Machining New Intake Angle - 440 Engine in Car

[PurpleBeeper]

My engine is sucking oil from the intake valley into the intake ports (440 six pack cast iron). I've struggled with this issue for years. I "think" the block was milled .040" & I "think" the heads were milled .020" (going from memory only 20+ yrs. ago). I do not "think" the intake face of the heads were milled.

The intake bolt are a PIA to line up & difficult to tighten. The bolts set at the very top of the intake manifold. I have oil in all the intake ports, the plugs oil up, I use a lot of oil & the engine smokes at high rpm. Over the years, I've re-sealed the intake at least 6 times. Valley pan only, "tried" using paper gaskets top/bottom of valley pan but I couldn't start a single bolt, RTV + valley pan, "shellac" sealer + valley pan.... I even tried cutting the intake sealing part off a stock valley pan, seal it to the heads with RTV & run a single set of paper gaskets to seal the intake/heads.

I've had this problem with BOTH my current six pack (cast iron) intake and a 4bbl cast iron intake. Years ago, I milled .010" of both intakes' head mounting surface (just a conservative guess) and sealing got better, but not really fixed. Now, with a lot of RTV and a stock valley pan, I can get the six pack intake to seal for maybe 6 months at a time...bolts still at the very top of the intake manifold holes....but then it starts sucking oil into the intake runners of the heads again. The engine is in a licensed, insured, running car.

My diagnosis is that I need to mill the intake manifold face (easier than pulling heads off) and likely "angle cut" the intake so that I take a little more off the bottom of intake runner where they meet the heads and a little less off the top of the runners so the valley pan gasket will get "pinched" just a little more at the bottom vs. the top.

So, my question is.... how do I figure out what to tell a machinist about how to mill the intake face correctly? I guess I "could" just do a conservative guess, machine, re-install, test & repeat....but is there a way to get it right the first time?

THANKS FOR YOUR HELP!

 

[Challenger340]

Angle milling your Intake Manifold should not be a problem for any Machine Shop, we've had to do occasionally over the years, Intake and Exhaust Manifolds, etc., any part warped or otherwise poorly sealing.
I am curious though, that if you suspect Oil is entering the ports from the bottom, would you not want more removed along the top of the runners versus the bottom, so the bottom seals harder when bolted down ?
Anyways, for descriptive purposes with your machinist, refer to the Angle Mill as, and only for example here: a "Zero to .005" Angle" bottom to top,(if that's what you need, NOT saying it is) and then the amount down from there for both sides, ie: .010".
This means he will setup to remove approx .005", and when it has cleaned all the way along and is taking the last cut to reach the .005", it will just then be cleaning along the bottom of the ports.
I would probably recommend, that you just get the Intake "cleaned" first, ask him to hold the Machine setup, run home and trial fit, even play overnight or a weekend, then come back with more accurate directions for milling with the machine still setup for your Manifold.
That's what we try to do, because it can be difficult to get it right the first "fit".

Trivia: with BB Mopars, for each .010" removed from a Head or Block Deck, we find about .008" off the Intake face(either the Manifold or the Head face itself as easier), to be best up to around .050".
I know the "published" data specifies .012" off the Intake face for every .010" off a Head or Deck, we've just always found easier to take more off if we need it, as opposed to a guy can NOT put it "back" if we take too much ?

 

[lewtot184]

best way to check angle is with feeler gauges and the intake mounted with no gasket. the way the fel-pro gaskets are stamped doesn't help sealing and the "protrusions" that hang down from the bottom of the port window on the manifold don't help.

 

[Cranky]

If your bolts are at the very top of the intake, it sounds to me like the intake is sitting low. Were the heads angled milled at one time? Generally, the angle of the intake stays the same if the heads were not angle milled....

 

[PurpleBeeper]

I am curious though, that if you suspect Oil is entering the ports from the bottom, would you not want more removed along the top of the runners versus the bottom, so the bottom seals harder when bolted down ?

You're right challenger..... I had it backwards. I should take more off the top of the intake runners than the bottom so it pinches at the bottom. I believe I have a "triangle" opening at the bottom where the intake meets the heads & this is where I'm sucking in oil.

So what I'm hearing from you is to do the "mill a little, test & repeat". That costs more $ and time, but it will get me there. I shouldn't be lazy, but it's a PIA to take a cast iron intake, 3 carbs, 3 fuel lines on/off the car....yeah, I shouldn't be lazy. I "wish" I knew a shop that was good with Mopars and had their own machining equipment.

 

[PurpleBeeper]

If your bolts are at the very top of the intake, it sounds to me like the intake is sitting low. Were the heads angled milled at one time? Generally, the angle of the intake stays the same if the heads were not angle milled....

This makes complete sense cranky. I think I need to just pull the intake and look again to be SURE what my situation is. Maybe I've got this backwards & the bolts are at the bottom. I'm sure they were a PIA to get started. IF the bolts are at the top, then the intake would be too low, not too high, and I might be able to seal it up with one of the paper gaskets.

