Swapping from 241's to 853's

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Aug 23, 2016 | 10:40 PM

josh2002-ws6

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From: Frederick, Maryland

Swapping from 241's to 853's

I have a 2000 SS that has 350k miles. The drivers side head has now thrown 2 spark plugs in the past 6 weeks. They are stock 241's. I'm pretty sure they are just worn out from the mileage on the motor, it is 100% stock. Instead of putting another helicoil in I am just gonna swap the heads out with replacement lower mileage ones. I can't seem to find that many low mileage replacement 241's but have found a few 853's. If I switch, do I need to change or look at anything else? The car is staying stock, so don't suggest looking at anything else. Thank you.

Aug 24, 2016 | 01:53 AM

A.R. Shale Targa

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From: Fredonia,WI

If going through all that work, I'd pop some new lifters in there and a set of stock unmolested 243/799 heads

Aug 24, 2016 | 03:24 AM

HCI2000SS

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From: Howell & Fenton MI

Quote:

Originally Posted by A.R. Shale Targa

If going through all that work, I'd pop some new lifters in there and a set of stock unmolested 243/799 heads

Exactly!

Aug 24, 2016 | 05:16 AM

Tim john---

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I do not have the mileage Josh has but am curious as well. I have a stock 2004 GTO LS 1 with the stock/factory 241 cylinder heads on it, will the 243's be a direct bolt on, I mean will everything else fit, align and perform as intended. (just do a head swap) Engine is factory stock. Thank You.

Tim john---

Aug 24, 2016 | 08:14 AM

farmington

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From: Little River SC

as long as the heads haven't been cut on the decks you're good to go. if they have been cut in the past might need shorter pushrods

Aug 24, 2016 | 08:31 AM

Darth_V8r

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If you put the 243 on you can use MLS head gaskets. If not, use the composite gaskets. There's a notch on the 853/241 heads that won't deal with MLS

Aug 24, 2016 | 09:41 AM

kinglt-1

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From: Ft. Wayne, IN

Quote:

Originally Posted by A.R. Shale Targa

If going through all that work, I'd pop some new lifters in there and a set of stock unmolested 243/799 heads

I posted the same thing then deleted it because of the snarky last sentence. "don't suggest looking at anything else"

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Aug 24, 2016 | 09:56 AM

A.R. Shale Targa

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From: Fredonia,WI

Quote:

Originally Posted by kinglt-1

I posted the same thing then deleted it because of the snarky last sentence. "don't suggest looking at anything else"

Kings tend to be a bit snarky cuz; well......they're kings.

Aug 24, 2016 | 11:01 AM

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Darth_V8r

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Quote:

Originally Posted by A.R. Shale Targa

I thought the casting notch was only on 97-99 perimeter bolt v/c styles ??

nope. I have center bolt style. It's on them too. And into some 2000 models. That's why I mentioned it. OP should look for the notch and purchase gaskets accordingly

Aug 24, 2016 | 11:32 AM

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Tim john---

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What kind of performance gain could one expect with the swap from 241 heads to the 243's, all else being factory stock on a 2004 GTO LS 1 engine sans Hooker/Holley Blackheart mid length stainless steel headers. Being the compression would go up a tad would that be an issue w/ fuel, computer tune as is ? Would the 2004 LS1 GTO fuel rail covers still fit (2004 is different than 2005/6). Thank You.

Tim john---