Intake fit up issues

[84BuickGNYorkPA]

The machine shop cooked/chemical cleaned my heads and decked them(I did not ask for) on this last rebuild, how much metal came off, I'm not sure. I barely got all the intake bolts started, but once started they all torqued down well (but you can see the bolt threads are rubbing the intake mounting holes). Now to the point, I've got coolant getting into the engine and with only running 15 lbs boost on this fresh motor I'm having a hard time believing I blew out a head gasket ( I will do a compression check this morning). I'm starting to wonder if I should have rethought the fitment of the intake to the heads... perhaps coolant is leaking at the intake/head ports from misalignment?

I took the intake off last Sunday to put my old lifters in and had to change the oil after getting some coolant and gas in the motor. When I drained the engine oil two days ago I discovered just over 2 gallons of fluid in the block ( I do have the RJC 7.5 quart oil pan), and discovered that I had the dreaded chocolate milk for oil.

I understand why so many people bail out on these cars after a while, it seems like ALL my free time is spent under the hood and it's getting old fast.


Chuck

 

[fastblackracing]

With your intake bolts leaving witness marks on the bolt holes you are most likely not getting
full clamping force on the intake to head mating surfaces.

Are the threads binding on the bottom or top of the holes?
From what you describe I would assume the bottom....from the heads
being cut which would bring things lower.

What intake gasket are you using...If it is the thicker felpro you may
be able to use the thinner steel factory type gasket to gain some space
though you may need to open the gasket up for good port match.
Also the rubber end rail seals can cause issues...you can leave them out
and put a bead of permatex ULTRA sealer on there and it will take
some of the pressure of the bottom of intake.

Most are not aware that that the block,heads, intake and heater core
can see as much as 60 PSI water pressure at high rpms...so water passage
sealing is more important than you may realize.

I would put the intake on without a gasket and using sets of washers of different
thicknesses taped on the block end rail surfaces you can look through the
plenum area and juggle the spacer thickness until you get the alignment right.

at this point you can use feeler gauges to determine the available space between the
head and intake....this will tell you what room you have and then factor in the
crushed gasket thickness you will have a good idea if it will work or how much
the intake needs surfaced.

 

[Chuck Leeper]

at this point you can use feeler gauges to determine the available space between the
head and intake....this will tell you what room you have and then factor in the
crushed gasket thickness you will have a good idea if it will work or how much
the intake needs surfaced.

Additionally, check the gap at the top and bottom of the intake to head face. This will help determine that the intake face and head face are parallel.
The shop may have "angle milled" your heads..This will help determine that.

 

[bad V6]

After you figure out the thickness on the intake gasket you need, check with TA Performance. They have a few different thickness of intake to head gaskets.

 

[JToups386]

Dealing with the same problem on mine right now. I actually cracked the intake while torqueing it down on the passenger side rear mounting boss.
I went ahead and bought a virgin intake to replace mine and it was actually worse because it had not been cut, and therefore doesn't come close to mounting flush with the machined heads/block. So now I'm back to having my original intake welded to repair the crack as well as having them add some extra material on the back bosses to strengthen them since the overall mounting surfaces are now much thinner than an un-milled version.
Hopefully it'll all mate up correctly w/o cracking this time.
Just note you clearly have some geometry issues that may require having your surfaces aligned and milled to match by a machine shop. Not fun and not cheap, but a necessary evil once we've started shaving metal from various surfaces on these engines. Which in reality holds true to any engine.

 

[pacecarta]

chucks coolant leak which he believed to be intake issues turned out to be a blown felpro headgasket ...did the head go because of an intake fitment leak , who knows..

if you run felpro 1200 intake gaskets youll likely break the intake again, every cracked intake ive ever seen was at the passenger front corner due to those gaskets giving away allowing the intake to get pulled and crack before reaching torque
try the cometics , TAperformance but being on champ irons you shouldnt need need large port gaskets.. just run the felpro oe style pan gaskets and keep your pcv

 

[EVIL]

Check what Chuck said.

When i did mine someone recommended to lay the intake in the heads with no gasket and make sure it was flush.

I did this and shined a flashlight on end, back of motor, and pear between intake and head on other end, front of motor.

While moving the flashlight up and down along the angle the the heads and intake have i had light shining thru close to block and up high there was no light.

It was clear the angles were off.

i had the machine shop trim the intake from .030 from top to .000 on the bottom.

This did the trick.

When heads and blocks get cut this can be common.

I would’ve had some big leaks everywhere if i didn’t check this.

Here is a pic of what i had removed. The red lines show the trimming i did.

Good luck.

ps. Also. After doing this i was able to use the rubber intake gaskets that go on the ends. The intake sat too high. I just laid a good bead of The Right Stuff and done.

D

 

[TurboBuRick]

Pressure test the cooling system and try to determine where its coming from. Could be something with the front cover as well.

 

[Mike Licht]

when they machine the deck surface of the head they need to machine the intake surface too. You can machine the intake but after that it will only fit that set up and if you machine the block or heads again you will have more problems
Mike