|
|
|
|
Joined: Mar 2002
Posts: 1,739 Likes: 2
ChatMaster - 1,500
|
OP
ChatMaster - 1,500
Joined: Mar 2002
Posts: 1,739 Likes: 2 |
Hi all. I will be fitting aluminum Pistons to my 1929 block. As aluminum expands more then the original cast iron what clearance should be used? I believe the Pistons should not be fitted like 60s and 70s aluminum Pistons as there would be too much slop and wear. Has anyone the specs for this?
|
|
|
|
|
Joined: Nov 2001
Posts: 19,758 Likes: 63
ChatMaster - 15,000
|
|
ChatMaster - 15,000
Joined: Nov 2001
Posts: 19,758 Likes: 63 |
Are the pistons you are using recent manufacture or NORS? If modern then use the specifications for the pistons. If NORS then you need at least 0.001" for every inch of bore. If the piston skirts are split make sure that the split extends to the bottom of the piston. Some are manufactured with only a partial split to aid in stability for manufacture. If not split then they may stick when hot.
How Sweet the roar of a Chevy four!
|
|
|
|
|
Joined: May 2002
Posts: 6,149 Likes: 42
ChatMaster - 6,000
|
|
ChatMaster - 6,000
Joined: May 2002
Posts: 6,149 Likes: 42 |
A REPUTABLE machine shop will know what clearance is required and wont machine until he has the new pistons on hand to check what clearance to leave. Sometimes the piston manufacturer will supply the specifications they require in the box with the pistons.
Tony
1938 1/2 ton Hope to drive it before I retire
|
|
|
|
|
Joined: Mar 2002
Posts: 1,739 Likes: 2
ChatMaster - 1,500
|
|
OP
ChatMaster - 1,500
Joined: Mar 2002
Posts: 1,739 Likes: 2 |
They are new manufacture. Bought them about 8 years ago and don't remember maker. The skirts are slotted but not all the way down. The slot ends with a 3/8 to 7/16" hole close to the end of the skirt. The engine shop mentioned 0.0025" which is the stock gap. The ring lands are less diameter then the skirt so I believe they are constant clearance Pistons and are machined for typical expansion under running conditions. The engine shop is a reputable one that does engines from teens to today and everything from 1912 Cadillacs to Lamborgini and Maserati. They do super high performance as well as vintage restoration for Sotheby's among othersso I believe my block is in good hands.
|
|
|
|
|
Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
|
|
ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
The slots are never all the way down. I would follow the rebuilders advise....
Gene Schneider
|
|
|
|
|
Joined: Nov 2001
Posts: 19,758 Likes: 63
ChatMaster - 15,000
|
|
ChatMaster - 15,000
Joined: Nov 2001
Posts: 19,758 Likes: 63 |
I have had several sets of NORS aluminum piston that had a note in the box to complete the slot in the skirt. Wish I could remember the manufacturer. Have had at least one person that bought a set of aluminum pistons had them seize after only a short run. They had the note that was ignored by the experienced rebuilder. Sold them another set. I would follow the piston manufacturer's advise not the rebuilder.
How Sweet the roar of a Chevy four!
|
|
|
|
|
Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
|
|
ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
Yes IF you have the instructions that came with the pistons follow them. I was under the impression that the instructions were mising.
Gene Schneider
|
|
|
|
|
|
|
