R16 Timing Components and Cam-SAE vs. Metric

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jake7140
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by jake7140 » Mon Jul 15, 2019 2:45 pm

Thanks!
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Curtis
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by Curtis » Sat Jul 20, 2019 11:45 pm

The plot thickens.

I wasn't sure what I did with the cam bolt for my S.A.E. engine. While cleaning in the garage I found a cam bolt in a box. Checked the threads on it and it is 3/8-16. I get the cam from the engine and it goes right in. Tried the 10mm and it won't go in. Found a second cam bolt and it too is 3/8 and in it went.

So it appears I have a early cam with a metric gear. Have to wonder how that engine ran.

That makes me worried as to what is in my stroker. The cam that came out which I checked today is metric. The cam I put in was a performance cam I got and I believe I used the same cam bolt. I didn't change the gears as they were in good shape. BUT, now it is causing me doubt and makes me wonder if the problem I'm having with engine not running good in the mid range is a result of some mixed parts?

I think I'll pull the engine this Fall or Winter and check stuff and get a new rear main seal put in.
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by Curtis » Sun Jul 21, 2019 2:24 pm

Went to Steve's this morning and we compared the S.A.E. sprocket. You can clearly see the tooth off just a little from the metric.

20190721_100941.jpg

20190721_100953.jpg
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by JT68 » Sun Jul 21, 2019 3:46 pm

Bingo. If you need an early (for the 3/8 threaded cam) sprocket, I have some. As I said in the previous thread, if you mix up the sprockets, that 3-3.5ish cam degrees error is 6-7 crank degrees. That is a whole lot of cam timing error. It will run, but not well. J
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by Curtis » Sun Jul 21, 2019 5:04 pm

JT68 wrote:
Sun Jul 21, 2019 3:46 pm
Bingo. If you need an early (for the 3/8 threaded cam) sprocket, I have some. As I said in the previous thread, if you mix up the sprockets, that 3-3.5ish cam degrees error is 6-7 crank degrees. That is a whole lot of cam timing error. It will run, but not well. J
Thanks, Steve let me get a set from him. I got a heater core from him as well.

So what does the off timing make the engine run like?
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by JT68 » Sun Jul 21, 2019 7:06 pm

Curtis wrote:
Sun Jul 21, 2019 5:04 pm
JT68 wrote:
Sun Jul 21, 2019 3:46 pm
Bingo. If you need an early (for the 3/8 threaded cam) sprocket, I have some. As I said in the previous thread, if you mix up the sprockets, that 3-3.5ish cam degrees error is 6-7 crank degrees. That is a whole lot of cam timing error. It will run, but not well. J
Thanks, Steve let me get a set from him. I got a heater core from him as well.

So what does the off timing make the engine run like?
Assuming a stock cam and no valve/piston collisions, just about any poor running situation you can think of because ALL the valve events are out of sync with the crank and pistons.

At a minimum, it will never feel "right" or want to rev well. If you measure it with a dyno, you'll be well off the factory torque curve at most if not all rpms. Sluggish and mis-tuned.

The exact symptoms depend on what parts were swapped and whether the cam is badly advanced or retarded. If advanced it may idle fine, but be struggling at rpm. If too far retarded will have lousy low end, poor mid range and still underpowered in the top end.

Depending on CR and cam grind it may behave like the ignition timing is too retarded and may also run hot. Lots of possibilities, but lots of variables too, so a myriad of effects. In short nothing good.
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by S Allen » Mon Jul 22, 2019 9:01 pm

Not trying to steal anyone's thunder here but Dave Premo brought this issue to my attention when we were building my stroker motor for my 66. Dave and Stan figured this issue out years ago when they were building a stroker for Stan. So, at least a little credit is due Stan and Dave. On my three main early motor as I said I ended up going with a later metric cam and a Japanese aftermarket metric timing gear. I had not run into this issue with the first stroker I built as it was a later 5 main motor that already had the metric cam. At any rate it is good info for sure.


Steve
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by Curtis » Mon Jul 22, 2019 10:16 pm

Not trying to steal thunder but many people don't know this and I'm not sure this is in the wiki.

I think we should put a full write up about it in the wiki. Or did I miss it? Not something you might think to go looking for. On the other hand if you're shopping for parts the roadster vendors make a point of it.

However if one does a search on here to buy parts and goes straight to the forklift parts they can end up with a problem they didn't know about such as my engine by a PO. I have a feeling because of when this car was done in probably the 90's that they got the cam gear from either the dealer or a parts store.
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by S Allen » Mon Jul 22, 2019 10:25 pm

Agreed. I will get the info in the wiki as it is not there. Thanks.

Steve
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67 SRL311-00279-resto project
Stock '72 240Z-Blue
2002 Ford F250 7.3 Diesel 2WD Hauler
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by Curtis » Mon Jul 22, 2019 10:39 pm

Do you want me to take some better pictures to use?
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by S Allen » Mon Jul 22, 2019 11:17 pm

Sure, if you want to. That would be great. Thanks.

S
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by S Allen » Tue Jul 23, 2019 8:37 am

Here is the write-up. Anything I missed let me know. If you have better pics I will add them. Thanks.

Cam Sprocket SAE vs. Metric


Steve
66 Stroker-Viper Blue Eventually
67.5 Stroker-Purple
67 SRL311-00279-resto project
Stock '72 240Z-Blue
2002 Ford F250 7.3 Diesel 2WD Hauler
2008 Toyota FJ Cruiser
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by Curtis » Tue Jul 23, 2019 10:21 am

S Allen wrote:
Tue Jul 23, 2019 8:37 am
Here is the write-up. Anything I missed let me know. If you have better pics I will add them. Thanks.

Cam Sprocket SAE vs. Metric


Steve
That does the job, thanks.
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by JT68 » Tue Jul 23, 2019 1:55 pm

Nice write-up. Thanks Steve,Curtis, Dave & Stan👍👍
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Re: R16 Timing Components and Cam-SAE vs. Metric

Post by S Allen » Tue Jul 23, 2019 3:36 pm

Thank you JT for your in depth comments.

S
66 Stroker-Viper Blue Eventually
67.5 Stroker-Purple
67 SRL311-00279-resto project
Stock '72 240Z-Blue
2002 Ford F250 7.3 Diesel 2WD Hauler
2008 Toyota FJ Cruiser
2009 Smart ForTwo Passion Coupe
2013 Fiat 500 Abarth