This project started when I moved to Santz Cruz mid-pandemic and realized I could turn right out of my driveway and go 45 miles up Hwy 1 without any traffic lights.

I had a 914 that was a track only car, and I had finally ticked off the bucket list driving a Porsche at Laguna Seca in early 2021. I realized I would have more fun, more often if I could drive it up the coast. Besides, I still have a historic IMSA 914 to restore (build thread on that one will finallycome once this one is complete), so it was time to move one on.

I decided to sell my daily driver Miata and the 914 race car so I could find a really nice 4 cylinder chassis to convert to a six. Having had a couple of projects stall for years due to paint and body issues, I wanted something with a nice body, and the mechanicals weren't a critical factor, since I intended to upgrade the engine, transmission, suspension, and brakes.

In October 2021, found this 3 owner, one repaint in original color Gemini blue 1972 914 on craigslist in Colorado Springs. It even has a build date of 11/71, so we were both about to turn 50. I had a PPI done at a local shop and they said it was "as rust free as any they had seen", and while the engine was tired, it ran and drove well enough. So I took the gamble to flyout one-way to make the purchase and drive it back.

This was my first moment seeing the car in person.
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It was the time of year where the Aspens are turning so I decided to take the scenic route US Hwy 50 until it joins with I70 and then turn south on I15 through Las Vegas.

The climb up over Monarch Pass (11,300ft) was tenuous, but the little engine that could made it over in 2nd gear at about 45mph near the crest. The views along this route were spectacular, and once on the flats it would cruise comforably at 80+.

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I am in to follow this cool project !
Antoine

Ultimately the car proved more reliable than I did, and it made it the 12 hour drive from Salida to Las Vegas without any trouble, arriving at my room at 9:14pm:) I spent an extra night to get my leg to stop cramping. On the second morning, I felt much better and I was ready to finish the 8 hours back to Santa Cruz.

The route also took me past Arvin, a town named for my great grandfather who helped develop irrigation systems for the farmers around Bakersfield.

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Once home, the little Gemini hibernated in my garage at home for over a year while I got the workshop cleaned up and the white race car sold.

I debated for a while about just using the 2.8L engine from the white race car for this build, but ultimately decided that the modifications to make it streetable would be too much and I really wanted to build a fresh engine.

With the white car finally gone in July this year, I was able to get Gemini on the lift to actually see what I was in for. Underneath the car lived up to the PPI's claim, it really is remarkably straight and rust free. The only problem spot being very minor, where the driverside jacking donut had been ripped off its welds by a parking block at some point, something the previous owner had mentioned too. The hell hole area is completely intact.

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Up top, the body and paint are in great shape for a car I want to be able to drive and I am so excited to have such a great looking car to build on. The driver side trunk hinge has broken loose as they do.

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By the end of July, I had the old tired 1.7l and tailshifter removed.

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I didn't make any more progress in August, but I did find an uber rare set of early ATS 7x15s in Germany and they finally arrived. These wheels are my favorite style on a 914 and the 33mm offset makes them an easier fit than 7" fuchs (23.3mm offset)

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In September, my engine case returned from Ollie's, so I decided to build the engine before continuing with more chassis prep.

The specs for the engine are:
2.5L short-stroke (2464cc)
7R mag case
66mm CW crank
2.0 rods with ARP bolts
89mm Mahle motorsports pistons and cylinders
2.4 MFI cylinder heads with 38mm ports intake and exhaust
Eibach valve springs with Ti retainers
Elgin 306/288 cams with 102LCA (Mod-S plus)
Twin-plug crank fire ignition
TWM 46mm throttle bodies
Autronic SMC sequential injection

This combination should be in the 220-250hp range @7500rpm
And still be able to run on pump gas.

But first I had to prepare the space, and make sure all the parts are actually here.

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Work got crazy again and it was November before I actually started any assembly.

Rods weighed and matched in pairs. They are all within 1gm, and pairs are within 0.1gm.
ARP bolts tightened to stretch spec.

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Looks great so far. As always let me know if I can help in anyway

I like where you are going with this……

We are all going to enjoy watching this build come together.

Thanks for the encouragement everyone! I've enjoyed and been inspired by reading so many other build threads here. I am glad to finally contribute one:)

I was certain I would make a bunch more progress over Thanskgiving, but was thwarted by a missing ($0.75) dowel pin for the #8 main bearing. Doh!

