Lining up inlet manifolds to ports

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PSk
Posts: 100
Joined: Mon Feb 26, 2007 8:35 pm

Lining up inlet manifolds to ports

Post by PSk »

Tom,

I was just looking at your latest post: 2/19/13, 365 and 330, and the last photo shows a close up of a manifold and the heads assembled on the block.

I can see that vertical studs are used to pull the manifolds down into the V, but what ensures the inlet ports line up AND sufficient surface clamping pressure is exerted on to the cylinder heads to ensure proper sealing at the manifold to head joint?

I assume this are becomes a nightmare if a cylinder head or block needs to be surface skimmed. I again assume if a head has to be skimmed that the other would have to be skimmed the same amount AND the manifolds skimmed a certain thickness worked out to restore correct relevant positions.

What about head retorquing and the slight alterations due to new head gaskets being squished?

Just wondering. From where I sit it looks like a nightmare.
Pete
Jimmyr
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Re: Lining up inlet manifolds to ports

Post by Jimmyr »

As for head gaskets, the GT Car Parts head gaskets I have used do not require re-torquing. They seem to be made with modern materials and have seals around the studs and holes. As a routine I have re-checked the torque and it has worked on 250s.
Steve Meltzer
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Re: Lining up inlet manifolds to ports

Post by Steve Meltzer »

Pete, Not sure I can help you in the alignment process, but I just went through hell and back trying to seal the intake manifolds to the cylinder heads on my Daytona. I had a persistent vacuum leak between the air plenums and the ports that I've chased through 4 carb/intake R&R's! I think I finally sealed those boogers by buying O-rings thicke rthan those sold by most vendors (GT parts in my case). I used only grease, no sealants, and torqued the bolts only enough to hold them in place (8 foot-lbs). However, I'm only a novice and opinions from real experts might contradict me. Good luck. "Never enough time to do it right, always enough time to do it over!" steve
steve meltzer,
"I've spent all of my money on wine, a beautiful woman, and stunning cars. Then, squandered the rest."
PSk
Posts: 100
Joined: Mon Feb 26, 2007 8:35 pm

Re: Lining up inlet manifolds to ports

Post by PSk »

All,

Please note my question is a theoretical one only :-). I'm just curious, and Steve's post has indicated that this area is indeed troublesome.

Pete
John Vardanian
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Re: Lining up inlet manifolds to ports

Post by John Vardanian »

I have taken my intake manifolds off a few times and put them back on without problem. In my experience, the O-rings, if replacements, need to be thick enough. But the other trick I've figured out on my own is the need for equal torquing. This cinches down the nuts equally and also should get the decks of your three carbs in the same plain and reduce chances of leaking at the fuel manifold joints. I first tighten one manifold freehand and get a feel for what feels to be the right tightness, then determine approximately what torque it took to get there, then set all the the nuts at that torque. The torque is not that much I'd say between 2-3 lbs.

Wonder if Dyke has any advice...

john
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tyang
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Re: Lining up inlet manifolds to ports

Post by tyang »

HI Pete,

The alignment of the ports is not too much of an issue, but the sealing can be. If a enough material is removed from the head, sealing the intake ports will be the last of your worries! As you can see from Steve and John's posts, the 0-rings are the key. We too only use grease to insure the o-rings stay put and seal well when the intakes are tightened.
Image
The head gaskets are the widely available Australian made gaskets I've discussed before on older posts. Most of the suppliers offer this gasket like GT car parts and Partsource. We've stopped using Elring gaskets because we've found them too hard to seal the water passages on the Ferrari heads. I still get e-mails from unsuspecting rebuilders who assemble their engines with this gasket, only to find water leaking from the gasket. The Australian gasket is designed to crush against the cylinder liners that are supposed to protrude a couple thousandths above the deck of the block. If this protrusion is eliminated (I know a few engine builders that eliminate this protrusion during the machining process), the Elring gasket may work.

I wrote about some my findings here:
http://www.tomyang.net/cars/headgaskets.htm

To insure a leak free fit, we use a gasket dressing on this gasket anyway even though it's said it's not necessary. I've used several types from a spray on copper cote, to a high tack sealant that you brush on. After we had a couple of gasket failures after a fresh installation, we couldn't risk NOT using a sealant on anything we rebuild today.

Tom
'63 330 America #5053
Steve Meltzer
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Re: Lining up inlet manifolds to ports

Post by Steve Meltzer »

oh yeah...and one more thing! Be sure the O-ring material is gasoline resistant. I got my O-rings from the O-ring Warehouse. (http://www.oringwarehouse.com)
Fast service, friendly and excellent chart of materials, which I can send to anyone who wants it. I used the flurocarbon (75 durometer) rings, tho' nitrile is cheaper, but softer. I was meticulous in the careful torquing of the nuts, slowly going in a "criss-cross" pattern. For my Daytona, the size -326 worked great, so far.

steve "Never enough time to do it right, always enough time to do it over!"

ADD: I am uninfluenced by the O-Ring Warehouse, despite the "kickback" of $.06 they send me per O-ring purchased by Tom's cult followers. s
steve meltzer,
"I've spent all of my money on wine, a beautiful woman, and stunning cars. Then, squandered the rest."
DWR46
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Re: Lining up inlet manifolds to ports

Post by DWR46 »

john: Everyting stated so far is fine. A few comments:

1. Sealing the intake manifolds is usually not an issue (except for Steve). Just make sure the O-rings have plently of "crush". Except for Steve's experience, I cannot recall a problem sealing the manifolds, even on milled heads or blocks. We usually torque the manifolds to about 12-15 lbs.

2. Yes, the Australian gaskets are the best, but we have also had good success with Elrings. Just use sealant around the water holes and retorque them after 1,000 miles.

3. The only engines that can have intake manifold problems are the Lampredi V-12's. The design has the heads intregal with the blocks and then everything is spicketed into the crankcase. As such, it does not take a lot of pressure between the heads to move them apart and lock up the engine as the pistons and rods bind up. The early Lampredi's had springs under the manifold nuts, so you just tightened the nuts enough to compress the springs about halfway and that was all the pressure the manifold needed to stay secure. Tighten the nuts tight and then wonder why the motor would not turn over.
250GT
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Re: Lining up inlet manifolds to ports

Post by 250GT »

Lampredi intake manifold
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