Dokken10

iTrader: (18)

And the TPI looks so damn cool.

Any P/Ns for a LTI cam or the ZZ4 cam that would be and improvement without head work and killing gas mileage?

Dokken10

iTrader: (18)

Hydrogen has been proven to work with carbs with no problems but FI has not. So you could get the fuel economy with the Hydrogen generator and a carb.

intex1982

iTrader: (2)

my brothers vortec trans am gets around 23mpg with carb and his s10 with vortec gets over 20. head lift then his going to have to take the heads off

intex1982

iTrader: (2)

lt1 cam dont have a dizzy gear does it?

Dokken10

iTrader: (18)

Anyone?

InfernalVortex

iTrader: (4)

The differences are quite hazy. The concensus is that the 906 heads have a hardened exhaust seat that appears to have a 1 angle valve job done on it that hinders flow. Thus the 906 heads have a slight stigma about them. In practice, I think you should get a valve job done on used heads anyway and the problem is easily rectified.

Here's a shot of my old junk 906 heads that DANS87GTA RIPPED ME OFF with where you can see the hardened exhaust valve seat:



Sorry, Im still angry at the punk for ripping me off on them...

Dokken10

iTrader: (18)

062 didn't have hardened exhaust seat but a 3 angle valve job?
----------
How did that happen to your heads?

Stephen

iTrader: (12)

LT1s still use a dizzy-type shaft as an oil pump drive...Right? So I think a LT1 cam would swap right in, no problem. At least, I've never heard of anyone having to get a gear pressed onto the LT1 cams. Just the issue of the nose pin being different, for the Opticrap, which is easily swapped out for the right pin.

Dokken10

iTrader: (18)

I'm just going to stick with the L31 cam or the 90-92 L98 cam.

InfernalVortex

iTrader: (4)

He and his partner in crime ( shagwell ) ported 3 exhaust ports in the heads through to the water jacket, had them brazed back up and sold them to me as perfectly good heads. As soon as the car was run it just pumped out water and steam and set back my build by about 3 months and $600 for a set of junk heads.






But either way, it's a bit OT so I'll let your thead continue.

black89ws6

I have a 97 Tahoe with a 350 Vortec. It is still a reverse rotation pump.

The "reverse-rotation" is because of the serpentine belt system. Think about it for a second. Which pulleys on a serpentine system drive off the backside of the belt? The water pump, the tensioner pulley, and idler pulleys, are the ones driving on the backside of the belt on most serps. The easy way to remember it, is the belt wraps around the pulley in the opposite direction to drive of the back. Thus the pulley spins in the opposite direction.

It is not easily possible to mix them up. The pulley mount holes are drilled/tapped differently. Don't ask how I know that. It's one of those things one is embarassed to have done.

Dokken10

iTrader: (18)

I finally got it earlier, it was Advance, Autozone and Summit that confused me because of their descriptions of the WPs.

InfernalVortex

iTrader: (4)

You can use an L31 ecm to run a TPI?

Fast355

iTrader: (2)

SURE CAN

I am using a 0411 LS1 PCM with a 2002 L30/4L80E Van tune to run my 305 TPI.

TurbomanKnight

SUBSCRIBED! Thanks, been looking for a thread like this. My Camaro needs a valve job. And I have a Vortec 5.7 out of a 99 Express laying around that I wanna convert to TPI and drop it right in.

Dokken10

iTrader: (18)

I have heard the the Vortec heads are prone to cracking, if so where are the cracking at?

I believe I read some where on a aftermarket Vortec head manufactures website that the beefed up the area where the GM Vortec heads were cracking.

InfernalVortex

iTrader: (4)

I believe it's the valve seats. It may have somethig to do with that hardened insert, not sure.

jamon8

iTrader: (3)

tally what you spend and I will smoke you with a first gen block

170cc 64combustion cambers

why are these heads worth a ton

I would get some run of the mill 081 a carbide bit and some paper rolls and kill those heads

SpitotRs305

yeah you spend your time porting the **** out of those 081 heads and he can bolt up his vortecs and put down the same if not more without touching the heads... and if he decideds to clean them up a bit even better... there is a reason they say the vortec head is the best gen1 production head ever...


oh yeah try and find a difference in a "vortec block" and a gen I block

Dokken10

iTrader: (18)

I just got a recommendation to use a stock LT4 cam(not the LT4 HOT cam) in this L31. I know about the Memcal being programmed.

