| FAQ |
| Members List |
| Social Groups |
| Calendar |
| Search |
| Today's Posts |
|
|
|
#1
12-13-2025, 08:21 AM
|
||||
|
||||
Isn’t it a good quench that you’re looking for?
I thought I read somewhere once that Pontiacs were around mid teens for in the hole from factory.
__________________
72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007 (cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD 1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.45 @ 88.1 mph on slippery street tires.Bad 2.19 60ft.Owned since 86' |
|
#2
12-13-2025, 09:09 AM
|
||||
|
||||
|
Quote:
|
|
#3
12-13-2025, 12:13 PM
|
||||
|
||||
|
What I have noticed is when the compression get up around 11:1 the less difference quench makes. It is probably dependent on the engine platform, but most times if compression is 11 or higher for a pump gas engine it is better choosing a thicker head gasket and loosing quench than shooting for the tight quench and ending up with the compression at 12:1.
Part of it is the compression ratio changes faster with small changes in combustion chamber sizes as compression increases. But the higher compression engine is also more efficient than a lower compression engine, and may not need quench as much. I think the quench is more important on lower compressions 10 and below than 10 and up. With Aluminum rods the quench can change .050” or more cold versus hot. Blurr’s the lines defining quench. |
| The Following User Says Thank You to Jay S For This Useful Post: | ||
|
#4
12-13-2025, 09:18 AM
|
||||
|
||||
|
They vary a lot. The blocks typically are not anywhere near square at all so you get different deck height front to rear and side to side. Meaning a lot of the time the block is twisted. Even brand new blocks aren't square. I've got one right now that is about .014" different front to back on one side and back to front on the other side, meaning it's twisted. That doesn't sound like much but it does affect compression cylinder to cylinder going from 10.2 to 10.7 and everywhere in between.
That's a pretty big change and why I've always said it's important to deck and square up these blocks |
| The Following User Says Thank You to Formulajones For This Useful Post: | ||
|
#5
12-13-2025, 09:33 AM
|
||||
|
||||
|
Isn’t an ideal quench like around .040 ish? If I’m .035 in the hole and use a .045 head gasket isn’t that like .080 quench?
__________________
72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007 (cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD 1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.45 @ 88.1 mph on slippery street tires.Bad 2.19 60ft.Owned since 86' |
| The Following User Says Thank You to scott70 For This Useful Post: | ||
|
#6
12-13-2025, 11:44 AM
|
||||
|
||||
|
Quote:
|
| Reply |
| Thread Tools | |
| Display Modes | |
|
|
The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.
Hybrid Mode
