Most amazing thing I ever rode in was a 2L Birkin seven copy. Congrats. I will live vicariously through your updates.

 

Scooter has not been forgotten, but I've had to spend a fair amount of time getting the se7en in order. Only a couple more projects to complete (and Nate's RX7) before I can switch to the OS Giken and spherical swap. The machinist said he would be working on the block and head this week, and they should be receiving a few shims to measure initial lash before I make a full order of them. Should get some updates on the engine in the next couple of weeks though.

 

It's cool how you guys have some experiences with se7ens too! I hadn't seen or heard about them until I moved to New Mexico in 2017/2018. Birkins can be as good as Caterhams as far as I can tell and sometimes use the same engines. I consider a 180-200hp (any 2L) se7en a fast car. A lively, eager to slide, fast car.

 

Things are happening. Will have an update soon...

 

Caterham things?

 

Haha there has been a lot of that. I’ve been keeping track of that on usa7s
https://usa7s.net/ips/topic/15975-ch...-caterham-svt/

tomorrow I should have Scooter updates

 

Went to pick up the short block and head today. Got the rundown of what they did and he told me how he wanted me to brake in the motor etc. He didn’t have any concerns with how it all went together and I opted to keep the oil squirters. Bearing tolerances are on the loose side and I’m to run Valvoline VR1 20w-50 after the break in miles. They also did the least amount of head skimming and block decking as possible per my
request, which he said was basically nill.

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0.0


:(


:,(

Unfortunately I just found this small nick right where the fire ring sits. We don’t know how it happened, but the shop is going to inspect and fix the issue. Gotta make some time next week to take it back to ‘em. Small setback but it’ll be ok.

So for now I’m going to clean up the garage, organize and start ordering the tools I’ll need to measure the clearances and the final compression ratio.

 

Maybe this is the universe telling you to do an LFX swap

Is the shop going to charge you to fix it?

 

I’ve told myself it’ll go back to a stock motor if this doesn’t work out.

and they indicated it’s all covered. No extra charge

 

Can't believe you'd betray us all and join a second forum Jk, I'll have to scope your thread on there once I catch up on all my daily reads here haha.

Bummer about the nick in the head. What did they propose as a fix? Just weld a tiny bead on there and resurface the whole thing again?

 

That’s what they said. Hopefully that’s all it takes to get it fixed

 

I'm glad your turnaround was so much faster than mine! Can't wait to hear it sing.

 

Thanks, Option. I do feel relieved about that so far. I’m glad your car is a runner again though, aside from all the setbacks.

I went to the machine shop today, and they worked on the head right away. In the end they decided not to weld it and machine it down instead. It cleaned up well, and although the hole is still there it is negligible and was told to send it, so send it I shall.



Before machining, the head measured at the very top of the “new” head spec and it is now at the very bottom of the head spec. It measured 52cc of chamber volume. Total skimming was 0.009” or 0.010”, so basically stock as I hoped for this stage. Between the minor skimming, the pistons ~0.020 down in the whole (from the lower compression height of the Supertechs), and a 0.040” head gasket, I think it’ll be fine clearance wise but will still check. It’ll also probably be 10.7:1 compression, but I’ll do that math later once I take proper measurements of the piston to deck height.

Now gotta get off the gaming chair and work on this thing

 

Took measurements of the deck clearance and it measured 0.019" +- 0.001" accounting for my caliper's error. Right at the expected number based on the Supertech's having less deck height than stock. Plugging the numbers in the compression formulas:

Head volume: 52cc
Dome: 10.5cc
Deck clearance: 0.019
Head gasket: 0.040"

We get.....10.5:1 compression.... Rekt by deck clearance + head gasket thickness. But we're not done yet. I'm going to measure the clearances with the 0.040 MLS gasket and a stock 0.030" gasket. If the clearance measures out with the stock gasket I can get a Cometic in that thickness to bump compression to 10.8:1, which is closer to the goal.

 

Good good. Sounds like experienced shop guys. Loose bearings are correct for highly stressed, high RPM turbo engines. I also used that oil sometimes.

 

Good to hear! My only slight concern with 20w-50 is on the days when I start it at or near freezing temperatures, which happens often here. I wonder if Chafers 5w-50 might do well on those days but I’m nowhere near starting to think about this yet.

Tonight I spent a little while acclimating to what’s going on. I put on the head studs and slapped the head on it but didn’t torque it. I put on the oil pump and water pump, and timed it. Fiddled with the Maruha exhaust cam some, and then gave it a few turns and everything felt smooth! Starting to get a bit excited about this. Friday I’m going to do the putty check with both head gaskets with the intake sprocket 3 teeth advanced. Base on what I’ve read around here and that should simulate full VVT advance. I may also try opening my spare phaser and see if I can move it easier that way. Since the exhaust is now adjustable I think I’ll also play with that some too.

 

20w-50 will require an extended warm-up near freezing at startup. Never go into boost regardless of the oil, even in the summer, without being fully up to operating temperature. We frankly shouldn't put any load on an engine until warm, even in the paddock or heading up the street.

There's a chart of wear versus engine temperature produced by an engine manufacturer I've seen previously that shows a dramatic curve below 180*F.

Schaeffer has some fantastic oils.

The first number will be the base oil cold weight and the second number will be the weight at operating temperature. Bear in mind that the wider the gulf between those two numbers, the greater than number of long chain polymers added to the oil to extend the thickness range. Those polymers break down through mechanical action over time. Therefore, you will need to replace that oil slightly sooner or it might get thinner as you put hours on the engine.

I don't think the Schaeffer is a bad idea. Just always be fully warm before stressing the components.

 

Yes.

I have posted several times that my engine builder said that 80*c was the minimum OT before more than idling/low revs were to be used. His concern was for the cam lobes, the cams were aggressive high lift spec, and they could/would suffer lobe damage if not lubed well. That is why I used the Laminova oil/coolant heat exchanger, primarily to warm the oil after an open trailer ride to the circuit in freezing temperatures. In those conditions it was the only way I could get to 80* in the paddock prior to the first event/session, the Laminova made it easy and fast just idling.

I'll get off my hobby horse now ...

 

Valvoline sells VR1 in other weights. It's just not what is carried in most FLAPS. I ordered a 5w30 VR1 from Amazon a few months ago.

 

And I mix 5W-30 and 20W-50 VR1 to make my own 12.5W-40 blend. I'm a freak though, probably not at all necessary.