Time For Performance Upgrades For My '98 5.7

[98SheHulk]

Hello All,
My truck recently blew a head gasket that will require me to tear it down and probably take the motor out to replace. While I have it out and apart what kinds of mods should I look at doing to the truck?

I was thinking:
Headers (not sure if I should get long tubes or shorties)
Cam (I have no idea what needs to be done to have more power)
Custom Tune once the other two are done

Are there any advice on which parts to by or anything else you guys can suggest be done in addition to those? or to make those go smoother?

A little background on the vehicle. It is a 1998 Tahoe, 5.7, mostly stock except the engine has only about 25k miles on it. 6 inch lift kit, 35" tires and 4.56 gears. When I first got it I had custom exhaust put on it and a dynamax muffler installed and crosspipe lowered so I could clear the front drive shaft.

I can do all the work myself short of any machine that may need to be done for the heads or block. I don't want to go super expensive and buy a 383 stroker motor or whole new performance heads but I understand I will need to spend some money to make this beast a tire roaster.

Any and all help will be appreciated!

[6789olds]

have the heads machined for more lift , install some beehive ls6 springs comp 787 retainers . zz4 cam.. with long tubes and a tune will get you nice torque and about 350hp fly wheel hp shortie headers will probley kill 15 hp of that .

[the_husk]

Yes, go longtubes and DON'T look back.

If I remember correctly, you don't have to have the heads machined to run the zz4. Just get some comp 918 valve springs and 787 retainers, oh, and don't forget some hardened/chromoly pushrods. Standard SBC length will work, but it's always a good idea to test the length. Definitely get a custom tune with it.

[98SheHulk]

Would you recommend the ZZ4 cam over the LT4 Hot Cam? or Vice Versa?

Also what kind of machining will I need to do to put either cam in? I know I have to put in new springs and retainers but I don't know what kind of machining will be needed on the heads.

I will definitely be getting a tune and now going for the long tube headers.

For the Long Tubes does anyone have any good recommendations for which header to use? All the ones that specifically fit my vehicle (98 Tahoe 4dr) are all a lot more expensive then ones for a truck about a year or two lower. Whats the deal wit that?

One last question, have any of you had trouble with the front O2 sensors and long tube headers?

[Captainfab]

The ZZ4 cam has a little less duration, which would give you more bottom end than the LT4 hot cam. The LT4 hot cam is typically run with 1.6 rockers, so that would be an additional expense. You could always buy the LT4 hot cam kit, which includes the cam, springs, retainers, shims, and 1.6 roller rockers. With either cam, you will need to upgrade the springs. The beehive springs, when used with the correct retainers, are supposed to give you enough clearence for about .550 valve lift without machine work. Although the springs and retainers are a bit spendy. You might compare prices of the beehive springs versus regular springs and the needed machine work. It is always a good idea to check the retainer to valve stem seal clearence with whatever springs you go with. While the heads are being worked on, I would have them machined for screw in studs as well. Also if you do go with the hot cam and the 1.6 rockers, the pushrod holes in the heads will need to be opened up to accomodate the different position of the pushrods.

[speedjunkie]

Are you looking to do some machining on the block or heads? IF you are then go for the 383 and heads port and polish the heads and make sure they acomadate up to.600 of lift. Also what made your engine blow the head gasket? Long tubes and cutom tune for sure.

[gmctrucks]

LT headers no doubt.

[98SheHulk]

Thanks for all the advice guys! It's been really helpful in all of this

I am only going to machine the heads no block work.

Im not exactly sure what caused the blown head since I don't drive it really hard and the engine was a new crate motor that only had 25k. I didn't do the work myself so it could be shotty workmanship or possibly a faulty headgasket

[speedjunkie]

I would look into the cost comparason of new heads versus the working of the old ones. There are test showing that ported stock head out flow some nice aluminum ones. Just a thought.

[SUBURBIAN]

Want some good advice? Take a look at your csfi poppet system while the top end is apart.

[Captainfab]

I agree....


