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Discussion Starter · #1 ·
I’ve got a 97 model 5.7 vortec with the factory roller cam can one of you knowledgeable guys give me a list I will need to get to put a flat tappet cam in it I know it’s probably not the best thing I can do but I’m on a budget 3 divorces will put one in a bind lol and also I’ve got a set of .030 345np pistons if I have my block bored will these work in it and they are cast pistons thanks for any help
 

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Discussion Starter · #4 ·
why are you going flat tappet with it already has a factory roller set up?
I already have a nice flat tappet cam and the roller is $400 this is my first vortec motor I’m more familiar with the flat tappets than the roller I’m building it for a little s10 I bought my 2 sons have s10s but they ls swapped theirs and I’m wanting to carburate mine and I’m not 100 percent sure on putting the flat tappet in it yet
 

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The XE268H is an easy 400 plus torque and horsepower cam that runs nice on the street. But it needs a good supporting cast. The roller equivalent is the 268XFI which is a special order cam about a month out from your order.

To get into the 400’s it takes some mild porting on the vortec head just cleaning up the casting not making fundamental changes to the shape nor size, basically cleaning and smoothing not cutting deeper than the paste line where you see the core and cope mating line. If the seats are shot there is value in cutting for oversize valves to prevent sinking the seats.

The rockers need good stabilaztion to that end screw in 7/16th studs being no more expensive than 3/8ths while offering a lot more stiffness and stability to the rocker. Your spring choice is good they need the Comp 787-16 retainer and locks for the 11/32nds valve stem of these head’s. If you run a self guiding rocker I’d go with an aluminum roller, anything else should be push rod guided. Flat push rod guides are more tolerant of dimensional disparities than steped guides as these are working where there is more push rod motion so care in fitment requires more care.

Nothing like the Edelbrock Performer RPM for an intake with these but in an S10 space between the underside of the hood and the air cleaner gets tight.

Headers really need to be 1-3/4 long tube primaries but again the S10 is space limited as are off the shelf choices if you’re going to keep the inner fenders.

Depending on how you finish or can finish the build and installation getting 390 to 420 ft pounds and horsepower on the crankshaft at decent street RPMs is pretty easy with cams timing in this area of plus-minus a few degrees of 220 measured from .050 lift on the intake for a 350/355.

Bogie
 

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Discussion Starter · #11 ·
The XE268H is an easy 400 plus torque and horsepower cam that runs nice on the street. But it needs a good supporting cast. The roller equivalent is the 268XFI which is a special order cam about a month out from your order.

To get into the 400’s it takes some mild porting on the vortec head just cleaning up the casting not making fundamental changes to the shape nor size, basically cleaning and smoothing not cutting deeper than the paste line where you see the core and cope mating line. If the seats are shot there is value in cutting for oversize valves to prevent sinking the seats.

The rockers need good stabilaztion to that end screw in 7/16th studs being no more expensive than 3/8ths while offering a lot more stiffness and stability to the rocker. Your spring choice is good they need the Comp 787-16 retainer and locks for the 11/32nds valve stem of these head’s. If you run a self guiding rocker I’d go with an aluminum roller, anything else should be push rod guided. Flat push rod guides are more tolerant of dimensional disparities than steped guides as these are working where there is more push rod motion so care in fitment requires more care.

Nothing like the Edelbrock Performer RPM for an intake with these but in an S10 space between the underside of the hood and the air cleaner gets tight.

Headers really need to be 1-3/4 long tube primaries but again the S10 is space limited as are off the shelf choices if you’re going to keep the inner fenders.

Depending on how you finish or can finish the build and installation getting 390 to 420 ft pounds and horsepower on the crankshaft at decent street RPMs is pretty easy with cams timing in this area of plus-minus a few degrees of 220 measured from .050 lift on the intake for a 350/355.

Bogie
With this cam it says it’s the biggest that can be run without a stall converter but also says a 2000+ is recommended and I have a friend with a new 2000 stall for $100 in the box so should I go ahead and get it for the 700r4 tranny I’m running
 

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2000 is pretty much stock type territory anyway so if you have the $100 to throw at it you might see some benefit however that cam should also work just fine on the stock convertor too.
I've used it a few times and it's a pretty decent as is.
 