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The following weekend, I had the missing dowel pin (plus a couple extra for the spares bin, I won't be stopped by that one next time:)

Bottom end is together now, boy does that feel good!

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With this post we've caught up to the present, the day before Christmas I made a little more progress and got a few more things added to the case.

Breather cover, thermostat, oil pressure sender, oil pressure relief valves, and half of the new head studs are on now, height set at 135mm. I have the whole week off, so I'm going to post again at the end of the day with more!

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Great thread……I like your method of suspending timing chains and rods…..
Could you comment on that for possible use.
Curious as to what head studs you used.

I like build threads!

Gemini blue is rare, especially on a 914. Looks great!

I didn't fully read, looked at the pic and thought, damn, that looks a lot like Colorado Springs! Then I looked closer and saw my friends place, Chiba Bar in the background. Small world, cool project.

The owner must have had it a long time as we haven't had those emissions stickers here for decades..

When I saw the plumbing strap I was getting worried, then a few pics later it was clear. Good idea.

Great build thread! I will be watching your progress. I'm doing pretty much the same thing with my car. Keep posting your progress.

Haha yeah the straps are only needed while you put the 2nd case half over. The factory tools look nicer, but the pipe strap is stiff enough to keep things steady, but flexible enough to pull out of the way when you're done. Just cut to length and bend into shape until things are held steady BEFORE you start applying the various sealants:) I made this set when I built my last motor and was smart/crazy enough to keep it around.

I'm just using new factory stock steel headstuds $8 each at the dealer. The case has casesaver inserts in all those locations now. All the fancy aftermarket studs are just steel anyway, so they dont change the force on the mag case the way Dilavar does. Yes my cylinders are nikasil, but the case savers should do the trick.

The other one for the astute observers I didn't mention before are the NOS made in Western Germany Glyco main and rod bearings in the old style square red boxes. There was a bad batch of Glyco rod bearings made in S.Africa and its hard to tell sometimes for sure what you will get online. If I had to buy new rod bearings I'd get the AA Clevites, but I collected these NOS bearings over the years.

Very cool thread! I'm super envious of your work space.

--DD

Got a great question from @sixnotfour in a PM.
I figure deserved to be posted for everyone...



Yes, common practice is to change the pump to 4 rib when the oil bypass mod is done. Which reroutes oil that was being dumped into the sump when pressure is too high, back into the inlet of the pump. The 4 rib pump increases the pressure pump side, but it also reduces the scavenge side.

This 3 rib pump went to Glen Yee for his rebuild and blueprinting process, so while it doesn't have the enlarged pressure side of later pumps, it should be able to maintain plenty of pressure just fine, and still has the early larger scavenge side, which will help keep oil out of the sump at high RPM.

This engine will not be lugged around in traffic, it's meant to spin:)

https://www.glennyeemotorsports.com/gt1_oilpumps.html

I'm basing this engine and the overall build concept on the factory's 1971-72 911 "ST" 2.5 short stroke engine type 911/73.

The case is actually a rare small spigot 7R, originally from a 73.5 911T sportomatic, probably the least stressed, but strongest mag case possible, and was in great condition before I sent it to Ollie's. I was originally going to stick with the max piston that would fit in the small bore, but when this set of Mahle 89s showed up, I couldn't resist, so the case did get bored for the larger cylinder, but the low stress life it lived was the main reason I decided to go ahead with this case instead of using one of the 2.7 7R cases that would have been run harder and hotter with the larger displacement and all the emissions stuff.

I went a little smaller on the ports, since the factory race motor had 41mm intake/exhaust. Coupled with the Elgin cam, it should make much better low end torque, but still make power up to 8K rpm. I don't plan to spin it that high all the time for longevity's sake:)

I'll post pics of the pistons and heads and the CC'ing process soon.
Compression ratio will be 9.5:1 and with the cams chosen will still have higher dynamic compression ratio than the 2.7RS did with 8.5:1 pistons and S cams. The EFI and twin plugs will allow me to not worry about detonation with crappy CA 91 octane gas.

Oh man, building my dream 2.4 SS motor with EFI.

Seeing all those parts laid out nice and organized and ready to go is motivating!!

