5.3 Heads on a 6.0
Guys, will I be okay with this modification?
I have a customer that wants to bolt some 5.3 #862 heads on a LQ4 6.0 shortblock and i was wondering if that combination would have piston to valve clearance issues? Thanks in advance!! |
Re: 5.3 Heads on a 6.0
I'm sorry I have no idea, but I wanted to ask why they wanted to do this? I thought the point was to get better flowing heads, not more restrictive? I know we used to use 305 heads on 350s to build compression. Do 5.3 heads on a 6.0 do the same thing? Not trying to be a smart ass, just curious. For what it's worth I thought I read somewhere recently that you could go up in heads on blocks, but not backwards. Example: 6.2 heads on 5.3, but not 5.3 heads on 6.2.
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Re: 5.3 Heads on a 6.0
It would be a better idea to mill the stock 317s or find some 799/234s. The 317s are the same as the 799/234 casting just with a bigger combustion chamber.
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Re: 5.3 Heads on a 6.0
well yes they are for compression but give up flow. a lot of people try this mod because tsp has a big push for how much you can gain with the 5.3 heads. but that's only if you port and polish them like they do. your going backwards with stockers. I don't know all the part #s but I know that hot rod mag said that 317 are identical to the ls6 heads with bigger chambers. im pretty sure ls6 heads are cast #243 if im not mistaken the only diff from the 243 and 799 was that the 243s had sodium filled valves as opposed to regular ones and I think different springs (in stock form) casting I believe is the same
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Re: 5.3 Heads on a 6.0
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Re: 5.3 Heads on a 6.0
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Shawn |
Re: 5.3 Heads on a 6.0
If you are running a 4"+ bore, the l92 setup is pretty sweet. I would be running it but I don't want to give up my dbw setup, and from what i can find it doesn't fit the l92 manifold.
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Re: 5.3 Heads on a 6.0
mines dbw? You have the old 3 bolt TB right?
newer style (LS2 and beyond) TB is a 4 bolt. |
Re: 5.3 Heads on a 6.0
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Re: 5.3 Heads on a 6.0
oh OK.....was just gonna say remind you I had replaced my intake thinking it was causing my low vacuum...meaning I have a "spare" genIV truck (L92/LY6) intake laying around. ;)
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Re: 5.3 Heads on a 6.0
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Re: 5.3 Heads on a 6.0
I wish I knew that one too.
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Re: 5.3 Heads on a 6.0
The 5.3 heads, 862's and 706's, have a smaller combustion chamber and smaller intake valves than the 243's, 799's, and 317's. Now as stated above the 317's have the largest cc of the bunch. With a 6.0l one could take the intake valves out of the 317's and place them into the 5.3 heads. This will improve flow especially with a good valve job. The l92's and ls3 heads are a different breed.
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Re: 5.3 Heads on a 6.0
If the lq4 is an iron headed verson then the 862's would not be a bad idea...if they were free. Otherwise grab a set of 243' or 799's. I believe 799's are similar but not the same as 243's. A popular member on Ls1tech "Denmah" put a 799 and 243 on a 5.3 and the side with the 5.3 had lwoer compression. Not by a large margin though. I personally don't think l92s are worth the effort on a stock lq4. They can't touch the 243's for throttle response and power under the curve. Now you punch out that 6.0 to a 6.1 or better and the L92's come into their own and become an epic bang for the buck feature.
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Re: 5.3 Heads on a 6.0
Wouldn't the valve still be shrouded by the smaller bore?
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Re: 5.3 Heads on a 6.0
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I'll agree with your thoughts on L92/LS3 heads on a stock displacement LQ4. Now, if you're planning on a stroker motor down the road I would definitely do it once and be done. |
Re: 5.3 Heads on a 6.0
Why would GM put a different head casting on one side? I have a LS2 powered TBSS....and it must be rare as it has a "pair" of 243's. ;)
And as for the L92/LS3 heads.....I seem to hear more negative things about them from folks that don't actually own an engine with a set of these heads. I do own a truck with a stock displacement VVT delete LY6...a 6.0 with L92 heads. Just has a high lift cam (+ springs and c-moly p-rods) and headers. Guess I need to make a few videos and get it dyno'd.....plenty of power down low, in the mid-range, and up high. |
Re: 5.3 Heads on a 6.0
I have to chime in on the TBSS. We had an '06 and Our heads matched also. I remember looking at them one day just for grins.
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