Hey all,

Starting a new thread here...

I'd like to get some advice please.

Here's the scoop:

New motor. 9:1 2056 w/ceramic coated euro race headers. Stock D-jet and stock ignition. Running on Brad Penn break-in oil.

Two shake down drives for break-in (varying rpm and load, staying out of WOT and mostly below 4k rpm), and they both have the same basic symptoms. The oil temps get too high and idle turns to cr*p.

Drive one: 75 degree ambient, 40 minutes driving. head temps vary between 250-275, never higher than 300. Oil temps climbed to 230, and once hot won't idle worth a damn.

- backed off ignition advance to stock, was running at 30 degrees. Capped vacuum retard hose, seemed to idle better without. (mistake?)

Drive two: 85 degree ambient, 25 minutes driving. Head temps vary between 250-300, never higher. Oil temp went to 250. Hot idle just plain sucked.

I know I need to get a wideband on there to figure out what the mixture is doing, but if the mixture was going lean, I'd expect to see excessive head temps right? Can the oil temp simply be a tight motor on light oil? It doesn't seem right though.

Help? Advice? Suggestions? Last thing I want to do is lunch this motor.

-Josh2

Hmm, it was what 97 today? I know nothing about break in oil, but being a fresh build, I'm sure that has something to do with it.

Mine was running 230-40ish today on the highway. Needle covering the "M" on the word "temp" for console gauge with the small red area.

Anyhow, before people tell you, to retard the timing, Josh is about 5500ft elevation or more like me.

And Josh has his cooling flaps wired open.

I'm in for some replies.

Ferg

30 mm oil pump?

Melling. And a Tuna Can.

-Josh2

What shape is the oil cooler?

Personally I'd say trash the stock induction, but given that I don't think you have too much to worry about, temps on break in will be higher than normal operating temps for an engine with everything worn down. The oil temps are a bit higher than I'd like to see, but again, it's a break in.

I'd like an O2 sensor, but you can pull the plugs etc to see if you're running lean. I'd not worry too much about it, but be cautious.

Those temps aren't high.. The CHT is lower than normal and with the new engine the oil temps will be higher. What oil are you using??

With the low CHT and higher oil temp I'd say that the engine needs a couple of degrees of timing to optimize it, the CHT proves you can get away with more timing and retarded timing can drive up OT easily.

He said in the first post he's running brad penn break in oil(now I've never used this so I don't know what exactly it means).

Thanks for the responses!

Jake, glad to hear that the "common" wisdom that people were telling me (backing off on the timing) was wrong. It felt like the wrong way to go, and at altitude, I would expect to run more advance anyway (running 91 octane pump gas). But I didn't know that not enough advance could contribute to high oil temps. That's really interesting, what's the mechanism that causes that?

Any idea if my plugging of the vacuum retard line was a good idea or not?

What are the "best" CHT's and Oil temps to look for. Both for break-in, regular running, and hard driving (track/DE)?

Thanks all! I'll dial in a few more degrees and see how that helps. Still need that wideband to figure out what's up with hot idle though.

-Josh2

Jake is spot on as you would expect, you need to advance the timing back up. Retarding does in fact heat oil up, water if you had a water cooled engine will heat up too. And 250deg oil temps on a hot day and a new motor just breaking in seems completely reasonable to me. The BP oil is good stuff too and will handle that temp no problem.

As for a vacuum retard, if you are talking about the vacuum line to the "can" on the distributor, that should be a vacuum advance. It is possible I guess that when you had it hooked up, and had extra overall advance, that at idle you had a lot of initial advance and the engine doesn't like it. Just a guess but would surprise me. Frankly on many a drag race motor (tho' not a VW engine so a different animal maybe) we took the advance springs completely out of the distributor and just set timing to be max all the time - point is they idled just fine with 36deg of timing, even at 1K rpm, so dunno why your car would idle differently with the advance plugged in unless your diaphragm is leaking and you created a vacuum leak plugging into it. My race car has around 18-20 deg of idle advance and 36deg overall for another example of high advance at idle working fine.

