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Discussion Starter #1
I recently purchased a 76 highboy with a 390. It had a substantial oil leak from the rear intake gasket. I replaced the gasket and found out the new gasket was faulty. Therefore it started leaking water out the back and mixing with the oil. I took the intake back off and replaced the gaskets with a new set. I then did an oil change as well as replace the plugs and wires. I now have no leaks or oil in my water or water in my oil. I do however have white and gray smoke coming out my exhaust. I set my distributor to factory specs lining up the rotor towards the number one cylinder on the cap and facing the number 8 cylinder on the block. This was all done at top dead center. On the balancer it was reading TDC on all this. When I fire it up and try to time the motor the timing marks are towards the bottom of the balancer and the pointer is at the top. Needless to say I cant time it. My motor has a miss as well. I did a compression test dry on all cylinders. They were all equal but low. There isn't blue smoke so it cant be rings and all the cylinders are equal so it cant be a valve. What is it. I am at my wits end. I am fairly capable with a wrench but cant figure it out. I ran all the casting numbers and found out it is a 66 390 GT if that helps. Please help Thank you.
 

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As far as the white and grey smoke,....it's probably residual oil and water burning off that might have got into the cylinders. As far as your timing goes, pull #1 plug out put your finger in the hole and crank the engine untill the you reach the compression stroke. The dampner should be close to TDC. You'll see the timing marks rotate the engine to line it up at TDC, now reset your distributor rotor to piont to #1 on the cap, if you have a vacumm advance on the dist. make it point straight forward. You might have to pop the dist. out once or twice to make it fall into place nice and easy. hook everything up and start the motor.
 

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Discussion Starter #3
I Did all that and it is still doing that. I had actually done all that prior to posting. That is where I draw a blank. I have ran it for a while and it still smokes. There is also the miss. If it was a faulty intake gasket wouldn't the oil and water. be mixing. I also heard that it could be a loose timing chain. I don't have a clue.
 

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Is it possible that I got the wrong intake gasket set. I was just looking at summit and the gasket set I got has a water port right next to one of the intake ports, where none of the other gaskets have it. I really don't want to tear it apart again as I have done it twice now. Any input would be great. Oh my heads are stamped C8AE-H if that helps. My block is D4TE.
 

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Did you match the intake gasket to both the intake and the heads? The "H" heads have small velocity ports....If your intake has small ports they will match up fine, but if your intake has large or tall ports you need to use the gasket with the larger tall ports. Make sure the bump ridge on the gasket faces up. The water should only pass through the ports at the front of the head into the intake.
 

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No, I don't think you would have and oil and water leak you would have a very bad vacumm or air leak. If you use a set of gaskets that matched your heads (small port H heads) and your intake has large ports you would be getting oil splash from the engine valley to the intake manifold port where it is not sealed to the head and the oil splash would be getting into the head and piston chamber causing it to smoke. There may be a loud air hiss or whine from the vacumm leak.

If you have miss matched ports (large and small) always use large port gaskets
 

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Discussion Starter #11
So basically i need to tear it apart again. Everything seemed fine when I put it together. But a vacuum leak would almost seem like a miss and would cause it to not idle smoothly like it is doing. Right? My intake is stamped C6AE 9425-G with a large S next to it if that helps.
 

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It wouldn't raeally miss it would run rough, not smooth. The S code on your intake would be from a 390 GT "S" code engine. If you have a vacumm gauge or if you can borrow one hook it up to the engine any place on the intake or carb that is sucking air. If it doesn't read or is just above 0 inches of vacumm, break out the tools.
 

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Discussion Starter #13
I just tore apart the motor and the intake gasket ports were definitely larger than both the ports on the intake and the ports on heads. The gasket had bout quarter inch top and bottom larger than the heads and even more so than the intake. So would you say I need the medium riser gaskets for the 390 GT and if so why dont they have the port next to the intake port in the middle of the heads. I have an extra port on both heads. Could you recommend a gasket set. Thanks for your input.
 

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Discussion Starter #14
I had another question in addition to my last post. The manual I'm using says to rotate the motor 45 degrees after TDC to install the rocker arm assembly. How the hell do I do that without a degree wheel?
 

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Measure the distance around the balancer and divide x 4. Measure from TDC and start marking. A dressmakers tape works great for this. Should get you close enough.
 

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Discussion Starter #16
That solves one problem but how bout the intake gasket set. The only ones I could find with the extra port are the ones I had but the ports are way larger on the gaskets than on the heads or intake.
 

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By what you are saying it would seem that the gaskets were sealing just fine. line the gasket up with the head and if it goes around the port just fine then the gasket is OK. Next line the gasket up with the the intake if it lines up and seals the port then it's also just fine. If the ports are the same size, head and intake then use a gasket that matches the ports. If the intake ports are larger than the head ports or vice versa but not likely with "H" heads, use a gasket that matches the larger ports. Make sure the bump is facing up when you lay the gaskets on the head. *Remember, NO gasket sealer - ie: permatex, RTV on the intake gaskets! On the front and rear lip I like to use "Right Stuff" it's kinda pricey but never fails, use a ¼ in. bead and let it set up for about 15 minutes, then "Gently lay the intake on the the engine. Torque the intake to about 25-35 foot lbs. from the center outward. do this proceedure again 2 or 3 times untill the intake seats all around. *If you don't do this proceedure you will more than likely have an air/vacumm leak.

If you are using non adjustable rockers, just put them on and torque them down to 45 foot lbs. start at 25-30 ft. lbs. first then 45 ft. lbs. middle ones first outer ones second. You've already ran the motor so the lifters are already pumped up with oil.

I don't know what you mean by an extra port.... if it's long and very narrow next to an intake port it's the heat port. it just helps to warm up the top of the engine quicker.
 

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Discussion Starter #18
The ports on the intake and heads are the same size. The gasket ports are what are so much larger. Side to side they are about the same size as the ports on the intake and heads, its top to bottom that they are way larger. The only gaskets I could find with that heat port setup are the ones I already had installed. Is that something you can cover up. I'm new to this whole FE motor thing. The motor I got is balanced and blueprinted, so I don't wanna mess it up. So should I look for a gasket set with smaller ports or stick to the ones with the heat port. Thanks. And what about that whole timing thing. I stabbed the distributor at TDC with the rotor at #1 on the cap and vacuum advance straight forward last time. Start the motor and the timing marks are at the bottom side of the balancer on the passenger side, a good two to three inches from the pointer. I'm at a loss. I had used the cork gaskets front and back last time with sealant in the corners. Could this be keeping my intake up to high and not letting it seat all the way. That is how the guy had it I got it from, he just didn't put the sealant in the corners so it was leakin like a civ. And with that whole 45 degrees thing wouldn't it be to divide by 8. 8 x 45 = 360
 

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your make things harder than they really are!! If the gaskets with the small ports have the heat port, you can reuse those gaskets if you didn't tear them up taking them off. Set the intake on the heads with the intake gaskets, don't put the front and rear cork gaskets on, measure the space from the intake and the block lip, then measure the thickness of the cork gaskets. If the cork is smaller than the space between the intake and the block lip, you'll have a leak. You'll need thicker cork, or get yourself some right stuff.

As far as you timing marks not lining up, either the balancer is just no good or the timing chain wasn't installed properly. Are you sure your getting the compression stroke?? When you put your finger over the hole of # 1 and crank the engine it should pop your finger right off the hole and stop cranking immediatly!! The timing marks should be real close to the pointer.

I don't know about any 45 degrees Your just adding more worries to your life
 
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