machining intake to match heads

[71Scamper]

Ok so I have to shave my intake to match my ports and bolt holes better. If I remove my .040 think intake gaskets, the bolt holes are much closer to being centered but it seems if the gasket was twice as thick and removed, the holes would match perfect. So would I be right to have the intake machined .080 each side?

 

[krw340]

How does it line up without the gaskets ?

 

[71Scamper]

How does it line up without the gaskets ?

I edited what I originally wrote to make better sense lol. If I remove the gaskets the bolt holes match better but if they were twice as thick, the holes would be dead on. The gaskets measure out at .040 thick.

 

[69_340_GTS]

It would make a lot more sense to machine the heads properly. If you know how much was milled off the bottom of the heads, you need to take 95% of that amount off of the intake mounting surfaces.

 

[71Scamper]

I have no idea how much was milled off the heads, nor the block originally. I got the engine already rebuilt once. I only did a skim cut on the heads to clean the surface. This is why I'm going this route.

 

[krw340]

I edited what I originally wrote to make better sense lol. If I remove the gaskets the bolt holes match better but if they were twice as thick, the holes would be dead on. The gaskets measure out at .040 thick.

If the gaskets were twice as thick and the holes line up it sounds like you need a thicker gasket. Then the intake manifold don't need machined. Does the intake holes sit higher than the holes in the heads when the gaskets are installed ?

 

[fishy68]

Matching the bolt holes doesn't necessarily mean your ports will be aligned. Port alignment is what you need to be checking. It's as easy as laying the gaskets on the heads aligned with the ports then taking a marker and tracing the outline of the gaskets on the heads then take the gaskets and hold them up to the intake and align them to the intake ports and trace the manifold outline on the gaskets then drop the gaskets and intake in place and see how well the traces line up. Remember also that when you tighten the intake down it'll pull down some so with the intake just sitting there you want the intake sitting a little high

 

[69 Cuda 440]

Ok so I have to shave my intake to match my ports and bolt holes better. If I remove my .040 think intake gaskets, the bolt holes are much closer to being centered but it seems if the gasket was twice as thick and removed, the holes would match perfect. So would I be right to have the intake machined .080 each side?

You can use a 'Banana' to measure the distance.

Or get 'soft' poster board material to make a template, and form it
in place of the Intake on the engine between the Cylinder Heads.

Then measure the template.

Don't forget the end-rails on the Intake Manifold as well.

 

[71Scamper]

If the gaskets were twice as thick and the holes line up it sounds like you need a thicker gasket. Then the intake manifold don't need machined. Does the intake holes sit higher than the holes in the heads when the gaskets are installed ?

When the gaskets are removed the holes become some what close. What I'm saying is that, theoretically, if I removed intake gaskets that were twice as thick as what I have then the holes would match up perfect.

 

[71Scamper]

Matching the bolt holes doesn't necessarily mean your ports will be aligned. Port alignment is what you need to be checking. It's as easy as laying the gaskets on the heads aligned with the ports then taking a marker and tracing the outline of the gaskets on the heads then take the gaskets and hold them up to the intake and align them to the intake ports and trace the manifold outline on the gaskets then drop the gaskets and intake in place and see how well the traces line up. Remember also that when you tighten the intake down it'll pull down some so with the intake just sitting there you want the intake sitting a little high

Understandable but it is impossible to bolt this intake down the way it is. I can't start the bolts on both sides. The holes are off considerably. I can just get all the bolts to start with gaskets out though.

The gaskets when held to the head match perfect and the bolt holes are centers from the gasket to the head. If I center the bolt holes of the gaskets to the intake, the ports are also matched perfect.

 

[69_340_GTS]

Ok so I have to shave my intake to match my ports and bolt holes better. If I remove my .040 think intake gaskets, the bolt holes are much closer to being centered but it seems if the gasket was twice as thick and removed, the holes would match perfect. So would I be right to have the intake machined .080 each side?

Probably not. The most any competent machine shop would have milled off the bottom of the heads is .060"

Using the 95% rule, the most that should ever be necessary to take off the manifold surface is .057"

IMHO, take .040 off the intake surfaces and about the same off the front/rear seal surfaces too.

 

[71Scamper]

Probably not. The most any competent machine shop would have milled off the bottom of the heads is .060"

Using the 95% rule, the most that should ever be necessary to take off the manifold surface is .057"

IMHO, take .040 off the intake surfaces and about the same off the front/rear seal surfaces too.