The vacuum retard line comes unhooked, and plugged, from the factory.

Rich

I'm not worried about the oil per se, I'm worried about the low oil pressure that results from the hot oil. I guess I should have mentioned this earlier. When the oil gets to the 230+ mark, the oil pressure drops really low. So low as to make me nervous, and the warning light comes on near idle. Is there something wrong with the motor at this point? I'd expect a tight motor to have higher oil pressure no?



The distributor has two ports. Vacuum advance, and vacuum retard. I have disabled the retard (no jokes, I'm being serious).

-Josh2

D'oh!

Thanks!

-Josh2

the retard hose gets connected to the throttle body.
The hose gets plugged .

The port on the distributor is left open to the air, not plugged.

If you have run it for two runs and did a classic 20 minute break in at 2000 rpms to get the camshaft seated, then I , in my humble opinion, would change out the oil now to 20/50.

I may get yelled at for this but I run the motor with the break in oil for 30 minutes, then change the oil.
Its at that early time that all the little bits of foreign matter, cleaning solvents, contaminants get mixed up in the oil....so get it hot and dump it.

I pull the sump out also, and the taco plate to get as much of the oil out as possible...

New gaskets, new oil...then drive it like you stole it.
If it is gonna break...its gonna break.

RIch

how would retarded timing heat oil temps?, not to say it can't it just doesn't make sense to me. retarded (late) timing does in fact run engine temps. down. the more retarded the more heat/energy is blown out the exhaust. advance (early) timing drives temps up, as the combustion is in the cyl. longer. too much advance timing brings n.o.x. emmisions showing the direct corilation to the cyl. temps. going up over 2500*... even before preignition.

the reson i earlier asked if you had a 30mm h.v. oil pump was the oil heat issue. there are many threads on the extra pressure acually overideing the bypass, that consequentley bypasses the oil cooler, raising oil temp'.s. jake correct me if i'm wrong, but i've read you acually steer away from 30mm?

cylinder temp.'s normal, oil temps. high... probably running break in oil on a tight new engine under 85* normal driving.

let us know your findings

mike

If we're talking about a stock D-jet equipped 1974 engine, that's not true.

The Cap'n

Retarded timing heat soaks heads and pistons and the charge out the exhaust valve can possibly still be burning while the exhaust valve is open... retarded timing is the #1 cause of most tuning issues that cause engine failures..

People tend to be conservative with timing, thus compromising their engine due to their fear.

These engines continually prove to love 28-30* full advance @3500 RPM.

For my recommendations on temperatures see the classic thread here on 914 world.

SET MECHANICAL TIMING WITHOUT ANY VACUUM HOSES ATTACHED! This timing is all that matters, then reattach the vacuum.

Its all in the tune... Thats what I do better than anything.

Just going on what DD said years back.
Seems some had it, some did not.

RIch

That's interesting. Seemingly counter intuitive until you know the mechanism going on.



That's what I did. I set the timing to 28 degrees, no vacuum hoses attached, 3500 rpm.

So... 30? 32? I understand that running at altitude demands more advance, is that true?

-Josh2

Not plugged, though--the advance fitting would be left open to the air.

--DD

What did the CR end up being? What cam does it run?
Unless these engines have huge deck height, super enlarged chambers or low CR coupled to a bigger cam they generally like 28 degrees.

To optimize an engine takes experimentation or a trip to a dyno with an operator that has some sense.

9:1 CR. FI grind webcam (73 if I recall). 96 mm KB P&C's. 0.016" deck height.

Intake valve clearance to piston top: 0.22"
Exhaust valve clearance to piston top: 0.33"
Piston ring end gaps: 0.020"
(measurements made by a friend)
Melling oil pump.
Tuna Can sump extension.
Welty oil pressure relief pistons.
Euro race headers, ceramic coated. Stub pipes port matched with heads.

Stock D-Jet.
Stock Ignition.

That pretty much sums up the build.

-Josh2

WOW!
You only have .016 deck height??

