OST-070: 7AGE for an N2 Levin

[oldeskewltoy]

(08-29-2020 09:26 PM)Vaptor Wrote:  The Exhaust gasket you are using here, what specific model is it, and from what company?

The gasket was a collaboration between myself, and SV3* (before they closed). Essentially it is a Blacktop gasket(35mm port exit), that fits both 16V and 20V heads. It also has slightly "adjusted"(.020" down) bolt holes, for better port alignment.


* - http://sv3power.com/_p=939/

unfortunately it is no longer available - (35mm sold out)... although I am trying to see if they will make more.

I do know they do have about 8 of these gaskets remaining designed for full Atlantic ports - 38mm


35mm under 38mm




now 3 down.......


chambers....




and exhaust ports....




more to come.....

[oldeskewltoy]

Bowl #8... as it transitions from stock to oversize




a different perspective.... on the transition





head is now ready for the new seats to be cut......





more to come...

[Vaptor]

Love the details

As I am going to use a TVS supercharger 900 or 1320 on my build, with High Lift cams, I was commended to go with 38mm (37mm) Exhaust port.
Do you perhaps know if the 38mm gasket is a 1:1 copy of an TODA gasket?

Just to compare what the local tuner recommends compared to your work, What diameter did you get the new bovls machined to?

I think I read somewhere, that you use some old SR20 valves, when doing the chambers, is this correct? Is there a certain size valve that you use, or is it the same size, as the oversize 4age valves IN32mm EX28mm?

Oversize valve work, is new to me. so hope that I can drain you for some knowledge

[oldeskewltoy]

(09-12-2020 09:16 PM)Vaptor Wrote:  Love the details

As I am going to use a TVS supercharger 900 or 1320 on my build, with High Lift cams, I was commended to go with 38mm (37mm) Exhaust port.
Do you perhaps know if the 38mm gasket is a 1:1 copy of an TODA gasket?

Just to compare what the local tuner recommends compared to your work, What diameter did you get the new bovls machined to?

I think I read somewhere, that you use some old SR20 valves, when doing the chambers, is this correct? Is there a certain size valve that you use, or is it the same size, as the oversize 4age valves IN32mm EX28mm?

Oversize valve work, is new to me. so hope that I can drain you for some knowledge

1) copy of Toda - nope... ours is "better" ... because we took into account the gasket drop, so we adjusted ours .020" (bolt holes down, or if you prefer ports up)

2) the bowl/seat diameter (32mm/27.5mm) will be different depending on how much lift you are running.... under .350" lift - keep seat/bowl to 85%, over .400" lift - 88%

I have used other valves to protect seats when I've done the chamber work in the past - when I have machined seat to protect, in this case the seats haven't been cut, so I didn't need to protect them.


the pistons finally arrived....




more to come.....

[oldeskewltoy]

So... While this is going into an N2 replica, it is being fitted with timing covers to protect the timing belt, and to keep the cam seal retainers*. This requires some fabrication, as there never was a 7AGE, so the timing covers don't readily fit. Additionally, an idler is being added to the long side to eliminate belt slap.

* - not many realize that the rear timing cover is also used to keep the cam seals firmly in the head

Essentially this is a 2 part job - part one, build the foundational parts(rear cover), part two - make a filler panel.



So the rear cover is cut so that it can be lengthened, in this case it was also the area that was needing clearance for the idler.



Note that the "clocking" of the bottom section has changed slightly... this is do to fitting this to a 7A block, as well as keeping the middle timing cover lower exhaust side mount correctly positioned.

This type of work is easier done when using the block and head, while a jig could be made, this is easier.... but if a "production" version were to be made, a jig would likely be better.


So this is what needs to be done to build a 7AG rear timing cover....




with all the mods performed...... (sans refinishing)





and side by side.....




more to come.....

[banpei]

Nice work!
But it's a lot of work to keep it "stock"

[oldeskewltoy]

(09-23-2020 09:27 PM)banpei Wrote:  Nice work!
But it's a lot of work to keep it "stock"

Not stock..... but part of the requirement on this job.....



over coming "challenges"......

oldeskewltoy Wrote:Essentially this is a 2 part job - part one, build the foundational parts(rear cover), part two - make a filler panel.

So, the filler panel would need to be light, and strong, and easily shaped - that would hold its shape.





Aided by CAD (cardboard aided design).......





and the preliminary fabricated filler panel






So.... besides the timing cover challenge, there were a few other "challenges" we had to overcome....

1) the pressure plate (needed to balance the rotational assembly) never showed.... - lost in transit... so the process of reporting it, and tracing it, and finally getting another.....

AND....

2) overcoming the "wrong" rods...... for some reason this set of 7AG Saenz rods were not machined for Toyota bearings.....



This set of rods were somehow machined for Nissan SR20 rod bearings - where the tang sits further out then the Toyota bearing tang does.... the correct set of ACL bearings.... and all the rods are now @ .0017"


More to come........

[Vaptor]

Love the details

Newer thought about the timing cover needed to be modded, but makes sense when the timing belt needs to be longer in order to fit an 7age
Luckily I got a lot of those plates and covers to mod myself.

Thanks for this detailed build tread

[oldeskewltoy]

A quick look at the "new" bottom end before it gets closed up.... can you spot any new balancing??





So with the proper head gasket on order, some of the details need further planning...


For one... what to do with a smallport head drain on an engine that didn't have a receptacle for the drain..... so a bit of work to be done on the MRP oil pan.....




Adding a new bung.... and a bit of a trim to the flange - partially to look good, but also to allow a full parameter weld - this bung is not going to leak as it is welded on the inside, and the outside..





Also, as this is a 7A, the MRP pan needs a small spacer to keep the rods away from the internal windage tray.



I have found that when closing up the bottom end, that stacking, could just be stock pan, and windage tray, or this combination - spacer and MRP pan, that using some dowels really helps keep things cleaned (fewer FIPG fingers) and easier to assemble




more to come....

[oldeskewltoy]

Cometic delivered a new .023" (their thinnest) head gasket.... (the deck on this engine was .012" down)

making sure it is installed correctly...




If installed incorrectly the red circles are where the oil drains would be...


As you see, this build is using the ARP head stud kit...... torqued to 60 pounds



with the slightly shorter stud in the distributor location




more to come.........