What about port alignment? I would think that if I do just the .040 that the ports won't line up perfect. Whats boggling my mind is the fact that the block seems like it may have had a skim cut at some point in its existance, but nothing substantial, considering the pistons are coming out of the hole .003 more than spec. Also, the chambers in the heads cc'ed out to 70cc after I polished the chamber and added flat faced valves, so this tells me that the heads couldn't have had any substantial material removed either. The intake is not a cheap chinese air gap but is a real deal Edelbrock unit. So what gives? I'm extremely frustrated and about to give up right now because this engine has fought me tooth and nail to go back together. I have spent 3x the amount of time and money building this engine versus the other two of the big three.

 

[cdavis]

You also need to take into consideration the amount of crush the intake gasket might have when torqued.

 

[71Scamper]

You also need to take into consideration the amount of crush the intake gasket might have when torqued.

ya that thought ran through my head and right out the other side. There's no way the .002 to .003 that the gasket would crush down would give me enough clearance to run the bolts in.

 

[69_340_GTS]

What about port alignment? I would think that if I do just the .040 that the ports won't line up perfect.

Well,nobody ever said Edelbrock was perfect. The manifold might be made wrong.

Maybe the ports lining up perfectly isn't real important. I guess it all depends on what kind of horsepower you are trying to make. Ports seldom line up perfectly even if everything is brand new and bone stock!

 

[krw340]

When the gaskets are removed the holes become some what close. What I'm saying is that, theoretically, if I removed intake gaskets that were twice as thick as what I have then the holes would match up perfect.

Can you post a picture of the intake manifold sitting on the motor with the gaskets installed so we can see how far off the alignment is through the bolt holes ?

 

[fishy68]

ya that thought ran through my head and right out the other side. There's no way the .002 to .003 that the gasket would crush down would give me enough clearance to run the bolts in.

Most gaskets will crush a lot more than .002-.003. More like .005 to .010"...

 

[71Scamper]

Can you post a picture of the intake manifold sitting on the motor with the gaskets installed so we can see how far off the alignment is through the bolt holes ?

I tried to take pictures but they weren't clear enough to make out what I'm talking about. I brought the intake to my school and had the machine shop take .040 off each side and it fits perfect now. The ports match up good as well.

 

[Marcohotrod]

if the intake fits perfect after having .040" cut off u should have had .035" cut off = more gasket crush

 

[Rapid Robert]

I would make a horizontle swath of dykem across the top and bottom of the head & intake ports & a "turn up" of dykem at each end (cant think of a better way to describe it) you'll see when you get there then scribe a horizontle line in the dykem above/below each head/intake port (plus in the turn up on the ends then set the intake in place with your choice (thickness) of side gaskets in place/mocked up & level it side to side till the distance between the "turn up" scribe marks on all 4 corners is the same. measure that distance on the "slope" & give it to your machinist & let him do the math & mill the sides till the intake now sets down further in the V that distance for a dead on port match. you can elongate the bolt holes if/as needed but since you're having it milled you want the ports pretty much dead on just need good measureing on your part/good math on his part

 

[71Scamper]

if the intake fits perfect after having .040" cut off u should have had .035" cut off = more gasket crush

With the intake installed the ports are matched perfect and the bolt holes were just a hair off of center. I'm sure that when I torqued the intake down that the bolt holes ended up aligning close to perfect due to the crush.

I would make a horizontle swath of dykem across the top and bottom of the head & intake ports & a "turn up" of dykem at each end (cant think of a better way to describe it) you'll see when you get there then scribe a horizontle line in the dykem above/below each head/intake port (plus in the turn up on the ends then set the intake in place with your choice (thickness) of side gaskets in place/mocked up & level it side to side till the distance between the "turn up" scribe marks on all 4 corners is the same. measure that distance on the "slope" & give it to your machinist & let him do the math & mill the sides till the intake now sets down further in the V that distance for a dead on port match. you can elongate the bolt holes if/as needed but since you're having it milled you want the ports pretty much dead on just need good measureing on your part/good math on his part

Robert, I pretty much did what you are describing here to align the ports. All is good now. Thanks for the info.

 

[Inertia]

Poor guy that gets that manifold later on and wonders why it wont fit a stock block...

Maybe it was trimmed before to compensate for a poor head machining,, and that caused your prob.. .. lol..