Mismatched Heads
07-31-2020, 10:25 PM
#21
TECH Senior Member
08-01-2020, 07:28 AM
#22
It's lazy. And it's the kind of laziness that can be dangerous.
I wouldn't trust a d@mn thing about that engine. Who knows, they could have used bolts with threads that were "close enough", could have went with clearance/tolerances that were "close enough", might have mismatched internals, unbalanced rotating assembly... I think that it's a boat anchor, at best a bare block to be totally inspected for other nonsense.
I wouldn't trust a d@mn thing about that engine. Who knows, they could have used bolts with threads that were "close enough", could have went with clearance/tolerances that were "close enough", might have mismatched internals, unbalanced rotating assembly... I think that it's a boat anchor, at best a bare block to be totally inspected for other nonsense.
Some guy probably came into the a shop with a junkyard head and asked to have one of the heads replaced. Would I do it if the car were sitting in my shop half torn apart and the customer showed up with the wrong head? Yep. Warn him of the of the consequences, put the head on the engine, and move on. As long as it isn't safety related and it will run, it isn't worth arguing about.
The following users liked this post:
G Atsma (08-01-2020)
08-01-2020, 02:52 PM
#24
TECH Senior Member
Your compression with the LC9 flat top (07-09) or 3cc valve eyebrows (10-11) would be 10.47:1 (07-09) or 10.09:1 (10-11).
08-01-2020, 04:13 PM
#25
On The Tree
Thread Starter
08-01-2020, 04:19 PM
#26
TECH Senior Member
08-01-2020, 05:16 PM
#27
On The Tree
Thread Starter
08-01-2020, 05:35 PM
#28
TECH Senior Member
Then find a cam with as broad a torque range as possible. Road racing will have you all over the tach. With 706 heads you won't need more than .550 lift. The ports won't support more flow than that lift will handle. Duration in the mid to high 220's for intake and same or very little more for exhaust.
08-01-2020, 06:50 PM
#29
you just got someone's thrown together long block with different size cylinder heads
I've known more than once, not in my shop of course, where somebody basically swept up the garage floor and built whatever was in the dustpan... **it happens. A Friday afternoon build.
Monday morning ones bring a whole other set of concerns.The issue now is, not get all sand-in-your-vagina over whatever happened, but get INTELLIGENT about what do I do with this pile of ... monkey excrement I'm stuck with.
I think, given what CRAP you're finding at a level you can observe WITHOUT TURNING A BOLT, that it's a good idea to tear it down at least far enough to figure out what you've REALLY got.
The following 2 users liked this post by RB04Av:
01CamaroSSTx (08-01-2020), G Atsma (08-01-2020)
08-01-2020, 07:44 PM
#30
TECH Senior Member
See Post #18....
08-01-2020, 07:47 PM
#31
ModSquad
iTrader: (6)
08-01-2020, 07:50 PM
#32
TECH Senior Member
08-10-2020, 09:49 PM
#33
On The Tree
Thread Starter
08-11-2020, 07:14 AM
#35
Moderator
iTrader: (4)
Join Date: Jul 2014
Location: My own internal universe
Posts: 10,446
Received 1,838 Likes
on
1,146 Posts
personally, I would take the compression. If the motor were larger, I'd take the flow. You can have your cake and eat it too if you get the 243's and mill to 59cc. Up to you and your budget.