Head Removed. A few questions.

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01-21-2011, 11:30 AM

AbandonedBronco

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Head Removed. A few questions.

Hi all,
Finally removed the head on my '81 Bronco to see how things look. For the most part, everything looks to be in top shape. I haven't taken the valves out yet, so I don't know if maybe it needs new guides or anything, but visually, all the valves look healthy.

So, I'm going to take the head down to a place that rebuilds heads here in town and have it rebuilt and see what he says. (The guy really knew his stuff. Knew the valve length, rod length, head dimensions, type of rocker arm studs for the year, compression ratio, etc. of the 300 all from memory. Seems like the kinda guy I want working on it.)

What kinds of things should he check over? I'm going to have him put in screw in studs while I have it there, and maybe do some port work, but what else should be done? I'm thinking have some shaved off to bump the compression ratio up a bit, but how much? Will I need shorter push rods for that?

Also, I apparently didn't drain all the coolant out because once the bolts were loose, it started pouring down the sides of the block, and when I pulled the head off, all six of the cylinders will flooded with antifreeze. I siphoned it all out, and will be doing a full oil change before it goes anywhere, but because of this, is there anything else I should be concerned about?

Thanks.

PS: That is one big/heavy cylinder head. Good thing I've been working out.

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01-21-2011, 03:08 PM

Harte3

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I myself wouldn't have the head shaved any more than necessary for truing and cleanup and take what little bump in cr you get out of that.

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01-21-2011, 03:10 PM

AbandonedBronco

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Do people usually get their CR bump from shaving the block then?

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01-21-2011, 06:13 PM

Harte3

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Depending on how much one is shaved...have your machinist cc the chambers and project some estimated bumps depending on how much is shaved.

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01-21-2011, 07:40 PM

dustybumpers

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Quote:

Originally Posted by Harte3

I myself wouldn't have the head shaved any more than necessary for truing and cleanup and take what little bump in cr you get out of that.

nor woud I. if it ain't broke....... I would get a nice 3 angle valve grind, and lap the valves. I would also semi port and polish, basicly a good clean up.

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01-21-2011, 09:00 PM

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I'm curious why Dusty and Harte said not to mill the head. Is it because it is not new? stress on rings, etc.

I don't remember why you pulled the head, but if at all suspect, I'd have it magnafluxed. I also thought I'd throw in my .02 and paste a three angle drawing, and also something I found educational and amusing that FTF wrote about getting a v.job. Of course he may be on a different level than I am.

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9; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} </style> <![endif]--> Valve Job Info, What to ask for: Per The French Town Flyer:
A 3 angle valve job is better for flow than a single 45 degree one:

1. Ask him if he owns a valve seat runout gage. Tell him you want to check the valve seat runout after he grinds them to be sure the TIR is less than .002".
2. If you see the look of incredulous fear in his eyes find another machinist.
3. If he says "sure" then you can probably trust him to do a quality job without you actually having to check his work.
4. Ask the guy doing the valve job to place the valve seat contact pattern high up on the valve face, within .010 of the OD of the valve. They will flow better that way.
5. Blend the 60 degree cut into the bowl if possible.
6. Be sure he maintains constant seat widths.
7. Ask him to do a 30 degree x .060" backcut on the intake valves

"If you see the look of incredulous fear in his eyes" ... that part cracked me up.

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01-22-2011, 08:44 AM

dustybumpers

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the head plane/mill issue, I cut .20 off my 82, and am pleased with the higher compression, but the bottom end is new. I also have to run mid grade or better gas in it, or it will ping, and over heat, unless I back off the timing, then power, and economy are out the window. A fairly stock, 85 or newer head will crack from overheating

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01-22-2011, 10:02 AM

Harte3

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What dusty said...and I didn't say to not mill the head but to do so only enough to clean-up and true. When I had my engine done I told them to mill both the head and block enough for that with a CR of 8.5-9.0...but no more than 9.0.

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01-22-2011, 11:06 AM

AbandonedBronco

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Yeah, I was looking for just a little bump, around 8.7 - 8.9 or so. Nothing serious.

Well, took the head down to the guy yesterday and spoke with him for a good hour or so. Definitely a guy who knew his stuff in and out, and has been doing the type of work for 20 - 30 years. Lol, definitely not the incredulous look of fear in his eyes.

Interestingly, the head's been rebuild before. It had replacement valves, guides, , shims for valve clearance, etc. in it. I don't know the history of my vehicle at all, but I had always figured no one had ever been into it.

The valves were in pretty good shape, but the guides were getting some slop in them. Also, we pulled a few valves out while I was there, and NONE of them were fully seating. The seats were shiny on one side (from contact) and dull on the other. I imagine that's why no matter what I'd do, how much work I'd put into it, what I'd replace, what I'd tune....

