Intake Angle

[ply360]

I have an la 360 with magnum heads, and an edelbrock rpm airgap manifold. It is pushing out the gaskets/not clamping tight at the top, using the edelbrock 7277 gaskets. Intake was installed new in March, gaskets replaced in late August and need to be replaced again now. gap at top is large enough to slide a paper into the port itself from the top (or a thin leaf, ask me how I found that out) causing a large vacuum leak. Gasket pushes on both sides, but vacuum leak only on the passenger side as of now. All intake bolts are still tight.

Heads have been milled, however not on the intake side. BUT, wouldn't that cause angle misalignment on the bottom side?

I plan on pulling it apart in the next few days and checking fitment and angles, but what normally causes this sort of issue? Gasket thickness? Everything I've found is problems of a gap at the bottom.

 

[MOPAROFFICIAL]

Perma tack the gasket to the head. Something is up, ive not seen one push an intake gasket.

 

[MOPAROFFICIAL]

Have the manifold checked,or they angle milled the heads unintentionally. Thats all that comes to mind to cause or be the culprit

 

[ply360]

Perma tack the gasket to the head. Something is up, ive not seen one push an intake gasket.

It has to be just slowly wedging itself out, I'll see how indented the gasket is when I pull it apart

 

[ply360]

Have the manifold checked,or they angle milled the heads unintentionally. Thats all that comes to mind to cause or be the culprit

Hopefully the heads were milled correctly, it was done at a pretty reputable shop. My father has an endmill so if the angles end up being a bit crazy I'll be sure their perfect before it goes back together.

 

[MOPAROFFICIAL]

It has to be just slowly wedging itself out, I'll see how indented the gasket is when I pull it apart

Maybe check for soot in that port

Have you had any backfires, and was it the same brand gasket?

Set it on w/o gaskets and eyeball the gaps

 

[toolmanmike]

Hopefully the heads were milled correctly, it was done at a pretty reputable shop. My father has an endmill so if the angles end up being a bit crazy I'll be sure their perfect before it goes back together.

If you mill the heads and not the intake surface, the bottom will be tight and the top will have a gap. The intake does not sit down against the intake ports on the heads correctly. With a LA, the bolts are almost at a right angle to the heads so often times the holes won't line up. The Magnum bolts are vertical and it might not be as big of an issue there.

 

[MOPAROFFICIAL]

No. The angles stay the same, they just get closer or farther apart...and when that happens..the manifold drops down .

The only way it could be 'tight at the top' or 'tight at the bottom' and 'loose at the bottom' or 'loose at the top'... is because the machinist screwed up

 

[ply360]

If you mill the heads and not the intake surface, the bottom will be tight and the top will have a gap. The intake does not sit down against the intake ports on the heads correctly. With a LA, the bolts are almost at a right angle to the heads so often times the holes won't line up. The Magnum bolts are vertical and it might not be as big of an issue there.

I was thinking it would only cause am issue on the bottom side with that.

No. The angles stay the same, they just get farther apart...and when that happens..the manifold drops down .

The only way I could be 'tight at the top' or 'tight at the bottom' and 'loose at the bottom' or 'loose at the top'... is because the machinist screwed up

That or I didn't set and tighten the manifold down correctly. I guess I'll figure that part out when I take it apart

 

[toolmanmike]

No. The angles stay the same, they just get farther apart...and when that happens..the manifold drops down .

The only way I could be 'tight at the top' or 'tight at the bottom' and 'loose at the bottom' or 'loose at the top'... is because the machinist screwed up

Then when you machine the heads or intake and remove material the gap gets bigger. When I did mine I didn't pull the heads but machined the intake. The intake was setting high because the head surface was lower.

 

[toolmanmike]

The angle doesn't change but the space between the heads gets smaller because they are lower on the block as far as how the intake fits. . The intake will sit high so that or the head surface needs to be machined to open the gap.

 

[MOPAROFFICIAL]

Then when you machine the heads or intake and remove material the gap gets bigger. When I did mine I didn't pull the heads but machined the intake. The intake was setting high because the head surface was lower.

Exactly. The angle is the same... its just moved up because the two sides 'heads' have dropped at the same inward angle becoming closer to each other..

 

[ply360]

Maybe check for soot in that port

Have you had any backfires, and was it the same brand gasket?

Set it on w/o gaskets and eyeball the gaps

No backfires through the intake that I can remember. I had a big one in the exhaust when I missed judged a downshift at the end of a run at test and tune, but that's been it

 

[ply360]

Exactly. The angle is the same... its just slid up because the two sides 'heads' have dropped at the same inward angle...

So as I understand milling the intake side is mainly just for port and bolt alignment, for the most part?

 

[ply360]

I'll pull a bolt and check the hole alignment before I do anything, that should help tell something

 

[toolmanmike]

I'll pull a bolt and check the hole alignment before I do anything, that should help tell something

How much did you mill the heads?

 

[ply360]

How much did you mill the heads?

0.010", which shouldn't be too much of a difference. Everything still seemed to line up fine, at least enough not for me to be concerned about it at the time

 

[toolmanmike]

0.010", which shouldn't be too much of a difference. Everything still seemed to line up fine, at least enough not for me to be concerned about it at the time

That shouldn't be an issue then.

 

[MOPAROFFICIAL]

So as I understand milling the intake side is mainly just for port and bolt alignment, for the most part?

Yes.
As the heads are milled on the deck side..the ports get lower, or closer to the block...therefore the intake has to be narrower to fit and all n all 'lineup'.

 

[MOPAROFFICIAL]

0.010", which shouldn't be too much of a difference. Everything still seemed to line up fine, at least enough not for me to be concerned about it at the time

The stock head gaskets are .019-.021 thick, so adding an aftermarket felpro or other brand thats .039-.054 'depending on the part # ' usually offsets the milling. 'up to .045 does not drastically change the port relationship between heads and intake'.

 

[ply360]

The stock head gaskets are .019-.021 thick, so adding an aftermarket felpro or other. Brand thats .039-.054 'depending on the part # ' so milling up to .045 does not drastically change the port relationship between heads and intake

My felpro's are .040, so my alignment should still be alright, and makes sense to why nothing has caught my eye before. It's just a matter of checking the angles and making sure the machine shop milled the heads square and the intake angles were manufactured correctly. As well as making sure it's all evenly brought down and tightened when reassembled.

Thanks for the help, it's exactly the kind of input I was looking for!

 

[ply360]

So I took it apart, and discovered the gaskets are coming apart, as in the two layers are separating. It's the whole gasket, not just a top issue. Where I used rtv on the cylinder head and around the water jacket ports seems to be fine.

Before it got dark I took a digital angle finder and zeroed it out on one side and then took the angle on the other. The heads had an angle of 96*, which would leave the intake surface 3* off from the 90 of the deck surface, which I think I read somewhere that that's what it's supposed to be. The same thing on the intake manifold have me roughly 96.2*, but I didn't get a chance to make sure it was level and all, it could be even closer than that. Bolt holes seemed to be concentric, so everything lines up that way as well.