VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Intake Manifold Question

Is there supposed to be condensation on the intake manifold for a 28? I have a feeling the gaskets may be bad? Finally got it started but it smokes and is still missing...

Hi Grease,

You should only have condensation on the manifold for the first few minutes after a cold start, and will then dissapear.

This is providing you have the hot air intake tube connected from the exhaust to the carby intake.

If this is not fitted the condensation can almost ice up (depending on the climate) and the engine will not run at its optimum. They were designed to run a hot air intake.

This may account for the miss.

Good luck.

Cheers

Ray

Check for fuel in the vacuum line, my car was pulling fuel through the vacuum line from the vacuum fuel pump and the manifold was cold and wet even after warm up.

Thanks guys..Replaced the gaskets on the intake manifold. Helped some. Number three plug is really fouled and number 4 a little bit. One and two are fine. Replaced plugs three and four but still have the same problem. Adjusted the valves as this is a new valve job. Still missing. I suspect weak valve springs. Hot air pipe is fully connected...

When running does the idle speed decrease when you ground each spark plug terminal with a screwdriver (or similar). That should determine if it is a single cylinder. If all are the same then checking, points, condenser, coil, distributor cap are in order. If a single cylinder is identified as making little or no change then check the plug wire, spark plug first or rotate spark plugs and wire with a paired cylinder (1&4 or 2&3). Once everything electrical is eliminated then focus on mechanical. Testing electrical is quick, easy and normally much less expensive that other possible causes.

Hey Chipper..Have grounded each with a screwdriver and not change noted. Have new wires, good coil and new cap. Cleaned the points. Do you think it could be the condenser? It looks like it has been on there awhile. If it were the condenser...then why would only number three and four plugs be fouling???

Charles

I sure would change the condenser and make sure its case is grounded.

You may have a resistance to flow to the front cylinders, air leak to that leg on the manifold or valves not properly adjusted.

Thanks Chipper...will do.

Still carboned on number three plug. Changed the condenser and rechecked the valve clearances. All to spec. Checked the compression on the number three piston and it blew my guage out of the plug hole. Good compression which I am thinking would eliminate the weak valve spring issue. The only thing I can think of that is left is that an oil ring may be stuck. Poured Marvel Mystery Oil in number three and let it sit to see if it frees the ring(s). It maybe that I have to drop the pan, remove the head and replace the rings?? Thoughts appreciated..Charles

What type of spark plug are you running?Too cold a plug will cause them to foul up & misfire.

its possible you have the incorrect firing order,make sure its 1243 and not 1324,and mank sure your distrubutor points are opening the same gap on all 4 lobes in the distrubutor

Spark plug is an Autolite 3076. Firing order is correct. What I suspect is that the valve guide on number three is worn and not allowing the valve to seat properly. I have an after market accessory in the form of a cap that is placed on top of the guide that will help with the worn guide. Plan to work on installing them today and see what this does.

Hi Grease,

I would love to see a picture of your after market item if your able to post.

Cheers

Ray

Pulled the head this morning and just as I suspected, both valves on 5 and 6 were full of carbon. Cleaned the head and noticed too much play in the guide where the valve stem comes through the block. I believe oil was getting in as the valve was not seating properly. Now, if the guides in the head are worn, hooled out, what do I do? Is there an insert that could be placeed the guide? All Help is appreciated...

Installing guides is not a major chore for a well equipped machine shop. Instruct the shop that you want them to have sufficient clearance to prevent stuck valves. They like to make them skin tight.

When you button it up after the work, use 3077 instead of the 3076.

Good luck!

Thanks Ray..will do.

The Auto-Lite 3076 spark plugs are too cold a plug to use in a Chev 4,beside having too short a reach.Its Champion equivalent is a W16Y(Champion's recommended plug),but even it's still too cold a heat range.You'd be better off with AC 78S or Auto-Lite 3077 plugs.
The 3076's are more suited to Model A Fords's & Dodge 4's.

20 years ago I had worn valve guides in my 34 Master and I had them fixed easily. I don't remember the name of the method, but a special tool which looked like a thread cutter, but it didn't cut a thread, it dug into the edge of the guide forcing a thread like piece of metal out into the guide hole. This was then reamed and some sort of special lube was sprayed into the gaps. I've done over 40,000 miles since then and have no oiling up problems.
Maybe someone on this site who has better knowledge that me might know what the method is called.
Chris

Knurling is used to expand the inside diameter of the valve guide , following knurling, the valve guide is reamed to correct size.

Hi Jack and Chris,

If you are going to that trouble (removing the head and valves) but can still use the old valves, would it be much more work to fit new valve guides.

Cheers

Ray

The head is at my local machine shop. I took a new valve and the head so it should be ready sometime next week. Intersting enough he had a 28 head on his bench that Mr. Mooeny gave him years ago. Some of you may rembmer Mr. Mooney. He rean a Chevrolet Parts business in Goodrich, Tx about 20 years ago. New guides will make a great deal of difference as will the new valves.

I do remember him. I bought quite a few parts from him at the time. I think I still have his catalog that states that It will be the last one printed.
Richard

I remember Mr. Mooney. Bought several items from him. (Boy, does that date me).

grease!!in your preavious post you stated you had already had a valve job done,sounds like some one did half a job on your cylinder head,, as they should have checked the valve to guide clearance first,and you wouldnt be having this trouble now.

Hi Guys,

I am still after an explanation of after going to all the trouble of removing the head, and valves, why knurl instead of new guides?

Cheers

Ray