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junkyard 5.3 with 853 LS1 heads and intake thoughts?
Picked up a set of ls1 heads (853 casting) and intake for the cheap.Really just wanted the intake for my swap but guy tossed in the heads for $100. did some google searching and found mixed reviews on this set up. from what i researched this combo works best if the heads are milled .40 to get the engine back to stock compression however you would have the advantage of larger intake valves. i know the 243 heads are better however i already have these so i kinda just want to wrk with what i already have.
i dont have the bottom end yet. planned on getting a junkyard 5.3. swap in going into a 95 impala ss . any info would be greatly appreciated.
You'd be better off with the 5.3 heads. 706 casting probably if it ends up a 02 - 06 or thereabouts which is probably the eeeeziest one to use. Same for the intake: if it'll fit (no idea in that chassis), the truck intake is better. The 5.3 doesn't benefit from the larger valves in most situations. Just get a whole 5.3 and use it as much as possible as-is, but watch out for the Castech issue. Maybe change the cam but not the heads or intake.
Even a fairly mild cam will make that 5.3 feel a lot more lively. Look for "drop-in" cams that CAN use the OEM springs, but put some stouter beehives in it anyway for better valvetrain stability.
On a 5.3 the stock LS1 853 would yield about ~9.85 to 1 compression with a stock gasket. Chamber is probably about 66cc.
On a 5.3 the stock 706 truck head would yield about ~10.4 to 1 compression with a stock gasket. Chamber is probably about 61.5 cc.
NA, I'm not a fan of the 853 heads on the 5.3, due to losing the ~.5 pt of compression. The 853's bigger valves don't help on the 5.3's small 3.78 bore.
I'd sell the ,853's for a $100 and use that toward 243's or 706's etc.
We did similar once. Used 853, Milled 50 or 60? off ( it did mark the pistons up a little so be careful and clay test/notch if need be ) on a super cheapo budget deal with a 228? I think it was cam. long tubes, ported tb, and a good tune up. second gen Car ran mid 12's all day on pump 91
On a 5.3 the stock LS1 853 would yield about ~9.85 to 1 compression with a stock gasket. Chamber is probably about 66cc.
On a 5.3 the stock 706 truck head would yield about ~10.4 to 1 compression with a stock gasket. Chamber is probably about 61.5 cc.
NA, I'm not a fan of the 853 heads on the 5.3, due to losing the ~.5 pt of compression. The 853's bigger valves don't help on the 5.3's small 3.78 bore.
I'd sell the ,853's for a $100 and use that toward 243's or 706's etc.
Those compression figures are for a flat top 5.3, not your average LM7.
On a 5.3 the stock LS1 853 would yield about ~9.85 to 1 compression with a stock gasket. Chamber is probably about 66cc.
On a 5.3 the stock 706 truck head would yield about ~10.4 to 1 compression with a stock gasket. Chamber is probably about 61.5 cc.
NA, I'm not a fan of the 853 heads on the 5.3, due to losing the ~.5 pt of compression. The 853's bigger valves don't help on the 5.3's small 3.78 bore.
I'd sell the ,853's for a $100 and use that toward 243's or 706's etc.
yea thats what im hearing. would a 6.0 benefit from the 853 heads? i have a line on a 6.0 shortblock.
If you want to run it NA, then you will need to mill the 853 heads quite a bit. You would be better off using the heads that the 5.3 comes with from the junkyard.
11-11-2018, 08:45 AM
junkyard 5.3 with 853 LS1 heads and intake thoughts? 
