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Old 12-02-2012, 02:00 PM
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Difference between 87-up and pre 87 camshafts

Guys is there a difference between camshafts that fit 87-up and pre 87 vehicles. The reason I ask is because I have been running the cam below in my 94 c1500 for about two months now.

JEGS Performance Products 200002 JEGS Performance Hydraulic Flat Tappet Camshafts=

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Old 12-02-2012, 07:20 PM
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The biggest difference between them is the lobe for the fuel pump push rod. The newer motors with FI run an electric fuel pump and don't use a mechanical fuel pum.
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Old 12-02-2012, 07:48 PM
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Quote:
Originally Posted by ChevroletSS View Post
Guys is there a difference between camshafts that fit 87-up and pre 87 vehicles. The reason I ask is because I have been running the cam below in my 94 c1500 for about two months now.

JEGS Performance Products 200002 JEGS Performance Hydraulic Flat Tappet Camshafts=
A flat tappet cam will be the same thing regardless of the year (until you go back to the 265). Chances are- if your block is original to that truck- it came w/a flat tappet cam in it from the factory.

You and your cam are fine.
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Old 12-02-2012, 10:02 PM
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1987 and up cams

Beginning in 1987 small block V8 engines were equipped with hydraulic roller cams. There are differences in the block to accommodate a cam retention thrust plate and antirotation mechanism for the lifters. These blocks are identifiable by bolt holes for a cam retention plate behind the upper timing sprocket, as well as bosses and tapped holes in the lifter valley.

The camshafts on these engines have a step nose and smaller bolt pattern on the front of the cam. An earlier model camshaft may be used in these blocks by using the appropriate timing chain set and adding a thrust button when using a roller cam.
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Old 12-02-2012, 10:21 PM
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Just to clarify, not ALL '87-up engines came w/a roller cam. Some blocks weren't even equipped for the roller parts (no spider and thrust plate bosses, no machined lifter bosses for the dogbones). The non roller engines were mainly TBI truck engines.

Details/casting numbers: Help finding a 350 roller block
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Old 12-02-2012, 11:43 PM
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Difference between 87-up and pre 87 camshafts

Quote:
Originally Posted by ChevroletSS View Post
Guys is there a difference between camshafts that fit 87-up and pre 87 vehicles. The reason I ask is because I have been running the cam below in my 94 c1500 for about two months now.

JEGS Performance Products 200002 JEGS Performance Hydraulic Flat Tappet Camshafts=
If you block is a roller block and you installed a flat tappet camshaft it is recommended to install a cam button in the cam gear.
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Old 12-03-2012, 05:28 AM
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Nothing wrong w/using a cam button on a flat tappet cam in a factory roller block. Could help on ANY block type, actually. But it's not like it's necessary just because it's a roller block.

Now, if you're installing a retro roller cam into a factory roller block, a button IS needed.
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Old 12-03-2012, 07:46 AM
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The block in my truck is was in 87-91 camaros and says its supposed to be a roller but its not. When I hold the new cam (55-85), up to the original cam that came in my truck it looks 100% identical. I cannot see a difference. Im thinking they used the older style cams back when they built these engines. Thanks for the info. So it helps to use a cam button regardless if I am using a roller cam. There was some play in my cam as in I could pull it out somewhat. Hope it will be ok, its been fine so far. Also Cobalt327 I seen you said something about bosses for dog bones. Does a roller block machined a certain way to hold the dog bones. If so Ill have to go with retro lifters on the engine build.

Thanks for the help guys. Very appreaciated
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Old 12-03-2012, 10:23 AM
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Quote:
Originally Posted by ChevroletSS View Post
The block in my truck is was in 87-91 camaros and says its supposed to be a roller but its not. When I hold the new cam (55-85), up to the original cam that came in my truck it looks 100% identical. I cannot see a difference. Im thinking they used the older style cams back when they built these engines. Thanks for the info. So it helps to use a cam button regardless if I am using a roller cam. There was some play in my cam as in I could pull it out somewhat. Hope it will be ok, its been fine so far. Also Cobalt327 I seen you said something about bosses for dog bones. Does a roller block machined a certain way to hold the dog bones. If so Ill have to go with retro lifters on the engine build.

Thanks for the help guys. Very appreaciated
First, the cam in your engine is fine, perfectly normal and no worries there at all. Millions of SBC engines were built this way and millions have been modified for a LOT more power and they use the same type cam.


CAM BUTTON

Using a cam button on a flat tappet cam helps keep it from moving fore and aft, which causes the timing to vary a small amount and can also set up harmful harmonics in odd cases. But generally speaking, the way the lobes are ground w/a slight angle to them, along w/the way the distributor gear/cam gear interface, and the cam timing gear-to-block clearance and the timing set gear alignment all work together to keep the cam fairly well located in the block.

But if you have the time, desire, and patience to set it up w/a button and to be sure the timing set alignment isn't 'fighting' against the button, AND if the timing cover is sufficiently stiff to provide a solid point for the button to register off of, then go for it! Done correctly there's no real downside, even the cost is negligible.


BLOCKS:

Some '87-up SBC blocks were fully machined for the hydraulic roller cam. Some blocks had the bosses cast in place, but the bosses weren't drilled and tapped. And other blocks lacked the bosses altogether.

