L31 350 Build
 

While waiting for my car to sell I've been thinking of possible ways to revive it. One option that I found was this L31 short block:

http://www.skipwhiteperformance.com/....aspx?Item=L31

Doesn't necessarily need to be this exact one at this price (I can get it for $1200), but that short block (not really a short block because it comes without the cam/lifter/rockers) is a great start. From there I would need to figure out heads and a cam. Even if I get standard Vortec heads (maybe $300 each?) and a decent cam I will be spending less than a legit L31 short block so I'll save a little money. I will keep my TPI for now so I would get a Vortec TPI base ($400) and then just need some rockers and lifters.

L31 short block (kinda) - $1200
Vortec Heads - $600
Cam?
Vortec TPI base - $400

$2500 for everything would be awesome at this point.

Any cam ideas? Any flaws in my uneducated thoughts?





Just found some heads:

http://www.ebay.com/itm/96-99-CHEVY-...sories&vxp=mtr

So would you then be keeping it?

Yea. It pains me to see it in my driveway every day and I put way too much into that car to let it go for nothing. If someone offers me $3000 I'll take it, but with no interest so far I'm looking into try to save her.

Keep in mind the short block is missing the oiling system and timing system. And pushrods. You have to factor that in to your build too.

Have a look at this:

http://paceperformance.com/i-6484922...7r-cpi-hd.html

Maybe get it in and running as-is and then cam swap it, run a thinner head gasket for more compression etc later on.

Not a bad idea. I will try to use as many existing parts as I can but I'm assuming by your comment on oil and timing that they won't swap over.

Check this one out:

http://paceperformance.com/i-6484911...-8600-gvw.html


Will this L05 allow me to use my current TPI base since I'm assuming it has the older non-vortec heads?

I also saw that the L31 I originally linked to is 4 bolt main. Will that not match to my stock trans since my L98 is 2 bolt?

Wow that L05 has horrible heads... Pass.

I'd like to live my life without having to experience TBI and swirl port heads...

The tin may swap over (timing cover and oil pan) but you will want a new timing chain, oil pump, oil pickup, probably fasteners, etc. My point there is that incendentals may add up. And nothing is more depressing than a $250 Summit order with no glory parts in it... just bolts, oil, and gaskets. :mrgreen:

Haha true. I'll have to find out what exactly will swap over. Will my trans/flywheel be ok with the 4 bolt main L31 short block?

Trans, yes. Flywheel/flexplate I am pretty sure but you may want to check. If not, that's not an expensive part to find used.

Stock flexplate should fit because L98 and L31 short block are both 1 piece rear main seal. Sound correct?

To me, yes.

Ok so using the L31 actual short block:

L31 short block - $2000 (Jegs)

Vortec Base - $400


Ive read good things about the LT4 hot cam which matches the vortec heads well ($180 down the road).

LT4 Hot Cam Specs:
idle - 6000 rpm
@.05 in. - 218/228
.525/.525 with a 112 LS

Just make sure your heads can handle it. Vortec stuff is easily the best bang for your buck but the stock heads have some weak points that you must address.

Well the cam could be in the future. The stock L31 cam is pretty wimpy. The link below is a good read:

http://www.pacificp.com/forum/viewto...&highlight=787

L31 cam specs:
* Intake Lift- .414"
* Exhaust Lift-.428"
* Intake Duration @.050"- 191
* Exhaust Duration @ .050-196
* Lobe Centerline-111

According to a few sources, the vortec heads (062 cast) can flow up to .460 lift stock. I haven't been able to verify if the heads on this short block are the 062 cast.

L31 short block heads - 64cc,1.94" intake,1.50" exhaust

Not flow .460, they can handle .460 lift. But that's just the guide clearance. The valvesprings are too weak for more than stock.

I run 062 Vortecs :mrgreen:

Right sorry. I'll have to call and ask for the head cast number. What cam are you running?

Flat tappet XE268 Comp.

This and gm's 330hp cam http://www.jegs.com/i/GM-Performance...oductId=813788

http://www.jegs.com/i/GM-Performance...02476/10002/-1 edit scratch that, one is roller one is flat tappet.

I just deleted a few posts because I made a mistake copying/pasting. WF has the right long block, the one I posted was a non-Vortec engine. Although he posted a flat-tappet 330hp cam for a roller motor, which is not right. Trust me, you want a hydraulic roller cam.

This is supposedly an L31 with worked vortec heads and the LT4 cam already. Worth the extra $1000, I don't know...

http://www.yearone.com/serverfiles/f...5&cat=C&trk=22

The one you posted has vortec heads.

Wayfast posted up GM part 12530282 - GM Truck 1996-2000 3/4 and 1 ton pick ups (2 bolt main)

You posted GM part 12530283 - L31-R GM full size truck/van (4 bolt main)

Both motors have the same vortec heads, camshaft and compression.




I assume the 0282 is fine for my GTA. It's also $100 cheaper...

Yeah, gm uses that camshaft in the vortec crate motors just in roller form. If I could do this again that long block would've been a lot easier and I would've had a warranty. It's a great deal and you can always upgrade cams. The real problem here is I would want screw in studs and they might void warranty because of them.

Edit for a hundo get 4 bolt mains.

Whoops. I thought I posted the L05 link by accident.

For $100, go for the 4 bolt mains.

How much do the intakes run?