Procedure for clearancing block
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Procedure for clearancing block
OK, I will be attempting to clearance my block pretty soon to acommodate the 3.750 crank for the 383. I know that I will probably have to machine the bottom of the cylinders and the pan rails. What I am not sure of, and have not been able to find a thread on, the procedure for doing this.
Here are some of the questions that I have:
1) What type of prep work do I need to do?
2) Do I need to try to remove the cam bearings or are they OK to keep in?
3) I am planning on using a dremel, with a metal grinding bit. Is this OK to use?
4) When you are checking clearances for the rods, do you install the rod bearings?
5) How should the block be cleaned after the clearancing is done?
I am sure that this topic has come up before, but I have not been able to find it in my search. If there is another thread on this, please direct me.
Thanks.
Here are some of the questions that I have:
1) What type of prep work do I need to do?
2) Do I need to try to remove the cam bearings or are they OK to keep in?
3) I am planning on using a dremel, with a metal grinding bit. Is this OK to use?
4) When you are checking clearances for the rods, do you install the rod bearings?
5) How should the block be cleaned after the clearancing is done?
I am sure that this topic has come up before, but I have not been able to find it in my search. If there is another thread on this, please direct me.
Thanks.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
1. Plan on lots of time and many assemble disassemble procedures.
2.Cam bearings are OK to leave in
3.Dremel is a little light duty but I guess it can be done with one. I have a few die grinders that I use and they get the job done very well. The Dremel will just take longer.
4. Defintily. Unless you want to tear up the smoth journals of the crank.
5. Wash it down with soap and warm water and I use a high pressure water nozzle. After you are done blow it dry with an air gun and make sure all the grit is out. Get some oil or WD40 or something on the machined sirfaces quickly. It will start to rust almost in an instant. Clean the cylinder bores with a white paper towel with auto trans fluid. Keep doing this until the paper towel comes out clean. There is a lot of grit in the cylinder walls.
You want at least .050 clearance with the rods and crank. Make sure you check everything about 3 or 4 times before you put the grinder away. It took me about 6 to 8 hours to do it right and check it many times.
2.Cam bearings are OK to leave in
3.Dremel is a little light duty but I guess it can be done with one. I have a few die grinders that I use and they get the job done very well. The Dremel will just take longer.
4. Defintily. Unless you want to tear up the smoth journals of the crank.
5. Wash it down with soap and warm water and I use a high pressure water nozzle. After you are done blow it dry with an air gun and make sure all the grit is out. Get some oil or WD40 or something on the machined sirfaces quickly. It will start to rust almost in an instant. Clean the cylinder bores with a white paper towel with auto trans fluid. Keep doing this until the paper towel comes out clean. There is a lot of grit in the cylinder walls.
You want at least .050 clearance with the rods and crank. Make sure you check everything about 3 or 4 times before you put the grinder away. It took me about 6 to 8 hours to do it right and check it many times.
Last edited by Gordonm; Feb 1, 2007 at 02:06 PM.
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Forget the dremmal and do yourself a favor. Stick one of these carbide burs in a hand drill and be done with it!!!
http://www.grainger.com/Grainger/wwg...t=Carbide+Burs
Also can find these at home improvment stores. Got mine at Home Depot.
Eddie
http://www.grainger.com/Grainger/wwg...t=Carbide+Burs
Also can find these at home improvment stores. Got mine at Home Depot.
Eddie
Last edited by Edzred72; Feb 1, 2007 at 02:05 PM.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
absolutely use sacrificial bearings & a carbide burr. If you have floater rods, slip an old piston on there too ... 350 piston oK it'll just stick out the top of block ...no matter.
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
OK, it looks like the Dremel is going back to Home Depot. I only bought it for this project and it is still unopened. What size carbide burr should I get? I don't have a die grinder, so I will be using the drill.
The block currently has the 350 rotating assembly in it with about 5,000 miles on it. Can I just reuse those bearings as the "sacrificial bearings"? I don't know if they are standard size or oversized.
I plan on pulling the pistons in order to run a hone in each cylinder. I can just reinsert the old pistons when I do it.