Some '87-up blocks are fully machined for a mechanical fuel pump while others have partial machining w/o a hole drilled through to the cam for the pump push rod. The link I gave you above goes into some detail on this.


FACTORY ROLLER:

The dogbones hold the lifters in alignment and keep them from turning- which would instantly destroy the cam and lifter. The spider holds pressure on the dogbones to keep them in place. The retainer/thrust plate locates the roller cam in position; a roller cam lacks the angle on the lobes that work to keep a flat tappet cam from walking too much.

There are ways to use the factory roller cam spider and dogbones on a block w/o bosses. This requires drilling into the oil galley to mount the spider and the use of 3.4L V6 lifters (there are also other engines that use this same roller lifter). There are parts that are made to replace the dog bones that might give a better result. I have never used these retainers, so I can't comment further on them except to say the use of dog bones on an unmachined lifter boss doesn't seem like such a good idea to me, so the retainers might be a better solution. Now, there are early non roller engines running around just fine that are set up w/the factory dog bones- so that's my opinion alone.

My thoughts are that unless the block was something special, I wouldn't go about it this way and would instead either find a roller block or use a retro roller cam and lifters.

Factory spider, dog bones, and cam retainer plate
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Old 12-03-2012, 02:44 PM
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Quote:
Originally Posted by cobalt327 View Post
the use of dog bones on an unmachined lifter boss doesn't seem like such a good idea to me, so the retainers might be a better solution. Now, there are early non roller engines running around just fine that are set up w/the factory dog bones- so that's my opinion alone.
Ummm, yours and mine. If the tappet boss didn't need machining, then why did the factory machine them? You know they won't spend one red cent more than they have to in order to make something work.
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Old 12-03-2012, 04:02 PM
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Quote:
Originally Posted by ChevroletSS View Post
The block in my truck is was in 87-91 camaros and says its supposed to be a roller but its not. When I hold the new cam (55-85), up to the original cam that came in my truck it looks 100% identical. I cannot see a difference. Im thinking they used the older style cams back when they built these engines. Thanks for the info. So it helps to use a cam button regardless if I am using a roller cam. There was some play in my cam as in I could pull it out somewhat. Hope it will be ok, its been fine so far. Also Cobalt327 I seen you said something about bosses for dog bones. Does a roller block machined a certain way to hold the dog bones. If so Ill have to go with retro lifters on the engine build.

Thanks for the help guys. Very appreaciated
Check the VIN code, passenger cars came with roller cams with rare exception they had a flat tappet. Trucks came with a flat tappet cam in the blocks up to 95 can be no provision for a roller to all ready for a roller; this varies by casing number on the block.

For unprovisioned 350 flat tappet blocks look for casting number 10054727, 14079287, 14088548, and 14101148.

For provisioned 350 roller tappet blocks look for casting numbers 10243880, 14011148, 14088526, and 14093638.

Watch for the difference between unprovisioned 14101148 and provisioned 14011148.

This list may not be all inclusive.

The differences are that the roller provisioned block will have raised lifter blocks that are machined flat in pairs, there will be three bosses projecting above the main oil galley, the timing face will have two ears that project from the cam boss to mount the roller cam's thrust plate with bolts. The unprovisoned blocks may be missing all or some of these features.

A provisioned block may have a flat tappet cam most, if not all, pickups used a flat tappet cam whether the block is provisioned for a roller or not. A flat tappet cam in a roller block uses the exact same parts as used for a flat tappet cam in a conventional non-roller block. The cams may, or not, include an eccentric for a mechanical fuel pump.

The factory did not use a thrust button or plate for flat tappet cams in any of these engines. If you are retro fitting a non roller block from this era with a roller cam whether it is a factory roller or an aftermarket roller a cam button must be used. The OEM roller cam used like this must have a thrust plate with the mounting ears cut off to be used as a thrust washer to fill the reduced nose section of the cam between the must be used OEM roller cam timing set and the block. If you're a good machinist the non-provisioned block can be modified to use the OEM thrust plate, I generally don't say anything about this as if you don't have the machining facilities and abilities to do this it's way easier to screw the block up than not.

Your truck uses Throttle Body Injection (TBI) which is a Manifold Absolute Pressure (MAP) or sometimes called Speed/Density system. This system uses a map of fuel and ignition timing requirements developed by putting the engine through its paces on a dynamometer for a specific configuration of camshaft, compression, exhaust back pressure, etc. Changes to components that change the primary mapped relationships of RPM, manifold pressure (vacuum) and throttle position send erroneous information to the computer causing it to look in the wrong boxes of its fuel and ignition maps, this causes modifications as you did with the cam change to run not quite right to not at all depending on how far you've gone from what the factory mapped to. The cam you installed is off that mapping and may require a changed PROM chip. In some cases if the cam isn't too different the engine can be dialed in with an adjustable fuel pressure regulator.

Bogie

Last edited by oldbogie; 12-03-2012 at 04:16 PM.
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Old 12-03-2012, 08:09 PM
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For those looking to take the easy- if a little more expensive- way around cutting the ears off the roller cam retainer and using a generic cam button to use a factory hydraulic roller cam in a non roller block, LPE has a package that includes the spacer, cam button and button head cam gear fasteners. Cost is $30-$35.

Click on image for link to the part:

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