My Other Project...

[mysticj]

I decide to play with and build up a SOHC head. Why? Its the challenge I suppose: lack of domestic cam choice, springs and retainers, & head flow. The pictures above are 4G69 valve springs which are a different design to allow higher lift without binding. Seat pressure are the same as the 4G64/6G7x springs. The retainer is an aluminum magnesium alloy from Ferrea, which is much lighter than the stock retainernand the OE valve lockers do fit without modifications.

Waiting on a few things to come through such as the cylinder head w/cam so I can send the cam out to be reground from a very well known cam company. Stay tuned for updates.

[Silvertune]

Oh come now. You don't really think the masses will recognize more than maybe one of those springs. ;)

A domestic spring source is nice but it still doesn't make cams any easier to get.

[mysticj]

Oh come now. You don't really think the masses will recognize more than maybe one of those springs. ;)

A domestic spring source is nice but it still doesn't make cams any easier to get.

True. I guess I should update the first post. LOL

[keith6110]

Interesting, Sohc really needs some researching and documentation.

I wonder how much difference a lighter retainer would actually make...

[mysticj]

Interesting, Sohc really needs some researching and documentation.

I wonder how much difference a lighter retainer would actually make...

The Ferrea retainer is 0.1oz, the 4G69 exhaust spring is 1.2oz, the intake spring is 1.4oz. The SOHC spring is 2.0oz. The stock retainer is around 1.5oz

Going to remeasure in grams to really show the difference.

[keith6110]

Holy crap, that's quite the difference in retainer weight!

So you're saying the stock retainer weighs more than the intake spring? I definitely don't remember the spring being lighter than the retainer on my brothers 4g63 build.

[mysticj]

Holy crap, that's quite the difference in retainer weight!

So you're saying the stock retainer weighs more than the intake spring? I definitely don't remember the spring being lighter than the retainer on my brothers 4g63 build.

Oh crap! Typo, the stock weighs less than the 4G69 valve springs, somewhere around 1oz not 1.5oz. Still, I though the stock retainer were light compare to a stock 4G63 or 2JZ retainer. I'll post some pictures tomorrow on the letter scale.

[mysticj]

Stock retainer


Ferrea Aluminum retainer


Stock valve spring


4G69 Intake valve spring


4G69 Exhaust valve spring

[keith6110]

ohhh nice, Thanks for the pics!

About .9 oz difference with the 4g69 (intake/exhaust avg 1.3oz) and Ferrea retainer combination or 40% lighter!

[mysticj]

ohhh nice, Thanks for the pics!

About .9 oz difference with the 4g69 (intake/exhaust avg 1.3oz) and Ferrea retainer combination or 40% lighter!

The thing that bugs me the most is that the 4G64/6G72 valve springs are use in the 6G75. Same installed height, same valve guide. Only the valve length are the different for the 6G75, like 0.5 to 1mm shorter than the 4G64/6G72 yet it have the same seat pressure and rocker arm ratio. Perhaps different lifters?

[mysticj]

7G intake side oil drain casting pt1


7G intake side oil drain casting pt2. Going to have an issue with the aluminum retainer as it is too wide.


7G exhaust side bolt hole casting. There is room, just going to shave the area down a little.




8G exhaust side. Again there is clearance like the 7G exhaust side. Just shave a little off for a piece of mind.

There is no clearance issue with the the 24V SOHC heads. Also there are no spark plug tube or rocker arms interference with either SOHC heads with the aluminim retainer.

[Silvertune]

The thing that bugs me the most is that the 4G64/6G72 valve springs are use in the 6G75. Same installed height, same valve guide. Only the valve length are the different for the 6G75, like 0.5 to 1mm shorter than the 4G64/6G72 yet it have the same seat pressure and rocker arm ratio. Perhaps different lifters?

The valves are shorter because the chamber is deeper. Everything from the tip of the guide and above is identical in terms of depth.

When mits designed the 75 they took the second gen 24v heads and made the valves as big as they could without losing performance. To do that they had to move the valves further apart (which is why you can't mismatch heads/rockers) and the chambers were made far deeper resulting in the slightly shorter valves also. Otherwise the geometry is the same.

[mysticj]

The valves are shorter because the chamber is deeper. Everything from the tip of the guide and above is identical in terms of depth.

When mits designed the 75 they took the second gen 24v heads and made the valves as big as they could without losing performance. To do that they had to move the valves further apart (which is why you can't mismatch heads/rockers) and the chambers were made far deeper resulting in the slightly shorter valves also. Otherwise the geometry is the same.

Good one, Justin! I forgot about the larger compression chamber on the 6G75 heads.

[mysticj]

I hope I have luck finding these locally...Solid rocker arms.

[Ivory8g]

Omg! Look at those things! Beefy

Sent from my HTC6500LVW using Tapatalk

[oakrdrs187]

And have valve adjustment.

[99galantES]

Theres someone in PR that sells them.

[Silvertune]

What problems have you faced with the hydraulic units?

[mysticj]

What problems have you faced with the hydraulic units?

None. I have not heard of a HLA failing on a SOHC but I like to have options, options are always good. Too bad these guys won't work in a 6G75.

[mysticj]

Think I am going to try using the 4G69 intake valves on the head with lash caps to make up the difference between the valve tip and lifter.