Want some good advice? Take a look at your csfi poppet system while the top end is apart.

[98SheHulk]

what kinds of things should I be looking at when I take a look at those poppets?

[Brian G]

look for clogged poppets, there is a mpfi upgrade thats from gm.
Also, check that your head gasket is actually blown, thses trucks are famous for blowing out thier intake manifold gasket, which shoots antifreeze all over the place-ask me how I know.....

Headers Long tube is what I'm currently installing-I've read many places short tube don't do much, the pipes after the exhaust manis are tiny and need to be replaced.

Cams, Opinions vary greatly! Best cam advice I've heard is pick a specific cam for your application IE tow, race, daily, than go 1 size smaller.
Also, many have had luck with stoc (roller cam) ZZ4, LT4 cams.

Heads, Ive read the stockers are decent and are not much worse than the aftermarket-unless yur concerned with bigger valves and higher reving engine (not much reving with the stock intake BTW )
They benifit from some clean up port work and a little opening on the exhaust side.
Good luck.

[98SheHulk]

So I got the engine out of the truck finally (man there are tons of wires and sensors to unhook) and have decided I want to drop a 383 rotating assembly kit in it. Any of you had any experience with putting one in without buying an entire new crate motor?

I went with the ZZ4 cam, beehive springs and the comp retainers for the cam.

Any other advice you can give would be great! Especially regarding the 383 stroker kits.

[98SheHulk]

I've decided to go with the MFPI upgrade from GM (found a good deal on amazon for it).

Still a little nervous about putting headers on since the once I want dont have the provisions for the EGR tube (which was crinkled and crunched in the process of even loosening the nut that hold it into the exhaust manifolds) so if you have any advice on this please let me know.

[Trav_69Stang]

I went with Flowtech shorty headers, i love them but id rather go LT... i honestly had no idea that they made LTs for these trucks,i could only find shorties on Summit :( I seen they had some Pacesetter LTs on summit for a 97 C1500 like mine, but it looks like they belong on a LS1 with the EGR brakets

[98SheHulk]

I went with Flowtech shorty headers, i love them but id rather go LT... i honestly had no idea that they made LTs for these trucks,i could only find shorties on Summit :( I seen they had some Pacesetter LTs on summit for a 97 C1500 like mine, but it looks like they belong on a LS1 with the EGR brakets

Just looking on summit I was able to see some for your vehicle.
http://www.summitracing.com/search/Department/Exhaust/Part-Type/Headers/Make/CHEVROLET/Header-Style/Full-length/Year/1997/Model/C1500/?Ns=Price|Asc

Here is an assortment of headers on ebay from Shorties to full length:
http://motors.shop.ebay.com/i.html?_nkw=chevrolet+c%2Fk+header&_sacat=6030&_sop=1&Model%2520Year=1997&Model=C1500&_dmpt=Motors_Car_Truck_Parts_Accessories&Make=Chevrolet&_odkw=chevrolet+c%2Fk+++full+length+header&_osacat=6030&bkBtn=&_trksid=p4506.m270.l1313

I was able to snag these a few days ago on ebay and I believe they would fit your vehicle as well:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&vxp=mtr&item=150796491532#ht_2112wt_816
Best price I could find for stainless IMO and even if you dont use the AIR injection ports you can just block them off with a plate from Summit

Hope this helps you.

[Trav_69Stang]

Just looking on summit I was able to see some for your vehicle.
http://www.summitracing.com/search/Department/Exhaust/Part-Type/Headers/Make/CHEVROLET/Header-Style/Full-length/Year/1997/Model/C1500/?Ns=Price|Asc

Here is an assortment of headers on ebay from Shorties to full length:
http://motors.shop.ebay.com/i.html?_nkw=chevrolet+c%2Fk+header&_sacat=6030&_sop=1&Model%2520Year=1997&Model=C1500&_dmpt=Motors_Car_Truck_Parts_Accessories&Make=Chevrolet&_odkw=chevrolet+c%2Fk+++full+length+header&_osacat=6030&bkBtn=&_trksid=p4506.m270.l1313

I was able to snag these a few days ago on ebay and I believe they would fit your vehicle as well:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&vxp=mtr&item=150796491532#ht_2112wt_816
Best price I could find for stainless IMO and even if you dont use the AIR injection ports you can just block them off with a plate from Summit

Hope this helps you.

