1990 Suburban engine

[kd7kmp]

I have several questions regarding the engine in my 1990 V1500 Suburban. This ‘burban is used mostly for family vacations and is loaded full when we travel. It doesn’t see any extreme off-roading. I want a good balance between torque and horsepower. Here are some basics about the truck:

• stock engine internals and heads
• stock exhaust manifolds with 3” catalytic converter and cat back
• cfm-tech goodies: TB and injector pod spacers, Hypertech Power Charger, adjustable FPR
• 700R4 trans
• 3.73 gears
• 31” tires
• 124,000 indicated miles, though I believe there are more as I had to replace the odometer when I bought the rig.

The problem I am experiencing is a lot of blue smoke for several minutes after start-up. This is fouling my plugs and doing who-knows-what to the combustion chambers and cat. If I have to take the heads off to get the valve guides replaced then I may as well take the whole engine out and do a rebuild on it. The advice I need is on the head, cam and exhaust selection.

I have looked all over the board and believe that World Products SB-Chevy S/R Torquer Heads are a good fit for my motor. The reason I don’t want the Vortec heads is all the nickel and dime stuff, as well as the requisite GMPP intake manifold. If you have any other recommendations then please feel free to offer your opinion.

As for the cam…is my stock block set-up to accept a roller cam? Is it worth it to go to a roller cam? What cam should I look at? I have seen a lot of talk about Comp Cams stuff here.

Lastly, what headers should I run? I don’t have any lift and don’t want to have to move anything to make the headers fit. I have seen too many recommendations to know what to do with headers.

Thanks for all the help and advice. I really appreciate it.

Kevin

P.S. I know I will probably need a new chip. Can you give recommendations as to where to get this done?

 

[SUBFAN]

Try replacing the valve seals first. Not to bad a job, especially if you have an air compressor. This can be done with the heads installed.

Hooker makes a header that fit my '90 'Burb perfect. You will have to get a bung welded in for the 02 sensor, and possibly have to run a heated one. I did not notice much of an improvement after this, but my intake system was stock, and the 35's w/3.42's didn't help either. I never went the heated o2 route, but at 350,000 miles the truck was pretty much a dog anyways. Always made more noise than forward momentum.

Really, if it is only driven occasionally, I would just keep the stock manifolds. Headers will rot much faster in a rig that mostly sits.

Lose or replace the Cat, it is probably choking things up pretty good by now....

I called Comp Cams, and they said I could use their SMALLEST 4X4 grind in my motor. At 111.5 L/C, it should certainly make enough vaccum to run things properly.

You will not know for sure if your stock block is set up for a roller cam until you open it up....

As for the heads. There are better AND cheaper choices out there. Look into a set of Darts, or others with a more modern combustion chamber.

I believe the heads will give the biggest boost in performance, with the room to grow into even more when the rest os the bolt-ons are installed. A great motor is nothing with crappy heads.

 

[Hogback Fabrication]

I think looking into a roller cam (which I think your block should be able to take) and the L31 vortec heads. The roller cam will make a big difference in itself. The vortecs will only nickle and dime you if you are going for serious horsepower and performance (trust me, I have a set). If you leave them stock (which you will, the stock TBI can't take much cam anyway), they will make a HUGE improvement in power all by themselves. If you go with the vortecs, you will need a new intake manifold as you said ($200 max), and that will probably gain you some power as well. I got my set of L31's new for a little over $500 for the pair, assembled. Everything you need to go to vortecs will cost you less than other aftermarket heads alone, and I am positive they will make more power than other heads on the TBI setup.

 

[kd7kmp]

SUBFAN: What other head choices are there? I am relatively new to what is available.

38377K5: What intake manifold do you recommend for use with the Vortec heads? The GM part is $300. Does Holley or Edelbrock make one?


What about the self-aligning rocker arms? I don't know what to get for those.Thank you both for you input and help.

Kevin

 

[89GMCSuburban]

You can use the vortec manifold from GM, but I believe they sell head drilled up for the older style manifolds. If not, take them to a machine shop and have them drilled. Probably cost less than the manifold.

Use the Vortec heads, stock manifolds, mild cam, and new hi-flow cat if you have to stay legal. You have to remember, the more stock you are, the more reliable it will be. GM designed these engines well, and in my experience, when you start trying to make it "better" with aftermarket parts, it just gets less reliable.

My 89 engine was still standard flat tappet. As said, you will have to pull it apart to tell.

 

[SUBFAN]

Since the Vortec large ports are available to fit both early or late intakes, I would assume the small ports can be done also. There are some adapters that are supposed to let you slightly modify the early intakes to Vortecs, but I have never used them....

For the price and keeping it mild, Vortecs are hard to beat.

Some reading about heads....
http://www.chevyhiperformance.com/techarticles/41598/index4.html

Look for the highest average flow readings from .400 lift and under for your application. Some of the heads have very efficient intake to exhaust ratios. Usually, better power can be made with a single pattern cam, if that is the case. (Check for computer compatibility.)

The use of self aligning rockers depends on which head you use....

It is possible to use earlier style heads and intake with an adapter to mount the throttle body, which should give you the extra flow you are looking for....

 

[kd7kmp]

SUBFAN,

Thanks for the link to that article. It is very helpful and educational to see a comparison between different heads. I do have one more question...the Vortec head is looking good, but what about the smaller chamber size? How much of a bump in compression will net? I want to be able to run this engine on regular unleaded gas. Thanks.

Kevin