Engine block surfacing

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Dave Koehler
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Re: Engine block surfacing

Post by Dave Koehler »

The bottom should always be squished a little more than the top...because you are actually pulling the manifold more down than left and right.

You can bolt the manifold to one head without gaskets and measure the gap on the other head and get an idea of how thick of gaskets you need.
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Re: Engine block surfacing

Post by af2 »

1972ho wrote: Mon Sep 10, 2018 3:22 pm This is what the intake gasket looks like after removal it .062 thick I measured the top and bottom and the bottom was about .055 in places and the top was .062 or so.
Time to get them parallel to the head.
Way too much difference.
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Re: Engine block surfacing

Post by 1972ho »

This how the gasket looked before I removed it
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Re: Engine block surfacing

Post by groberts101 »

.007" top to bottom difference ain't squat. And that's one of the nice things about Fords 90 degree cylinder head intake surface.. long as you don't angle mill then no manifold mating angle correction is needed. Some factory tolerance stacking was much farther out than .007".

Imo, those smooth paper fiber gaskets are junk on manifolds or carbs for anything performance related. Get some better gaskets on there with neoprene style o-ring seals.. or at the very least dress them with a VERY thin(almost transparent looking) ribbon of grey rtv silicone on inside and out of that same style new replacement gasket. Just be sure to keep the applied ribbon about a 1/4" or better away from the edge of the ports to allow for squish while avoiding port intrusion. Then sequence torque to 30% of final torque value.. let dry overnight.. and final torque the next day. That will keep them measurable thickness of rtv that has dried and allow better preloading and sealing.
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Re: Engine block surfacing

Post by 1972ho »

I blued the intake surfaces and torque tightened the bolts with no gasket and looks like the flanges may be warped because in some places it didn’t appear to making any contact with the head ,no bluing appeared on the head flanges, tomorrow I’ll blue the head and see what I can see on the intake sides.
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Re: Engine block surfacing

Post by hondo383 »

I have had to skim previously corrected and flattened (by me)Intakes on freshens they always move/warp whatever set it on with no gaskets and try to feeler gauge between the intake and head you will see real quick..

If your port and bolt hole alignment is good with no gaskets you need to remove the gasket thickness from each flange to make it right when installed. If you dont it will sit too high and compromise sealing to the valley below the port if the bolts make it through. Technically the work you did decking and thinner hg moved the intake higher to the head port but I dont know how close that was before

Agree with Dave Kohler make a very slight interference angle so it wedges down tighter below the port also
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Re: Engine block surfacing

Post by geraldtson »

If you have a pcv valve pull off hose at carburetor and see if hose is wet with oil.If so it's pulling oil thru pcv system.If so there's a lot of options to fix.
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Re: Engine block surfacing

Post by 1972ho »

No oil was being pulled the pcv that I could see when I took the intake off there was oil sitting in some of cylinder head bowls.
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Re: Engine block surfacing

Post by geraldtson »

1972ho wrote: Mon Sep 10, 2018 9:00 pm No oil was being pulled the pcv that I could see when I took the intake off there was oil sitting in some of cylinder head bowls.
If pcv valve hose to carb was dry your OK. If it was wet and soggy there's your problem. Seen it happen before, and i was replacing intake gaskets and valve seals only to find out my pcv valve was being exposed to to much oil. Problem showed up just as you described.
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Re: Engine block surfacing

Post by geraldtson »

PCV valve hose may be routed to intake or carburetor. I said carburetor in previous post but could be just as likely going to intake manifold. Had one pulling oil directly from pcv to intake once that was causing a little smoking and finally fouling a couple of plugs and like your's most of the head intake ports were wet with oil. After finding a very soggy pcv valve hose for a quick easy(temporary) fix i installed an inline clear fuel filter about halfway back to intake on return hose and laid it low and flat on engine and it would catch the oil in the bottom of fuel filter (sump) and let the clean air pass right on thru to engine till the filter filled to about halfway up at what time i'd just pull filter and clean it out. Worked good till i had some weekend time to fix pcv valve being exposed to to much oil. May not be your problem,i'm just say'in?
As far as intake gaskets i always use red or black silicon ( i'm partial to red) on head side of water ports as well as intake side. As well of course to large weld type bead or smooth bead at front and back of block deck. Also some very thin lines between intake ports and at bottom of intake port surface on block and gasket.
If your problem is in the intake to head fitment have you thought about stacking two more intake gaskets maybe with a little less silicon? Seems to work a lot of times!
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Re: Engine block surfacing

Post by 1972ho »

I’m just thinking that it has got to be something with the squareness of the intake to head,because everything was fine until I had the block decked .008 and went to .007 thinner head gasket.
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Re: Engine block surfacing

Post by ProPower engines »

1972ho wrote: Tue Sep 11, 2018 12:17 am I’m just thinking that it has got to be something with the squareness of the intake to head,because everything was fine until I had the block decked .008 and went to .007 thinner head gasket.
as mentioned before check the intake alignment top and bottom as well as end to end.
With the gasket of choice secured to the head I prefer to use gasgacinch to locate the intake gasket then sit the intake in place and check the fitment.
If there is gaps in any part of the contact areas between the manifold and the gasket then this must be corrected by milling either the heads or the intake. You must take care at this point to be as accurate as possible but it seems to me that if the deck is cocked slightly by the amount removed it may not be an issue if the gasket is soft enough as well as thick enough for the intake to seal but a harder material may create a sealing issue if the thickness varies top to bottom on the gasket.

But as you mentioned now you have an oiling issue that did not exist before so the other area I may look at is the intake areas next to the exhaust cross over it it has one. I had a 460 with a similar issue and found the intake cracked And also the intake port in the valley area may have a crack that allows oil to be sucked into a only 1 or 2 ports and being an aluminum intake the warped and cracked problem at the same time could cause what you have going on now.
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Re: Engine block surfacing

Post by 1972ho »

Looks kind of warped to me what do you think.There is no contact where the pressian blue is still visible even on the rails in the rear not making contact. And this was with all bolts torqued to spec.
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Re: Engine block surfacing

Post by MadBill »

As I posted earlier: "After checking manifold and head surfaces for flatness..."
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Re: Engine block surfacing

Post by cgarb »

I would have the intake skimmed and go to a set of felpro performance style intake gaskets. I have had trouble in the past with Mr.Gasket intake gaskets leaking. In my case I think the methanol was deteriorating the gasket.
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