Inlet Manifold Gasket Woes

[malc]

So Iīm almost back to square one....
The motor just doesnīt want to run.
Itīll start and with gas will try to run but let off the gas and it dies.....dead.
While it runs and Iīm giving it gas the vacuum gauge goes bloody backwards.
My first thoughts are a lobe or two have been wiped out but I did all of the valves after the break in
following the firing order, every valve was where it should have been.
The break in oil I drained out was perfect not a sign of metal particles.
So I decided to check the cam installation relative to the crank,
Iīve got the timing cover off right now and the cam is where it should be.
Turned the crank while holding my finger over number one spark plug hole and verified the cam was right
on when number one hit itīs compression stroke.

The next guess is a huge vacuum leak but from where ?

[anotheridiot]

we had a timing chain set with a bunch of marks on the crank gear for advance and retard and never really figured that out, but keyway up around 2:00 is usually always right. Pulling the intake and carb off are where you would get a vacuum leak.bad manifold gasket, or maybe it fell down too low or up too high where its pulling from the valley area.

From what I learned though is to put a vacuum gauge on it and time it to where it says its right with vacuum.

[malc]

Thanks, manifold is off next, going to try and
get it off with carb attached....I'm running out of gaskets.
Only one set of inlet gaskets left.
I've never understood why the crank sprocket
has so many marks and how to use them.

[Loren]

I think if it were me I'd check that you are referencing the correct crank mark by sticking a wood dowel or something in the #1 spark plug hole and running (by hand!) the piston into it 'till it jams from each direction and marking stopping points on the damper, knowing that the mid-point between the two will be TDC, then with the dowel out set it at TDC and see that the crank gear mark confirms as it should. If your crank gear has different marks it presumably is the type with multiple keyways each machined in at a slightly different index vs. the gear teeth so that the cam can be slightly advanced or retarded vs. the normal position by using a different slot. If you're using a wrong mark altogether, the crank timing would be 120 degrees off and I doubt the motor would even run. If it's possible you're just off by a gear tooth or two, maybe take a piece of stiff paper and plot/cut out an accurate half-circle of the crank snout diameter to lay against the snout then with the edge vertical and crossing through the cam center the straight edge of the paper would show you if the marks really were lined up exactly. It's hard to get it just by eye sometimes.

The distributor timing position should then be checked again as well.

You could then test for a vacuum leak before you take the manifold off by running the engine and spraying starting fluid or something around the outside of the intake area and listening for rpm changes. If it speeds up when you spray a particular area, that's where the leak will be. Can be done without the water pump on for short periods.

[malc]

When I went to an 8" balancer I did the piston
stop check for TDC, appreciate the advise but
wood would splinter.
I bought a piston stop but it did'nt stop the piston,
I had to modify it to make it longer.

The manifold looks to be well sealed outside....
internally...
I used Gasgacinch to hold the gaskets in place
but the separation between the ports is so thin.
On one of the "reality fix your car" shows one guy used silicon sealer to glue the gaskets.
I thought that was wrong as silicon is pretty
slippy.
Anyone used silicon with success ?

[anotheridiot]

not a whole lot of success with silicone since it ends up squishing in the hole and you cant trim it out. We just put a dab on the flat spots to try to hold the gasket close while dropping the manifold on. For us the best answer was marking the top of the gasket before we drop the manifold on then take a sharp small screwdriver and pry it back up to the mark before tightening the bolts.

We went all the way to using a dial indicator to mark TDC on the crank, but the extra marks dont turn the crank, it changes the location of the cam in relation to the crank, so the intake ends up closing before BDC so you dont get the full suck. Yeah we battled this for weeks and months just to find the distributor is off some 30 degrees.

You have a vacuum gauge, does yours show late valve timing, good ignition ranges? Usually about 15 is good range. IF it wont run again just try timing the distributor to that gauge the old school way. Its something I constantly wish I would have done before tearing down the motor 4 times.

[malc]

Today I got the intake off.....
left side.


Right side.



As you can see the gasket is failing to stay put between the ports, and those gaskets are really stuck
itīs taking a long time to get them off, so far only one side is clean.
I think the bolt holes are badly situated they donīt hold the intake close enough to the ports or my manifold is warped.
I Gasgacinched the gasket to the head, prepared the intake and placed it in place using the bolts finger tight to hold it until the
glue had set up, then I tightened it down.

The vacuum gauge was totally useless the needle flying up and down.

I might try an Edelbrock intake gasket next.

[MadmanMark]

Here's my semi-anal process that I've had luck with. I put 2 studs in the head on one side, use your favorite goo on the head surface, and then carefully set the intake down over the studs and let it sit for a few hours (or overnight). Then when you remove the manifold you'll see if the intake got nicely glued down or moved. If all is well, add silicon to the end rails and drop it on. Too much bolt torque could push the center out again but it will be less likely if it has been glued down.

[malc]

Do you add glue to the inlet manifold too or
install it dry onto the glued to the heads gaskets ?

[cstmwgn]

Do you add glue to the inlet manifold too or
install it dry onto the glued to the heads gaskets ?

The advice I have been given (and follow) is to do as mentioned above - glue (I like Gasgacinch) the gasket to the head. I use wax paper or plastic wrap on the intake side of the gasket. Set the intake on a couple of studs in each head (front and back) and let it sit over night. After an appropriate amount of time, i remove the intake, and wax paper or plastic wrap. I apply a thin coat of white grease to the intake side and bolt them together. The white grease supposedly keeps the gasket from sticking to the intake when you pull it for routine inspection of lifters.

[wrenchn2]

The vacuum gauge was totally useless the needle flying up and down.

Flying needle tells me something is not correct with the exhaust. Worn cam,rocker arm off, plugged up pipe or convertor.
If the exhaust cant get out it goes out the carb the next time the intake opens.
Which equals pressure in the intake then vacuum then pressure which makes flying needle.
Or if your lucky spark plug wires are crossed

[MadmanMark]

The advice I have been given (and follow) is to do as mentioned above - glue (I like Gasgacinch) the gasket to the head. I use wax paper or plastic wrap on the intake side of the gasket. Set the intake on a couple of studs in each head (front and back) and let it sit over night. After an appropriate amount of time, i remove the intake, and wax paper or plastic wrap. I apply a thin coat of white grease to the intake side and bolt them together. The white grease supposedly keeps the gasket from sticking to the intake when you pull it for routine inspection of lifters.

I haven't tried the wax paper/grease - sounds like a good idea. I put a thin layer of silicon around the water ports on the intake, right stuff on the end rails, and any time the manifold comes off I replace the gasket.

[anotheridiot]

I have been impressed with Magnum gaskets, never trusted edelbrocks stuff. If you stick to Fel Pro try the 1206S3. That is a steel stamped with printo seal, it will stop that suck in deal with 1-3 and 2-4.

Not sure about his exhaust suggestions, but it does seem its just happening front half, so your suck is being swapped at both front cylinders and not the back two so, maybe..

[Loren]

Not sure if I'm offering helpful advice but (as a prototype machinist/fabricator and former QC manager I'd say that) no matter what sealer you are or are not using, that gasket shift should not be happening and indicates improper mating surfaces between the intake and heads/block. There would be ways to check for that. I have had the experience of buying an aftermarket intake manifold for $200 then spending another $200 on it having out-of-spec factory machining corrected.

[silver_bullet]

Fel-Pro 1266 gasket...they're thicker, so you might get better clamping force between the intake and head...