Length of Olds 400 push rods
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Posts: 77
From: Ringgold , GA
Length of Olds 400 push rods
I have just purchased a used olds 442 400 engine. I assume the specs of the pistons are .030 as the top of the piston has that engraved in it. How do I find out the stock length of push rods for. the 66 olds 400 engine?
How will I know if the main bearings and rod bearings have up sized to a 010 020. 030 etc....
How can I tell if the cam is still good to use!
The reason I ask all these questions is that when I pulled the head all the valves and spring and seat etc. had been redone. The valves had never even seen fire and still had marker numbers on each valve.
Thankzi Koop I’m
How will I know if the main bearings and rod bearings have up sized to a 010 020. 030 etc....
How can I tell if the cam is still good to use!
The reason I ask all these questions is that when I pulled the head all the valves and spring and seat etc. had been redone. The valves had never even seen fire and still had marker numbers on each valve.
Thankzi Koop I’m
Registered User
Joined: Sep 2017
Posts: 5,216
From: St. Paul Minnesota
I have just purchased a used olds 442 400 engine. I assume the specs of the pistons are .030 as the top of the piston has that engraved in it.
The pistons are most likely .030" O.S. if they are marked as such. What you don't know is:
1. the bore size.
2. how much piston clearance.
3. what is the deck height.
4. are the pistons cast or forged.
5. piston manufacturer.
I assumed they must have been aftermarket pistons because valve reliefs were sloppily machined into the tops from pictures on another thread.
How do I find out the stock length of push rods for. the 66 olds 400 engine?
One of the members on here will know, or Cutlassefi.
How will I know if the main bearings and rod bearings have up sized to a 010 020. 030 etc....
They could be marked on the back side of the bearings. Measuring the crank rod and main diameters with a micrometer will tell you.
How can I tell if the cam is still good to use!
First, you need to identify the camshaft and manufacturer. You may want to use a different camshaft, depending on what you have.
The reason I ask all these questions is that when I pulled the head all the valves and spring and seat etc. had been redone. The valves had never even seen fire and still had marker numbers on each valve.
I hope you have a notebook to write down the answers. I hope you have a Chassis Service Manual. Do you have precision measuring tools ?
Thankzi Koop I’m
The pistons are most likely .030" O.S. if they are marked as such. What you don't know is:
1. the bore size.
2. how much piston clearance.
3. what is the deck height.
4. are the pistons cast or forged.
5. piston manufacturer.
I assumed they must have been aftermarket pistons because valve reliefs were sloppily machined into the tops from pictures on another thread.
How do I find out the stock length of push rods for. the 66 olds 400 engine?
One of the members on here will know, or Cutlassefi.
How will I know if the main bearings and rod bearings have up sized to a 010 020. 030 etc....
They could be marked on the back side of the bearings. Measuring the crank rod and main diameters with a micrometer will tell you.
How can I tell if the cam is still good to use!
First, you need to identify the camshaft and manufacturer. You may want to use a different camshaft, depending on what you have.
The reason I ask all these questions is that when I pulled the head all the valves and spring and seat etc. had been redone. The valves had never even seen fire and still had marker numbers on each valve.
I hope you have a notebook to write down the answers. I hope you have a Chassis Service Manual. Do you have precision measuring tools ?
Thankzi Koop I’m
Registered User
Joined: Jul 2009
Posts: 3,190
From: Dallas-Fort Worth
Just for the heck of it, are you 100% sure it's a 66 short stroke 400E? Right next to the oil fill tube on the block the numbers should start with a 925...if its a 68 on up 400 it's all different..
Registered User
Joined: Feb 2013
Posts: 15,395
From: Phoenix, AZ
The early 400 engine used a 7” connecting rod. The 7” rod was also used in the 425 engines.
I would suggest you turn the engine so a piston is at TDC and measure the piston-to-deck clearance. Then cc the head combustion chambers. With this information, you can calculate the true compression ratio. Once you have that info, you can use it to determine an appropriate camshaft profile.
The cam you have may be OK, or maybe not.
I would suggest you turn the engine so a piston is at TDC and measure the piston-to-deck clearance. Then cc the head combustion chambers. With this information, you can calculate the true compression ratio. Once you have that info, you can use it to determine an appropriate camshaft profile.
The cam you have may be OK, or maybe not.
Last edited by Fun71; Dec 23, 2019 at 09:38 AM.
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Joined: Sep 2017
Posts: 5,216
From: St. Paul Minnesota
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