240psi is a ton of cylinder pressure unless the cylinder walls were wet with oil like after a fresh rebuild.

It's worth noting that the car would have to have been spec'd to run some sort of race fuel with single plugs and very high cylinder pressures. This would mean that if you're running 93 octane, you're probably knocking and the pre-detonation is the cause of the high temps. The jetting would also be for the race fuel and that would lead to the poor running at certain RPM and tip-in.

Since I dont know anything about the inside of the motor its impossible to know what the compression numbers are, without bore/stroke and chamber cc. but its a lot.
Ive taken to putting about half a tank of 100 oct in it to try to knock back any chance of it detonating
I am considering pulling the motor down and checking it out and while im at it twin plugging it, just not sure whats the best way to do that.
I also want to sort out the suspension, I have brakes sorted out thanks to PMB and some pelican members.
Its going to be Late S calipers up front and some fresh new rears with all new soft lines and brand new master cyl.

The over heating is largely in check now thanks to the working thermostats and 3.2L cooler as well as a electric fan on a thermostat.

Heres some crappy video from last night of the car up and running.

https://www.youtube.com/watch?v=W8igflj0MhI

Did a leak down with a porsche engine builder friend and the leak down numbers are not good so we may be pulling it out this weekend.
Might uncover some of the mystery's of this motor.
other than that i am just collecting bits to put on the car.
bilstein front struts, late s calipers, and some new control arm bushings. oh also adjustable spring plates and shocks all around.

So not so long ago this happened.
It was in effort to find out what was going on with this motor not ever wanting to run right.
http://forums.pelicanparts.com/uploa...1560468315.jpg

"So my car seems to have difficulty going into 5th/Reverse."

Start in reverse; instead of in 1st. Because of the catch protecting reverse it is the tightest position. Put trans in reverse, shifter in reverse, loosen rear coupler. Now move the shifter around while staying in reverse. You should feel the motion limits forward and back and side to side. Sort of defines a rectangle? Place the shifter in the middle of this box and tighten the coupler. Now shift into 1st. Is it good? If it's too short to slide into 1st, go back to reverse, loosen the coupler and pick a spot in the rectangle a little closer/forward to neutral. Test again. Likewise, if the shifter won't move left enough to reach 1st, pick a location a little more to the left in the rectangle. When finished, the shifter should not be pressed against any of the walls of the rectangle, nor should it "trapped" in 1st. If those two opposite corners are good, everything else will be also.

This assumes all the bushings are in decent shape.

well were way past that now.... I did replace all the bushings when i bought the car.
motor is torn down to the case going to hopefully split the case tomorrow.
turns out it was 11:1 on single plug and 3.3L

Should I even keep updating this?
 

So here is where I am at currently.
As of right now we have learned the motor was set up like this.
70.4 crank
100mm pistons that were a 105mm bore in register
11:1 compression
single plug
Solex center oiler cams
and SC oil pump.
heads are from a 80 that have been ported to 40mm ports.
The bores have some pitting pistons measure out good
crank looks good

So what this tells me is no matter what it was never going to run correctly on 11:1 and single plug.
It was a weird choice to go with solex cams and 46mm carbs.
Also 3 bearing rather than the 4 bearing it came with.
So we are getting a plan together to get the motor back together and working properly.


http://forums.pelicanparts.com/uploa...1560709611.jpg
http://forums.pelicanparts.com/uploa...1560709611.jpg
http://forums.pelicanparts.com/uploa...1560709611.jpg
http://forums.pelicanparts.com/uploa...1560709611.jpg
http://forums.pelicanparts.com/uploa...1560709611.jpg
http://forums.pelicanparts.com/uploa...1560709611.jpg
http://forums.pelicanparts.com/uploa...1560709611.jpg
http://forums.pelicanparts.com/uploa...1560709611.jpg

How did you determine the 11-1 CR? I don't see a lot of dome on those pistons.

By CC'ing the combustion chamber and then doing some extensive math.
The person helping me is/was a Engine builder for PMNA and was trained in Germany by a well known engine builder so I am extremely lucky to have him as a friend and guide on this engine build.

http://forums.pelicanparts.com/uploa...1560714365.jpg
http://forums.pelicanparts.com/uploa...1560714365.jpg

58cc for the combustion chamber is probably not correct, if that is what is shown there.

SC heads usually are 90cc.

If you post your deck height and piston dome volume, someone here can verify your CR.

58cc is what the chamber measures out at with the piston at TDC because of the dome.
Using this information and a few other measurements is how we established the compression ratio.
I am certain we are correct.
The pistons are a 11.5:1 mahle Motorsport kit. So with the spacers under the cyls as we found it supports our conclusion.

Maybe show a pic of the combustion chamber and a side view of the piston? They sure look flat, but maybe it's the angle.

Sounds like a fun basis, short stroke 3.3 and 11:1.

Ill post a picture of the pistons tomorrow.
the cyls are already out at EBS to get re finished.

Obviously you have it figured out. I just don't understand how you arrive at a 11:1 CR with a piston dome of 30ml. What am I missing?

I mean I posted the math?