Also, in regards to Gordonm's suggestion about the air hose, I don't have an air compressor, will a blowdryer work?
Am I on the right track with these items?
Thanks for the input.
The block currently has the 350 rotating assembly in it with about 5,000 miles on it. Can I just reuse those bearings as the "sacrificial bearings"? I don't know if they are standard size or oversized.
I plan on pulling the pistons in order to run a hone in each cylinder. I can just reinsert the old pistons when I do it.
Also, in regards to Gordonm's suggestion about the air hose, I don't have an air compressor, will a blowdryer work?
Am I on the right track with these items?
Thanks for the input.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
The compressed air really blows out the debris that is left and dries it much quicker than a blow dryer. You need to get into some little places with the air line. I'm sure it has been done without one so just do your best. You can use the piston just remove the rings and yes the old bearings will work.
Here is a picture of my clearanced block
Here is a picture of my clearanced block
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Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Gordonm, I see the clearancing at the bottom of the cylinder walls. Did your block not require any clearancing of the pan rail?
Also, I may see if anyone I know has an air compressor that I can borrow to blow off the block.
BTW, thanks for the picture. That puts everything in perspective for me. I've never seen the places that need machining.
Also, I may see if anyone I know has an air compressor that I can borrow to blow off the block.
BTW, thanks for the picture. That puts everything in perspective for me. I've never seen the places that need machining.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I did not have to clearance any of the pan rails for my rods. They are stroker rods and I was able to use the stock pan also.
I did have to clean up a little bit at the rear of the block at the pan rail but it was just some casting flash, no real clearancing was needed.
Last edited by Gordonm; Feb 1, 2007 at 04:22 PM.
Le Mans Master
Joined: Oct 2001
Posts: 5,943
Likes: 3
From: Wildwood IL
Had to clearance my 400 block pan rail a bit for 6" rods. Die grinder is best for optimum material removal....but a drill will work in a pinch. Especially if you don't have a compressor. (which I assumed you didn't) Heres a pic.
Eddie
Eddie
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
That will make it much easier and faster. Just watch out on the carbide grinder. They cut fast and I'd hate to see you hit water and have a boat anchor for a block.
Race Director
Joined: Sep 2003
Posts: 16,839
Likes: 341
From: Database Error Indiana
I have done 2 strokers. One was a 4 bolt block that required almost no grinding. One was a 2 bolt that took a little more. Remember, if you just need a little clearance for a rod nut, its ok to grind the nut a bit instead of the block. 
Thread Starter
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Just a little caution here- WEAR EYE PROTECTION!! Hearing protection is not a bad idea either..
And if you use a die grinder (I'd recommend one too) be careful. They tend to grab and will walk right across where you dont want it to.
And if you use a die grinder (I'd recommend one too) be careful. They tend to grab and will walk right across where you dont want it to.
Racer
Joined: Oct 2004
Posts: 285
Likes: 0
From: Stockholm
Nothing wrong with a Dremel!
I used a Dremel to grind of some material from the block yesterday.
For me the Dremels wasn't to small! Work was done within 1-2 hours.
First I installed the rotating assy and marked/took lots of photos of each collision. When rotating assy is away you will forget where and how much you need to remove.
Maby I was lucky, but there was only three collisions at all, on the whole assy. And I didn't need to go deeper than 0.1"
If you need to remove lots of material you might consider a larger grinder.
The rods I use is 6" Manley streetmaster, they are very "tight" and it looks like they are designed to get good clearance with the block.
I used a Dremel to grind of some material from the block yesterday.
For me the Dremels wasn't to small! Work was done within 1-2 hours.
First I installed the rotating assy and marked/took lots of photos of each collision. When rotating assy is away you will forget where and how much you need to remove.
Maby I was lucky, but there was only three collisions at all, on the whole assy. And I didn't need to go deeper than 0.1"
If you need to remove lots of material you might consider a larger grinder.
The rods I use is 6" Manley streetmaster, they are very "tight" and it looks like they are designed to get good clearance with the block.
Le Mans Master
Joined: Apr 2005
Posts: 6,363
Likes: 429
From: Seattle Area WA
Scott