Draw through Baja build

[Maddward]

Well I finally finished up my baja draw through setup and now have some time to post. I lurk and read daily and have gained so much knowledge off everybody on here and STF I figured I have contribute back. And I hope this does.

It started out N/A and undercarbed with some Weber 34ICT's. The engine ran good before but, as it always goes, I want more
Video is pre-turbo

Link


I've had a carbon sealed AiResearch T3 50 trim in my garage for the last 5 years and decided to finally use it on this car. The Engine is a 94x69 with a W120 cam, 40x35 heads, 1.1 rockers on solid shafts, and 8.8:1 compression. The transmission is a 002 built by transaxle engineering with weddle internals. 3x3 arms, 930 cv's and 300m axles. I'm running charlynn powersteering too.

This is the engine before I started

So I started by taking off the exhaust to measure cylinders 1&4 top exhaust stud to stud and gave the measurement to CarCraft for my header. Mine was 19 3/4". CarCraft actually had a coated one in stock my size so I bought it. The fit was pretty good but i did have to open up the flange holes on cylinder #2 about .020" so it slid on easy.

Then I bought 2 weber sidedrafts, a 45dcoe and a 48spo/2, Rajay turbo, heated manifold, and intake manifold off craigslist. I wanted the 45dcoe and manifolds so I went through the 48 and sold it here on the Samba, and the Rajay had just been rebuilt so I sold that here too. Funny is that I actually made $50 on the deal and kept what I wanted. To get it up and running I rebuilt the carb and set it up as follows thanks to help from Madmike!
30mm vents, 50F8 idle jets, 180 main jets(biggest I had to start with and now 160's) 170 airs, F16 E-tubes, 250 needle,0 exhaust jet, and 45 pump jets drilled out to 70's.
For ignition I just drilled and tapped a 6-32 thread in the weight stop on a spare 009 I had in the garage. I was able to adjust the screw to get my timing to 10 deg at idle and 24 deg full advance. This is just a starting point and I'm sure I'll be tweaking this later.

For the turbo oil feed I bought a 1/8npt to 3an fitting with a .065" through hole and put it in a brass T fitting where the oil pressure outlet goes. I'm using a 3/8npt to 1/2 ID barb fitting to drain into a fuel pump block off plate I had. It drains pretty good.
I'm using a 38mm turbosmart wastegate with a 7lb spring and I bought from CB Performance. I also bought a cnc'd top and check valve from pacific customs to make my holley 12-804 regulator boost referenced. I know it's not needed per say but I read and was told that the float bowl in the sidedraft can empty pretty fast at WOT so this will help fill it faster while under boost.

I bought a 5 bolt and wastegate flange from ATP turbo and fabbed my own exhaust. Then coated it with VHT flameproof in the can and baked it as the directions said too. It looks pretty good actually, but not as good as the header! I plumbed my full flow oil lines through the manifold and hooked up my old AEM failsafe wideband. I buttoned it all up last Saturday and this is how she sits now.

And here is a video of it idling and a quick 1st-3rd gear pull. I'm getting a full 7psi of boost but still need to come down a little on the mains I think. I saw 9.8:1 to low 10's on the gauge.
What do you guys think my target WOT afr should be?
I always shoot for 12.7:1 on a NA engine but this turbo is a new ballgame for me. Please excuse the shaky video

Link

[kangaboy]

Good job, looks cool.
I think 11:1 - 12:1 is a good target for your 8psi. Clone will chime in, as he as been down the carbed boost path before...beware, he will try to sell you on FI
As far as timing, what are you running? Locked 009 @ 24°? This is the one thing that I haven't been able to get my head around. A locked distributor...just doesn't jive well in my head.
_________________
-74 Standard - "CaliBug" 2084T, MS3X w/FI and Crank Fire
-76 Westy - "Gandalf"
-18 GTI SE

[Maddward]

Thanks!
I tapped and added a set screw in the weight stop of a spare 009 to "Limit" my travel not lock it. Right now it's limited to 14 degrees total travel. Idle is set at 10 degrees and it swings to 24 at full advance, the weight now hits the screw instead of the stop.

[Maddward]

I forgot to mention that I also had to modify my power steering pulley because the lower section of the belt now hit the turbo header. So I machined a counterbore on the backside of the pulley to locate it on the alternator shaft. Then I machined a new longer alternator bolt to hold both pulleys together.

Then I bolted it together and transfer punched the existing roll pin hole on the power steering pulley to the outer alternator pulley half. I used a longer roll pin and now they're locked together when bolted. And I can still use factory shims to adjust the alternator belt tension. The power steering pump is adjustable so belt tension is set by that.

