Intake not fitting- rebuilt engine, Help!!

[kobi67]

Just got my 67 L-79 back from the rebuilders, tried to bolt the intake on and the bolts won't line up. My builder is out of town for 2 weeks so, I have to try and figure it out myself. The bolt holes in the manifold are a tight fit and maybe if I make them bigger, I can get the bolts to line up properly. I also noticed if I sit the manifold on the engine without gaskets, it rocks a bit. I assume this this will be corrected when the manifold is torqued down, it must twist a bit.
Anyone run into this??? Thanks, Kurt

 

[Subfixer]

If the block was decked and/or the heads shaved, the manifold will have to be machined a little also. Talk to your engine builder to find out what he did.

 

[kobi67]

The block was square decked and the heads were also surfaced. I figured the head gasket thickness would be increased for this machining?? The rocking of the manifold worries me. I wonder if the manifold will twist a bit when torqued. Thanks, Kurt

 

[Ken Anderson]

The block was square decked and the heads were also surfaced. I figured the head gasket thickness would be increased for this machining?? The rocking of the manifold worries me. I wonder if the manifold will twist a bit when torqued. Thanks, Kurt

And your rebuilder didn't ask for the intake to match it to the motor!
Good luck with your motor!

 

[Gerry]

Nothing ever goes smoothly, good luck and I hope you solve the problem.

Gerry

 

[JohnZ]

When the block is decked and the heads are too, the sides and front and rear of the intake have to be machined to compensate; any competent machine shop has the formula for how much to cut the manifold based on how much they cut the block and heads. The manifold shoud NOT "rock" if the heads were set up correctly for parallel cuts in the mill (assuming it was square when it came off). You need to have a discussion with your machinist.

 

[stepinwolf]

Try This

Kurt,

Any shop doing this kind of machining work, and not modifying the intake manifold to match up, doesn't really deserve your business. :nono

Table legs can be shortened to stop any rocking motion, not manifolds.

In your post, you didn't specify if your builder and machinist were one of the same, so I will assume that it is the case. A lack of knowledge on his part would prompt me to seek a second opinion, especially since he ( they ) will not be available for 2-3 weeks.

Take it to a reputable engine re-building shop, and inquirer about the problem, and the remedie. Personally, those responsible for the initial work would NEVER, be doing any more work or repair on any of my engines.

Good luck
Bob

a.k.a. Stepinwolf

 

[kobi67]

Here is an update.. I spoke to a friend who has several Camaro Z-28's about this issue (Z-28 uses same type manifold). He advised me to find the proper drill size for the intake bolt holes and from the bottom side, run the drill thru to reshape the hole. He says, these aluminum intakes will distort the bolt hole smaller at the top, when the bolt torques down on the aluminum. Sure enough, every hole I was cutting material just at the top edge only.. This hole size reduction must be from torquing the manifold over the years.
Now, I set the manifold on the engine and the bolts go in. A few are a bit tight but go..
The rocking issue may be from the manifold sitting down on the block (china walls) without a gasket. With gaskets, it does not rock and it sits up about 1/8" off the block (china walls) at both ends. I assume this gap under the manifold is to allow the manifold to pull down on the heads, when torqued.
I think my problem is resolved.. Thanks for the feedback. I won't strangle my engine builder just yet!!! Kurt

 

[stepinwolf]

Kurt,

I'm glad to hear you think you have solved your fitment problem, but the fact that remains, is that the work was not done correctly in the first place. You might be able to cheat the mounting holes by enlarging them in order to try and clamp the intake down, but the mounting, angle remains incorrect, and I believe you are setting yourself up for some serious leaking problems down the line.

Don't forget, if you can't find the time to do it properly now, how will you find the time to repair it later.

Good luck with your decisions

Stepinwolf

 

[vintagecorvette]

I agree with Stepinwolf

Fix the problem, do not make it worse and do a Bubba job on it.


People using drills and grinders in around or on aluminum intakes can be scary.


Just my 2 cents.........


oWEN

 

[kobi67]

I think I will be OK.. All I did was make the bolt hole the same size GM did.. I also used a angle finder and checked the angle of the intake mount on the engine and compaired it to the intake.. I was OK here too.. Now that it fits right what would a machine shop do to the manifold?? If I can get the bolts to line up thru the factory size holes (Correct resize), then what is the hidden problem.. Remember, GM when they made these engines were not perfect??

 

[stepinwolf]

You know what !

Kurt,

I was always told that " you can lead a horse to water, but you can't force him drink " :nono All the best with your decisions, I hope everything works out for you and your engine.

Bob
a.k.a. Stepinwolf

 

[Mike McKown]

Kurt,

I was always told that " you can lead a horse to water, but you can't force him drink " :nono All the best with your decisions, I hope everything works out for you and your engine.

Bob
a.k.a. Stepinwolf

With all due respect to whoever told you that, you can make a horse drink. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

EDIT by 67HEAVEN: I don't think so. :nono

 

[stepinwolf]

That's a great idea,, however

Mike, that's the best thing I have heard all day, however I would like to recommend a new twist the the technique.

EDIT by 67HEAVEN:
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx


Stepinwolf

Ride your poney as if each day was your last