That is what I don't understand. How do you arrive at 55.726? Is that your combustion chamber and your deck volume? Your combustion chamber is 58? Then to that you should add the deck volume. So how do you get 55.726?

CR = swept volume +deck height volume + combustion chamber volume / deck height volume +combustion chamber volume.

Your swept volume is 552 and combustion chamber volume is 58 . So how do you arrive at 55.726? What is your deck volume? Looks like 2.274?

2.274 should be added to 58, not subtracted, right? Must have been a very small deck height BTW.

Should be something like 9.5 or 10-1 CR?

https://www.kfz-tech.de/Biblio/Formelsammlung/Verdichtungsverhaeltnis.htm

Is what we used, the 55 came from the volume of the cyl with the piston at tdc and the combustion chamber combo filled.

anyway. Moving on from that.
I have since checked fit on the 964 pump we plan on adding.

We did discover the car had as i mentioned before 1965 Solex center oil cams
They do have some damage to them, we plan on not using them because for the compression/size of the motor its not optimal.
The new cam will be coming from Elgin
Id like to sell these off to someone but with the damage I dont know what they are worth.
http://forums.pelicanparts.com/uploa...1561677450.jpg
http://forums.pelicanparts.com/uploa...1561677530.jpg
http://forums.pelicanparts.com/uploa...1561677600.jpg

I also have the nuts and parts needed to fasten them to the sprockets.

With that being said I do need a pair of 4 bearing large bearing cam towers.
If anyone has a pair they would like to part with that would be awesome.
Means I can sell my two pairs of small 3 bearing cam towers.
Did anyone ever mention the cost of the rebuild on these motors adds up?
Cause is currently clean.



http://forums.pelicanparts.com/uploa...1561677630.jpg
http://forums.pelicanparts.com/uploa...1561677630.jpg

Not going to hurt my brain with the math for CR but those pistons do not look anything like 11:1 compression pistons. There isn't enough metal above the deck to be high compression. They look lower CR than standard 8.5:1 early 3.0 pistons.

http://forums.pelicanparts.com/uploa...1485907319.jpg

Left is 8.5:1 and right is 9.3:1

Regarding your brakes - Did you have a vacuum source for your booster hooked up? With the carbs, i'd assume that you would have a large vacuum hose going to cyl #2 intake manifold for the booster. If you didn't, might explain why they feel so weak.

Keep in mind the much larger bore means you need less dome to create the compression
Also note when we compression tested it it was in the 240 psi range supporting our assessment that it was in fact 10.9 to be exact.

Also as it being a 76 it was a pre boosted car so it has manual brakes.
Since I swapped the rear brakes and pads its gotten much better, I anticipate it being perfectly fine once i put the late S calipers on my car it will be fine.

Not much to update cams have showed up to replace the ones i have as well as the rockers re finished.
going to a 4 bearing large journal cam.

http://forums.pelicanparts.com/uploa...1576453887.jpg

Well its fixed and back together, I did the gearbox also.

Now that it's twin plug, any need for race fuel?

So far no, the compression is slightly lower at 10.3:1 we found the deck clearance on the motor as it was assembled to be somewhat questionable.
I also changed from the Solex cams that generate a ton of midrange cyl pressure to create torque to something that makes peak torque a little later.
That said I only have 100 miles on it so far and am shifting at 4k but its plenty torquey.

I do want to do some other odds and ends for clean up but the name of the game right now is to get miles on the motor and get it broken in.
I also swapped to bilstein front uprights and S calipers up front, new master cyl because this one was old.
I was going to put adjustable spring plates on it but I have never changed them and I need this car on the road after 7 months I did not want to have it turn into a bigger project than it needed to be.

Only updates I have made is i replaced my Fuel pressure regulator and pump with a much better pump and regulator.

http://forums.pelicanparts.com/uploa...1591736988.jpg

Bought the aeromotive version as I often use this on a lot of the race cars i maintain.
the holly units just do not hold up in my experience.

now I am looking for some new front sport seats and working on re finishing the front trunk.
And I cleaned up the sun roof mechanism.

http://forums.pelicanparts.com/uploa...1591737047.jpg
http://forums.pelicanparts.com/uploa...1591737047.jpg
http://forums.pelicanparts.com/uploa...1591737047.jpg

Oh and I bought a heat shrink printer to number my plug wires, Seemed like a really handy thing to do at the time.

http://forums.pelicanparts.com/uploa...1591737116.jpg

And since everything seemed to be going ok and I was able to turn my attention to the bottom of the car. Obviously at some point this car was dragged over something pretty serious and it will in the future need some floor pan repair. I decided that the sway bar that was ripped off needed to be replaced.
The way to do that was buy a factory rear and some parts from restoration design, I cut off the destroyed mounts and re welded some new ones on and got the bar mounted.
its certainly made the car much easier to rotate and power slide. I may at some point make changes to the suspension but this was a nice affordable fix that I am pretty happy with.
I could keep posting updates but I don't know if anyone seems super interested.

http://forums.pelicanparts.com/uploa...1591737277.jpg
http://forums.pelicanparts.com/uploa...1591737277.jpg
http://forums.pelicanparts.com/uploa...1591737277.jpg

You'd be surprised who all watches these threads.
Sometimes you generate a lot of comments, sometimes you don't.
No reason to not keep sharing. Adding to the vast pool of knowledge here is never a bad thing.