I will see if I can get out into the garage today and pull that intake.

 

[PurpleBeeper]

This makes complete sense cranky. I think I need to just pull the intake and look again to be SURE what my situation is. Maybe I've got this backwards & the bolts are at the bottom. I'm sure they were a PIA to get started. IF the bolts are at the top, then the intake would be too low, not too high, and I might be able to seal it up with one of the paper gaskets.

I will see if I can get out into the garage today and pull that intake.

And I don't believe the intake/heads were angle milled at any time. I rebuilt this motor many years ago (mid 80's) using then in-touched factory heads & block.

 

[PurpleBeeper]

best way to check angle is with feeler gauges and the intake mounted with no gasket. the way the fel-pro gaskets are stamped doesn't help sealing and the "protrusions" that hang down from the bottom of the port window on the manifold don't help.

Thanks Lew. I've been reading on the internet about this. I does seem like a good idea to see how the intake manifold sets on the heads without any gasket. I do have a 3rd intake now I can use as a reference. I have a couple sets of feeler gauges and I can check the corners of the intake at the same time I check the position of the bolts vs. intake holes.

 

[Cranky]

And I don't believe the intake/heads were angle milled at any time. I rebuilt this motor many years ago (mid 80's) using then in-touched factory heads & block.

Keep in mind that factory tolerances sucked back then and things didn't always align like they were supposed to. Ever heard of someone buying a 'freak' that ran WAY better than 95% of the factory hi-po Mopars? They mainly existed because ALL of the tolerances ended up being on the money! Then you had the dogs where ALL the tolerances went the other way lol. There were also engines that had good fit but the cam was off a bit due to missed tolerances on the alignment pin location in the cam, or sprockets or both. When I was building engines, I always did mockups to make sure things fit like they were supposed to and even used a degree wheel for cams going into a stock build.....more work but it pays off.

 

[lewtot184]

Thanks Lew. I've been reading on the internet about this. I does seem like a good idea to see how the intake manifold sets on the heads without any gasket. I do have a 3rd intake now I can use as a reference. I have a couple sets of feeler gauges and I can check the corners of the intake at the same time I check the position of the bolts vs. intake holes.

check top and bottom first with feeler gauge. don't angle mill unless you have to. the best sealing surface is flat. I've done all this several times but usually on an engine stand. clean up the gasket you took off and look at the sealing surface for irregularities. put the gasket back on with a clean intake and the bolt holes in the head should center with the holes in the intake. sometimes this is trail and error if you don't have an exact baseline in dimensions. if the head holes are at the bottom you need to mill the intake. blocks that are decked don't seal perfectly unless the end rails are machined too. a lot of stuff to look at here.

 

[Challenger340]

I am curious though, that if you suspect Oil is entering the ports from the bottom, would you not want more removed along the top of the runners versus the bottom, so the bottom seals harder when bolted down ?

You're right challenger..... I had it backwards. I should take more off the top of the intake runners than the bottom so it pinches at the bottom. I believe I have a "triangle" opening at the bottom where the intake meets the heads & this is where I'm sucking in oil.

So what I'm hearing from you is to do the "mill a little, test & repeat". That costs more $ and time, but it will get me there. I shouldn't be lazy, but it's a PIA to take a cast iron intake, 3 carbs, 3 fuel lines on/off the car....yeah, I shouldn't be lazy. I "wish" I knew a shop that was good with Mopars and had their own machining equipment.

Anybody with a "Mill" should be able to help you out for the "cut, trial, repeat as necessary" approach ? Maybe a local hobby type guy with one at home ?
Just say'in... doesn't have to be an "Engine" Machine Shop ?
I mean we are an Engine Machine Shop, and yes we have 3 different surfacing Machines from a Sunnen CBN Surfacer to an old Block Master(upgraded), but also a 10X50 Bridgeport we primarily use for Headwork ?, but is also handy for other surface milling projects ?

IMO, might be worth a try to find a home based hobby guy with a Mill for this project ?

 

[PurpleBeeper]

check top and bottom first with feeler gauge. don't angle mill unless you have to. the best sealing surface is flat. I've done all this several times but usually on an engine stand. clean up the gasket you took off and look at the sealing surface for irregularities. put the gasket back on with a clean intake and the bolt holes in the head should center with the holes in the intake. sometimes this is trail and error if you don't have an exact baseline in dimensions. if the head holes are at the bottom you need to mill the intake. blocks that are decked don't seal perfectly unless the end rails are machined too. a lot of stuff to look at here.

Thanks Lew. Since the motor is installed in a running/licensed car & I'm SURE the pan rails were not machined that "might" be part of the problem. I was talking to some guys on moparts and a couple of them had some good ideas.
1. For the pan rail issue....check this & maybe notch the corners of the intake to clear the pan rails. I may just take a dremel grinding disk to the corners to be sure this isn't the problem.
2. How to mill the intake.... another guy directed me to a Hughes link. Basically, you lightly bolt the intake down over some 0.100" wax rope (super thick plastigage) & you space the intake off the heads with some precision washers (must be identical thickness). You wet the wax rope with WD-40 so it won't stick to much. You squish the wax rope (around the ports at the corners) and take a caliper to the squished wax. As long as the washer spacers are EXACTLY the same thickness, you can measure the alignment of the intake ports vs. the head ports.