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I’ve got a set of ls6 springs I’m going to put in the heads
With any cam over .470" valve lift (if that much) you will need to install the LS6 springs at 1.750" using CompCams retainers and locks. And even that will only handle .520" lift or so.
Have to say I would wait a payday or two and figure out a way to get a roller cam. Howards has several roller cams for your block in the $300-$330 price range. Howards Chev SB Hydraulic Roller Camshafts
 

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Discussion Starter · #14 ·
The XE268H is an easy 400 plus torque and horsepower cam that runs nice on the street. But it needs a good supporting cast. The roller equivalent is the 268XFI which is a special order cam about a month out from your order.

To get into the 400’s it takes some mild porting on the vortec head just cleaning up the casting not making fundamental changes to the shape nor size, basically cleaning and smoothing not cutting deeper than the paste line where you see the core and cope mating line. If the seats are shot there is value in cutting for oversize valves to prevent sinking the seats.

The rockers need good stabilaztion to that end screw in 7/16th studs being no more expensive than 3/8ths while offering a lot more stiffness and stability to the rocker. Your spring choice is good they need the Comp 787-16 retainer and locks for the 11/32nds valve stem of these head’s. If you run a self guiding rocker I’d go with an aluminum roller, anything else should be push rod guided. Flat push rod guides are more tolerant of dimensional disparities than steped guides as these are working where there is more push rod motion so care in fitment requires more care.

Nothing like the Edelbrock Performer RPM for an intake with these but in an S10 space between the underside of the hood and the air cleaner gets tight.

Headers really need to be 1-3/4 long tube primaries but again the S10 is space limited as are off the shelf choices if you’re going to keep the inner fenders.

Depending on how you finish or can finish the build and installation getting 390 to 420 ft pounds and horsepower on the crankshaft at decent street RPMs is pretty easy with cams timing in this area of plus-minus a few degrees of 220 measured from .050 lift on the intake for a 350/355.

Bogie
I was looking at the XE268H cam and there is a computer controlled one land a non computer one I don’t want to look stupid but if I’m running a carb then I’ll need the non computer controlled correct and the kit comes with everything except the push rods so those should be all I’ll need to switch to flat tappet right?
 

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1979 Chevrolet Malibu 496-TH400-9" (cruiser). 1992 Chevrolet S10 355-700r4-7.625" (daily driver).
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With this cam it says it’s the biggest that can be run without a stall converter but also says a 2000+ is recommended and I have a friend with a new 2000 stall for $100 in the box so should I go ahead and get it for the 700r4 tranny I’m running
Does the 700r4 you plan to use have a lot mileage on it? Is this the 700r4 that was behind a 4.3 in this truck?

As mentioned above, I would run what you have. I would buy it and keep it in the box if anything gave me the sense that I would be building the transmission soon.
 

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Discussion Starter · #16 ·
Does the 700r4 you plan to use have a lot mileage on it? Is this the 700r4 that was behind a 4.3 in this truck?

As mentioned above, I would run what you have. I would buy it and keep it in the box if anything gave me the sense that I would be building the transmission soon.
Yes the 700r is the original tranny behind the 4.3 seems to shift out smoothly
 

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1979 Chevrolet Malibu 496-TH400-9" (cruiser). 1992 Chevrolet S10 355-700r4-7.625" (daily driver).
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Yes the 700r is the original tranny behind the 4.3 seems to shift out smoothly
Install a "Corvette Servo" in the transmission. It's a cheap upgrade, easy to install.

The logic here is that the clutch pack that engages for 3rd gear and stays on in 4th is a known failure point. The fact that this was a 6 cylinder unit increases the likelihood of a failure behind a V8. The 6 cylinder 700r4 has 5 clutches in the 3-4 clutch pack and has a reduced torque capacity because of this. The V8 units had 6. GM upgraded to a 7 clutch 3-4 for the 4L65e.

The servo upgrade increases the apply in 2nd gear and gets the oil to the 3-4 clutch pack faster. This results in a cleaner 2nd gear and 3rd gear shift. I think it would be worth the 20 bucks to help this area out.

I'm a hobbyist and not really transmission guy, but that's what I would do along with keeping the factory converter in place.
 

