L31 conversion to carb
 

OK here's the deal. I have a ZZ4 motor and I'm converting it to a carb. What do I do with the sensor that's on the front of the crankshaft? If I remove it will the balancer go too far onto the crank? Has anyone gone through this? What's the solution?

Re: ZZ4 TBI to carbed conversion
 

Your talking about the reluctor for the crank sensor... Just leave it in place. It won't hurt anything being on there. You could have a spacer machiened or there may be one avalible but not any advantage of delteing it.
You'll need it or a spacer to keep the ballancer/Timing gear/reluctor all tight and alligned.
~Scott

Re: ZZ4 TBI to carbed conversion
 

Thanks Bro. My main concern was having the balancer going to far onto the cranshaft and possibly rubbing on the timing cover.

Re: ZZ4 TBI to carbed conversion
 

I just had our 98 GMC Jimmy 4.3L front cover off and I know they are setup the same basic way. That reluctor has to be in there or like you said the pulley will be off and the ballancer will be too deep as well.

Good luck,
Scott~

I'll have to admit I don't have a clue what you're talking about. ZZ4 crate engines don't have a sensor on the front of the crank, and I've never heard of anything like that on TBI.

Re: ZZ4 TBI to carbed conversion
 

The one I saw DID have the production L30/L31 reluctor ring on the crank and the Vortec truck composite timing cover without a sensor hole drilled in it.

That would explain it, then.

Although it doesn't explain the "TBI" part of the thread title.

Re: ZZ4 TBI to carbed conversion
 

Actually it's multi port fuel injection but I assure you it's a ZZ4 truck motor with vortec heads. The casting number is 10243880. Look it up.

http://www.mortec.com/castnum.htm

Re: ZZ4 TBI to carbed conversion
 

:lol: That's the biggest pile of mutual incompatibility and "buzzword bingo" that I've seen for a long time. You just WON the GRAND PRIZE for the month of November!!!! :lmao:

"I assure you" that you DO NOT have what you say you have, because it doesn't exist.

The ZZ4 is not TBI, and it is not MPFI. It comes set up for a carb.

The ZZ4 does not needbecause it's ALREADY set up for a carb.

The ZZ4 does not come in trucks (or any other vehicles, for that matter). It's an over-the-counter PERFORMANCE service replacement engine.

The ZZ4 does not come with Vortec heads. It comes with 113 casting aluminum heads, the same casting as the TPI Vettes had from about 87 to the end of the run; with slightly different setup parts.

The ZZ4 does not come with the crank sensor provisions. It's carbed. It comes with a carb intake already bolted down to it. I happen to have a take-off one bolted to one of my cars.

The ZZ4 ignition does not use a crank sensor. It comes with a pre-computer large-cap HEI. I happen to have a take-out one in another one of my cars.

The ZZ4 uses the same block casting as alot of other later-model 350s. You CANNOT identify an engine as a ZZ4 by its block casting; just like you can't tell a L98 block from a L05 block by its casting # (both of those are 638).

Here's a link to a REAL ZZ4 engine, so you can tell what a ZZ4 REALLY is. http://www.sdparts.com/product/24502...ateEngine.aspx

Leave the buzzwords behind, don't try to pull a snow job on us by trying to bogusly convince us how exalted your motor is, and talk about what you REALLY have.

If you have a motor with a crank sensor, it IS NOT a ZZ4. All you need to do in order to run a carb is to put a plug in the hole in your TC where the sensor goes, and leave the rest of it alone. Then bolt a carb intake, a carb, and a non-computer-controlled distributor into it. Done. No buzzwords.

Re: ZZ4 TBI to carbed conversion
 

You don't have to be a smartass about it. None's trying to "snowjob" anyone. I got the advice I needed and I appreciate it, so move along. Nothing to see here.

Re: ZZ4 TBI to carbed conversion
 

His question was answerd... He can call the engine he has a LS1 or LT1 for all I care.. :idiot:

He just wanted to know if the reluctor ring needed to stay in for spacing or not.
No need to drag stuff through the mud for a mistake calling a engine one thing or another or do you just like to hear yourself talk about somthing that is realy irrelivant. :blah:

Sheesh. :confused:

I disagree.

If we don't know what engine we're talking about, the probability of providing useful information is greatly diminished.

ZZ4, as sofa states, is an over-the-counter performance crate engine. It doesn't share anything with the L31 (with the possible exception of the block casting - my ZZ3 block is a 638 casting; the block casting they used changed over the years). If you have a "Vortec" engine, then call it "Vortec". Or L31. But, no-way, no-how is it a ZZ4 if it came from the factory in a truck.

