This information has been added for general interest only and not to downplay the quality of the original timing chain and gears.
The following 2 pictures show the timing chain deflection in a new Chev engine. This engine hasn't run yet and the chain has a half an inch of deflection.
Picture 1 Chain deflection
Picture 2 Chain deflection
Picture 3 shows the front of the centre oil galley that interferes with the installation of an aftermarket timing chain set. Part of the boss needs to be removed for timing chain clearance. Also the oil bleed holes are shown in the lifter galley expansion plugs.
Picture 4 shows the removal of the obstruction that is necessary for the new chain and cam gear clearance requirement.
The next 2 pictures show the installation of a Cloyes double roller chain with no deflection.
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With the chain that loose it's seems they are trying a cheap way to get that variable timing everyone is raving about lately. Although because it's uncontroled variable timing, maybe it should be called random timing?
Nice catch to not only notice it, but to properly address the situation before it became a bigger situation!
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"If I could get back all the money I've ever spent on cars...I'd spend it ALL on cars !!!
Being a mechanic for for 27 years I have replaced a few timing chains. When they go in their tight. Give that engine 10k and it will be looser than the one you pulled out.
Not saying that you didn't do a good job of upgrading the chain but I know it won't stay that tight very long.
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Being a mechanic for for 27 years I have replaced a few timing chains. When they go in their tight. Give that engine 10k and it will be looser than the one you pulled out. Not saying that you didn't do a good job of upgrading the chain but I know it won't stay that tight very long.
Being married for 25 years... Ah, never mind !! I'll save it for the Off-topic section.
I had a '74 Impala years ago..... Musta been a year or two before I gave my head a shake.....anyway, with a timing light on it, the mark was dancing all over the place! The 350 had some hard miles on it, somewhere around 145,000 I think, but timing during a tune up was a best guess situation. I was young and broke and about to upgrade to Fords at the time, so I didn't put a new chain and sprockets on it.
Lightspeed: I find it hard to believe a new one would end up looser than that after only 10,000 Ks and if that's the case, how loose would that brand new, already loose one be after 10,000 Ks? My old Impala was probably that loose after 20 years!
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"If I could get back all the money I've ever spent on cars...I'd spend it ALL on cars !!!
Id have to agree with Mike . 1/2 " of play on a chain that size will be close to the recommended setting . Trying to tighten it any more will just make it stretch faster until it reaches the point were it wants to be then settle in and it will take forever to stretch more.Over the years Iv found this to be consistent with any type of drive chain .
Being a mechanic for for 27 years I have replaced a few timing chains. When they go in their tight. Give that engine 10k and it will be looser than the one you pulled out. Not saying that you didn't do a good job of upgrading the chain but I know it won't stay that tight very long.
funny i had to replace the oil pan in my truck a few years ago and i pulled the front cover to change the crank seal and the double roller chain i installed four years earlier had a minute amount of play in it but definitley not worn out. if a chain develops that much slop in 10k theres something else going on.
Lots of these newer OHC engines have these super long chains to drive the cams, but they also have tensioners with chain guides built-in. So maybe they aren't tight in a traditional sense, but definitely don't have lots of slack either. I say: you want lots of slack? Go see "Slack Alice"!!!
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"If I could get back all the money I've ever spent on cars...I'd spend it ALL on cars !!!
This information has been added for general interest only and not to downplay the quality of the original timing chain and gears.
The following 2 pictures show the timing chain deflection in a new Chev engine. This engine hasn't run yet and the chain has a half an inch of deflection.
Picture 1 Chain deflection
Picture 2 Chain deflection
Picture 3 shows the front of the centre oil galley that interferes with the installation of an aftermarket timing chain set. Part of the boss needs to be removed for timing chain clearance. Also the oil bleed holes are shown in the lifter galley expansion plugs.
Picture 4 shows the removal of the obstruction that is necessary for the new chain and cam gear clearance requirement.
The next 2 pictures show the installation of a Cloyes double roller chain with no deflection.
i recall something about core shift in some small blocks that was so bad they required different timing chains to make up for it, i wonder if this is a timing set for that purpose
To be honest, I'm happy to see some people commenting on a post I started. I should have provided a bit more information when I posted this topic. The engine is a new (never run) 602 Crate engine that is used in stock car racing and its normal operating range is between 4000 and 6400 RPM and it spends its entire service life in this range. Traditionally, I have found the original timing chain on these engines to be prone to breaking which is extremely hard on the valves and pistons. As Fordy Acres pointed out, a chain this loose will cause the ignition timing to bounce all over the place and if the engine was connected to an old time scope, it would show quite a bit of spark scatter.
The solution to this loose chain is to replace it with a good quality true roller chain (my choice is Cloyes) and solve a possible problem down the road. As Fatstax pointed out, he didn't have any noticeable wear in his roller chain so I wouldn't think this one to be any different.
When I posted the original information, it was to show what had to be done to modify a newer style Chev cylinder block so it would accept a double roller chain. The older style Chev cylinder block didn't have the raised boss on it so it didn't interfere with the chain and cam gear.
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i recall something about core shift in some small blocks that was so bad they required different timing chains to make up for it, i wonder if this is a timing set for that purpose
The timing set I used was for a stock distance from cam centre to crank centre but you can buy a timing set that is about 0.005" shorter between the two gears for an engine that has been line bored.
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What's the point of writing a response if its only going to get deleted.
i recall something about core shift in some small blocks that was so bad they required different timing chains to make up for it, i wonder if this is a timing set for that purpose
Core shift is something totally different. Core shift causes cylinder wall to be different thicknesses, as well as other problems. Core shift does not change the centerline of the cam bores in relation to the centerline of the crank. This is a set number and is a machined operation. What does affect this, is align honing the crank, but by only a few thousands.
The "602" mentioned is not a displacement, but a part # . GM part# 19258602 is a crate smallblock 350ci. , designed for hobby class stock car racing . Different classes/tracks allow different modifications to be done to the engine. Most require that a stock block and rotating assembly be used.
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This past spring we decided to replace the chain/gears on the Falcon (1969 Ford 302) as the timing had become a little erratic.
I ordered up TRW (worked there 23 years) parts and replaced them. My wife and I were heading through Welland to Humberstone Speedway when she went dead. NO warning. I pulled the dist. cap, had Sue click it over and observed no movement on the rotor.
HAH!, I assumed the roll pin in the distributor gear sheared. Had that happen once years ago. Flat bedded the car home. Pulled the distributor - nope. roll pin was fine. Clicked the engine over while watching the cam gear. NO movement.
Pulled the front off the motor again. The chain was snapped, cam gear was alright upon inspection. Pulled the crank gear and found a split keyway from front to back!
I returned the parts and the jobber sent them to TRW for inspection. Meanwhile I bought a better quality double roller set, installed and running with no issue.
Recently the jobber sent me the results from TRW.
" ....no defect found in any of the pieces, failure due to improper installation"
Yeah, been building these motors since I was 14. Never had one fail. Apparently I don't know what I'm doing....well, that could be true - but I don't buy TRW any longer.