Per all of your suggestions (good ones), the first thing I will do is check the intake without gaskets directly on the head with feeler gauges at all the corners, top/bottom of each port. I have another intake, so I will check that one too on this motor.

I have the wax rope, thumb wheel ratchet & precision-ground washers on the way now.

 

[Cranky]

Years ago when I felt a heck of lot more ambitious I milled a set of junk heads .100" mainly to see how much needed to come off the intake side...plus was getting familiar with my new milling machine at the time. They were open chamber and ended up being closed chamber lol. I was surprised to see how different intakes fit. Out of 3 stock intakes, one was pretty close while the other two really needed to be machined but the real shocker was a Eddy TM 7 fit like a glove! I looked over the TM 7 and it still had a thick flange but couldn't tell if it had ever been machined. Overall, it was surprising that a stock intake actually fit decently after milling that much from a set of heads. Also, the stock intakes used came off of cars that I had parted in the mid 70's so I'm pretty confident they had never been machined.

 

[beanhead]

Last time I had to have an intake cut, the machinist requested I measure how much the bolts needed to move to be centered all the way down and he was able to figure out how to get it there..The amount he cut wasn't quite the same as the distance the bolts were off but he worked his math magic and it worked good..

 

[Garys1969RR]

I agree with what's been said, put a clean intake on a clean head with no gasket. I would finger tighten a few bolts too, just to keep it from moving around. Then see how tight of a feeler gauge will go into the top of the port where it meets the head. WRITE EACH MEASUREMENT DOWN. Then take the same measurement at all 4 corners of the manifold at the bottom of the port. Write down the thickness of the feeler gauge that fits in, if any. You will prob find that the manifold fits tightly against the head on top, but has a ten to fifteen thousandths gap at the bottom. I had the same problem with my 6 pack intake bolt holes not lining up just right. I just elongated the bolt holes a little. Worked just fine. Actually, the bolt holes not lining up are probably keeping the intake from pulling down tightly against the gasket, causing it to leak. Good luck, let us know what happens!

 

[oldbee]

Actually the cut on intake side of head was .0123” per .010” on combustion side of head; this only allowed any stock intake to fit? If you cut the manifold it’ll only fit your head/block configuration. Had a “few”, so brain may not be working quite as normal as could be.

 

[BSB67]

One approach is as you suggest and others have responded too. Try to figure out the angles. I've been down this road more than once, and it was never simple. The dimensions and angles will change from front to back, and from side to side. You can and likely will end up with a different number on each of the four corners. And it does not take a lot for the pan gasket to leak. If you go to local guy with a Bridgeport and ask him to take an extra 0.007" here and 0.003" there it will likely still leak when you are done, in my experience.

As an alternative, take what you have now to the machine shop, have him remove 0.080" - 0.090" from both sides of the intake as is, and use a 0.030" gasket on either side of the pan gasket. The imperfections in the alignment and angles will be taken care of by the paper gaskets. Add or remove 0.015" gaskets to get the alignment you need.

 

[PurpleBeeper]

One approach is as you suggest and others have responded too. Try to figure out the angles. I've been down this road more than once, and it was never simple. The dimensions and angles will change from front to back, and from side to side. You can and likely will end up with a different number on each of the four corners. And it does not take a lot for the pan gasket to leak. If you go to local guy with a Bridgeport and ask him to take an extra 0.007" here and 0.003" there it will likely still leak when you are done, in my experience.

As an alternative, take what you have now to the machine shop, have him remove 0.080" - 0.090" from both sides of the intake as is, and use a 0.030" gasket on either side of the pan gasket. The imperfections in the alignment and angles will be taken care of by the paper gaskets. Add or remove 0.015" gaskets to get the alignment you need.

This is another good idea I believe. Paper seems a lot more forgiving that tin/steel.

I tried a "similar" idea years ago when I cut the "gasket part" off of a valley pan, sealed it up with gobs of RTV silicone & tried using just one set of the paper gaskets to seal the intake. I considered this approach again & even looked at the 440source valley covers, but I don't really want to pull a head to try one, not with the motor/headers in the car anyway.

 

[Garys1969RR]

You may want to just try elongating the bolts holes with a grinder first. The bolts hitting the top of the bolt holes may he preventing the manifold from pulling down onto the gasket all the way, especially if they are hitting at the top of the holes. The manifold won't pull down all the way to the head.

 

[Garys1969RR]

Or you may be able to raise the manifold up enough to clear the bolts by putting a paper gasket above, AND below, the metal part of the valley pan. If the bolts are hitting at the top of the holes, as you stated, then milling the port side of the intake will only make the problem worse.