I have most of the parts and a decent set of cases, just gotta clear up some projects and get off my butt and get it going.

Thanks for posting this great project. There is something about driver quality hot rods with great motors and sound mechanicals that hit the sweet spot for me!!

Thanks! 100% agree about driver hot rods, it's what they are for after all!

Finished the head studs today. It's remarkable how long it can take to do what seems simple at first look. Every one of mine got quite difficult around 138mm. I needed to chase them all with a bolt and they were still pretty tight for the last two full rotations, but I prefer that over loose.

Also got the chain ramps installed.

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Thanks Dave, it's my happy place for sure! Here's a top down shot.

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Look good Dug!
Can't wait to visit and drive the beast

When u see the big numbers to build one of these engines you gotta remember that there really are a lot of time consuming repetitive multiple tasks - all of those head studs, case through bolts with nuts and washers and o rings, all of those rocker shafts, rockers and seals, individual cylinders, individual heads etc etc etc

Even if you have your stuff together and you have done it all before, it just takes a bunch of time.

Sounds like a nice build. I have a recently built long stroke 2.5 ( 70.4mm x 86mm) with JE pistons 9.8 final compression. Heads are ported with 36mm intake 35mm exhaust. Cams are Elgin MOD S. I am using Zenith 40TIN carbs with 36mm venturi and all the jets and air correcters changed.
I am also planning on building a short stroke 2.5 on another case I have as well as a higher power 2.7. You might want to consider bigger cams based on your RPM goal.
Below is dyno of my 2.5 and a 2.7 both with Elgin Mod S cams in the same car and same gear for testing. Here is also a link to several other motors with dyno charts I have built in the last couple years.

https://forums.pelicanparts.com/porsche-911...-2-4l-2-5l.html


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As you can see from the dyno runs the Elgin MOD S cam makes great mid range but is pretty much done by 6500 RPM. The MOD S cam is also nice because you can use stock springs and retainers. I am planning a larger cam for my 2.5 short stroke and 2.7 builds, probably DC 43 or DC 60. These will require aftermarket springs and retainers but should rev higher.


https://www.drcamshafts.com/911profiles.htm

john

Hi John,
Thanks for the detail on your builds and sharing your dyno results. I agree the Mod-S cam is a bit tame, but thats not what I'm using. The Elgin 306/288 (he used to call it "Mod-S plus" in his old catalog) has more duration than a Mod-S and DC43, closer to a DC60, but with a little less lift. Elgin shared a dyno sheet for a 2.2 race engine that made power up to 8K.

Cam specs are
Elgin 306/288. Int / Exh
Duration @.050" 262 / 249
Lift. .475" / .450"

Today I got to do the super fun task of epoxying the case plugs. It was cold and rainy so it was taking forever to set. Meanwhile I got to unwrap the exciting parts like the freshly replated cylinders from LN Engineering, the pistons and the twin-plugged and ported heads. I was getting ready to check the ring end gaps, when I realized I had cut my thumb pretty deep taking the first ring off with my thumbs instead of using the tool like a smart person. Those rings are sharp! I was cleaning the rings off and thought the red residue was from the Marvel Mystery oil I had used to cc the pistons, but it was everywhere?!?

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Speaking of red stuff, here are some pics of CC'ing the heads and piston dome volume when I did that last year. Notice in the first pic of the head, that I forgot to prime the tip of the burette, don't forget to do this, or you'll be off by a couple cc.

Heads measure 68cc
Piston dome is 25.6cc
With 1mm deck height, this will give me 9.45:1 compression ratio
We'll see tomorrow how close I can get to that with the 0.50 and 0.25 base shims I have.

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Looks like a super fun project and it's giving me inspiration to potentially try rebuilding my 2.7 on my own someday (oil leak). Love the color! FWIW I have DC42 cams with 38mm intake/34mm exhaust ports and Weber 46s; peak power's at 7500 but midrange torque is plenty for street driving. Pretty extensive work on heads including AASCO springs & retainers.

What a great progress, thanks for sharing !
Bests
Antoine

Its truly inspirational to see such expert and meticulous work, way beyond my limited 4 cylinder experience. Thanks for your posts, and keep them coming!

Great pictures of the Southwest and your build.

