Heavy build up on valves. What does it mean?

While disassembling the heads this is what I found. Same appearance on the other set of valves. Something tells me they are not suppose to look like this. What does it mean?

 

50 years of oil , gas, lead. Other dirt. That's actually not bad.

 

Oh seriously? Phew Was actually hoping someone would say something like that. I was fearing some major issue having never taken apart cylinder heads before. I'll chalk it up as a lesson learned. I will be replacing them with new ones though.

 

Leaking intake valve seals, and I can tell you that I have seen FAR worse, as in, it was hard to understand how air and fuel flowed into the combustion chamber.

 

Going bigger? If you are replacing then the only way to go is up

 

And don't forget to have new guides installed.

 

Yep, looks normal.
You have to remember, yesteryears gas wasn't as "clean" as todays gas, todays gas has to keep injectors, and the rest of the emissions stuff clean (o2 sensors, catalytic convertors)

 

No. I'm just doing a backyard cleaning and port and polish of the bowls and intake. Then new springs and valves. I do not have the funds to have it machined, etc. I guess I should have the guides replaced if its really crucial.

 

Why get new valves unless your going bigger or they are damaged. You want to save money, have the old valves reused. Any that are not reusable the shop will tell you

 

X2

 

Port bowl . Runners don't need it at this level of build. A lot of wasted time.

 

They don't appear damaged just severely layered in carbon, oil etc. I guess I should then clean them up and reuse, which will save me money. I appreciate the honesty and knowledge.

 

Good to know. I'll port and polish the bowls and only a quick polish of the runners.

 

Don't polish the intake runners, leave them rough that will help aide in mixing the air fuel mixture.

DO NOT gasket match the intake ports either, that will hurt flow more than help it!

If you want to do the runners then one of these would help to be able to measure the runner to make them all the same;

http://www.ebay.com/itm/Spring-Insi...110973?hash=item1c3985237d:g:YYIAAOSwPcVVpdCp

Use the inside calipers to see where the pinch point is, meaning the narrowest point in the port because the heads will only flow as much as that smallest point. After finding the smallest of 8 set those calipers another 1/16" of an inch bigger and open up the areas of one side of the port so the caliper fits in while still lightly touching the port walls.

After all 8 are done with the above step, open up the calipers another 1/16" an inch and repeat doing the opposite side. The spots that the calipers don't touch don't worry about those areas because they are still bigger than the pinch point.

Use the gasket to outline the top of the port and DO grind the top to that line and just taper that down to the valve guide. DO NOT take the bottom of the port lower at all! For the bottom of the port just grind it some what uniform taking the least amount of material off the bottom of the port as possible.

Being a beginner you should probably not mess with the short turn radius unless you look up some of the porting threads with pictures of cylinder head cutouts that explains how to remove the material there.

If you had a bare block you could mount the cylinder head on it so you could scribe a circle where the cylinders line up with the heads. Having that reference line would allow you to do some unshrouding in the chamber, a lot of potential flow just doing this. If you can get those reference lines you would grind to the line making sure to save the line tapering down to the valve trying to follow the radius of the intake and exhaust valves.

Seeing how a sbb 350 head's flow maxis out in the lower lift, having the valves back cut helps with lower lift flow so if there is any $ left in the budget you might want to consider having that done. Seeing how the sbb 350 heads flow is basically all in the lower lift range this should be a good addition to have done.

With the mentioned bowl work in one of the above posts from Andy, the above mentioned equalizing the runners out, getting the valves back cut and unshrouding the valves should net you around another 20 to 40 CFM maybe even more if you get the short turn radius right?

The exhaust just needs the imperfections ground smooth and you can polish the exhaust runners, that will help them flow better. You don't need to get carried away though because they will eventually get covered with carbon, not as bad as your valves though. GL


Derek

 

That's a lot of good info. I'll have to study it a few times before setting out on doing so. Thanks.

 

If you are staying with stock valves, and need to replace some severely pitted ones, I have a bunch of clean used int. & exh. extras you can have. I probably ground them already, just need to be lapped in.

Wire wheel that carbon off and see which ones you can save. Mic the stems for wear also. Save the larger diameter, straighter ones.

 

Here's what I have. Most are ground already and back-cut.

 

Hey Mart not trying to steal the thread here but if racerxjj67 doesn't snag them I would love to take them off your hands. I'm gonna be doing some mild stuff coming later this summer such as putting on a factory 4 barrel intake that I'll be cutting the dividers out of the forward and rear holes while keeping the middle divider and plan on pulling the heads to replace the seals and polish the bowls while I'm at it. I'd be more than happy to shoot you a couple bucks too.

 

Skippy, I'll keep you in mind. You are in Washington so shipping might be on the high end. I just got back from Seattle.

 

Another factor related to the coloring on the valves is the fact that most people drive around with only the primaries open on the Q jet and this gives far more fuel to the front cylinders vs using both primaries and secondaries. On light duty use on mainly the primaries the front plugs will show rich and the rear will show lean.