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TBI 350 with Roller Cam Provisions?

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dj31499

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Here are some pictures of the engine I pulled out of my 89 Jimmy. Didn't have any plans for it, but I may be looking to do some upgrades on my 91 and decided to take a closer look at the old block. 2 bolt main, Block Casting # 638 and 193 heads seem to be pretty standard for these trucks. Two things caught my eye though, the drilled & tapped bosses in the valley and the "0.030"stamped on the pistons. Don't have a t-gauge to check the bore accurately at the moment, but I'm assuming its been bored out at some point. Motor (at least parts of it) looks to have been rebuilt at some point (globs of silicon on the cam in the rear, several hand-stamped numbers/letters all over). Anyone able to confirm if those bosses in the valley means it can take a roller cam? If that's the case, I'd guess this block would be the one to upgrade if I had to choose between it and the one currently in the 91. 638 casting.jpg
intake valley.jpgcamshaft rear or block.jpg30 thou stamped piston.jpg
 
Looks like the 96-99 factory roller cam block to me.

Roller cam 5.7L build

I disassembled the free boat motor last night. The block is cracked in 3 places from not being drained over the winter but with 300 hours on it, the is not much wear. I was hoping for vortec heads, but it isn't. Any idea if these heads are better than what would be stock on a late 70s 350? My...
ck5.com ck5.com
 
Captainfab said:
As long as the front of the block is drilled and tapped for the cam retainer plate,
you're good to go for a roller cam upgrade
Click to expand...
Looks like we're in business; two drilled & tapped holes on the front. What is odd (and possibly concerning) is the "627" cast below the timing cover. From what I've seen, that's a code for a 305. It is stamped "638" on the back and on the front driver's side (can barely see it in the picture). I'll grab a t-gauge & mic from work to confirm the bore size.

627 Casting Number.jpg
 
The bore size difference between a 305 & 350 is big enough that you can eyeball it with a tape measure - 3.736” v/s 4” add a little if it’s been bored already.

Just letting ya know if you wanted to solve this w/o having to get a mic from work.
 
We're saying the casting number is 14093638 correct? I don't see data showing that casting number can be anything other than an 87-95 350. 2 or 4 bolt main, flat or roller tappet cam.

Dont worry about it. If there were 305's that shared the same block casting number, the data would be out there. It's not. That's modern in terms of SBC, there aren't many mysteries about that vintage stuff. GM had thoroughly consolidated production at that point, thus why that block could be 2 or 4 bolt and flat or roller tappet cam...it could have been used as the basis for an engine in any car or truck made those years that spec'd a 350...high to low performance car, light to heavy duty truck. (All SBC trucks to 1995 were flat tappet cams. I think all the SBC cars were roller from '87 on)

Suffix code on the passenger side pad just forward of the head (you'd be looking straight down to see it if installed in the vehicle) would tell you exactly what it was installed in, but those are typically gone after a rebuild.

Really doesn't matter, only thing you can't tell at this stage is whether it's a 2 or 4 bolt block.
 
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Good point, the bores are gonna be pretty different from one another. Checked with a caliper, right around 4.030” (digital one drifts a little, I prefer the dial ones, but close enough).

Here’s the stamping in front of the passenger head: I’m reading “VO(or 0)111TRA” and then it looks like part of the vin might have been stamped on there as well (will have to double check if it matches up with the old truck).

IMG_2856.jpeg


IMG_2858.jpeg
 
TRA is the suffix code, but unfortunately looks like GM reused that one, and the only reference is to 1972, which clearly isnt what you have.

If you want more info on decoding the engines:
www.nastyz28.com

NastyZ28.com Chevrolet Decoding Guide

How to decode Chevy Engine Codes and block casting numbers
www.nastyz28.com
 
Appreciate all the replies guys; glad to know I’ve got options with this block I otherwise would’ve gotten rid of.

Not sure when I’ll get around to building it. The 91 runs okay now, and I’m not sure what direction I’d like to go in with the build. I’d rather not throw out a random hp/torque number to hit because I don't have a good idea of what that actually means in terms of “feeling” it behind the wheel. I’d just like some more power out of the truck, something that won’t bog down when trying to merge or pass on the highway.

I’d like to keep modifications to a minimum; I really don’t want to hack up the original wiring or completely bypass it with aftermarket efi. Wanting to keep the factory setup (since a lot of the stuff is tied to the ECM) corners me into keeping the tbi and trying to work from there, which isn’t as popular an option. If anyone’s got any suggestions on what they’d do if they had that block, I’m all ears.
 