Looks like this conversion is going to be very nicely done. Looking forward to watching it come to fruition. I’m also doing a six conversion but will be farming out the engine build as I don’t have the expertise. Super jealous of your work space and knowledge. Sounds like you live in north Santa Cruz. I’m close by in Capitola area.

Today I removed all the rings from the pistons and cleaned them, then started cleaning pistons just to get the ring lands nice and clean, but then got carried away trying to remove all the carbon build up on the domes. Then I forgot to take a picture even showing one of them.

But I did get around to setting up the degree wheel and I almost started torquing the flywheel bolts when I remembered I got a new digital crank angle sensor I haven't used yet. Setup TDC with the dial gauge. Its really nice to have both the big degree wheel and the more precise angle sensor. I didn't trust it until I could see it repeat the result on the big wheel, but it really does remember the zero point when it powers off.

Checked ring gaps on cylinder #1 and then reinstalled rings and assembled the first cylinder with an 0.50mm shim (from Ollie's for the decking) plus a std 0.25mm shim from the gasket set. Measured deck height with caliper at four points around piston as about 0.70mm.

Looks like I'll need a 1mm shim instead (or I could stack another 0.25), but since I need to order them anyway, might as well get the 1mm. Which should put final deck height at 0.95mm, and eek my compression ratio up to 9.5:1.

Tomorrow I will add another 0.25 shim and then check piston to head clearance in a few spots with some clay.

Then while I wait for the new shims to arrive, I will have time to remove the spray bar plugs from the cam housing and clean the cam spray bars.


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Thanks for the update & pictures, enjoying watching your progress. BTW, I love the ATS wheels, they will look great on a 914.

Nice Dug. I totally understand the thought behind buying a decent car over doing a full resto. I am doing the same with my 911- a build 2 sell one approach.

As you know I fully agree with the ATS choice as well….. looking at getting mine widened.

Looking forward to seeing this progress!

Pete

Finished cleaning pistons and ordered 1mm shims from Autohaus AZ today.
Didn't get to stacking shims and checking pistons to head clearance today, hopefully tomorrow.


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Great looking build, I am yet to try a /6, but might be coming but maybe not.

Thanks for posting, myself as I am sure many will be following

Yesterday I decided I wanted to knock the sharp edges down on the pistons. I just did this by hand with some 220 grit followed by 400. First pic has the before in the background and after in front. It's a subtle change, but reduces hot spots on the sharp edges and the radius at the crown can have a noticable impact on power according to the pros.

Then I gave them all one last scrub with a stiff brush in hot soapy water to make sure all the abrasives were rinsed off thoroughly.

Then I repeated the deck height check on #4, but with 2 of the 0.50mm shims stacked. It looked perfect at 0.91mm. Then I added the clay and bolted on a head, and spun through a couple of revolutions. The squished clay measured between 1.1 and 1.2mm so we're good to go.

And the 1mm shims arrived already! I ordered them Thurs night with standard shipping, they shipped Friday and arrived Sat! So today I will get to actually install all 6 pistons and cylinders for good:)

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Back to weekends only now that work started up again. At least I have an extra day tomorrow:)

Two weeks ago I was all ready to assemble pistons and cylinders after shims arrived quicker than expected, and then I broke an oil ring. Doh! On the bright side I'm glad in broke on the bench and not in the engine.

Had to wait until Tues Jan 2 to try my luck finding a replacement for an unobtanium set of 89mm pistons. LN Engineering informed me that Mahle doesn't stock this ring set any more, but told me to talk to Total Seal. The tech at Total Seal was super helpful and tracked down the parts for 3 piece nikasil compatible oil rings with non-chrome rails. Not cheap, but they were in stock and shipped the next day. Bonus feature they are 5gm lighter. They arrived last week and I got all the end gaps checked, assembled and compressed into the cylinders.

Today I finished installing pistons and cylinders with 1mm shims and new total seal 3 piece oil rings. Then attached the cylinder cooling tins, an easy to forget step because the heads are so exciting and you just want to put them on once the cylinders are on, but fortunately I have a good friend who made that mistake already and reminded me:)

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Looks great and no corners cut there.

Thanks Ben!

Nicely done, Sir!

I'm envious of your big degree wheel!

I want one but Google didn't help...

Big ones are much easier to use IMO!