The Yella Terra Heads For My Holden 308 Are Ready!

[@borismcfinnigan3430]

You don't look tired, you look beautiful.

[@petergill8819]

Good to see you love your old engines old school is good school

[@staceonwheels]

You're so right. I keep looking at LS engine bays and all that STUFF they need... just looks messy. Our old engines are zen.

[@diggingwithphasetech]

Ohh, they've come up real nice 👍

[@stuarterskine7745]

Fantastic, the heads look awesome Stace. Cant wait to hear it running, and also the cost so far will be great to see. Keep up the great work👍👍👍

[@staceonwheels]

Thanks mate... I'm working on the cost video... still waiting for a few last parts.

[@Shanes_Shed]

Heads are looking good!

[@jono7017]

Awesome work Stace. Can't wait to see the next vid. I've just pulled my 308 apart with yella terra heads , everything's looking good I just don't know whether it's worth renewing any internals before putting it back together. Can't wait to see the cost too! For very selfish purposes 😂

[@staceonwheels]

Snap... re the heads. You could always get a machine shop to take a look and do some testing? But you may still have to pull it down for that...?

[@craigritchie1933]

In reference to the welded accessories mounts, all you need to do is put the repaired head on the LH side so the mount is facing the firewall, thus unused. The earlier HT and HG Holden V8 heads didn't have accessory mounts on both ends of the heads , so if they were my heads, I'd cut off the damaged mount and flapper disc the area smooth , it's purely cosmetic thing. The cost for machine work and new parts have spiralled out of control in recent years 😢

[@staceonwheels]

Yeah you read my mind about the head orientation. I will give them a good clean and going to test valve clearance soon too, before finishing assembly.

[@glengrant3884]

SHINE BRIGHT STACE!💥🙌💪

[@staceonwheels]

🤣🤣🤣

[@ChrisArmstrong-ir3fg]

Nice !! Closed chamber heads will boost up the compression and give some good horses to a sleepy 308. I think it was around the wb and early commodores, Holden started painting their engines blue, You’ll have to get a ‘torquer’ intake manifold and cam , for a good tuff street combo, mouse

[@staceonwheels]

Hey mouse. I thought it was the pollution stuff that was the start of the blue 308, and I also think my HZ falls into that era. Will sort this problem out later though. With the flat top pistons, this 308 should get close to 10:1 compression which is probably all it needs. And the cam is as big as I'm prepared to go for this build. (did you see the cam video recently?) Intake manifold is the Performer, but that's easy enough to swap out later if I want to try the torquer - a few have suggested this to me, but I already have the Performer and got that cleaned up looking nice.

[@craigritchie1933]

ADR27A, thus, full pollution controlled engines started at the introduction of the HX's in 1977. Swapping from a Performer to a Torker will just shift the power curve upwards, if you were to gain, say, 10 hp at 6500rpm, you'll trade it for about 10 hp lose at around peak torque say 4500 rpm . It's hard to beat a Performer on a street driven car 🚗 .

[@staceonwheels]

The cam I have is gonna make it hard enough down low, I thought...? So yeah sounds like the performer is likely better for this build. But hey, it's all an experiment for me 😁

[@craigritchie1933]

@staceonwheels The camshaft you chose for the tonner has a 109 LSA . The tight LSA process higher cylinder pressure down low in the rev range than a wider LSA, however, it also chops the idle around. Once you Aget off idle and the cars moving, it'll produce strong torque numbers. 308's with standard size valve sizes require tighter LSA's than engines with larger L34 valves for best results ,a LSA of 109 is a good number for a standard stroke Holden V8 with L34 valves

[@staceonwheels]

@craigritchie1933 you are quite the fountain of useful knowledge! And I like how it helps justify my choices 🤣. So far, at least!!!

[@oo0Spyder0oo]

Exciting times for you, I can’t wait to start on the mechanics side and a change of scenery. Just did the floor and back panel today. The spray gun is great, I’ll be getting a smaller nozzle for it for when the body paint goes on. Not sure whether to go with a twin carb/manifold setup or a twin barrel Holley, more for asthmatics than performance really. First world problems!

[@staceonwheels]

To stay sane, I'm doing both engine and body in parallel! If you have the space, it works. How much carb can you get away with Spydey? (These engines seem to be notoriously over carbed by many guys...)

[@oo0Spyder0oo]

@@staceonwheels You multitasker you! 🙂 Well I could put triple webers on the 202, basically one carb per inlet, you get better performance and running if you can meter for every cylinder, but it costs heaps. It's around $3300 or so for a kit like that. I suspect a 350 holley on it will do the job, anything is better than the old stromberg.

[@staceonwheels]

Well you're inspiring me bow with Trixie's original 202... triple carbs look quite groovy. Go and splurge!! 🤣🤣🤣

[@craigritchie1933]

Yes , Yella Terra did machine the combustion chambers to unshroud the valves and to help equilize combustion chamber volumes. Port work by Yella Terra is minimal at best ,significant improvements in airflow can be achieved with some basic porting, especially on the short turn side

[@staceonwheels]

Ah, thanks for clarifying that about the machining! Tge intake ports at least show some porting but I'm no expert at judging how much.

