Ignorant small block head and intake questions

[Erik the Awful]

If you're putting a TBI block in a Vortec, you'll need to tap the coolant bypass hole under the water pump and put a set screw in it.

 

[Schurkey]

If you're putting a TBI block in a Vortec, you'll need to tap the coolant bypass hole under the water pump and put a set screw in it.

I thought the Vortec heads covered the hole in the right-bank deck surface, so that no water could get to that passage. Perhaps I'm wrong, I haven't yanked my Vortec long-blocks apart--but I have one with the drilled bypass hole in the water pump surface. I'm assuming that the matching hole from the deck surface down was also drilled. This is suspected, not confirmed.

My understanding is that the 2-bolt-main Vortec blocks were not machined for the bypass hole, or for the engine-driven fuel pump. They had material, but not drilled and tapped for the additional two bolt holes for the old timing cover. At least some 4-bolt-main Vortecs had the full machining for an engine-driven fuel pump; and at least some of the machining for the bypass hole. MAYBE even the extra two bolt holes for the old-style timing cover.

 

[Erik the Awful]

The Vortec water pump does not cover the coolant bypass hole in the TBI block. For the short time that my TBI block was in my '99 Suburban, I had a set screw threaded and sealed into the bypass hole. As far as the timing cover, not having those two bolts in the cover didn't affect it.

 

[Schurkey]

The Vortec water pump does not cover the coolant bypass hole in the TBI block.

That hole is a two-part drilling. A horizontal hole from the water-pump face rearward, intersecting with an angled-vertical hole from the deck surface downward.

Far as I know, the Vortec cylinder head does NOT have a matching hole, so coolant has no opportunity to flow into the bypass hole. No need for a plug, because the cylinder head itself does that job. Easy enough to verify--LOOK at the gasket surface of the cylinder head. No hole = no problem.

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[PlayingWithTBI]

Computers don't like huge cams. You can get a big lumpy cam to work. But it's a pain in the ass to tune idle

^^^Ditto - I gave up trying to tune Closed Loop @ idle with my fairly mild (208/[email protected], .464/.484" w/1.6rockers) cam. I couldn't get rid of the stumble so, I went to Open Loop and set SA @ 20*. Now it idles a lot better. This is on a TBI with no MAF (of course).

 

[Postmech]

After 243,*** miles, my stock 5.7 in my Suburban is starting to get more than a little worn out. I've been wanting to do some motor work. I recently got a parts truck with a good running tbi 5.7 that I'm planning on building and swapping in it in. I'm not planning on a super fancy build, just a cam and valve springs as well as a few parts to replace wore out stuff.
I should be able to just put my efi intake on the other motor shouldn't I? And as far as heads go, which would I be better off with, the Vortec heads on the motor that's currently in my rig or the heads off of the tbi motor?

Some of the earlier blocks will not seal with plastic timing cover used on Vortec engines.

 

[CrustyJunker]

^^^Ditto - I gave up trying to tune Closed Loop @ idle with my fairly mild (208/[email protected], .464/.484" w/1.6rockers) cam. I couldn't get rid of the stumble so, I went to Open Loop and set SA @ 20*. Now it idles a lot better. This is on a TBI with no MAF (of course).

Really? What's your LSA? I'm running closed loop on a 212°/218° at .473" at 575 RPM hot. Can't even tell it's cammed unless it's super cold outside which is lean for the first minute or two.

 

[PlayingWithTBI]

Really? What's your LSA? I'm running closed loop on a 212°/218° at .473" at 575 RPM hot

It's 112 LSA, I have the cam retarded 2* for a little more top end (grind is 4* advanced), I know I should be able to run CL but it just won't stop stumbling/surging with WBO2. I flattened out VE and SA all around the target idle and still got stumbling. Now it idles nice and smooth.

 

[CrustyJunker]

Ah, okay. Just trying to learn stuff/help if you wanted to maintain your closed loop idle. If you got it running good in open, leave it alone!

Only problem I had with mine was on super windy days (40 MPH wind gusts or greater) my idle would stumble in closed loop. Not sure if it was so much an O2 thing or more of a MAP thing at the time.

 

[PlayingWithTBI]

If you got it running good in open, leave it alone!

Yeah, as soon as I start moving it goes into CL and when I get over 40MPH it'll go into HLC with ~39* and 16.7 AFR at ~50-60MAP, a little lower with more MAP so, I'm pretty happy with it now. Just the 1 tire fryer is pissing me off, lol.