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gpjed55 03-15-10 12:45 PM

HELP with 390
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.

kdtrucker 03-15-10 07:14 PM

Re: HELP with 390
As far as the white and grey smoke,'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.

gpjed55 03-15-10 07:44 PM

Re: HELP with 390
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.

kdtrucker 03-15-10 08:28 PM

Re: HELP with 390
Did you get the firing order right?? counterclockwise from #1 on the cap 1-5-4-2-6-3-7-8

gpjed55 03-15-10 08:58 PM

Re: HELP with 390
I got it right.I used my intake stampings for reference.

gpjed55 03-16-10 07:39 AM

Re: HELP with 390
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.

kdtrucker 03-16-10 08:37 AM

Re: HELP with 390
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.

gpjed55 03-16-10 08:40 AM

Re: HELP with 390
If the gasket was wrong wouldn't it be mixing the oil and water like the first bad set.

gpjed55 03-16-10 08:42 AM

Re: HELP with 390
And would that cause it to miss

kdtrucker 03-16-10 09:46 AM

Re: HELP with 390
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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