Thanks for the help those OBX's are nice no doubt! I started looking after i posted this also... now i have LT fever. I've really been thinking about an EGR delete/block off about im curious on the effects... i think it would help but my auto instructor says and i quote... "will decrease my gas mileage because the fuel will have a richer mixture and the EGR helps cool the cylinders" I could careless about the cooling part, my truck runs 160-175 all hot summer long with problem. The fuel mileage though, im getting about 19-21 and id like to keep that or improve it more.

[The Fiddle]

Yes, go longtubes and DON'T look back.

:yaoming:


If I remember correctly, you don't have to have the heads machined to run the zz4. Just get some comp 918 valve springs and 787 retainers, oh, and don't forget some hardened/chromoly pushrods. Standard SBC length will work, but it's always a good idea to test the length. Definitely get a custom tune with it.

It is a little known fact that with 918 beehive springs the stock Vortec 350 heads will take ~.520" lift at the valve before she taps out, but they need the Comp 787 retainers to run. The only machining I had done on my heads were some bowl work and cleaning on the exhaust ports.

The ZZ4 is a great cam for an essentially stock 350. It'll pull plenty hard down low up to around 5000 rpm. However, I'll stand by Lunati's "Voodoo" line and highly suggest one of those cams.

[The Fiddle]

So I got the engine out of the truck finally (man there are tons of wires and sensors to unhook) and have decided I want to drop a 383 rotating assembly kit in it. Any of you had any experience with putting one in without buying an entire new crate motor?

I went with the ZZ4 cam, beehive springs and the comp retainers for the cam.

Any other advice you can give would be great! Especially regarding the 383 stroker kits.

Scrolled back up and saw this.


Here's my 383 thread:

http://www.fullsizechevy.com/forum/general-discussion/performance/engine-swaps/430913-fiddles-383-stroker-thread.html



edit: And going with the 383, I'd highly advise a different, larger cam. The ZZ4 will be done around 4500 rpm.

[98SheHulk]

Scrolled back up and saw this.


Here's my 383 thread:

http://www.fullsizechevy.com/forum/general-discussion/performance/engine-swaps/430913-fiddles-383-stroker-thread.html



edit: And going with the 383, I'd highly advise a different, larger cam. The ZZ4 will be done around 4500 rpm.

What about using the zz4 with 1.6 rockers? Would that help it pull past 4500? Also can the vortec heads with the zz4 and 1.6 rockers handle the exhaust lift?

[The Fiddle]

Probably not. I wouldn't use the stock springs on the ZZ4 to begin with. When adding any sort of aftermarket cam, always upgrade the springs. Even if that means having them machined to accept the lift.

[98SheHulk]

Probably not. I wouldn't use the stock springs on the ZZ4 to begin with. When adding any sort of aftermarket cam, always upgrade the springs. Even if that means having them machined to accept the lift.

I've got the beehive springs and comp retainers for the heads. From the research I've done the heads with those springs and retainers will handle .540 to .550 lift.

I'm also a bit confused because the HT383E crate motor that GM sells has a milder cam then the ZZ4 that I have yet still puts out respectable horsepower numbers.

Edit: I also need the torque down low for towing and 4x4 so having the can run out of juice in the higher rpms might not be such a bad idea

[The Fiddle]

I've got the beehive springs and comp retainers for the heads. From the research I've done the heads with those springs and retainers will handle .540 to .550 lift.

I'm also a bit confused because the HT383E crate motor that GM sells has a milder cam then the ZZ4 that I have yet still puts out respectable horsepower numbers.

