202 mods

[Bas NZ]

Stayed with Holden, twin throt of Torana, Bas

[able]

i had my red 173 high compression head (to go on my 202) in getting what it needed to run straight gas but it turns out it has been plug welded and is a no go'er... (would have been nice as i got it for free)

i was searching around the wreckers and no one had a spare 173 high comp but one had a 186 high compression red head.

now.... it looked to me that the only difference between the 173 and the 186 high compression heads was that the 186 had adjustable valves.... the rest looked identical.

is this the case??? and does anyone know if the push rod lengths are different if im using this head on a 202.   

[MaTTe]

i still recommend getting in contact with your local HQ racing club, for the price you'll get a much better head if you can find one 45cc or less. Most people wont go to the effort to dish their pistons to be able to use a head under 45cc, and a 186 head is well more than 45cc i'd say. I'd say the same for a 173 head, high compression head or not, they still have more metal on them than a race head does, and a race head is open chamber design.
Your pistons wont be above the deck most likely, so you wont have a massive compression, but depending on where your pistons are, you should be able to get 9:1-11:1 fairly easily.
With a 45cc head and pistons 17thou above the deck we have about 11.5:1. With a 36.5cc head we were able to achieve 14:1.
On gas 11:1 is fine, thats about where my van is with the 350, we run 98octane with 11.5:1 and have run 98octane on 12.5:1, but we have the carb and distributor specifically tuned for it, and the motor is always pulling and revving, a street car wouldn't be as happy on 98..
But even if you have to pay $200 for an ex race head, it will have had things done to help it that no street head would even consider having done, and these things will help you in ways you'll never know.

There are plenty of things you can do to make a race head even better, but we're not allowed to do them, so an ex race head on the street has alot of potential in the hands of a GOOD machinist.
I'm tempted to buy a hq to run around the streets, as they have aLOT of potential, i'd even buy a beddy and drop a 202 in it, and make an animal out of it.. 
a bit of food for thought.

[Rothu]

You'll see what I'm running from my tag at the bottom of my post. It has heaps of grunt and unbelievable torque. And it has never been more efficient!

The pushrods for all the red, blue, black engines are the same 230mm. You can get hardened pushrods for $70 off ebay.

[able]

did you get the hardened valve seats rothu?

im told you will get 50 thousand or less out of the head if you don't with lpg..

230mm for all... good news indeed.

[ben]

my old man got 20 thou out of a 253 on gas with no hardened valves. and he drives like a grandpa!!!!

[able]

yep ben... it just melts them.

[Rothu]

Luckily the reconditioned 173 head had new stainless valve seats. Otherwise I would've got them inserted. So no problems on gas!  Make sure you bleed the hydraulic lifters as well!

[John Abbott]

I got this motor a couple of weeks ago and was wondering am i right to say that it has a 12 port head on? And if so, is this going to make the engine breathe a bit better for a slight performance upgrade?


 

[able]

looks like a standard red head to me.