INTERNAL ENGINE MODIFICATIONS Valvetrain |Heads | Strokers | Design | Assembly

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Old Sep 9, 2018 | 03:51 PM
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OK, so I just picked up a 5.3 block that has been bored to 3.898 as the start of my 247/5.7 build for my Suburban

Seller is throwing in a set of 862 heads.

I also came across a set of 241 heads.

I know everyone talks about the vaunted 243/799 heads, so what are your thoughts on using one of the other two sets?

I believe the 241's use the same 2" intake valves as the 243's.

The 241's combustion chambers are +/- 2cc larger while the intake runners and exhaust ports are slightly shorter/smaller.

All of this "matters" the big time LSx guys building them for F-bodies and Vettes looking for HUGE how numbers and top end.

I question how much they would make a difference that would make in my Suburban build.

Keep in mind, the Burb is a DD and part time tow rig.

I'll be running stock crank, stock rods, flat top pistons, Comp trunion upgrade, Blue LS6 springs, stock rockers, new 7.4" pushrods, new Delphi lifters, a cam in the 208-214/208-214, 108-114 LSA range, shorty headers, Flex Fuel injectors, and likely a TBSS intake.


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Old Sep 10, 2018 | 11:51 AM
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Run the 862s. More power was made, even on a 6.0. Everyone’s gonna hoop n holler about compression ratio but I just don’t think the velocity is high enough with the larger runner. Cut the 862 .030 and send it. Also, get at least a 24” breaker bar or ratchet for the head bolts. That last 90 degrees is a real bitch.
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Old Sep 11, 2018 | 09:19 PM
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Originally Posted by Drspencer
Run the 862s. More power was made, even on a 6.0. Everyone’s gonna hoop n holler about compression ratio but I just don’t think the velocity is high enough with the larger runner. Cut the 862 .030 and send it. Also, get at least a 24” breaker bar or ratchet for the head bolts. That last 90 degrees is a real bitch.
Frony research I expected my CR to be in the 10.x : 1 range based on the flat tops, larger cam and the CC size of the 241/243/799.

Don't the 862's have an even smaller CC and also the smaller intake valves? I don't have the comparison info in front of me.

I'm on my phone, I'm exhausted, it's been a long day between work, hurricane prep and finishing putting the front end of the POS back together.

Work comes early at 0400 again tomorrow.

Look forward to more feedback .

CMC
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Old Sep 12, 2018 | 10:08 AM
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The 862s have 61.5cc combustion chambers and 1.89/1.55 valves. Yes. They’re smaller, but we don’t have any definitive evidence that shows the smaller valve makes less power.
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Old Sep 14, 2018 | 05:29 AM
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This is who I want to use to do the machine work , the assembly work that I can't do, and lean on for guidance based on what they find.

http://centralvirginiamachine.com
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