I suppose it depends what you want to do with it. If you want high RPM power that opens the door a lot wider than trying to get more low end power out of a SBC.

IMO the L31 (Vortec) was the high water mark for standard SBC's (edit: for trucks). The injection system isn't where power was made, so it's the roller cam and Vortec heads with the right compression that makes substantially more power than TBI. Here's what I wrote in another discussion on it: "LO5 is 210hp on a good day, while the L31 is 255? 25hp for the Vortec heads in any testing you'll see, leaving 20 for a roller cam and compression bump." Thats without running headers which would open up some additional power. Having driven an LO5 truck for awhile, I can attest to how much more power the L31 has.

The real problem will be trying to use the stock system (which I agree with doing) to feed a much more capable engine. The only option I'm aware of at this time, that is probably still pretty well supported, is EBL. https://www.dynamicefi.com/

If there are systems out there that are plug and play with your TBI harness but maybe only require an ECM swap, that would be ok, but I don't know of any. Otherwise you are into re-doing a lot of components. You'd have to dig into EBL more, I'm not sure if the ECM connectors are the same and what not. I tend to think they are, which increases the appeal. You'll just have to read up on it.
 
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I have a Lt1 stock cam with roller lifters and hold down parts . Plus a new set of roller tip rockers . If your interested send me a pm . Back in the day this cam was a good upgrade and easy to get a chip for it .
 
The lt1 cam is only 207 duration. I’d use it for a door stop first
 
dyeager535 said:
I suppose it depends what you want to do with it. If you want high RPM power that opens the door a lot wider than trying to get more low end power out of a SBC.

IMO the L31 (Vortec) was the high water mark for standard SBC's (edit: for trucks). The injection system isn't where power was made, so it's the roller cam and Vortec heads with the right compression that makes substantially more power than TBI. Here's what I wrote in another discussion on it: "LO5 is 210hp on a good day, while the L31 is 255? 25hp for the Vortec heads in any testing you'll see, leaving 20 for a roller cam and compression bump." Thats without running headers which would open up some additional power. Having driven an LO5 truck for awhile, I can attest to how much more power the L31 has.

The real problem will be trying to use the stock system (which I agree with doing) to feed a much more capable engine. The only option I'm aware of at this time, that is probably still pretty well supported, is EBL. https://www.dynamicefi.com/

If there are systems out there that are plug and play with your TBI harness but maybe only require an ECM swap, that would be ok, but I don't know of any. Otherwise you are into re-doing a lot of components. You'd have to dig into EBL more, I'm not sure if the ECM connectors are the same and what not. I tend to think they are, which increases the appeal. You'll just have to read up on it.
Click to expand...
So by using the EBL flash you can use the TBI now with upgrades and tune it to work?
That is a good option.
I wonder if it would do better on an L31 block but with TBI instead of the MPFI?
 
imiceman44 said:
So by using the EBL flash you can use the TBI now with upgrades and tune it to work?
That is a good option.
I wonder if it would do better on an L31 block but with TBI instead of the MPFI?
Click to expand...

Yep, I read a bit on their page, the connectors should be the same at the ECM, they say you might have to change a couple of pins around, but I would think with the TBI ECM that isn't likely since it has so little functionality. It's not difficult anyway. Also supports WBO2, which is supposed to be the bees knees for tuning. Supporting lean cruise, that would pretty much be a necessity. I'm all for lean cruise lol.

GM ran TBI on Vortec (Apparently G30HD, over 8500GVW, it's why TBI Vortec intakes exist) so I don't see why there would be any issues. You'd be dumbing down an L31 running it with everything else injection-related to the square body (No crank sensor and no sequential injection) but I've seen nothing to show those to be worth the failure modes they introduce. The Vortec was a solid mechanical design in terms of the block/heads/cam IMO. But in terms of electrical advancements over prior TBI/TPI injection systems, I don't see it having any particular value. Still runs a fairly unreliable distributor (arent they plastic or fiber construction??), unreliable (comparatively) poppet valve setup, and just generally overly complex for what they were putting out. Can't find any HP/TQ specs for that Van Vortec/TBI combo, that would be an interesting comparison.

LS' was a step forward on all fronts, the L31 was, like TBI, a half-assed way for GM to make things cheaply, but still show improvement in the truck line. The mechanical aspects (cam/head design) of the L31 came from existing designs/research, those were not really new. Cars were getting solid, reliable designs of port injection (TPI) starting in 1985, L98 heads in 1986, roller cams in 1987, whereas trucks as we know took until 1996 to basically begin catching up to where 1987 cars had been.
 
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