Holley 4160 carb tuning questions

[Mike T]

WC, a couple of things. If you don't fix the manifold leaks first, any adjustments you make will be tuning the motor to the leak. If the leaks are bad enough it's going to make your afr very unpredictable whenever you change from one static condition to the next. Probably why your afr spiked to 17 after you adjusted it to 14 and tried to move the car. Increasing the rpm and the manifold started pulling more air in and the fuel mix went mega lean, all at once.

What makes it dangerous to the motor is that if the manifold is only leaking into a couple of cylinders, those may be running much leaner than the afr indicates. Good way to burn up valves/pistons. The manual choke is probably not making any difference because the motor is pulling in enough air through the leaks not to make it run rich when you choke it.

The upside is that fixing the manifold leak may go a long way towards eliminating the bog problem that started this post. Please let us know how this goes and good luck.

 

[WisconsinCutlass]

I will be doing some research and hopefully starting to pull the intake off Friday after work. Never done an intake manifold gasket before. Wouldn't think it'd be to difficult. Anything I need to look for? I know I need to keep the lifter valley clean. When I buy a new gasket should I use the rubber end gaskets if it comes with or just a bead of rtv?

 

[fleming442]

I had a problem with a Performer intake once. According to Edelbrock, the intake is designed to be used with "stock type" intake gaskets (i.e- the turkey tray and RTV). Thus, their intake valley angle may be slightly off. This becomes a huge problem if you're using fiber gaskets (i.e.- Ultra Seals) as it can let coolant into the oil (like mine did). I checked mine this way:
-Pull the intake, and clean all mating surfaces
-Set the intake in the valley
-Slide the intake to one side (this is a very small adjustment)
-Observe the clearances on the intake mating surfaces (the side with the larger gap will be easiest).
I was able to get a .0013 feeler gauge at the top of the side opposite the direction I slid, but the bottom of the flange was tight to the head. So, I took it to a machine shop, and had them mill 0 bottom to .0065 top off each side. It seems very small, but I never had a leak after that. Mine was a coolant seep issue, but it would apply to a vacuum leak as well. Check your oil, too.

 

[WisconsinCutlass]

So on break at work I ordered the Fel-Pro #MS96027 stock style intake. This is what Edelbrock recommends for the intake. I also finally bought a torque wrench. I'm going to start taking things apart this afternoon and see what else I can find wrong.

 

[WisconsinCutlass]

Got home from work and didn't have any plans so decided to go out in the garage and take the intake off. It was much easier than I thought it was going to be. I now have more questions. I really don't know what I'm looking for as far as issues. Does anything stand out in the pictures? The coolant in the valley came from the water passage at the back after I took the intake off. (I hope) Also the front bolt on the driver side was super dirty, gritty, when I took it out. Is this from the water passage not being sealed properly? I think I'm going to buy an intake bolt kit just to be sure the new ones are good. And also chase the threads in the block to clean them out. 1 thing I'm wondering is there's a 5th passage in the center of the head with a metal block in it. On 1 side I can get the block out with a magnet the other side I can't get out. What are these? Are they supposed to move freely? The second is I've had an engine rattle that I couldn't pin point. Pretty sure I found the cause. The rod on the #6 cylinder I can wiggle it and it rattles. I linked a video of this. What needs to be done to fix this? Is it a major concern? I'll finish cleaning everything up and then the cars going to sit over the weekend cause I'll be gone. Hopefully next week I'll get it back together.

 

[fleming442]

The iron slugs block the exhaust crossover from the intake, and they will rattle.
You should be fine hooping a turkey tray in.

 

[Mike T]

WC, Most of what I know about tools and cars I had to learn the hard way. I didn't have a car guru as a mentor till I was almost 40. What I am putting in here you may already know. I'm not trying to be a know it all or talking to you like you are ignorant. I don't know what you know and on many occasions, I would have loved the advice of someone who had done it once or twice. Please take it in the spirit it is offered.