And, the L31 didn't have TBI. It is a port-type injection, the precise name of which escapes me right now (mostly because nothing I've heard about it impresses me enough to even consider running it in anything but a stock Vortec truck). It has a throttle body, but that doesn't make it "throttle body injection". And, you don't need a crank sensor with TBI.

The picture I had in my mind was a crate ZZ4 that had been put under a TBI set-up - it's been done - that the originator wanted to now convert to carb. Obviously, as the real information became available, that's not even close to what's going on.

So, the thread title will now read "L31 conversion to carb".
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Let us moderators handle that, please. If you don't know how to report a post, ask.

If you had read the whole listing, and not let your eyes get drawn to just one piece of it, you would have noticed that "Vortec truck" was the first application listed. It was also used for "Gen I crate motors", of which the ZZ4 is one, but certainly not the only one.

Re: L31 conversion to carb
 

Thanks five7kid. You are correct. It's a vortec truck motor but that's not all that important in the scheme of things. I'm not the sharpest pencil :confused: in the box when it comes to this stuff which is why I and many others come to the board seeking guidance from those with more experience. The main thing is it's a 350, 4 bolt main motor that was fuel injected when we pulled it out of the truck and I wanted some advice about what to do with the reluctor ring since we're going to put a carb on it. I appreciate all the useful info provided by you all.

Re: L31 conversion to carb
 

Right, sounds ALOT more like you have the L31, than the ZZ4.

To convert the L31 to carb, all you need is a Vortec-specific intake manifold (Performer RPM is the usual, but certainly not the only, choice); a carb (duh); and a non-computerized distributor.

As said before, just leave the reluctor ring alone. It won't bother a thing.

Re: L31 conversion to carb
 

That's what it is. I did just what five7kid said and breezed right by all of the mortec description except the ZZ4 part....duh. I've already bought an Edelbrock airgap vortec intake. I'm trying to get the money together to get some roller rockers and plan on buying the GM performance 350ZZZ cam for it as well. Had the heads reworked and put on some slightly larger springs. Unforunately I didn't have the cash to go all out with it. Any, thanks for the advice.

Re: ZZ4 TBI to carbed conversion
 

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Re: ZZ4 TBI to carbed conversion
 

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Re: L31 conversion to carb
 

errrr... you do realize that this thread is 12 years old right ?

Re: L31 conversion to carb
 

im hopeless i guess:
i get into a thread and forget to look at the dates,ESPECIALLY if it applies to what im doing.
im drawn into it like its in real time(moth to a flame ,durp a durp) if that makes any sense.

so maybe you can answer me this,ive got a very good running L31 ,(pulled now and on a stand)
an edlebrock rpm intake,baby LT4 cam. BUT and this is the part that's messing up my mojo.
ive also got a lower mileage L98,so my conundrum is,which 350 do i build with out doing a
metric sh#t ton of high dollar machine work.im thinking rings,gaskets,crank and rod bearings,
timing chain and reusing the block,pistons,rods,crank etc(if it is suitable)ill probably dingleball
hone either block as long as the cross hatch is still decent,ill check all bores,clearances etc(machinist)

Re: L31 conversion to carb
 

Given that choice of short blocks, pick the one you don't have to do ANYTHING to. It'll probably work out better in the long run than messing with it.

Other than that they're virtually identical in terms of your project.

My guess would be, the better one is likely to be the newer (L31). Unless it was abused somehow during its previous life; run low of oil, oil never changed, stuff like that.

Don't stick your fingers in where they don't need to go. ;) Especially if it's "very good running". THIMK... JUST EXACTLY WHAT would you accomplish by dinking with such a short block? Do the benefits outweigh the costs? Risk vs reward? Use all of those commonsensical approaches to making an INTELLIGENT UNEMOTIONAL RATIONAL decision. Not the way a human would do it, IOW.

Re: L31 conversion to carb
 

thanks sofa,ive got a video of the l31 running(and running well from what i can see)just prior to removal for a 383 stroker swap.
it was the ONLY reason he took it out.spotless,wickedly maintained,oil and gunge free.the L98 however looks to be run through
the ringer,dirty,grimy,oily
https://cimg2.ibsrv.net/gimg/www.thi...996667e52b.jpg
l31 before removal
https://cimg6.ibsrv.net/gimg/www.thi...ca4500e818.jpg
l31
https://cimg2.ibsrv.net/gimg/www.thi...b8da53b982.jpg
l98 still in car.