[@craig8187]

YT 's basic valve unshroud and seat cut on these actually flow very well at moderate valve lifts even compared to some more fancy looking well ported heads. Dont be fooled, what YT do to these is far better than what a lot of "no so clued up porting folk manage to do", these will be perfectly fine for the job.

[@staceonwheels]

@craig8187 great to hear! I love the idea of them in any case. Retro performance.

[@craigritchie1933]

@craig8187 Back in the 1980s I owned a VB 5.0 4 speed car with the standard smallvalve heads,, it had a baby Wade 25 65 ,65 25 thus a 110 lobe separation angle, i, it had HM headers , twin 2 inch exhausts and nothing else of significance. In totally street trim running on 205 radial tyres, it ran easy 14.6's . The VC HSV cars of the time had Yella Terra heads , and many ran in the 16's over the 1/4 mile with some manual cars ran high 15's , With the introduction of the VK group A cars , HDT combined the yella Terra heads with a Crane 276 cam ( more lift and dura than my cam) plus a much better 955 intake manifold. A friend of mine owned one then and still does , it was a solid low 15's second car, and never outran my almost stock 308 Commodore. There's nothing wrong with Yella Terra heads however a 308 with properly ported small value heads in a true mildly cammed street car will outrun a big valve car . It doesn't seem like it could be true, but it's a fact.

[@craig8187]

@@craigritchie1933 i know what you are saying, but, you straight up had a better exhaust system than the factory hdt 308 cars of the era, the 955 intake yes better on a more modded setup destined for the track at higher average rpm and without the restrictive factory exhaust but on the road hdt cars the bigger cam(compared to that wade you mention which is a great road cam) bigger intake,( obviously used on road cars for homologation as a stock 4 barrel made no hp difference on tha road engine, ) bigger valve(lower velocity) then a restrictive exhaust made for a poorer performing engine. You had a great road combo, high flow velocity, good exhaust for the power level. Hdt did what they did to improve over a factory stock 308 and set the basic car up for homologation reasons. I agree the small valve 308 heads are great when combined with an appropriate cam and intake. Keep in mind that the cam being used in this combination is a near on copy of the Crane 286h , 108 lsa, 230@50 and in this scenario the larger valve is an absolute plus.

[@oo0Spyder0oo]

Hey Stace, I was putting the two air vents back into the plenum today and the passenger side one that gets the air from the firewall hole seems to be missing some joiner as I have about a 2 inch gap between the inlet and the firewall. Would you mind taking a look at yours and seeing what this part is please? It's the air vent duct with the wire that has the open/close slider on it. It's either a foam joiner or another plastic one. I just can't find it amongst my bits and pieces. I wanted to put the air ducts into place and place some sealer around them before welding the cowl into place. If I know what I'm looking for I might spot it. The Gregory's manual is hopeless, doesn't cover the air vents and ducting at all. Cheers

[@staceonwheels]

Will do what I can... as mine is in pieces too. Standby, it might take me a few days to get back to the shed.

[@staceonwheels]

Spydey I just had a look and I reckon there us a rubber seal that's needed but I cannot find it in my "passenger side vent" box. I will trawl through my notes in case I took a photo when I disassembled.

[@staceonwheels]

🤣🤣🤣🤣🤣 run off with mine!

[@oo0Spyder0oo]

@@staceonwheels Yay I found it! It was hiding under another part. Turns out it is a piece of foam, mine must have been hanging off and it had a split in it so it got thrown aside. It would have been glued to the air vent initially as I can see the crud still on that part. Simple visit to clark rubber or bunnies and grab another piece of foam to cut out a new one. I will get a thicker one to make it compress for a better seal as well. Phew! rare spares didn't have anything so I couldn't figure out why that was, it's just not worth their time and will be too cheap anyway. Yours may still have the foam attached, but easy to fix if yours was falling apart like mine.

[@staceonwheels]

@oo0Spyder0oo no mine doesn't have foam attached but I was just planning on doing exactly what you're doing! Thanks for updating.

[@erikleypoldt8275]

Is there a code or mark on the heads that tells you they are Yella Terra? I will check my 308. Thanks

[@staceonwheels]

No. YT apparentlytook stock heads from Holden back then and worked them. Given mine had YT valves in them and the same work done it's just our best assumption. My research suggests they didn't stamp their heads but have YT on the valves, and obviously larger valves.

[@craigritchie1933]

@staceonwheels Back in the day, you could head down to your local parts store and exhange your old heads for a set of fully reconditioned , big valve and painted yellow Yella Terra heads, as they were just exchanged used heads they don't have different. Eventually, because of, core shift, corrosion, previous machine work, or cracking eventually led to Yella Terra not being able to get good usable cores, so they stopped offering the service

[@staceonwheels]

@craigritchie1933 yeah I thought YT just worked Holden heads. I love the history and it's mostly why I was so excited to find these on my 308!

[@craigritchie1933]

@staceonwheels Yella Terra also produced a head for the 253 V8 Commodore cup cars, a race series backintheday , the heads had smaller 1.82 thou compared to the regular L34 sized 1.94 values innyour regular Yella Terra heads. The standard factory small value heads have a 1.76 intake value for comparison