914-6 runs HOT - solved? Options

[porschetub]

You would hope that the OP's engine builder allowed for the extra displacement when rejetting the carbs,I don't have webers but I know on the 914/6 and 911 carbs of that era the idles ,mains and vents were small much like the jetting in the latter zeniths.
Perrys comment about bearing is a valid one, cases are sometimes torqued up without checks for free rotation of the crankshaft,also were the rings "gapped" properly in the pistons ?,have the valve clearances been rechecked after the initial ''run in'' ?,I would suggest that the OP limits driving the car and returns it to the engine builder asap.

[porbmw]

There are far more knowledgeable persons than I who have already weighed in on this.

However, there may be one other means of helping to lower engine heat...by increasing air flow...by using the two air deflectors that later models of 914s were supplied with...If I recall correctly, in around 73/74...affixed to the underside, one on each side of the underbody, just in front of the engine

[porschetub]

There are far more knowledgeable persons than I who have already weighed in on this.

However, there may be one other means of helping to lower engine heat...by increasing air flow...by using the two air deflectors that later models of 914s were supplied with...If I recall correctly, in around 73/74...affixed to the underside, one on each side of the underbody, just in front of the engine

Yea good point,I believe they really made a difference.
Not sure in this cause perhaps things are a little deeper (IMG:style_emoticons/default/sad.gif) .

[767driver]

There are far more knowledgeable persons than I who have already weighed in on this.

However, there may be one other means of helping to lower engine heat...by increasing air flow...by using the two air deflectors that later models of 914s were supplied with...If I recall correctly, in around 73/74...affixed to the underside, one on each side of the underbody, just in front of the engine

I know these exist, but have never seen them. Anyone have pics or a source for the parts? Apparently they help create a low pressure area under the engine bay thereby increasing the total airflow through the engine bay.

[mskala]

If you want to check the various gauge components:

[rgalla9146]

An additional oil cooler should not be necessary on an engine of your displacement and state of tune.
Hole in firewall ? oh please !
If your car does not have an original (914 6) flywheel mark the one you have at TDC and use an adjustable timing light to
check proper timing.
There are various methods for determining true TDC

[Cairo94507]

Here they are. I believe they came standard beginning in '73. I am adding these (I know, my Six did not come with them) on my car because it can't hurt to get a little more air flow for the motor.

[Justinp71]

Here they are. I believe they came standard beginning in '73. I am adding these (I know, my Six did not come with them) on my car because it can't hurt to get a little more air flow for the motor.

Hmm, I wondered what those were for. I guess these help because at higher speeds the flow across the bottom of the car is too strong for the air coming thru the engine to merge? Does anyone know?

[Justinp71]

In 60f Weather on the freeway I'd think the car should stay under 200f Oil Temp.

How does the engine run? If its lean with carbs I'd think it wouldn't feel very smooth in transition from idle to mains.

I'd also look for a blockage in the air system or a slipping/bad belt like others have mentioned.

Does it have a 5 blade fan?

Maybe the wrong belt pulleys were used and the fan runs too slow? If that was the case you'd probably have an alternator problem at night when the lights are on.

[914forme]

What RPM is your engine turning on these highway runs?

I do believe there was a reason the factory installed a Z gear in fifth instead of the ZD in the -6.

It is about a 200 RPM difference, not a huge deal, but at low RPM that 200 RPM could make a difference. Especially if you are bogging the engine a bit.

What happens when you drop down into 4th?

[toolguy]

What RPM is your engine turning on these highway runs?

I do believe there was a reason the factory installed a Z gear in fifth instead of the ZD in the -6.

Increased cooling with the higher RPM's is exactly the reason the factory used the Z 5th in Six's. .
Have you checked you oil level when the motor is hot. . full 9 quarts?. . 30 psi at freeway speed is low.

[billh1963]

What RPM is your engine turning on these highway runs?

I do believe there was a reason the factory installed a Z gear in fifth instead of the ZD in the -6.

Increased cooling with the higher RPM's is exactly the reason the factory used the Z 5th in Six's. .
Have you checked you oil level when the motor is hot. . full 9 quarts?. . 30 psi at freeway speed is low.

My CIS 2.7L runs on the cool side (I posted about it a couple months ago). You shouldn't need an external oil cooler.

Installing an AFR gauge will tell you if you are lean

30 psi at 3K rpm is still within accepted norms (10 psi per 1K). However that is for a more worn 911 engine. I think he should see higher.

But, if his oil is running over 220F he absolutely would see lower oil pressure even with a recently rebuilt engine.

[Dave_Darling]

I guess these help because at higher speeds the flow across the bottom of the car is too strong for the air coming thru the engine to merge? Does anyone know?

Something like that. The flaps create turbulence behind them, which is slightly lower pressure than the other ambient air. That lower pressure helps pull air through the cooling fins on the engine.

It's not a huge effect by any means, but it is there.

--DD

[767driver]

I haven't driven the car in a couple of days and it's new to me so I am going from memory here...

I want to say the RPMs are about 3500 at 80mph. The PO said the car had airport gears in it and that he did not like the high RPMs on the highway. Said he replaced 4th and 5th with normal gears. Don't know what those are but I can tell you the RPM drops a full 1000 going from 3rd to 4th...that seems like a lot. And 5th is pretty tall now. Also car is said to have a 930 LSD.

[767driver]

And now I have found this thread...see posts 5 and 7.

http://forums.pelicanparts.com/porsche-914...ear-ratios.html

Damn...could it really be that simple?? ANSWER:NO... I drove the car at highway speeds using 4th instead of 5th...still got hot.

[gereed75]

Rgalla, not trying to be argumentative or steal this thread, but how does retarded timing increase temps??

My understanding is that timing advanced beyond optimal increases peak internal combustion pressure. That higher pressure results in higher heat and reduces engine output.

What mechanism/physics makes retarded timing produce more heat/higher temps??

[767driver]

And from the owner's manual graph you can see 3500RPM should be 75MPH. My gear seems taller...I will have to drive it again to verify.

[mskala]

Don't assume speedo and tach are super accurate. Also, those graphs would be
true only with the original tire diameters.

Not to sound like I'm putting down your car, but really it looks like you have so
many unknowns that there is no way to even come up with a reasonable guess
at what's going on over the interwebs. I think you're in for a lot of local
investigation.

Why did somebody have an engine rebuild then sell the car without driving it? (you
said it now has less than 600 miles). There are shitty engine builders and/or
mechanics out there.

[Kansas 914]

Don't assume speedo and tach are super accurate. Also, those graphs would be
true only with the original tire diameters.

(IMG:style_emoticons/default/agree.gif)

[rgalla9146]

Rgalla, not trying to be argumentative or steal this thread, but how does retarded timing increase temps??

My understanding is that timing advanced beyond optimal increases peak internal combustion pressure. That higher pressure results in higher heat and reduces engine output.

What mechanism/physics makes retarded timing produce more heat/higher temps??

Retarded timing allows partial combustion pressure to escape through the opening exhaust valve which raises cyl. head/ oil temp.
There is more to it than that.
Google ignition timing vs. engine temp