The piston to valve clearance you state is also way too tight on both the intake and exhaust valves. If those clearances are that tight cold, what do you think they are doing hot and fully expanded?

With that tight of deck your engine might like as little as 2^* advance, but you'll be colliding pistons to the heads at any kind of revs once the engine is fully expanded.. The least deck I have ever successfully ran was .021 and even then it was knocking the carbon off the chambers and piston tops.

Okay, now I'm sweatin' bullets.

These were the numbers provided to me the friend who was building the motor. If you can give me ball park numbers what you think they SHOULD be, I will confirm that these were the actual numbers taken.

Car is on hold until then. Have I already wasted it?



-Josh2

Waiting for my friend to call me back with actual number he recorded during the build...

Feeling nervous...

-Josh2

Okay, now he -thinks- that it was more like 0.032" deck height. He hasn't checked his notes, but will let me know when he does.

Now, about the valve to piston clearances. Jake, I thought that .22" and .33" valve to piston clearance was pretty large. It's a stock combustion chamber, 59.5 cc's each (measured by the head builder - professionally built heads - years before this build).

Is this motor reasonable? Or am I just a bozo in a world of hurt now, and should give up and buy a miata? (kidding about the miata...).

-Josh

Well... He looked for his notes and couldn't find anything.

Sigh... I'll be taking the motor out, and pulling the heads...

After re-measuring the deck height, and if the pistons and heads pass visual, would it be reasonable to slide a .020" gasket in there? 0.030"?



-Josh2

That being said...

Should I run a head gasket, or shim the jug? If head gasket, copper or ??...

humbled and sadly asking for advice...

-Josh2

So is that clearance .022 or .220?? Huge difference!

No on the head gaskets, the factory recommended against that years ago.

0.220"

-Josh2

man, I would think 0.220" is more than plenty, tho' if Jake thought you said 0.022" I can see why he would freak out

I used to run as tight as 0.100" on intakes but no less than 0.125" on exhausts on full race, domed 9500 rpm V8s, and as low at 0.080" on ti intakes one time against my wishes but the engine owner went for it as he found the heads on a Th and was racing Friday, and we ended up not having any issues.

side note... Ti expands less than stainless steel (8.5ppm/C for Ti v. around twice as much 15-17ppm/C for stainless steel) and I knew that at the time, so I was sorta willing to take the chance but was sweating bullets with him road racing the next day at no less than 6500rpm and shifts around 9K on that engine

I think it's the deck height value that Jake jumped at. And somehow, even though it had been measured, it got overlooked.

Plan at this point is engine out, heads off, shims on, and all back together again...

-Josh2

snipped that from a post above and he also asked about 0.220 v 0.022 which was a piston to valve #... that is what I was referring too It seems to me he like neither the piston to valve nor the deck height. I think piston to valve seems totally reasonable unless I am missing something that is somehow specific to T4s. I know nothing about T4 deck ht specifics.

Learning experience here... cliche central.

you get what you pay for...
no such thing as a free lunch...
buy cheap, buy twice...
want something done right, do it yourself...

My friend was well meaning, and I really greatly appreciate his work. But there are enough questions about the measurements made during the build (even one would be too many), that I have no choice but to pull the motor and tear it down. Hopefully, it means nothing more than adding the right shims to get enough deck height and valve clearance. But suffice to to say, it's gotta happen before I turn the key again.

Here's what I have gathered...

Deck height: 0.010 - 0.012 per inch of bore. That means at LEAST 0.037 deck height up to a minimum of 0.045. That is way more than the 0.016 that was measured.

-Josh2

Yeah... Finding out that tearing down the motor is a certainty. Motor's on the engine stand now, finding loose this, and loose that. And that's still outside the motor.

Bottom end at this point is suspect too. It's all gotta be torn down.

That being said... What's the desired bearing clearance that I should strive for when everything goes back together?

I hope to pull the heads in the next couple days. Hopefully metal-to-metal contact was avoided.

Any bets?

-Josh2