Vortec 350 Intake manifold gasket + MPFI upgrade any tips?

[MrSpicy]

Hi all,

In the process of replacing the lower intake manifold gasket on my 99 Yukon. Doing some other work while im at it along with doing the spider upgrade. Replacing plugs, wires, cap, rotor, spider, intake bolts, thermostat, and pretty much any gasket involved. Also am cleaning everything best as possible- intake was unbelievably filthy. Cleaned throttle body as well.

Any tips or advice? Anything else I should replace while im at it?

 

[SunlitComet]

just use the correct makers of parts that's all. delphi or delco for ignition stuff. can use autolite for plugs as well. bolts and gasket from fel-pro and get the MS98000T type of intake gasket. be careful about replacing the water connection coupler on the manifold. it's threads can become corroded over time and if you remove it with it really bad it will destroy the manifold threads with it. maybe leave it alone if it looks okay. otherwise just follow your torque spec and take your time to re-align your dizzy to avoid P1345 alignment issues.

 

[Tbruz]

Sunlit
This is next up on my list of to-do/upgrades as well
Should a new dizzy gear be installed when you're in this deep?
Tbruz

 

[SunlitComet]

if needed. if it still looks good with the mileage that is on it then leave it.

 

[MrSpicy]

Thanks for the tips guys its all going back together today so ill let you guys know how it goes.

 

[MrSpicy]

Well I got it done, but what should have been a pretty straight forward job turned into a major pain in my ass thanks to dex-cool it seems. I should have double checked that water coupler on the manifold again while I had it off. Thought I just needed a new plastic quick connect piece and the rest was fine didn't need to touch it but turns out, after putting the manifold all back in that is, noticed the whole insides were corroded. Simple fix right just get a new one? no damn thing snapped off at the manifold. Luckily I was able to channel my anger into getting it fixed. First tried to cave it in by chiseling it with a screwdriver (there was still about 1/8 sticking out). That only broke everything off up top. Then did what I should have done in the first place- took a hacksaw and cut the blade narrower with tin snips so it could fit in the tube and cut away in 3 spots down to the threads took me a good while . Then chiseled those out very carefully and had to be ever so carefully and to my absolute surprise I got it out with the threads in the manifold 90% intact. Metal shavings did fall in but that's ok I can live with that. Put some rtv sealant on the threads of the new one and popped it back in.

All in all it was totally worth it, I've never been one to do upgrades and such but if your doing the Intake gasket you might as well upgrade the spider when you can get an Acdelco one for less than $300 on Amazon. Now my Yukon runs Phenomenal I didn't know that it could run so well, its so much quieter, smoother, 25% at least improvement in overall acceleration, idles smooth and just sounds really healthy Cant wait to see how gas mileage turns out just 1-2 more mpg that will really make it worth it... might just be wishful thinking though. Hope this post helps someone finds this thread helpful

 

[SunlitComet]

cool beans.

---------- Post added at 02:50 PM ---------- Previous post was at 02:49 PM ----------

how did things look inside like cleanliness or dizzy gear or other issues?

 

[99Vortec]

Nice! I chose to do the same dual upgrade for my Vortec, and was quite pleased with the end results.

Quicker starting, increased throttle response, and it quieted down a noise I had coming from the passenger side for some reason. I also cleaned the MAF sensor. (1996-2000 models?)

Still have to check out and clean my idle air control valve though.

On my Yukon Denali, the distributor drop-in was the trickiest part for me. (It was so close to the firewall.) I initially had a hard time aligning the oil pump drive shaft. I ended up droping it in, gently pulling it up while rotating slightly clockwise and repeating until I had my reference marks lined up.

 

[saif najd]

I would say why don't you replace the rotor to fully aluminum (summit have it)
Do the fix for the gaskets
Think about the manifolds spacer
That's my advice
And yes the wider throttle body.

Sent from my GT-I9505G using Tapatalk

 

[MrSpicy]

Yes the dizzy as you guys like to call it was a major pain as well. luckily I had my brother working on this project with me and he had done the gaskets on his old caprice last year so was familiar with the task. Although it still probably took 30 min or more to line it up.

As far as cleanliness, this baby was filthy beyond belief, we spend several hours cleaning the intake manifold as well as the plenum and tb. probably a good 1/8 inch grime on the intake. I found that b12 (think that's the brand) chemtool carb/tb cleaner worked wonders on the tb. Used acetone, fuel injector cleaner, carb clean, gasoline all at different times to clean the intake. In the end it still wasn't as clean as I would have liked but there is only so much one can do sometimes. Terrifies me to wonder what gets ignored when this is performed at a shop.