replacing valve guides
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Joined: Nov 2004
Posts: 108
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From: Norfolk, VA
Car: 86 Iroc-Z28
Engine: 305 TPI
Transmission: 700r4
replacing valve guides
Anyone ever replace your leaking valve guides on a 305? Is this a job for a home mechanic or a seasoned professional? If a home mechanic can do it, must the heads be removed to do the job or can it be done in the bay?
since you're asking without a doubt you need to take it to someone. i've replaced a few but all in all it's way easier and not much cost to just replace guides, usually if you have to replace guides you also need other associated work preformed as well that drives up the cost. you need to r&r the heads
Are you sure the guides themselves are worn out, or just the seals that are leaking?
Stock heads the guide itself is just a hole drilled through the cast iron. Replacing them requires special equipment to over-drill the hole (while still keeping it straight) and then press in the replacement guide sleeve, then hone it out for proper clearance around the valve stem.
If you're very **** about things you'll probably have the valve seats re-cut becuase the guide won't be perfectly concentric with the seat any more.
All that is more than an average weekend warrior wants to tackle (or has the tools for).
Seals, on the other hand, can be done by an experienced weekend warrior in a day with the heads still in the car with access to a few easily obtained tools (valve spring compressor, most notably).
Stock heads the guide itself is just a hole drilled through the cast iron. Replacing them requires special equipment to over-drill the hole (while still keeping it straight) and then press in the replacement guide sleeve, then hone it out for proper clearance around the valve stem.
If you're very **** about things you'll probably have the valve seats re-cut becuase the guide won't be perfectly concentric with the seat any more.
All that is more than an average weekend warrior wants to tackle (or has the tools for).
Seals, on the other hand, can be done by an experienced weekend warrior in a day with the heads still in the car with access to a few easily obtained tools (valve spring compressor, most notably).
Joined: Jul 2000
Posts: 6,522
Likes: 92
From: Aridzona
Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Re: replacing valve guides
Originally posted by BigBiscuit
Anyone ever replace your leaking valve guides on a 305? Is this a job for a home mechanic or a seasoned professional? If a home mechanic can do it, must the heads be removed to do the job or can it be done in the bay?
Anyone ever replace your leaking valve guides on a 305? Is this a job for a home mechanic or a seasoned professional? If a home mechanic can do it, must the heads be removed to do the job or can it be done in the bay?
It can be done in the engine bay. I would strongly recommend having an air compressor and the plug adapter to hold the valves up when you do each spring. With a small inexpensive compressor (I picked up a Craftsman to do my seals in July,) the compressor tool (rented from Autozone) Definitely have a magnet tool to grab the locks as you compress the spring. Tap each valve with a hammer before you begin compressing (loosens the retainer from the locks) and you can do this job.
SBC valve guides are generally not worn out quickly or easily. The seals are a wear item and are a good idea to service around the 60k mile mark.
Good luck.
Last edited by jmd; Jan 2, 2005 at 01:16 PM.
Joined: Jul 2000
Posts: 6,522
Likes: 92
From: Aridzona
Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Originally posted by ede
jmd i think you've either been misinformed on what's required to replace valve guides or don't have a very good understanding of what's required, or both.
jmd i think you've either been misinformed on what's required to replace valve guides or don't have a very good understanding of what's required, or both.
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Joined: Jul 2001
Posts: 3,974
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From: Pueblo Co
Car: 1989 C4
Engine: L98
Transmission: 700r4
Axle/Gears: 307
You know there are a few things to consider when doing this, Damon mentioned them.
If the engine has over 100k on it its well worth it to take the heads off and have them gone through. Good chance the factory stem seals have been trahsed for quite while and a with funtional EGR valve it should have some nice deposits on the intake valves that hinder flow. Also the seats are probably worn from typical wear. In this situation it is well worth the extra expense.
If the engine has over 100k on it its well worth it to take the heads off and have them gone through. Good chance the factory stem seals have been trahsed for quite while and a with funtional EGR valve it should have some nice deposits on the intake valves that hinder flow. Also the seats are probably worn from typical wear. In this situation it is well worth the extra expense.
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Thread Starter
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Joined: Nov 2004
Posts: 108
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From: Norfolk, VA
Car: 86 Iroc-Z28
Engine: 305 TPI
Transmission: 700r4
Thanks for the input guys. Based on the responses, I probably have leaky seals. I get smoky exhaust on startup...but no smoke during normal operation. So my question is related to sealing off the oil that's dripping into the chamber when she's not running. I figured the valve sleeve or a seal or something would keep the oil from just draining into the chamber.
Whether I try it myself or take it to my mechanic, it's a project I'll tackle far down the road...just wondering what yall had to say about it.
Whether I try it myself or take it to my mechanic, it's a project I'll tackle far down the road...just wondering what yall had to say about it.
Originally posted by BigBiscuit
Whether I try it myself or take it to my mechanic, it's a project I'll tackle far down the road...just wondering what yall had to say about it.
Whether I try it myself or take it to my mechanic, it's a project I'll tackle far down the road...just wondering what yall had to say about it.
Joined: Jul 2000
Posts: 6,522
Likes: 92
From: Aridzona
Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Originally posted by kevinc
In other words, just wasting everyone's time. Next time add the 'just wondering' part to your first post so it will receive the appropriate attention.
In other words, just wasting everyone's time. Next time add the 'just wondering' part to your first post so it will receive the appropriate attention.
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