Same. I like your engine build, seems like it was over before it started.

:)

Sent from my Nokia 7.1 using Tapatalk

I do have more involved pictures of the engine build, I can post them up. same with the trans build.

Keep posting. Im doing my sunroof and those two photos help a ton on my 83 unit. Thanks!

Please do!

Specifically I'm interested in the cylinders used; were those 964/993 cylinders, 3.2/3.0 cylinders bored to 100mm, or new nickies made to size? Was cylinder stud spacing changed?

What cam did you end up with?

Best,
Dan

my sig. may help

LOL we know each other from Instagram. The reason for the sunroof being pulled apart was to replace the seal. If you get stuck doing yours let me know.

The cyls were Mahle motor sport and the case had to be cut to fit them. They were a weird and rare kit they sold back in the day its very hard to find now but from what I have seen they are 6 to 8k
No cyl stud spacing change. And I would never ever use nickies.

http://forums.pelicanparts.com/uploa...1594407492.jpg
http://forums.pelicanparts.com/uploa...1594407492.jpg

as requested here is the cam specs

Very cool I've never heard of a mahle kit bigger than 98mm. Do you mind saying more about nickies? I don't know of other options for big cylinders, never heard of a problem with nickies.

Sent from my Nokia 7.1 using Tapatalk

I just welded in the solid Elephant sway bar mounts as my rather obnoxiously large rear Tarrett sway bar snatched the stock ones right off of the chassis.

Your thread is fun to follow. Keep posting.

Just been driving it a bunch,

Started doing rust repair on the passenger side door.
Id like to get a set of better exhaust for it.
the thinking is either the larger SSI Style heat exchangers for quite a bit of money Or doing a header with a heater box. Not a ton of great data on larger high performance motor exhausts with dyno testing. I know that the GT3 muffler is the way to go but I just dont like that look on a old car.

Current exhaust sounds like this.
https://www.youtube.com/watch?v=GB_GmX6LKE4


Another thing I was considering was going to a boxster caliper but jury is still out on that one. Currently I have Late S calipers up front and standard rears but the fronts leak a bit and its a little annoying.
Other than that its just find some correct year sport seats if possible.
Oh and what I really need is a new e brake lever for in the car, some great ape bent mine to death before I got the car. http://forums.pelicanparts.com/uploa...1641011012.jpg
http://forums.pelicanparts.com/uploa...1641011012.jpg


Ive been gearing up to build my 914 a 6 cyl motor so that will be next.
I also bought 944 that while nice is not for me. so that will be for sale soon.

So originally I mentioned that the transmission had some bad habits, Originally I did the linkage bushings and adjusted the clutch then adjusted up the shift linkage. It was a bit better but still not quite right.
That being said this thread never did do a great job of the amount of time I spent waiting on things during the engine build. Ultimately it took around 7 months of having the motor scattered to the wind. The heads even went to Germany to have hoeing motorsport do the machine work. They are also known as Wicked Sixes.
Regardless of the reasons it for the delays it caused me to open up the trans and just see what we had on our hands.

Ultimately, I found that we had some broken parts and worn out teeth.
I started with throwing the entire thing in our parts cleaner. Under rated tool right there.

http://forums.pelicanparts.com/uploa...1660787412.jpg

During the disassembly part the main shaft nut was found to be hand tight, Nothing good about that.

http://forums.pelicanparts.com/uploa...1660787412.jpg

turns out the hub? (Unsure on term) that holds the shift sleeve had one half of the three feet broken off. Not sure if this is common or not. However once I started looking into this it seems that Porsche updated it on the later cars. The update consisted of larger asymmetrical dog teeth meaning I needed the shift sleeve the hub and both sets of dog teeth. A unexpected expense but what can you do.
committing to owning a old car is committing to unplanned expenses.

http://forums.pelicanparts.com/uploa...1660787412.jpg
http://forums.pelicanparts.com/uploa...1660787412.jpg

I replaced all the worn dog teeth I needed, and then a whole fistful of synchro's.
While doing this I managed to not have to remove the shift forks from the rods making re aligning all of this a lot easier.
The main bearing in the case was actually really loose, that's a common problem on these mag case 915 trans. The motor was "healthy" and after talking to the previous owner he was not kind to it. Knowing it was thrashed a lot i was not surprised to find this.
It was tight enough i chose to put some sleeve lock into it and pressed it back into place. Will it hold? So far it has. I know its not a forever solution.

None of this would have been possible or nearly as successful with out the help of my Porsche shop owner and friend Frank, Hes retired now but still has some willingness to help. hes been a great asset on Porsche stuff or talking baseball.



http://forums.pelicanparts.com/uploa...1660787412.jpg
http://forums.pelicanparts.com/uploa...1660787412.jpg
http://forums.pelicanparts.com/uploa...1660787412.jpg

Awesome thread. keep it up.

Great thread. Thank you.