Yet another head thread, Need advice |
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Yet another head thread, Need advice |
bbrock |
Nov 11 2017, 06:37 PM
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#1
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914 Guru Group: Members Posts: 5,269 Joined: 17-February 17 From: Montana Member No.: 20,845 Region Association: Rocky Mountains |
This is related to the AA/HAM head GB but I didn't want to hijack. But that offer means I need to make some decisions sooner than anticipated on my resto. The main question is whether to rework these heads or buy new? My very strong preference is to rework what I have, assuming the castings are good. They have not been cleaned so I was thinking about walnut blasting them myself so I can inspect for cracks before deciding whether to move forward on reworking. Is there any reason I should not blast them myself? Any spots that should be masked or blocked before blasting? Basically, I just want to get to a decision point on whether to rework or buy new. After reading so much about how hard it is getting to find good original castings has me a bit spooked, and if I hit a dead end on reworking, I'd like to do it while the HAM GB is still an option. I also don't know what a basic head rebuild will cost. Anyone have a ballpark estimate? I used to be able to send them out to Cali for a couple hundred bucks, but those days are gone. Here's a short version of the history my engine. It's GA 2.0L engine that I rebuilt the bottom end on in the late 80s, but the project stalled before I got to the heads. My best guess is that the engine had about 110K-120K miles on it when it was split. That's a guess because the odometer quit at about 92K shortly after I bought the car. The engine ran strong when the FI cooperated when it was pulled, so no reason to suspect any major issues. Other than a busted exhaust stud, the heads look good with no broken fins and very little carbon in the combustion chamber. So, overall, I feel these heads are a good candidate for rebuilding but would appreciate any advice or opinions. |
McMark |
Nov 28 2017, 12:15 PM
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#2
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Dental type picks are a good way to get the gaskets out. The exhaust ones can be pretty challenging and a pick may not be able to apply enough force to grab it.
Don't straighten fins. They may break off instead. And it's not going to affect the cooling. Full rebuild would be new seats, new guides, new springs, new valves, new retainers, new keepers, and flycut the sealing surface to ensure it's flat. If the sealing surface is flycut, then a matching amount of material need to be removed from the face of the heads so they don't hit the cylinder fins. |
bbrock |
Nov 28 2017, 12:51 PM
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#3
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914 Guru Group: Members Posts: 5,269 Joined: 17-February 17 From: Montana Member No.: 20,845 Region Association: Rocky Mountains |
Dental type picks are a good way to get the gaskets out. The exhaust ones can be pretty challenging and a pick may not be able to apply enough force to grab it. Don't straighten fins. They may break off instead. And it's not going to affect the cooling. Full rebuild would be new seats, new guides, new springs, new valves, new retainers, new keepers, and flycut the sealing surface to ensure it's flat. If the sealing surface is flycut, then a matching amount of material need to be removed from the face of the heads so they don't hit the cylinder fins. Man, not only did you answer all my questions, but also one I was thinking of asking about nditz1's situation to avoid having a similar problem. Now on the valve replacement, does that include exhaust? These are the original sodium-filled valves. Forty years old - yes... but only in service for about 15 of those years. I realize this subject is a can of worms, but I value your opinion. (IMG:style_emoticons/default/stirthepot.gif) |
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