Cam Install (Newbie)
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Joined: Oct 2005
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From: Ottawa Ontario
Cam Install (Newbie)
I’m installing a S/R, new heads, intake etc. on my 86 L98 and have a few questions for the experts:
When installing the cam, is the timing marks dot over dot, or are both dots at the 12 o'clock position? I 'am getting conflicting instructions from different manuals.
When installing the S/R plenum to the runners, are the bolts head to be in the plenum, or are the nut portions to be in the plenum? S/R instructions are not that clear.
Thanks for the help.
When installing the cam, is the timing marks dot over dot, or are both dots at the 12 o'clock position? I 'am getting conflicting instructions from different manuals.
When installing the S/R plenum to the runners, are the bolts head to be in the plenum, or are the nut portions to be in the plenum? S/R instructions are not that clear.
Thanks for the help.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Same old, same old. The only difference is whether the #1 (and also the #6) piston is at TDC on the compression stroke, or the exhaust stroke. It doesn't make any difference until it comes time to drop in the distributor. Then, you want to know there the engine is set.
RACE ON!!!
Melting Slicks
Joined: Aug 2003
Posts: 3,393
Likes: 392
From: Lakeville MI
Regarding superram installation:
The 16 1/4-28 12 point bolts are intended to thread into the plenum from the bottom.
Do you have a used superram that has been modified for use with nuts and bolts to make installation easier? Please explain.
Note: My plenum is studded with 1/4-28 x 1/4-20 studs and attached with 1/4-20 kep nuts or k-locks from below. It went together quite easily in this manner.
The 16 1/4-28 12 point bolts are intended to thread into the plenum from the bottom.
Do you have a used superram that has been modified for use with nuts and bolts to make installation easier? Please explain.
Note: My plenum is studded with 1/4-28 x 1/4-20 studs and attached with 1/4-20 kep nuts or k-locks from below. It went together quite easily in this manner.
Le Mans Master
Joined: Feb 1999
Posts: 9,919
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From: South Carolina
St. Jude Donor '03 & '05
Are you talking about the timing gears? The dots should be at 6 O' clock for the big one and 12 O'clock for the little gear and they are facing each other.
I have a gif at home that shows this, but it should be relatively easy to find a picture in a manual etc.
If I am tottally off base here guys, please forgive.
I have a gif at home that shows this, but it should be relatively easy to find a picture in a manual etc.
If I am tottally off base here guys, please forgive.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
That is the easiest way to make sure they are properly aligned, but 12 o'clock to 12 o'clock or 12 o'clock to 6 o'clock is the same thing. The only difference is whether #6 or #1 is in the firing position. Remember, the crank sprocket goes around twice as fast as the cam sprocket. By the time the crank sprocket has made one full turn, the cam sprocket will only have moved 180° and will be in the position opposite of where you elected to set it.
RACE ON!!!
RACE ON!!!
Large Impressive Member
Joined: Jul 2003
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by steve40th
Are you talking about the timing gears? The dots should be at 6 O' clock for the big one and 12 O'clock for the little gear and they are facing each other.
I have a gif at home that shows this, but it should be relatively easy to find a picture in a manual etc.
If I am tottally off base here guys, please forgive.
I have a gif at home that shows this, but it should be relatively easy to find a picture in a manual etc.
If I am tottally off base here guys, please forgive.
1843
6572
Now, each pair of numbers that are above and below each other will be at TDC at the same time. The way to tell which is, is to watch the valves. When a piston is approaching TDC, if the exhaust is closing and the intake is just beginning to open, it will be the other (paired) cylinder that is at compression or the firing position. Remember this when indexing your distributors.
