Blue head on Red block

[PeteR]

Hi,

I'm planning on a re-build in the near future and am considering fitting a blue head onto the ol' 186. I know the blue head doesn't "fit straight on" and some mods are necessary.....are these mods to the head or block? (or both ? :-/)

I was hoping to build up a blue head (with LPG in mind) and have it ready for when the block is refreshed.

Thanks for any advice,

Pete

[Jockster]

Hi Pete
I carried out several of these nodifications some years ago when my workshop was into modifying holden engines.
The modifications are done to the block, from memory, I think we drilled two extra water jacket holes at the back and one at the front. The easiest way is to sit a blue motor head gasket on the red block and drill wherever a water jacket on the gasket sits on the  the undrilled block face.

This modification always worked well, we usually fitted stellited valve seats and valves to the heads and used Lynx Manifolds with 400 Holley 2 barrel carbs and in most cases the original commodore cast headers without the EGR Flap.
Hope this helps
Jockster

[PeteR]

Thanks Jock!

Pete

[Chuck]

Hey Jockster, or any one else who may know
I'm considering putting a VK black head on a 186 red so that I am able to use the fuel injection set up and avoid the cost of an aftermarket injection kit (a few thousand $'s - ouch).
My questions are: is the head conversion as simple as the blue onto the red described above and, would I need to change the injector size as the VK motors are a 202 and mine is a 186 or would the computer automatically compensate for this?  Finally, would the cam need upgrading to suit fuel injection or would the standard be OK?
Any help would be greatly appreciated.
Cheers
Chuck

[gree]

hey chuck,

thought it was gonna be a no fuss rebuild? he he  

[Chuck]

Despite the best of intentions, any project can get a little more involved than originally planned, but I guess that is what always happens when you start mucking around with old Holdens.  Either that or I'm just a sucker for punishment  

[Jockster]

G'day Chuck
The fitting of the black head to red block is the same as for the blue motor head (a technical poiny here but the EFI heads are painted red anyway). As far as the injection system goes it all should be suitable, even better if you take the 186 out to 192. If I were to do this conversion myself I would opt for a Motec control system rather than the original Holden as the Motec unit is programable.
Cheers
Jockster

[Chuck]

Hey Jockster

Thanks very much for the advice.  Just to back track a little, what is the main advantage of putting a blue head on a 186, the reason I ask is because I can get one for free so I thought that if there were reasonable power gains it would be well worth the effort.  Also, if I was to do this, what inlet manifold and carbie would be the best way to go?

Cheers

Chuck

[Jockster]

Hi Chuck
The main advantage of the blue motor head is that it is a genuine 12 port head, whereas all of the red motor heads were siamesed ports, which are not as efficient, although they can be modified to be almost as good as a 12 port head, but it is an expensive exercise. If you use a blue head off of a 173 motor it is much higher compression ratio than the 202 head, so couuld caus detonation problems with the crap fuel we have these days.
We used to fit LJ XU-1 Intake valves on stellite seats with   dual valve springs and give the blue head a mild port job, which it responded well to. Back then we were restricted to using the standard VC manifold with a 350 Holley or Falcon (shudder) Weber adapted to it. I believe that there are now performance manifolds available through Redline.
Cheers
Jock

[Chuck]

Hey Jockster

Thanks again for the help, I am going to grab that blue head and give it a go.  Late last night I found a series of articles in Street Machine from early 2000 that talked about modifying a blue motor.  In that they compared the standard Varajet carbie against a Holley 350 and it turned out that the Holley robbed power (and from experience, probably had fairly poor fuel economy).  The article went on to say that the Varajet provided good economy and efficiency so I think that I will give it a go initally.  Do you think that I would need to re-jet it to suit the 186 or just leave it the way that is?

Thanks

Chuck

[Jockster]

Hi Chuck
Well I'm afraid I don't agree with Street Machine regarding Varajets, they are one of the worst carbies I have ever come across, but if you can find a good one, the standard jetting should be ok. As they are a 2 stage carby they would probably return marginally better economy (in theory) than a Holley which has both throats opening together. A better carby to use i if you want a two stage carby is thw weber off of an XE Falcon which will work ok with its standard jetting and is a brilliant carby...NOTE do not use the weber off of an XF as they are nowhere near as good.
As a point of interest I ran an XU-1 Torana as a Rally car for about 8 years, it was fitted with a blue motor head,
lynx manifold and 350 Holley (the triple strombergs gave too much problem in dusty rallies). It had good power spread through the whole rev range and would do a competitove 140 kilometre Rally (which is driving as hard as you can in every gear on half a tank of fuel and it was fitted with an inboard 10 gallon tank not the standar XU-1 25 gallon tank which reduced ground clearance. Most of the other rally cars (Datsun 1600's, 180B's, Rotary Mazda's etc, had to refuel at the halway mark, so the economy of the Holly in that case was very good.
Cheers
Jock

[Chuck]

Hey Jock

Thanks for the good oil on the Varajet, I was a bit unsure myself about the Street Machine article anyway.  I will take your advice and track down a holley and manifold.  Will let you know how it goes.

Cheers

Chuck

[nicko]

Holley have a very nice 320cfm unit now that is much Better suited to 6 cylinders,apparently they dont tend to flood like the 350's always do