240z SCCA vintage race car, restoration

[AydinZ71]

1 hour ago, calZ said:

Right to the cage is how I prefer it, as long as the straps end up at horizontal or with the mount points lower than your shoulders. I'm sure both the harness manufacturer and the SCCA have specs for the acceptable range. You'll have to check for rubbing on the seat as well. 

oh good! Then I can cut this silly, thick, heavy plate out. You can see the bar is slightly below the seat pass-through, and my shoulders are slightly above. Sounds like that works! Here comes the cut-off wheel….

[clarkspeed]

To the cage is fine.

[AydinZ71]

@clarkspeed thanks friend  

[AydinZ71]

Hello friends,

 

Although I am working as fast as I can to get the EP car done, I have a few irons-in-the-fire for future long-lead projects that I’d like to chat about. One of them is a 3.0 L-series motor I am building at the moment. 
 

Since an EP motor (which I have a head for) is very narrowly specific, I wanted a motor that I could use for vintage racing (wider rules tolerance). My priorities for this motor is reliability/durability first, followed by power. 
 

I have the block at my local machine shop waiting on CP rods and pistons. They have already straightened the LD28 crank and checked the cylinder walls of the core. Il be shooting for a modest 87mm bore. 
 

I have a decent N42 core head with my porting magician, and I’m trying to settle on a manifold to match to.

 

I do have a call into VARA to get a better understanding of how I could be classed with SU’s, vs. triples, vs. EFI. Besides that, I wanted to get some feedback from the community before I settle on a manifold which is the prerequisite to having the head finished.

 

would love to hear your pro/con for these three options, and which option you would go with given my goals and priorities. 
 

1) DCOE racing carbs by OER (47mm)

2) Jenvey ITB manifold. I believe this is 50mm throttle, 40mm port-side and is intended to be port-matched.

3) conventional EFI manifold. I have a protuners model which was intended for a turbo build on the street car. 
 

Mon a personal level, I have zero experience with DCOE’s but have confidence in running/tuning EFI before a full dyno tune. 
 

looking forward to your thoughts! 

[Dat73z]

I don't have much to add, but since you'll likely be running at WOT most of the time and if it's an option in the budget OER is making the 50mm carbs again (they were NLA for years). The OER carbs are easy to set up and tune with the external and accessible pump stroke and float level adjustments, but once they're set you're not really messing with those parameters much anyways. Parts are also readily available but shipping from Japan has been expensive this past few years. 

[clarkspeed]

Whew, you will get as many opinions as there are assholes! I can throw in my experiences:

1. I have never run 50mm carbs, but others I know have struggled with tuning them. Could be their fault. 

2. We ran 45mm carbs on a 3L fairly well. 

3. Keep in mind that DCOE carbs have a neck down venturi to 34, 36, 38, etc. They need this to make vacuum.

4. A 40mm EFI ITB flows much more than a 40mm carb because of the venturi.

5. A 45mm or bigger ITB is not a good mix for the street. Like an on off switch. Fine for racing though.

6. I think most all the time a well tuned EFI system will make more hp and torque than carbs. Lots of posts in Hybrid on that. I don't have definite proof, but that has also been my experience. Even at WOT with same F/A ratio. I assume it is the venturi. Again no experience with 50 carbs.

7. I don't have much experience with single NA TB on ported Nissan EFI manifold in a race application. I have started to do it a few times. Would save a little money, but I can't believe it flows better than ITB's. Not sure a custom intake would flow better. Fine for turbo apps. ITB's have such a straight shot to the valve, they don't make any vacuum. You most likely can not run a map sensor with ITB's.

8. No experience with the Jenevy's. They look super cool. Maybe for future project. I use the TWM (borla).  The new Chinese stuff looks decent also.

9. You should port match what ever you end up with. The manifold is kind of independent to ITB's and carbs on head side.

10. Price? I don't know. EFI has gotten cheaper and carbs parts are expensive x 6. 

 

 

 

 

Edited April 27, 2022 by clarkspeed

[AydinZ71]

Thanks @clarkspeed ! 
 

I was already leaning towards EFI, but your assessment is is consistent with mine! Yep, it’s the manifold I need to settle on before the head can start porting since it needs to be matched and possibly indexed. You know Mike Yoes? He is doing the porting for me. 
 

I called VARA yesterday and the EFI/carb won’t effect the class. I’m already bumped to GTU for the 3.0. 
 

thanks again for all your support! 

[clarkspeed]

That's where I am at with the tube car. So I am maximizing all the other rules to compensate. I will run efi also, because I can. It will never compete with the 700hp monsters that show up in this class, but I plan to embarras a few people. And the monster cars don't show up for every race, so I have that also.

[AydinZ71]

On 4/26/2022 at 4:01 PM, Dat73z said:

I don't have much to add, but since you'll likely be running at WOT most of the time and if it's an option in the budget OER is making the 50mm carbs again (they were NLA for years). The OER carbs are easy to set up and tune with the external and accessible pump stroke and float level adjustments, but once they're set you're not really messing with those parameters much anyways. Parts are also readily available but shipping from Japan has been expensive this past few years. 

I chatted with my head builder about this. He and a few other experienced folks feel the 50mm DCOE’s are too big for a 3L L-series. Il ask them what the down-side is. It may be throttle response? You are correct that most of the time is spent at WOT (vs. partial throttle), but there is also a lot of off-throttle between shifts, braking, etc. the 50mm is also a big leap in price from the 47mm. Good point on the EFI cost vs. carbs. Definitely a reason I’m leaning EFI. 

