco and other piston makers still have USA production lines running, that is where I would spend my $$$ for any motor I was building.
For the $$$ Mahle piston kits are the best bang for the $$$ in todays market. Speed Pro still makes this piston in India with the old USA tooling but, they have earned themselves a bad reputation after initial quality problems, maybe things have gotten better but, I wouldn't spend my money on being a guinea pig for them.
KB, SRP, Weisco and other piston makers still have USA production lines running, that is where I would spend my $$$ for any motor I was building.
I purchased my rotating assembly with some KN pistons and they look pretty good
.
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Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
What are the cam specs? It is a hydraulic roller right? If so you will need to drop compression. The hydraulic rollers are all designed to run umder 6500 RPM. The duration is usually not enough to run 11 to 1 on pump gas. If you have stock pistons you will need to go oversize. Haven't seen a 40 year old engine yet that has so little wear you can get by without boring it. Torque plate hone will be a must also.
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 3,791
Likes: 428
From: Aarhus, Denmark
What are the cam specs? It is a hydraulic roller right? If so you will need to drop compression. The hydraulic rollers are all designed to run umder 6500 RPM. The duration is usually not enough to run 11 to 1 on pump gas. If you have stock pistons you will need to go oversize. Haven't seen a 40 year old engine yet that has so little wear you can get by without boring it. Torque plate hone will be a must also.
It was the std. 69 L46 cam that was in the engine.
http://www.compperformancegroupstore...Category_Code=
http://www.compcams.com/Cam_Specs/Ca...?csid=175&sb=2
Last edited by c3_dk; Mar 15, 2010 at 07:10 AM.
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 3,791
Likes: 428
From: Aarhus, Denmark
You need to check the piston skirt clearance/wear to the cylinder bores. I would bet it is over 0.006" when factory high side specs are around 0.0045" of clearance.
For the $$$ Mahle piston kits are the best bang for the $$$ in todays market. Speed Pro still makes this piston in India with the old USA tooling but, they have earned themselves a bad reputation after initial quality problems, maybe things have gotten better but, I wouldn't spend my money on being a guinea pig for them.
KB, SRP, Weisco and other piston makers still have USA production lines running, that is where I would spend my $$$ for any motor I was building.
For the $$$ Mahle piston kits are the best bang for the $$$ in todays market. Speed Pro still makes this piston in India with the old USA tooling but, they have earned themselves a bad reputation after initial quality problems, maybe things have gotten better but, I wouldn't spend my money on being a guinea pig for them.
KB, SRP, Weisco and other piston makers still have USA production lines running, that is where I would spend my $$$ for any motor I was building.
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
If you don't have the cam yet.. Have it ground on a steel billet core with a pressed on iron dizzy gear.. It is only about $40 extra and definitely worth the peace of mind.. I would be scared to use that cast core!
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 3,791
Likes: 428
From: Aarhus, Denmark
What are the cam specs? It is a hydraulic roller right? If so you will need to drop compression. The hydraulic rollers are all designed to run umder 6500 RPM. The duration is usually not enough to run 11 to 1 on pump gas. If you have stock pistons you will need to go oversize. Haven't seen a 40 year old engine yet that has so little wear you can get by without boring it. Torque plate hone will be a must also.
If I deside for new pistions (and I think I will) what about a stroker kit?
How big can a stroker kit be in a std. 1969 SB engine?
And if don't want a "made in Chain" or top $ US kit, what is the best buy then?
Race Director
Joined: May 2005
Posts: 10,674
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From: Millington Illinois
St. Jude Donor '08-'09
http://www.cnc-motorsports.com/produ...86&CtgID=28765
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
You can go 396 3.875 stroke crank but it requires more clearancing. A 4" stoke is available but I wouldn't go there on a factory block. The 383 is a solid build and won't require much clearancing. Any bigger gets into small base circle cam, oil pan clearance issues, excessive clearancing that does weaken the block or could break through into a water jacket. Also your piston compression height gets short if you go with a longer than stock rod which would really be a good idea.
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 3,791
Likes: 428
From: Aarhus, Denmark
Thanks Mako,
I will go for the kit you recommend.
Yesterday I bought the EZ-EFI kit for one of my engines (not the "stroker engine"), I hope it will be a success.
P.S thanks for your help, it is very hard to be informed about all this, when I live on the opposit side of the world
I will go for the kit you recommend.
Yesterday I bought the EZ-EFI kit for one of my engines (not the "stroker engine"), I hope it will be a success.
P.S thanks for your help, it is very hard to be informed about all this, when I live on the opposit side of the world
Last edited by c3_dk; Mar 17, 2010 at 02:08 PM.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Before you get carried away buying parts the block should be inspected in the bores for taper and to see exactly what size pistons to order....if they are even necessary. The ring lands on your original pistons will help decide if they are even acceptable for a new stock bore engine block...Your original will probably need a bore or hone to .030 over after the pistons have been acquired...or determined if pistons are needed.
It may not need anything if your lucky...or at least very little in parts
It may not need anything if your lucky...or at least very little in parts
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Before you get carried away buying parts the block should be inspected in the bores for taper and to see exactly what size pistons to order....if they are even necessary. The ring lands on your original pistons will help decide if they are even acceptable for a new stock bore engine block...Your original will probably need a bore or hone to .030 over after the pistons have been acquired...or determined if pistons are needed.
It may not need anything if your lucky...or at least very little in parts
It may not need anything if your lucky...or at least very little in parts
You need to measure bore and taper. I would say 95% plus will clean up fine @ .030 overbore if it has stock pistons in it now. Haven't seen a 40 year old original engine yet that has so little wear you can get by without boring it. Torque plate hone will be a must also. 
