6 replies to this topic

[slar]

Hi to all the engine gurus out there, I would like some help with a couple of sets of 308 heads that I got given for my rebuild.

The following are 2 separate sets of heads.

 

First of all the casting numbers for the heads are, head 1 (2812174) and head 2 (7449033) can some on tell me what these are off.

Secondly head 1's valve set up is a little unusual as its not standard and not l34 spec, intake valve is 1.93 inches and exhaust is 1.47 inches this makes it half standard and half l34.

What is this combination good for and is it a normal setup.

Thirdly head 2 valve set up is equally unusual, intake valve is 1.85 inches and exhaust is 1.60 so this head has a large exhaust valve but the intake is not l34 spec but larger than standard.

What is this set up good for.

Im confused lol

 

Now there are a couple of other things as well, if you look at the following pictures you will see head 1 has had the combustion chambers relieved near the exhaust valve although the valve is standard and head 2 has no relief but has a large exhaust valve. Whats the purpose of this?

 

And the rocker gear off head 1 is not standard its been changed to 7/16 studs with adjustable rocker pivots, single post for each rocker.

Head 2 was running standard rocker set up.

 

Ok thanks for letting me confuse you all but some answers to the above would be nice if any one knows what its all about.

Cheers

Al

 

 

 

 

 

 

 

[slar]

Anybody ?

[yel327]

The 7449033 head is a HT-HG Holden V8 head, the 2812174 head is a HQ-HJ, LH-6/76 LX Holden V8 head. The 744 head will be missing an accessory hole on each end of the head so no good for HQ-HJ cars with A/C and/or power steering.

[TerrA LX]

Oversized valves are fitted at service time if a seat can not be reclaimed by normal cutting (it will go too deep) so they cut the seat wider and fit a larger valve.

 

In the above cases it seems that someone has saved some money each way, one set replacing the inlets and one set replacing the exhaust.

 

FWIW 1.94 is the standard size for the L34 (more over the later large valve head) 308.

[slar]

Ok thanks for the info people.

Do you think head 1 (the relieved head) would be a good head to have the exhaust valve machined out to 1.6 inch l34 spec as it already has a 1.94 intake or head 2 to have the intake valve machined out to 1.94 inch l34 spec instead of what's in it now (1.85). as it already has a 1.6 exhaust valve.

 

Both heads are in reasonable condition however I've just noticed head 2 has bronze valve guides and I'm wondering if they can be replaced.

Or should I just recon head 1 the one with the machined relief and leave valve sizes the way they are.

 

I've read somewhere that a large intake valve with a small exhaust valve will give the engine a lot of low rpm torque is this true as I would like my engine to have low to mid torque as this car isn't going to be a top end racer but ide like to have a bit of punch from a standing start. Also depending on my cam choice of course.

 

Sorry for all the questions but I'm a little unsure on this one.

Thank you

cheers

Al