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I was looking at the XE268H cam and there is a computer controlled one land a non computer one I don’t want to look stupid but if I’m running a carb then I’ll need the non computer controlled correct and the kit comes with everything except the push rods so those should be all I’ll need to switch to flat tappet right?
Computer controlled cams tend to have LSA values higher than 110 degrees which is also suitable for carburetors used for street and occasional track performance. Cams aimed at either intentional rough idle to emulate the sound of performance cams of the 1960’s or are cams actually intended to take racing use LSA’s less than 110 degrees. The problem you get into with these tight LSA rough idle cams on the street is they tend to drop a lot of bottom end torque. Back in the 1960’s the path around this was for the auto factories to jack the compression ratio up to 11.5 to 1 and the fuel companies to offer 110 octane fuel. Today with 91 to 93 octane at the pump engine builders need go in different directions since you can’t cover lower end torque looses with more compression, but there are other ways to push this limit a bit which is what the L31 Vortec head was all about. The chamber used by that head is incorporated into nearly everything in the aftermarket and GMPP’s aluminum Fast Burn head’s. Aluminum is popular because it moves heat faster than iron which tolerates if not demands more compression ratio. While at a straight up comparison of all things being equal aluminum loses power against an iron head. But since things aren’t really equal between these material’s thermal characteristics it turns out you can run at least a ratio more compression without detonation vis-a-vis iron which more than compensates for the fast heat transfer rate of aluminum. Plus it is more heat tolerant than iron so you can easily run the cooling temps another 10-20 degrees higher without rising the all to famous Chevy head cracks.

If I was building on a factory roller cam block, I wouldn’t go back to a flat tappet cam as that exposes you to the common failure modes of these cams. This can be reduced but not eliminated. The factory roller can that’s using a thrust plate for positive control of cam walk just reduces the cam lobe and lifter failure issue to something really close to zero. While most flat tappet cams survive and thrive it only takes the once event to trash the money you saved by going with a flat tappet. You should note it’s a bet none on the OEM’s were willing to ride with.

Bogie
 

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Discussion Starter · #19 ·
The XE268H is an easy 400 plus torque and horsepower cam that runs nice on the street. But it needs a good supporting cast. The roller equivalent is the 268XFI which is a special order cam about a month out from your order.

To get into the 400’s it takes some mild porting on the vortec head just cleaning up the casting not making fundamental changes to the shape nor size, basically cleaning and smoothing not cutting deeper than the paste line where you see the core and cope mating line. If the seats are shot there is value in cutting for oversize valves to prevent sinking the seats.

The rockers need good stabilaztion to that end screw in 7/16th studs being no more expensive than 3/8ths while offering a lot more stiffness and stability to the rocker. Your spring choice is good they need the Comp 787-16 retainer and locks for the 11/32nds valve stem of these head’s. If you run a self guiding rocker I’d go with an aluminum roller, anything else should be push rod guided. Flat push rod guides are more tolerant of dimensional disparities than steped guides as these are working where there is more push rod motion so care in fitment requires more care.

Nothing like the Edelbrock Performer RPM for an intake with these but in an S10 space between the underside of the hood and the air cleaner gets tight.

Headers really need to be 1-3/4 long tube primaries but again the S10 is space limited as are off the shelf choices if you’re going to keep the inner fenders.

Depending on how you finish or can finish the build and installation getting 390 to 420 ft pounds and horsepower on the crankshaft at decent street RPMs is pretty easy with cams timing in this area of plus-minus a few degrees of 220 measured from .050 lift on the intake for a 350/355.

Bogie
Just one last question about switching to the flat cam as you seem to really know your stuff and thanks for your advice in advance but if I put this xe268 in my vortec motor what length pushrods would I need thanks again
 

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The change to a flat tappet cam takes you back to the 7.8 inch pushrod. That could be variable a little depending on if you check the rocker contact pattern on the stem. Dialing that in to the best narrow and centered pattern as found by the mid lift method requires some adjusting of the push rod length.

Also, just in case your not sure the use of a flat tappet cam or what today is called a retro roller cam these use the older timing gear set not used by the factory roller cam. The flat tappet cam and timing set does not use the roller cam thrust plate on the roller block.

Bogie
 
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