I'm not an Olds guy but I believe the plugs in those fifth passages are to block the egr system from recirculating exhaust gas back through the engine. They do this to reduce noxious gasses and lower emissions. The egr system is hell on performance and mileage and most people block the passages if they have to go into the engine. Not telling you what to do but if it were my ride, I would leave them be.

Can't say for sure but from the pics it looks like you haven't had a long term water leak into the valley. Coolant water leaking into the valley can be hot enough to push oil away from the valley floor and will show traces of "rust" or discolored metal over time, because it tends to pool in the same spot.

It looks like the manifold may have been leaking a little water to the outside where the grimy bolt hole is.

Before you start chasing threads, check to make sure they aren't bottomed out. (Threaded to the bottom of the hole) Most blocks have the intake bolts threaded into the water passages but almost always have a couple that are a hole that doesn't go all the way though. These are blind taps and require a special tap to be chased properly. Using a regular tap can ruin the tap when you hit the bottom of the hole and can also ruin the threads if you try to "power" through when the tap binds. Also, a tap is not a bolt and is meant to be turned into the hole in increments. Be very sure that you are properly in the thread before applying pressure, use a little light oil (WD40 or similar) to help move the grime out of the hole and turn the tap in a little at a time. Depending on how much resistance from damaged or dirty threads you can go 1/2 turn to 11/2 turns. Clean and oil the tap when you get done or it will be worthless next time you reach for it.

One of the very first "tools" I bought when I started building engines was a 30" straight edge. Other than my micrometers and dial gauges, it is the tool I take the best care of. Any time I work with heads, intakes or any of the flat faces of a block (head deck, oil pan rail, time chain surface, etc.) I put the straight edge on it as a rough check. It has kept me from having installation problems several times and has been well worth the minor expense. I think I saw them at Lowes the other day for about $15. Just lay it on the mating surfaces to be sure they are straight.

What 442 posted above is a good way to check you installation when you go back together.

Let us know how it turns out.

 

[Mike T]

Almost forgot. The slack in the push-rod should not be there if you you are running hydraulic lifters. First thing to do is look at the tops of all of
your rocker studs. They should all be about the same height and should have pretty close to the same number of threads showing above the adjusting nut. If you have pressed in studs, this one could be backing out of the hole.

Some other possible issues, although I doubt it is one of these:

• If you have springs that are too strong, they will sometimes collapse the lifter by forcing the oil out due to too much pressure.
• Sometimes the rocker arm can be tightened down too far and that can collapse the lifter.
• Sometimes the lifter assembly just fails and won't pump up or sometimes the push-rod gets clogged with grit and "starves" the lifter of oil causing it to collapse.
• Sometimes the valve springs break or just get tired and won't keep enough "down" pressure on the lifter.
• One last thing I can think of, if they are roller rockers, is an issue with the rocker arm assembly for that push rod. (Broken pivot, worn needle bearings, etc.)

 

[WisconsinCutlass]

I missed the emails that there were more replies to this thread. I just saw them. I went ahead and put the intake manifold back on this morning. Left the blocks in the heads. I also didnt think to check the heads with a straight edge, I could of grabbed the one from work to check it I wouldn't be surprised if I had to go back and redo the gasket. Wasn't absolutely sure what I was doing with the rtv if I had it thick enough, not thick enough etc. As of right now I'm going to worry about the slack in the pushrod. I'm pretty sure the rattling I was hearing was the slug rattling in the block. It sounded like there was rocks under the valve cover. I'm probably going to wait till this weekend to get everything back together. I also have some other general questions not related to this I'm going to ask in my build thread.

 

[truracer20]

What do you know about this engine? The reason I ask is it has aftermarket pushrods which leads me to believe it's had some head and or cam work. Olds valve train is non-adjustable and improper head work can lead to lifter preload issues like you have. Also broken or worn rocker bridges, worn pushrods and worn rocker arms can also cause loss of lifter preload. You need to check all of the pushrods when their respective valves are closed. Those exhaust crossover plugs can be massaged with a hammer to keep them from rattling.