93 K2500 Suburban 454 Holley Sniper Upgrade

[Supercharged111]

Even the roller motors eat cams, but supposedly soft cores are the reason there.

 

[LC2NLS6]

To do a roller, I would get new dist gear, drill and tap bolt holes for a cam retainer, washer/thrust button, bigger pushrods, then guideplates, then adj rockers, which means taller valve covers. It was *********** quickly. One more shot, then I'm yanking it for a rebuild or slap in a fresh 496 or 598 engine and send this out as a core.

 

[Schurkey]

To do a roller, I would get new dist gear,

Why? All OEM TBI distributors have gears suitable for roller cams. Many--but probably not all--aftermarket distributors also have melonized gears. Hard to know what the Communist Chinese are up to these days.

drill and tap bolt holes for a cam retainer, washer/thrust button,

Why? Almost all Chevy big-blocks have the holes already drilled 'n' tapped. Mine did. Have you verified that yours doesn't have the two threaded holes that retain the thrust plate?

I'm fairly sure I'm seeing the upper bolt hole in the picture in your first post. On Gen 5 engines, the bolts are top and bottom, not left and right--but they're the same distance apart, so the same thrust plate works.

bigger pushrods, then guideplates,

SHORTER pushrods. Bigger-diameter if the cam has significantly more lift requiring stiffer springs, and/or leading to more RPM than the OEM application.

What diameter pushrods do you have now? 3/8 should be fine, 5/16 might be a little skimpy.

then adj rockers, which means taller valve covers.

Adjustable rockers are a nice upgrade, but if the base-circle of the new cam is similar to the base circle of the OEM cam, you wouldn't need adjustables. IF (big IF) you did need an adjustable valvetrain, you could install the conversion rocker studs, and use the Mark IV adjustment--no height difference from what you have now.

I have Comp Cams "Pro Magnum" steel roller rockers under OEM valve covers. I think I had to use two valve cover gaskets on each side to clear the tall adjustment nuts. First, I had stamped-steel OEM covers, later I switched to the OEM cast aluminum covers that appear to be the same as the ones you have.

 

[LC2NLS6]

I have a Holley Hyperspark distributor. Depending on the cam material, sure it might need a new gear, might not. Composite ones are $115. Yes stock Gen V should be 5/16 pushrod, yeah shorter and thicker on new ones. Comp 911 springs, 5/16 should be ok since I shift at 4250 ish. I called comp, they said cups are fine for either dia rod on the 812 lifter. I don't "need" adj valve train, but I'd be measuring custom pushrods, so why not go bigger, if bigger then new rockers, if getting new, get adjustable roller trunion that will fit when I get alum heads on a 598 and 230/240 at 50 cam. My stock valve covers have the oring style thin rubber gasket. This is mostly for fun. In theory, if base circle was the same I'd just get the difference in cup base to tip height of the lifters on the new 5/16 rods and use stock rockers.

Easiest is just slap another cheap cam and lifters in and try this again.

I'll go over each lifter bore and test fit each lifter instead of slapping it together.

What I think really happened, I sprayed brakecleaner on the cam bolt holes when installed before I threw the top sprocket on. If those holes aren't blind, I hit the first lobe with brakecleaner...My best guess as to why it went bad at this point, by blasting the assembly lube off even for a second...

 

[LC2NLS6]

You're right, I dug through my pictures, my block has vertical holes for a retainer plate. Ok that makes it easier.

 

[Schurkey]

I have a Holley Hyperspark distributor. Depending on the cam material, sure it might need a new gear, might not.

Contact Holley for distributor gear compatibility, and verify cam material with your cam supplier.

What diameter is the distributor shaft. Three common sizes--skinny 'TBI" shaft, the "ordinary" 0.492 that GM used for years and years, and the "MSD-Sized" 0.500 shaft that's gotten popular in the aftermarket.

Composite ones are $115.

But who would buy a composite (plastic) distributor gear? Get the right cam core, and a $50 melonized gear--which you might already have--would be fine.

Yes stock Gen V should be 5/16 pushrod, yeah shorter and thicker on new ones. Comp 911 springs, 5/16 should be ok since I shift at 4250 ish. I called comp, they said cups are fine for either dia rod on the 812 lifter. I don't "need" adj valve train, but I'd be measuring custom pushrods, so why not go bigger, if bigger then new rockers, if getting new, get adjustable roller trunion that will fit when I get alum heads on a 598 and 230/240 at 50 cam.

You wouldn't have to buy most of that stuff. The only thing you'd HAVE to buy is pushrods, although guideplates would be nice so you could increase the pushrod diameter.

My stock valve covers have the oring style thin rubber gasket.

Ooops. Yes, tough to "double gasket" when using O-rings. My covers LOOK like yours, but must be from the earlier Mark IV TBI big-block.

One wonders if the covers machined for O-rings would still seal against old-style gaskets. I've got an 8.1L engine in the barn that has O-ringed valve covers, I"ll have to take a look at that sometime.

Easiest is just slap another cheap cam and lifters in and try this again.

I'll go over each lifter bore and test fit each lifter instead of slapping it together.

I install the cam and lifters, mark each lifter with a Sharpie. Spin the cam, and see if the Sharpie marks rotate around the lifter bores. They may not spin the same speed, but they all have to spin. Some spin faster than others.

I also mark a paint-stripe on the pushrods above the guideplates. When the engine is installed and running, I can SEE the pushrods spinning. Which means the lifters are spinning. Which means the cam/lifter should last a long time. A windowed valve cover makes this less messy. This is my "Pontiac" valve cover set.

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What I think really happened, I sprayed brakecleaner on the cam bolt holes when installed before I threw the top sprocket on. If those holes aren't blind, I hit the first lobe with brakecleaner...My best guess as to why it went bad at this point, by blasting the assembly lube off even for a second...

Be nice if that was the reason. (Don't do that again...)

 

[LC2NLS6]

I'm gonna check the lifters can spin freely in the bores. I have a set of gen 4 valve cover gaskets, I don't think they overlay on the oring ones on my gen 5, the oring goes around the bolt holes. I can try that when I pull them off this weekend.

 

[Supercharged111]

I put the Comp adjustable conversion studs on my dually and my dad used them on his GenV 454 as well. They retain stock rocker arms.

 

[LC2NLS6]

This time I got the boat in storage and pulled it into the garage so don't have to wrench in the rain.

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[LC2NLS6]

I put the Comp adjustable conversion studs on my dually and my dad used them on his GenV 454 as well. They retain stock rocker arms.

Thanks that's something I didn't know about - good stuff to fit under the valve covers perhaps. I think that'd help if I order pushrods that aren't within spec from front to back of block.

https://www.summitracing.com/parts/cca-4514-kit/make/chevrolet