[oprn]

[Maddward]

Exactly. Locked at 24*... have fun trying to start a hot engine with that timing

[madmike]

Hey Cody, Thanks,Glad I could help,, I try
"Gear reduction starter" turns over my 2276 w/ locked dizzy just fine
well it doesn't have to turn it long as it motor firers up instantly ,I barely touch the throttle even after sitting for weeks at a time,, can't do that with my DCOE
_________________
'Black Ice'Drag Buggy 'Turbo'
Rail Buggy 1915 turbo
76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works"

[Krochus]

I limited my 009 on my blow through (was in my draw through) simply by bending the limit tab for the secondary weight. Mines running quite well with only 10 degrees of advance all in at 25 idle at 15

It’s still pretty ghetto though. I’m going to order a black box this weekend and just tig weld my advance into place to lock it.


I’m my opinion every 009 even in NA application should have the timing limited so that idle would be around 10-15 degrees. They’d have a much better reputation

[oprn]

Brigs and Stratton, Tecumseh and many aircraft and tractor engines are set up with fixed spark advance but they all have a very limited RPM range that they run in. I don't know but I suspect this idea came from the drag strip where again, RPMs are limited to flat out. Set it to what works best at the top end - that is where it will spend all it's time anyway. And if it works on the strip it must be best for everyone - right?


I can't help but think that for street use you would be throwing away a lot of drivablity and fuel economy running with a locked timing. As for starting an engine at 24*, if your CR is low enough or your engine is worn badly I can see it working. Henry Ford even found it was nessisary to put a retard lever on the model T or it would launch the guy on the starter crank into orbit!


I would challenge you locked timing guys to try running a proper advance curve and see the difference.

[Maddward]

My plan was/is to eventually run a CB black box too. I'll be spending the majority of my time cruising this in the desert and the occasional trip around town. It won't be seeing a drag strip...well at least not a concrete one, so I want drivability over flat out performance.

Krochus please let us know how the black box install goes! You might make me buy one faster

And again thanks Madmike! I can't believe the difference between the ICT carbs and now the turbo with only 7psi. I still have a huge grin on my face

[Bugsy61]

[Maddward]

I have a pertronix SVDA too but my 45 dcoe doesnt have any ported vacuum spots. Well it does have these dimpled locations next to the progression ports that look like they were centerdrilled already in preparation for it??? Anybody have advice on this?

[clonebug]

It’s a little more of a challenge to get boost retard on a distributor with a draw through setup due to the carb reference port not seeing boost.
_________________

[Bugsy61]

What happens is that as the throttle opens wider, ported vacuum goes away, so you lose whatever you gained in ported vacuum advance, and end up at 24 degrees, or whatever your initial and limited centrifugal advance adds up to. So no retard is needed.

[Krochus]

[oprn]

Great discussion and some good input from practical real life experience!

If the engine is basically stock there is no need to change anything in the advance curve or timing settings as long as the boost is at a low level, depending on the individual engine that would be up to the 6 to 7 psi range. As pointed out above the extra vacuum advance comes off automatically once the throttle opens past a certain point anyway whether it is under boost or not so that is not an issue. You can forget about it as it takes care of itself.


Also there is no need to limit the total centrifugal advance to 24* unless you are above 6 psi or so or have modified the engine to a higher compression ratio. That is when to start to retard the spark and yes doing it digitally really takes the tinkering out of the process. I wish that had been available back when I did mine!

[oprn]

[Krochus]

From an engine safety standpoint you are correct Oprn.

However from a performance standpoint leaving the timing alone sucks.

In my experience with two engines the difference in the way boost comes on with the timing set at 25 ish vs 32 even at lower boost levels is night and day. At 32 even with a small AR ratio on the hot side will be laggy and struggle to make boost. Back that timing down and the engine will get punchy and the boost will come on early and hard.

This is why mechanical systems, vacuum retard or even boost based boxes kinda suck. You want that timing to retard way back BEFORE you make boost. Because when you do you can make boost much faster.

[Maddward]

So having a SVDA hooked up to ported vacuum would only help with drive ability at low speed and cruise. And gas mileage if you were actually concerned with it? Now, could a SVDA vacuum can push the timing retarded when boost comes on? That would make it a little more interesting...

I’m sill wanting to get a black box but I had 3 spare 009s in the garage so I used one to get me going.

Can the black box retard timing before it sees boost? I do understand that retarded timing helps built boost and that’s why they have a 2 step option

[Krochus]