v8 heads and inlet manifolds..explained

**ozbox** · 13-07-2010, 06:35 PM

these are a great point of confusion for many...there is three types of heads and 5 types of inlet manifolds and not all will interchange with each other..
for ease of explanation i am not going to get into the finer points of 253/308 valves etc..kiss principal is what im workin on here..

first... we have pre pollution heads for HQ HJ and 2 inlet manifolds which are 2 barrel and 4 barrel.
second.. we have what i will call red pollution for HX HZ and 2 inlet manifolds which are 2 barrel and 4 barrel.
third...we have blue motor pollution heads for WB and only 1 inlet manifold for wb and that is 4 barrel..

include black v8 commodore motors in anything i have to say about blue motors...ok..;)
i am also not going to get into injected heads and harrop manifolds..

all these heads will fit any of the v8s..its the matching of manifolds to heads that gets confusing for the unknowing.
blue heads stand alone for interchange...you got blue heads then you have to use 4 barrel blue inlet manifold...
more to come with pictures later this week...

**HK1837** · 13-07-2010, 07:08 PM

Originally Posted by ozbox

these are a great point of confusion for many...there is three types of heads and 5 types of inlet manifolds and not all will interchange with each other..
for ease of explanation i am not going to get into the finer points of 253/308 valves etc..kiss principal is what im workin on here..

first... we have pre pollution heads for HQ HJ and 2 inlet manifolds which are 2 barrel and 4 barrel.
second.. we have what i will call red pollution for HX HZ and 2 inlet manifolds which are 2 barrel and 4 barrel.
third...we have blue motor pollution heads for WB and only 1 inlet manifold for wb and that is 4 barrel..

include black v8 commodore motors in anything i have to say about blue motors...ok..;)
i am also not going to get into injected heads and harrop manifolds..

all these heads will fit any of the v8s..its the matching of manifolds to heads that gets confusing for the unknowing.
blue heads stand alone for interchange...you got blue heads then you have to use 4 barrel blue inlet manifold...
more to come with pictures later this week...

Edited to try to make it simpler as per Greg's post:

Greg, I think it's great to KISS it, but there are a few important things that people may need to know that may affect Sandman restorers at some stage:

HT-HG heads and manifold are different to HQ-HJ. Can interchange but differ significantly especially if wanting to fit air and steer in HQ-WB. A picture will fix this!

Some late HJ got HX heads and inlet manifolds just to confuse the issue! These should have ADR27A on the ADR plate.

I do think it is important that the "308's have bigger valves" myth needs to be put to bed once and for all!! Educate the restorers and the word will get around eventually.

**ozbox** · 21-07-2010, 08:15 PM

i will be getting back to this post as soon as i have the time to take pics ..:eek:

**adam perth** · 12-08-2010, 10:34 PM

Originally Posted by ozbox

i will be getting back to this post as soon as i have the time to take pics ..:eek:

i fly home next week and should actually have some spare time
i have a HT / HG 4 barrel inlet with a 281xxx part number, so that would make 6??
i have a pic of it.
here it is (edit)

**agr071** · 03-12-2010, 08:29 PM

In regards to heads:
The VN heads (that i currently have) don't use 2 bolt holes in the valley of the block. (usually has 2 short bolts).
So is it possible to run early heads on the motor and not use these 2 holes, or is there a specific reason for these 2 bolts?

**L31 Sandman** · 03-12-2010, 11:06 PM

You don't need those 2 bolts, throw them away! If you use those 2 bolts make sure you only tighten to first Nm level otherwise you break the thread away in the block. I know i broke my block. When I said to my engine builder OOPs, he just said throw the bolts away. That was a 400hp 308 in a Torana and never gave me grief, well no issues with the bolts not in anyway.:geegee:

**HK1837** · 04-12-2010, 07:15 AM

Originally Posted by adam perth

i fly home next week and should actually have some spare time
i have a HT / HG 4 barrel inlet with a 281xxx part number, so that would make 6??
i have a pic of it.
here it is (edit)

Adam is correct, HT and HG inlets are different to HQ-HJ but only by a hole for a heater hose - that is what the blank boss is on the water runner coming from the passenger's side front towards the thermostat. If you look in the picture you can just see the round boss above the thermostat cover. As this one isn't drilled it is a HQ-HJ or LH-6/76 LX manifold.