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Discussion Starter #1
Line honed block and the timing chain has a bunch of slop in it. I can move it about 5/8" or so on the slacked side. I called my machinist, he said there was a .005 under or .010 under chainset available....what do these numbers refer to...the distance between cam and crank centerlines? Whats the stock distance? Is there any other way to solve this problem?
 

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Nope. The crank centerline is now closer to the camshaft. The only fix is to use a timing set that's ready for the different arrangement.
 

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Line honed block and the timing chain has a bunch of slop in it. I can move it about 5/8" or so on the slacked side. I called my machinist, he said there was a .005 under or .010 under chainset available....what do these numbers refer to...the distance between cam and crank centerlines? Whats the stock distance? Is there any other way to solve this problem?
Jesel :D

GT:)hand
 

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I just went through this.
It appears how the slack is corrected (in the Cloyes set), the top cam gears teeth are cut shallower thus making the gear larger in diameter and the chain tighter.
Cloyes offers .005-.010-.015
Rollmaster offers increments of two .002-.004-.006-.008 etc
 

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Discussion Starter #5
I just went through this.
It appears how the slack is corrected (in the Cloyes set), the top cam gears teeth are cut shallower thus making the gear larger in diameter and the chain tighter.
Cloyes offers .005-.010-.015
Rollmaster offers increments of two .002-.004-.006-.008 etc
I saw your's right after I made my post...LOL.

I've got a couple different sets that should be here this afternoon...we'll see what happens.
 

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Line honing?

This is why I shy away from align boring BBC blocks. About half the time the shop screws them up. Most, not all, but most BBCs are within a reasonable tolerance from the factory and it takes quite a bit to mess them up during use. (Spinning a main bearing is tough to do, and usually scraps the block, or is destined to be a grocery getter engine))....I know, I know, I'll probably get flamed for this post, but so often it is un necessary to re bore the mains. Of course if you change caps then it is a must, but most BBCs with factory original caps are good to go.....Big difference between align honing, and align boring. I find it strange that an "align honed" block would be that far off..........Ray

PS Pay very close attention to the thrust surfaces. Something smells kinda fishy.
 

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What brand is the timing set? Offshore or somebody's "house" brand?(same thing in most cases). Lack of quality control in the cheap stuff is an issue. .005,.010,.015, undersize sets are an acceptable answer for this problem. I have seen MANY cases where there is unacceptable chain slop in an unmachined new or used block too. Production tolerances can stack up even with all new parts, including aftermarket blocks. Our experience is that about 85% of the used blocks and 30% of the new blocks are out of spec in the line bore in diameter or alignment. Since WW II when winning the war was more important than quality/longetivity of the engines in the planes,tanks,jeeps,etc. most manufacturers haven't allowed their castings to "relax" before machining them. I worked for Allis-Chalmers in the 70s, and they had a 20 acre ageing yard next to the plant in Springfield,IL. They allowed all of their castings to sit outside for a minimun of 1 year before they machined them, all of them, even the castings used in pushbeams and mold boards, and those are of a non-critical nature. Cast iron "moves" just like wood does and it is common to see new-old stock blocks that are out of spec in most dimensions. We stress relieve all of our new blocks in an oven by cycling them as is recomended in the Ford,Chevy, and Mopar factory performance books before we machine them. A poor quality line hone or the desire to "save" a block by excessive honing can also be a problem. IMHO, use a shorter timing set and be happy. No flame, just fact. TIMINATOR
 

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P.S. If my experience was that a shop screwed up things half the time, I would look for somebody else to do my work. Just my humble OPINION. TIMINATOR
 

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Discussion Starter #9
P.S. If my experience was that a shop screwed up things half the time, I would look for somebody else to do my work. Just my humble OPINION. TIMINATOR

True...but I've dealt with several other shops over the years (I had 2 race cars....I go through quite bit of engine work) and they screwed up considerably more....then would charge me to fix it.

The guy that I currently deal with always makes right in the end. My core had a spun main, and that's why we had to hone it...or bore it, I dunno which he did...either way, the mains are straight now. I'm getting the new chain today, I'll update in the morning.
 

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Discussion Starter #10
OK...got an EnginePro .005" under timing set....it's better than the standard set, but still has a bit of slop in the chain. I decided to see exactly how much this would affect the cam timing. 3/8" or so wiggle in the chain gave me less than 1/2° of rotation in the cam....good enough for me...so I ended up using it.
 

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Inspection equipment

P.S. If my experience was that a shop screwed up things half the time, I would look for somebody else to do my work. Just my humble OPINION. TIMINATOR
And how many DIY builders actually have the necessary inspection equipment to verify the work???. An extemely loose timing chain is a sign, but not an absolute with all the variables "stacked" up...True position, and parallelism, won't be found with a tape measure. Checking the block, from end to end, for actual numbers from crank C/L to cam C/L takes one hellofa surface plate. Not to mention a height master and a good height gage. I won't even start on cylinder perpendicularity.......So many people have that "feel good" feeling after a block is align bored, but in reality, they are depending on the shop, the equipment, and the human part of machine work. I'll stick by my statement that most are better left alone unless caps are changed. Very few shops have the inspection capability to really inspect their own work and depend on the equipment doing the job, not the post machining inspection, which seldom happens..........Ray
 

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Discussion Starter #12
And how many DIY builders actually have the necessary inspection equipment to verify the work???. An extemely loose timing chain is a sign, but not an absolute with all the variables "stacked" up...True position, and parallelism, won't be found with a tape measure. Checking the block, from end to end, for actual numbers from crank C/L to cam C/L takes one hellofa surface plate. Not to mention a height master and a good height gage. I won't even start on cylinder perpendicularity.......So many people have that "feel good" feeling after a block is align bored, but in reality, they are depending on the shop, the equipment, and the human part of machine work. I'll stick by my statement that most are better left alone unless caps are changed. Very few shops have the inspection capability to really inspect their own work and depend on the equipment doing the job, not the post machining inspection, which seldom happens..........Ray
I agree, but this block had spun a main bearing and needed it.
 

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numbers, only numbers

I agree, but this block had spun a main bearing and needed it.
So how far off is the crank centerline to the old/original bore angle? Was the block re bored using the "new" crank centerline? As I said above, yes you can save the block but the end result may be less than desired in anything other than a grocery getter.......Don't forget to deck the block to the new bore angle, and if the intake doesn't seal to well, you'll need to address that as well. It is a never ending battle. Good luck......Ray
 
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