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98 vortec questions

Chickntrk

Chickntrk

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Hey guys, few questions:

I picked up a 98 vortec 350 awhile back with the intent to swap it into my 78 at some point. I was going to swap it over to v belt and use all my original front stuff but in reading the recent AC thread now I’m thinking maybe I’ll just keep the serpentine setup which bring up my questions,
Will the alternator that’s on the vortec work in a 78 or is the regulator in the PCM? What about steering? Are the power steering line fittings compatable? I guess my question about the cooling fan was already answered, it fits within the factory shroud.
 
The pcm does not control the alternator on a Vortec setup.
 
The power steering is metric/o-ring on the
Newer pump. Your 78 might still be standard/flare. Easy to deal with though. I use the -6an adapters and make my own lines.
 
Need to consider an electric fuel pump set up. Being as the vortec block has the mechanical fuel pump blocked off.
 
Jimmy85 said:
Need to consider an electric fuel pump set up. Being as the vortec block has the mechanical fuel pump blocked off.
Click to expand...
So many conflicting opinions on this, I thought so too originally, pulled the block off plate off and mine was drilled for the pushrod and has a cam lobe for it :dunno:

I’ve heard conflicting opinions on vortecs having been drilled or not, I am prepared to run an electric pump tho so that’s no biggie
 
i ran a american thread p/s pump from late 70's on a 90's serp belt setup no problem minus bolt thread swap out and used the serp belt pulley .

yaa try and run mech fuel pump on vortec or just go electric and key hot with relay for the overall win and less problems if your combo wont work .

my k30 budget beater build ( sig line below ) has a L31 vortec 350 and i like the power and smooth engine running . but i kept efi via edelbrock pro-flo-4 setup .
 
Chickntrk said:
So many conflicting opinions on this, I thought so too originally, pulled the block off plate off and mine was drilled for the pushrod and has a cam lobe for it :dunno:
Click to expand...

Hmm. Every tbi & vortec block I’ve seen has had the lobe cast filled. I have seen the block off plate there, but that was always on reman engines. But the world is a funny place.
If you can use a mechanical pump, that will save some headaches & work.
 
Last edited:
sweetk30 said:
i ran a american thread p/s pump from late 70's on a 90's serp belt setup no problem minus bolt thread swap out and used the serp belt pulley .

yaa try and run mech fuel pump on vortec or just go electric and key hot with relay for the overall win and less problems if your combo wont work .

my k30 budget beater build ( sig line below ) has a L31 vortec 350 and i like the power and smooth engine running . but i kept efi via edelbrock pro-flo-4 setup .
Click to expand...
So you think I could keep my 78 pump and just swap it into the bracket on the serp setup? I never gave that a thought!
 
Jimmy85 said:
Hmm. Every tbi & vortec block I’ve seen has had the lobe cast filled. I have seen the block off plate there, but that was always on reman engines. But the world is a funny place.
If you can a mechanical pump, that will save some headaches & work.
Click to expand...
Yea everyone I talked to has said the same, they had no pushrod hole, some had a block off plate to nowhere and some had no plate and just a pad that was cast filled….I was really surprised when I found the hole so I stuck a push rod in and turned it over and sure enough it has an eccentric
 
And you know it's a Vortec engine?

I'd be a bit curious if it was a replacement that someone threw Vortec heads on if I found it had an eccentric. Vortec V8's were all roller cams, only V8's I can think of that would have used a carb but roller cam were late 80's cars.

My crate L31 (Vortec) direct from GM will not take a fuel pump rod. No blockoff, no hole. Of course, that's modern production.

Just curiosity I suppose, doesn't really matter, do you have the block casting number?
 
Fastereddie said:
The power steering is metric/o-ring on the
Newer pump. Your 78 might still be standard/flare. Easy to deal with though. I use the -6an adapters and make my own lines.
Click to expand...
Is the pump really any different? Can the outlet fittings swap between the two pumps? If not, it might be possible to swap the reservoirs to make the old pump mount to the new brackets. P-pump spans a LOT of years.
 
I was under the impression that GM offered two L31 crates now, one with and one without mechanical provision.
 
Blue85 said:
Is the pump really any different? Can the outlet fittings swap between the two pumps? If not, it might be possible to swap the reservoirs to make the old pump mount to the new brackets. P-pump spans a LOT of years.
Click to expand...

As I recall, the pump uses an adapter fitting, but the threads in the pump body for the adapter are the same.
 
Chickntrk said:
I was under the impression that GM offered two L31 crates now, one with and one without mechanical provision.
Click to expand...

Apparently that casting was used for the Vortecs, HT383s, ZZ4's, and some LO5 (TBI) apps, as well as LO5 crate replacements supposedly.

Is there anything stamped into the passenger side of the block on the pad behind where the alternator normally sits ? Apparently ZZ4's are stamped ZZ4 there.

All info I got from google searching, but it sounds reasonable.

That is really confusing for the consumer if GM was drilling some blocks for the fuel pump and not others. I can't imagine ordering a crate engine and finding out it wasn't setup for it, knowing full well some of them were.

The heads are 906 or 062 castings?
 
I’ll try to look, all the accessories are still on it so I may not be able to see it
 
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