Still undecided about a cam for my 5.7

[Hipster]

Yeah, it's a crap shoot. If you can find a block out of a Caprice, it may already have a roller cam in it. My Mr Goodwrench long block from ~2000 has drilled and tapped bosses for the spider and drilled, but not tapped holes for the cam thrust plate.

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I'm not seeing the clearancing/machining for the lifter dogbones I see in factory roller blocks either.

 

[PlayingWithTBI]

I'm not seeing the clearancing for the lifter dogbones I see in factory roller blocks either.

I haven't measured them but I think maybe the journals for the lifters aren't as tall as a Vortec block? I've been threatening to swap out my flat tappet cam, once it wears out, for a roller one. Then I'll check it out or, go to link bar lifters.

 

[Supercharged111]

Friend has a 1990 and we roller cammed it. Bosses were there and tapped. I thought at some point all Caprices went roller with TBI.

 

[PlayingWithTBI]

I thought at some point all Caprices went roller with TBI.

Me too but, I wasn't positive.

 

[Hipster]

Thinking the same on the Caprice's but I don't think many, if any, of those blocks made it into trucks in 5.7 version. 305's may be a different story.

There's a youtube video out there somewhere where a guy welds nuts to the valley above the cam and gets to digging around the lifer bores with a die grinder to make it happen, but that's a bit too freehand for me in an area where there's water jackets. lol

 

[Supercharged111]

The trucks were definitely hit or miss in the TBI era for that, but more than a scant few seem to have been recipients.

 

[stutaeng]

I know that I don't know anything about cams and that kind of stuff, but what kind of MPG gains are you going for? The TBIs were just not known for being fuel efficient. Maybe the Vortecs were a bit better, but I don't think they were that much better, and improvements were probably from a combination of things I would imagine.

A bigger cam will allow more air to get into the engine, but also more fuel. Will surely result in a increase in power, but may also get a bit worse fuel efficiency, especially if you learn to appreciate the extra power, if you know what I mean!

Seems like fuel efficiency is more related to weight of vehicle instead of power. My Dad bought an 89 Sierra RCSB sometime around '98 or so. The 5.7 had some work to it from the previous owner. I remember the Crane Cams (or maybe Comp Cams) sticker on the radiator plastic thingy. Must have been a pretty aggressive cam...Anyways, that truck was pretty fast, but it also drank gas like nobody's business. Unfortunately, the engine developed a knock a few years ago and he had a 5.7 swapped from a junkyard that was told came from 90 Suburban. I think he did mention the replacement engine was not as powerful, which was not a surprise. I haven't asked him if his MPG is better, but he wouldn't even know how to calculate it, LOL. And frankly, not driven enough to notice.

My brother bought a 90 RCSB a few years back also with a 5.7 that the previous owner had dropped a JEGS crate engine. I believe it's a factory spec engine. He said his truck does better on gas, but we don't really know what the gear ratios were of each truck, for an apples to apples comparison. It's still a gas guzzler.

Point is that I'm not arguing you get more power with a cam swap, just doubtful you will get better MPG, at least to notice.

Now cam-swap away!

 

[Frank Enstein]

All 1987 blocks have the tall lifter bores and will accept the factory style roller cams. You may have to drill and / or tap the holes but the casting is the same.

 

[Frank Enstein]

I was/am a little hesitant on using the 1.6 rockers. Sounds like my fears are unfounded. Lots of 1.5 rockers for sale on FB marketplace. Should the spacer be an open design or closed (just two holes)?



HMMMMMMM!! LOL

Ken

I recommend that spacer because I know for a fact that they are dyno tested. They help at low to medium rpms by mixing up the air/fuel mixture so the cylinders se a more uniform mixture. They don't do as much at full throttle but they help noticeably at part throttle.

 

[kenh]

This rebuilt block I'm getting is at least a more modern version as it does not have a provision for a manual fuel pump. Now weather that means the valley is drilled and tapped for the lifter spider I have no clue. I know my current engine is drilled and tapped as I had the heads off and checked for that!

Ken