Small Base Circle Cam
Thread Starter
Instructor
Joined: Feb 2000
Posts: 172
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From: Potomac Falls VA
Small Base Circle Cam
I am in the process of building a 396 LT4 stroker with a small base circle cam and my builder wants to verify that we can use the Cadillac racing hydraulic roller lifters or will they sit too low for the links and the spider retainer.
Thanks,
Ray
Thanks,
Ray
Last edited by TWNTRBO; Nov 11, 2010 at 02:01 PM. Reason: info
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
I'm not too sure I understand your question thoroughly, but wouldn't you want just a small base circle cam w/ stock lifters & custom pushrods? My stroke is 3 7/8" in a gen I block & that's what I did.....
Maybe an LT block is different, but I think you'd just get a good profile rod & you're good to go. Assuming you pay attention to the geometry of course
Maybe an LT block is different, but I think you'd just get a good profile rod & you're good to go. Assuming you pay attention to the geometry of course
Melting Slicks
Joined: Mar 2002
Posts: 3,108
Likes: 126
From: S.L.C. UT
If you use the right stroker rod, you won't need a small base circle cam with a 3.875" stroke. I use the Crower Sportsman stroker rods and with a 3.875 stroke, you can use off the shelf cams. If you get down to a .900" base circle or smaller, the lifter barely sticks up enough for the directional plate links to grab ahold of it. And then you have to buy a aftermarket style tie bar lifters, or Crane made some OEM style lifters that use the GM hold parts, but they are taller so the directional plate links can grab ahold of them. They are $500+. A .950 base circle would probably be ok with the GM hold down parts, but it will be close. You would want to check it closely. If you use a 1.00" base circle or bigger avoids the problem. Standard base circles are commonly around 1.20"
I don't know about the Cadillac roller lifter mentioned. If it has a taller body for small base circle cams.
I don't know about the Cadillac roller lifter mentioned. If it has a taller body for small base circle cams.
Burning Brakes
Joined: Nov 2006
Posts: 1,102
Likes: 1
From: Portsmouth Virginia 396LT4 435RWHP/400RWTQ Best so far 11.26 @ 123mph
If you use the right stroker rod, you won't need a small base circle cam with a 3.875" stroke. I use the Crower Sportsman stroker rods and with a 3.875 stroke, you can use off the shelf cams. If you get down to a .900" base circle or smaller, the lifter barely sticks up enough for the directional plate links to grab ahold of it. And then you have to buy a aftermarket style tie bar lifters, or Crane made some OEM style lifters that use the GM hold parts, but they are taller so the directional plate links can grab ahold of them. They are $500+. A .950 base circle would probably be ok with the GM hold down parts, but it will be close. You would want to check it closely. If you use a 1.00" base circle or bigger avoids the problem. Standard base circles are commonly around 1.20"
I don't know about the Cadillac roller lifter mentioned. If it has a taller body for small base circle cams.
I don't know about the Cadillac roller lifter mentioned. If it has a taller body for small base circle cams.
I was able to get a 1.020" base circle billet comp cam to fit with 5.875 Lunati pro mod rods in my 396 LT4 without a problem in order to feel more comfortable with the dogbone/lifter support. Could have probably went with about a 1.100" but Comp talked like the billet cores dont usually come that big and may not clean up completely after grinding to reach 1.100 let alone stock dimensions. Still have about .090" rod to cam clearance though. Running a .900 base circle only gives you a little over a 1/16" to less than an 1/8" lifter support in the dogbones. To close for my taste. Chosing the right type and length stroker rod for a 396 should give you clearance using a standard base circle cam but you will likely have to grind on the rods for adequate clearance. You could also do a mock up with the actual crank and rods being used and any LT cam with a known base circle to determine what will work for you before ordering the actual cam to be used. Just a thought.
Rick
