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post #1 of (permalink) Old 08-23-2001, 07:38 PM
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I need to replace the heads on my 305. Any advice on putting new heads on an older engine? I'm worried about creating blow by thru the rings.

If it don't fit force it, and if all else fails get a bigger hammer!
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post #2 of (permalink) Old 08-23-2001, 09:28 PM
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Re: Heads

couldn't you replace the rings since you already have the heads off? Just undo the con-rods and push the slugs out, re-ring then put em back and retorque the rod caps? Or do you have ifs and can't get to the pan?

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post #3 of (permalink) Old 08-23-2001, 11:49 PM
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Re: Heads

It's OK to just replace the heads on an engine. But! it's always nice to know that the heads were the problem from the beginning.

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post #4 of (permalink) Old 08-24-2001, 06:39 AM
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Re: Heads

I have IFS. I know the valve seals are shot, but I also have higher compression on a cylinder. I figured I'd have the heads cleaned and rebuilt while I had them off to remove the extra carbon. I'm just not sure if the increased seal in the top would force blow by thru the rings. Wouldn't I also have to hone the cylinders before installing new rings.

If it don't fit force it, and if all else fails get a bigger hammer!
post #5 of (permalink) Old 08-24-2001, 07:14 AM
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Re: Heads

Yes, you absolutely would have to hone the cylinders before you install new rings. If you want to see some blow by, put new rings in without honing.

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post #6 of (permalink) Old 08-24-2001, 07:39 AM
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Re: Heads

you should hone them, and if your cylider walls are worn much you might need to use a ridge reamer to get out your pistons. If I was going to go through the work of replacing rings I would pull the motor and freshen every thing. Wouldnt mess withit if it wasnt on a stand just my .02$. For the Q's about heads....do you want more power? If so after market heads or some worked over stock heads might not be too bad world torquers are pretty cheap and afr's especially their iron pro action I think they are called. With a small motor you want to keep the runner size small. Dont go for the bigger is better approach cuz it aint. Also depending on what size chambers you get it will alter your compression wich can be a good thing. But I dont know if it will mess with all your computer mumbojumbo[img]/wwwthreads_images/icons/tongue.gif[/img] You can replace the valve seals while the hears are on the motor. Valve seals only keep oil outa the cumbustion chamber. If you buy good aftermarket heads you can use them on a new rebuild of a 350 or something. Dont believe the marketing though, given equal flow capabilitiesiron heads make more power period

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post #7 of (permalink) Old 08-24-2001, 10:52 AM
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Re: Heads

Do a cylinder leakage test.do it once before you take the heads off and then do it with the heads removed so you know true leakage of the rings only.If you get more then 12 to 15% on the ring check you'll have lots of blow-by when you put the fresh heads on.All case's of "ring failure" after a head job is because they were wore out before and by rebuilding the heads you get rid of the 16 extra "pcv valves" built into the head......most guys call them valve guides but they "act" as a pcv when they are worn to loose.

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