@clarkspeed that makes a lot of sense. The motor would be swapped in-out of the EP car so it will be competitive, just not THAT competitive 😂. Widening the track a few more inches and running wider wheels would be some quick-fix improvements from EP. This all assumes I can drive worth a damn, which is yet to be seen. The local VARA president was super nice and we chatted quite a bit yesterday. Busting my ass to finish this damn thing. 

 

[Dat73z]

@AydinZ71 yeah outside of WOT it's going to come down to airspeed. I think the smallest venturis they make for the 50s is something like 40mm. Ime most of the bog at very low airspeeds you can make up for in the pump shot. With 47s and a 3.0 NA you would likely be running a 36-38mm venturi? Without a doubt you are going to get better control and performance with EFI. I was thinking you were considering carbs for some vintage racing class rules or something

[AydinZ71]

12 minutes ago, Dat73z said:

@AydinZ71 yeah outside of WOT it's going to come down to airspeed. I think the smallest venturis they make for the 50s is something like 40mm. Ime most of the bog at very low airspeeds you can make up for in the pump shot. With 47s and a 3.0 NA you would likely be running a 36-38mm venturi? Without a doubt you are going to get better control and performance with EFI. I was thinking you were considering carbs for some vintage racing class rules or something

ahh, gotcha. Yeah my head builder thinks the 50mm OER’s are too big for my needs but the Venturi orifice is definitely smaller than 50mm. I’m going to talk to him about the jenvey manifold now. 

[AydinZ71]

Ok, so I am sold on EFI ITB’s. Now, who’s to buy. It looks like OER sells a set for $2100, and of course Jenvey. Y’all have any experience with either, and any opinions you can share? Any other alternatives? 

[ihavearustedz]

Whitley tune. 

 

https://www.whitleytune.com/sports-injection

[AydinZ71]

Beautiful! Same price range as the Jenvey and OER 😕 New Zeeland. I wonder if anyone is state side. 

[AydinZ71]

On 4/24/2022 at 7:04 PM, calZ said:

Right to the cage is how I prefer it, as long as the straps end up at horizontal or with the mount points lower than your shoulders. I'm sure both the harness manufacturer and the SCCA have specs for the acceptable range. You'll have to check for rubbing on the seat as well. 

i realized I never thanked you for your input! I removed the old bolting plate and palm to mount straight to the roll bar. Thanks!! 

[AydinZ71]

Updates:

 

- replaced PO’s cage welds. Confirmed with SCCA that grinding the welds is acceptable as long as a filet remains. 
 

- added cage attachment points to the door jam and unibody near the roof. 
 

-continuing to remove finish and prepare for primer

 

-will be completing the body (filler, sanding) prior to painting the interior so I don’t need to mask it off. 
 

- quarter panel window (polycarb) mounts replaced and OEM lap joints stitch-welded and ground. 
 

-another nearly 3lbs removed from the chassis 

[AydinZ71]

PS: updates on the 3L…

 

I went with the Jenvey ITB’s. Configured on their website direct from UK. I called Datsun spirit to ask them a few questions about the ITB they listen on their website but I could not justify the value-add purchasing through them. It seemed they were adding their margin while I could source their supplied parts on my own. 
 

spoke to my shop working on the block today. They will be attempting a longer rod geometry and departing from the OEM pin height. I will share the final specs if y’all are interested. 

[clarkspeed]

21 hours ago, AydinZ71 said:

PS: updates on the 3L…

 

I went with the Jenvey ITB’s. Configured on their website direct from UK. I called Datsun spirit to ask them a few questions about the ITB they listen on their website but I could not justify the value-add purchasing through them. It seemed they were adding their margin while I could source their supplied parts on my own. 
 

spoke to my shop working on the block today. They will be attempting a longer rod geometry and departing from the OEM pin height. I will share the final specs if y’all are interested. 

Yes, do tell.

[AydinZ71]

Cool 😎il share as soon as my machine shop and CP have settled on them. I went with Mountune here in socal for the block. I liked that they were local and do both modern Race engines for Honda, and thier bread-and-butter are cosworth racing engines. The head is with Mike Yoes up near Antioch. Il have Mountune do the final fitup and mark my adjustable cam sprocket so I can disassemble the motor at home without having to “dial in” each time.

 

im curious how much of bottom cylinder wall they will need to eyebrow, but that happens to be the thickest spot when we checked wall thickness, especially on the thrust sides.

[AydinZ71]

Hi all! 

Asking for advice from you race car folks out there. 

 

1) Did you perform your own bodywork? If so, can you describe your process briefly? I have several spots on body where I gouged out with a. Wire wheel because rust had penetrated through the finish or the finish had cracked. Did you remove any of the factory leading? I have tried, but it’s not easy and quite messy (not to mention toxic). Knowing Gracie cars get banged-up, I don’t want to over-do-it as if it were a Street car. 

 

2) if you are running an L-series, what size exhaust are you running? I got a great deal on a bunch of 2.75” 16-gauge 316L tubing which I planned to use, but I know many folks run 3”. Ideally I’d like the same exhaust to work for my 2.4L EP motor and the upcoming 3L. The header certainly has the capacity with 1-5/8” runners and two 2-1/4” collectors. 
 

3) I’d really like to get this guy as quiet as possible so I can tune it at home without the neighbors calling our friendly blue uniforms. I plan to terminate with a burns stainless unit, but would it help to run a resonator as well? 
 

4) I planned on using standard undercoating (asphalt) over the DTM 2K epoxy primer in my wheel wells. Assumed this would be more durable than paint plus clear, and only marginally heavier. My floor pans are done this way now. 
 

5) have you ever had (or almost had) something break-off, pull-off, or otherwise deform at speed? I have my eye on the hood, but curious if anything else has caused you trouble. 100-120mph is not unheard or at willow springs.