What would I gain from the stock LT4 cam compared to the 90-92 stock L98 cam or the cam in the L31?

FYI, I'm sticking with the 90-92 SD TPI setup with the Vortec TPI base.

Specs on the stock LT4 cam



INTAKE: DURATION/LIFT

@0.05 191 .418

EXHAUST: DURATION/LIFT

@0.05 196 .430

LOBE SEPARATION 111

90-92 stock TPI cam:

10111773 202/207 .413/.428 .441/.457 114.5 90-92 350,305

Fast355

iTrader: (2)

The LT4 cam is an awesome cam upgrade for the L31 Vortec engine. It has more lift, more duration, and a wider LSA. It has more area under the curve as well. It is a very smooth idling camshaft that likes to rev. The LT4 cam fits in with vortec heads very nicely, with LT4 .050" offset retainers, shims, and a good set of valve springs. I have one in my otherwise stock L31 Vortec longblock in my Fullsize G1500 Conversion van. With the 2,000 rpm converter and Tri-Y headers, it came to life all over the powerband. It pulls hard from just off-idle all the way to the 5,600 rpm fuel shut-off on the stock tune.

Dokken10

iTrader: (18)

What if you took out your LT4 cam and replaced with a 90-92 L98 stock cam in your G1500?

What difference would you see?

Again, I'm weak on cams and the L31 stock cam will not be used.

BigBadBranBran

Hey everyone. Just registered. Glad to find people that know a little bit about the Votec 350/5700/L31... Whatever you want to call it. I have a 96 L31 in my 77 Camaro.
I'm glad to find out that the cam is a roller cam, that makes it a lot easier to swap it out without having to get a "retro-fit" roller cam.
So I keep hearing that the Vortec heads are awesome and they'll sell really well any everything. I understand that they outflow other OE heads and everything, but why should I keep them over buying a new set of something like Edelbrock E-Tec 170cc heads? Obviously with the E-Tec 200cc heads there's a bigger intake runner which makes it clear why that head would outperform the stock head. But would the 170cc E-Tecs actually outperform the stock heads with the stock cam?

And just how much will the OE Vortec heads go for?

Also, how many horses will the rotating assembly take before having to change that out? It's probably a cast crank and pistons?
Lastly, I read that the max lift on the stock head was like .490. That's just because of the valve stem length right? How far till you reach the piston?
I guess what I don't get is, if I put an E-Tec head on my L31 and the max valve lift is .575 and the cumbustion chambers are still 64cc, There must still be room with the stock head to change out the vavles and springs for a higher lift then, right?

Pocket

iTrader: (24)

People go vortec because they are cheap. Plain and simple. Of all the OEM heads they flow the best

Setting cost aside and going aftermarket heads, the usually cant compare without significant porting, and even then a ported aftermarket usually trumps them again

Compare flow charts. Most likely, yes it will

Check the classifieds and ebay there is no set value

Max lift is based on the stock valve springs. They are rated for the stock cam, no more. The issue with upgrading springs is clearance around the valve guides. While a minor job for a machine shop, its an unforeseen cost to the cheap hotrodder

Match your cam to your head flow and intake design, match the valve springs to the cam

Further reading
http://www.customclassictrucks.com/t...evy/index.html

Stephen

iTrader: (12)

The problem is with spring bind, which can now be overcome at home, with zero machine work done.

There is now a conical spring set available to replace the stock ones. Which like any other spring set.....You can replace the Vortec ones at home, with no more than pulling the rockers off.

Upping the calve lift ability over stock. Simple upgrade.

Or you can buy brand new Vortec heads that already have the spring replacement done for you.

1986Z28OWNER

iTrader: (1)

just leave the vortec cam in there, it is almost identical, and not really worth the effort to take it apart, the vortec cam is a little better aswell. it will run just fine on the stock prom