mrobvious34

I am putting together a LY5 to swap into my dads 84 C10 and I’m not sure which heads to use. When I got the motor some one had taken the original heads but I do have a set of 706 and 799s that I could use. I don’t know they history of either set so whichever ones I use will get a trip the the machine shop. I just looking for suggestions on which heads to use. Motor is stock bottom end LY5 with 222/232 .550/.550 112 lsa cam, .052 head gaskets, gen4 truck manifold, long tubes, 3200 stall, 4l60e, 3.73 gears. Best gas I can get around here is 91 octane. Street driven toy, not a race car and not used for towing

Option 1: stock 706 heads = 10.3:1
Option 2: stock 799 heads = 9.9:1
Option 3: milled 799 heads
Option 4: CNC ported & milled 799

local machine shop recommend using the 799 and not milling them because that would be stock and would work just fine (true), they also quoted me $750 to do a clean up mill and vale job (sounds high to me). For $150 more I could take them to Texas speed and have them CNC’d but would I notice any difference on a 5.3?

shakenfake

$750 I think is probably the going rate. I would consider a mill and cnc job though for the $150 more

smokinlmm

I’d run the 799’s and have them milled and valve job. That would make it more snappy down low.

shakenfake

Who tf is seriously choosing 706 heads???

Drspencer

iTrader: (1)

Those who recognize that the 7hp gain at 6,000rpm is less valuable in a 4500lb truck let alone the additional $300 in cores....lol.

shakenfake

Awesome, HP that is barely felt seat of the pants.




$300 core charge huh?

Drspencer

iTrader: (1)

Another Texan thinking the world is just like the bubble around him. Lol. And are those U-pull prices? Have you been outside? Lawd, I’ll pay someone $100 to pull a set of heads.

Check marketplace. 799/243 heads are $400 in most places.

shakenfake

Have you ever used car-part? These are auto recyclers so they pull everything u-pick up.





Marketplace sucks *****.

shakenfake

Here is Florida just for you sweetie.

_zebra

iTrader: (5)

looks like you ran a compression ratio calculator... cool, but did you check dynamic compression differences between the stock LY5 cam / 799s and your cam + whatever heads? that looks like a relatively healthy bump stick with a converter to match, so the SCR gain of 706s might get you back closer to factory DCR, and a port & valve job would open them up enough to flow nice good for a N/A truck.