Edit: I also need the torque down low for towing and 4x4 so having the can run out of juice in the higher rpms might not be such a bad idea

Some hp/tq number goals would help here.

[98SheHulk]

Some hp/tq number goals would help here.

I would love about 350 hp out of the motor. 400 would be great but let's be realistic here haha

The reason I'm leaning towards the ZZ4 is because I already have the cam and would rather not try to sell it and try to come up with the money for something else but I will still be open to suggestions

This truck will be mostly for towing a trailer around.

[The Fiddle]

The ZZ4 in a 383 will make a lot of low end torque. It would probably be in the 330-350 horse range.

[CRW97RADO]

do the longtube pacesetters from Auto Anything, those guys are great!!, i got mine 15% off of 280 which was like 240 to the door..i didnt do the egr either..just bought the egr plug from custom billet works (ebay)..o2 sensors went in perfect, and it sounds boss with open tubes..i recently put on the tubes and a blackbear, must say it has a mean low-mid range but like all vortecs not much up top..maybe took 2 hours tops to install, very happy

[CRW97RADO]

not to hi-jack but is there a good cam, where i can just slip it in, with out having to do the springs and what not..ill def do the heads later on but for right now, any just bolt on cams?

[The Fiddle]

not to hi-jack but is there a good cam, where i can just slip it in, with out having to do the springs and what not..ill def do the heads later on but for right now, any just bolt on cams?

I wouldn't put any larger cam in there without upgrading the springs.

[CRW97RADO]

Well I tried deleting that post..shortly after that I found a link that explained why, and all that..I found that springs retainers and locks are essential to camming a vortec..correct?

[cancritter]

x2+ on the lunati voodoo line....long tubes if availible..custom tune..none of that over the counter chip crap that fits all(waste of coin) and 3 in single exhaust..forget the duals(waste of coin)...o2 issues can be solved by useing a 3 wire heated unit in the long tubes

[JaredPuk]

o2 issues can be solved by useing a 3 wire heated unit in the long tubes

What is that?

[SUBURBIAN]

Howards Cams is a small old school cam company out of Wisconsin. They grind all of their cams, unlike some of the commercial big boys. They are made in the USA, they are made from strong durable cores, and they stand behind their stuff. There are a number of grinds in their catalog for racing classes restricted to stock lift numbers. One of these is RIGHT up your alley. There's one or two that would be ideal for what you're trying to accomplish. This is the best advice if you want to keep the stock valvetrain hooked up. Let me know if you can't find the website/catalog.

[cancritter]

What is that?

2 wire 02 sensor on your exhaust manifold may not give correct readings if placed incorectly on headers and they take a few mins untill they start registering and sending correct info where its needed,,,

a 3 wire is a o2 sensor that is heated...it basicly eliminates all these issues as it starts working from the get go providing smoother starts ect..bottom line for a few dollars more the 3 wire o2 is a good improvement over stock....hope l got this right

[Tahoejoe99]

Good cam choice, should have nice down low TQ with 383 and 4.56 gears.
Don't have to much machine work done, all that needs done to vortec heads is a .020-.040 mill, pin the studs, a lil bowl work, pocket port the exhaust and thru out, don't touch the intake runners. Comp ultra pro magnum 1.6 ratio, full roller rockers will compliment the rest of the valve train upgrades you made.
Get thE compression up and the quench down, hooker Lts, single 3" out muffler, clean up the lower intake plenum thru out and flashing at the end of the ports to help it breath. A V-max will add more plenum vloume and aid in low lift flow.

[JaredPuk]

2 wire 02 sensor on your exhaust manifold may not give correct readings if placed incorectly on headers and they take a few mins untill they start registering and sending correct info where its needed,,,

a 3 wire is a o2 sensor that is heated...it basicly eliminates all these issues as it starts working from the get go providing smoother starts ect..bottom line for a few dollars more the 3 wire o2 is a good improvement over stock....hope l got this right

Makes sense, do these plug in or do you have to source a 'hot' wire? he he hot wire.