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| Romac timing chain - install sprocket before or after putting crankshaft in block? https://slantsix.org/forum/viewtopic.php?t=65694 |
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| Author: | MadScientistMatt [ Fri Jan 08, 2021 10:03 am ] |
| Post subject: | Romac timing chain - install sprocket before or after putting crankshaft in block? |
Now that I finally found the correct main bearings, I can put the crankshaft in the block. Normally one would put the timing chain sprocket on the crank before installing the crank. But it looks like with the multiple keyways, I'll need to have the crank in there before I can put the sprocket on - unless there's a good way to determine which keyway to use before I'm a lot further along in the assembly process? Any particular tricks to use here? |
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| Author: | volaredon [ Fri Jan 08, 2021 10:26 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Multiple keyways can be a cluster. The square or triangle mark by the correct keyway for the amount of offset isn't the timing mark used to line up the crank and cam. Don't ask me how I know. That one cost me dearly on a 360 magnum once. |
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| Author: | Charrlie_S [ Fri Jan 08, 2021 11:11 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Personally, I don't like multiple crank key ways. If it were me I would put the crank sprocket on "straight up", and use a offset cam bushing. Crank sprockets fit tight, and are a pain to remove, and you have to remove the cam sprocket any way, to change the crank sprocket. |
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| Author: | Dart270 [ Fri Jan 08, 2021 12:22 pm ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
I'm with Charlie on the bushing vs. keyways. I've always put gears on (w/mallet/pipe or HB installer) w/crank in block, but others don't like this. Lou |
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| Author: | Greg Ondayko [ Fri Jan 08, 2021 1:06 pm ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Many times those multiple keyway rollon / iwiss romac sets are marked. They also tend to be wicked tight. Some light dremel work on the id can be helpful. I would also use the harmonic balancer install tool to properly put it on. Greg |
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| Author: | GregCon [ Fri Jan 08, 2021 6:36 pm ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
I'm missing something here....regardless of keyway count, you're gonna need to install the crank pulley at the same time as the cam pulley and chain. I'm assuming your set is new and not used. A new chain will be too tight to allow you to install it without both gears being mobile. Or, even if you 'can', it's better not to do so. On the Romac's Ive used, the lower pulley is really tight on the crank. I'd recommend, if it doesn't fit on with only slight force, honing the ID a bit. |
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| Author: | CNC-Dude [ Sat Jan 09, 2021 7:08 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Quote: I'm missing something here....regardless of keyway count, you're gonna need to install the crank pulley at the same time as the cam pulley and chain. I'm assuming your set is new and not used. A new chain will be too tight to allow you to install it without both gears being mobile. Or, even if you 'can', it's better not to do so.
It is tight, but it also is on most all other engines as well. Install the crank gear on the crank before you install it in your engine. A scenario that was told to me many years ago by a professional engine builder was like this. Place the crankshaft standing vertically on either your right foot or left foot while barefoot and standing on a concrete floor. Place the crank gear over the crank snout, and with a 5 pound hammer and a short tube placed over the crank snout, ...hammer away! The pain and damage you do to your foot, is also the same damage and pain/stress you are causing to the thrust bearing. I have seen several people that should have known better install crank gears this way and wiped the thrust bearing out of an expensive engine before it ever makes into their cars. Working on engines correctly can be expensive, but having to refix them is even more. We all like to take shortcuts, don't get me wrong! If you can't find a friend to loan you the correct tools, then rent them. As Lou and Charlie mentioned, using offset bushings is a simple solution if you can't find a balancer installer or puller, or just don't want to deal with taking the gear on/off several times. Either method is correct and can give you the same end results, just do either one correctly. Other companies that make timing sets state in their instructions that the crank gear requires honing before installation to get the proper fitment. So double check your instructions to make sure this set doesn't also require that.
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| Author: | Rick Covalt [ Sat Jan 09, 2021 9:41 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
I honed mine with a piece of sandpaper wrapped around a PVC pipe. I then make it it so that I can heat the gear up and bump it on with minimal force at all. When it cools it is tight. Want the gear off? Take your torch and warm the gear up and push it off with 2 pry bars. Minimal force. Only did it once but I did take the gear off 2 times to get the degreeing right. Worked fine for me. 
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| Author: | GregCon [ Sat Jan 09, 2021 9:51 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
I wouldn't hammer any gear on, no matter what. If it won't slip on, or gently tap on, I'd use a gear installer that uses screw force to press the gear into place. A hammer has no place in this equation. |
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| Author: | MadScientistMatt [ Mon Jan 11, 2021 7:13 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Thank you for the suggestions! So it looks like my options would either be: 1. Install the crank sprocket straight up before installing the crank, then use offset dowels to adjust the cam. 2. Install the crank with no sprocket, and adjust using the offset keyways by installing the sprocket with a threaded puller. |
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| Author: | cpslntdchrg [ Mon Jan 11, 2021 8:20 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
I installed one with the engine in the car. It bite the tip of the crankshaft when installing it (specially were the key slots are in the hub). I heated it but with a toaster oven... probably not enough to properly expand the sprocket. I had to remove it, smooth the crankshaft tip, and remove a little material from inside the sprocket to install it without problem (so far at least). I asked a machined shop to remove a little material, I forgot how much. |
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| Author: | GregCon [ Mon Jan 11, 2021 8:45 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Offset dowels are their own little nightmare, IMO. The reason the crank gear has all the keyways was done as an 'upgrade' over the dowel method. My best advice is make the crank gear fit properly - that's part of good engine assembly - then use the keyways as intended. |
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| Author: | CNC-Dude [ Mon Jan 11, 2021 1:53 pm ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Over time, crank snouts get nicks and burrs on them. To begin with, if the key can be removed easily, take it out and lightly file the snout smooth to remove those burrs. The key also gets banged up over the years and lightly run the key over a smooth grain file. This is often overlooked, and can make the crank gear fit on much easier since its not having to plow over those nicks and burrs. But i'm with GregCon, I prefer to use the multi-keyway gears. The bushings require the cam gear to be drilled, and this can be a simple task for many, but it isn't in everyone's wheel house to do it without issues. Then the gear needs to be peined around the bushing to keep it from moving once you degree the cam. Again, not a process that is in everyone's wheel house. |
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| Author: | SpaceFrank [ Wed Jan 20, 2021 11:07 pm ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Why would you need to peen the cam gear around an offset bushing? Wouldn't the offset keep the bushing from spinning after the gear is bolted onto the cam? The pin is a fixed distance from the camshaft centerline, so unless there's slop in the oversized hole for the bushing, everything should be geometrically constrained. The bushing can only spin if there's no offset, in which case it doesn't matter if it spins. |
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| Author: | emsvitil [ Thu Jan 21, 2021 12:28 am ] |
| Post subject: | Re: Romac timing chain - install sprocket before or after putting crankshaft in block? |
Different offsets = different bushings. https://www.summitracing.com/parts/cca-47604 |
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