...the idle would always pop and buck. Explains some things.

He'll be doing a full 3-angle valve job with the rebuild, and will be giving me a price quote on all the work here in a few. When he does, I'll be able to give the go ahead on a port & polish depending on how much the rest costs. Hope so.

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01-22-2011, 05:43 PM

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AB--sounds like you found one of the good ones. Also, if something is popping, I would Magnaflux magnaflux magnaflux the heck out of that head. I think it is like $40--$50. Wouldn't you like to be sure?

Dusty-- I took .020 off the block, and the same off the head. I run 14 degrees advance, and 87 octane gas, and it only pinged once when it got to be 110 outside. I'm glad I did the mod. It has worked well for me. I don't know what mpg I'm getting on the freeway now with the Edelbrock, but when I had the autolite 4100 I was getting 16 mpg on the freeway, with a C6 and 3.31 rear gears, w/o overdrive.

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01-22-2011, 06:40 PM

dustybumpers

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price should run between $140-$180 without the port and polish. I usually charged around $70 for a good gasket match and polish, that's really all you will need. as far as .40, I can see that for an older head, but keep in mind the emission heads are fast burn, and thin, they crack easy. .20 seems to be the magic number for Maryland weather, and smog fuel. they change the fuel here, every 3 months. the winter fuel boils over and vapor locks in the summer, the summer fuel barely fires the truck over in the winter. I don't use the 82 a whole lot, in fact, the gas that's in it right now, was bought last August. I start all my "prizes" every couple of days in the winter. the 82 barely starts, and gives you a hard way to go, until it warms up. the I'6's with the lean burn heads fire right off, stumble once, then say, let's go.

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01-24-2011, 01:14 PM

AbandonedBronco

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I definitely agree that it'll be magnafluxed. We discussed that while I was at his shop. No way I want to have work done to a bum head!

Dusty, fortunately I don't have to worry too much about the gas issue, since I drive it every day. It's usually refilled every few weeks, so it always has whatever gas is the current hot trend. =P

I wouldn't mind a little compression bump, but won't worry about it if its an issue. Maybe I'll discuss it with him when he calls with a price quote.

In the mean time, I have some questions I'd like to run past you guys about the lifters, pushrods, cam, etc.
Before I had my "screwup" with my cam, it ran nicely, but had a bad lifter tick. When I tried to adjust it, I put the wrong size washers on as shims and it jammed it all up (miscalculated the internal diameter of the shim by forgetting the stud gets wider at the base). It ran and smacked pretty hard when it fired up, so I turned it off. Once I finally got the washers off and put the right size on and adjusted it correctly, the engine ran rough and sounded horrible.

I rotated the crank by hand and watched the rocker arms. About two or three of them didn't rise and fall nearly as much as the others did. My first fear was flattened lobes on the cam.

Since then, I removed the rocker arms and pushrods. Inspected the pushrods and none of them were bent. Removed the lifter cover and rotated the crank by hand and watched and measured the rise and fall of the lifters. All of them rose and fell the same amount. That leads me to believe the lobes on the cam are okay.

I then inspected the lifters and none of them have any visible damage, such as a dented or mushroomed base, and from the outside, the internals look normal.

What could have been damaged that would cause some of the rocker arms to not rise and fall as much as the others? Since the cam lobes seem okay, push rods aren't bent, lifters aren't visibly damaged, I'm not sure. Could the internals of the lifters been damaged somehow?

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01-24-2011, 01:36 PM

Rogue_Wulff

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Could have collapsed the lifters. They have hydraulic plungers in them that depend on oil pressure to remain "pumped up". The plungers could be stuck, or simply lost their prime.
Pull out the questionable lifters, place in a shallow pan with oil covering them, and try pushing down on the center where the pushrod sits. Best policy here is to use a pushrod to depress the plunger, as it has the correct ball end to prevent damage.

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01-24-2011, 01:37 PM

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Did you roll the p.rods on a piece of glass or something absolutely flat? If so, then I would guess lifters. That would be the weak link, right? It seems like they would fail before rocker arms bend or stud pulls out.

I'm interested to read what others think.

Good luck. I would mention it to your machine shop and have them examine the lifters, etc. He'll prob go right to the prob. and save you loads of stress.

Good luck.

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01-24-2011, 02:24 PM

AbandonedBronco

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The guy I spoke to mentioned it could be collapsed lifters, but if they are, I should replace the cam as well, since cams/lifters are a very matched pair. Thoughts?

I tried depressing some of the lifters but wasn't able to get any of them to move. Maybe I was too timid.

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