CHT seems high - oil normal? Options

[FlacaProductions]

74 2.0 (details below)
Very gently rolling 2-lane roads. 3000-3500rpm cruise 55-65-ish MPH. Mid-90’s.

This is not a new concern but something I’ve been noticing/monitoring since I got this car 4 years ago. It’s kept at our other home where I get 5-7 day-access 4-5 times a year so it goes in fits and starts. Nothing has made a noticeable difference.

My concern is that head temps seem to skew high as confirmed by Dakota CHT gauge under #3. Pulling a gentle grade, it went to high 300’s and asking a moderate acceleration, CHT goes above 375. Touched 400 a couple of times.

Oil temps stay low 200’s (225) as confirmed by taco plate gauge and Manley dipstick thermometer and react accordingly (ie: in direct but slow relation to the CHT)

According to Jake Raby’s writings: "Engines that cruise at 375 are generally out of tune or may be misconfigured creating more heat.”

Am I making too much of this? In my head, CHT over 400 is baaaaad.

I’m going to run a snake camera around the top of the tins and check the condition of the oil cooler fins today - that’s about all I can think of at this point.

Input? What’s to tune?

Status: timing confirmed at 28 degrees. Idles at 1000 steady. 195/55’s w/speedo calibrated. All tins present and thermostat/flaps are functioning. New oil less than 200 miles ago - Driven DT50 Full-Synthetic 15w50.

Engine specs: “stock performance” rebuild by Brad Mayeur in 2010 with new, original Mahle European pistons and cylinders, Raby FI cam and lifters new German K&S bearings on a std/std crankshaft. Heads completely rebuilt, new stainless valves and new springs by Tuttle’s Parts Exchange.

[VaccaRabite]

Make sure all the air leaks around your tins are sealed.
Make sure you don't have mouse nests or other debris packing the tins.

Once that is done...

Try changing the timing one degree at a time and seeing if that helps, go up and down.

Confirm fuel pressure.

Zach

[FlacaProductions]

Will do - starting with checking tins today.

[rfinegan]

I recall reading that stock Djets/Ljets runs a little Hotter than carbs ( less tuning) I agree to check the timing and fuel pressure as Zack says.
Your oil temps sound good. Sound like they may have bumped up the compression a touch? What fuel are you using?
All setting seem to have gone out the window with the Quality of fuel each year changing. Use 28* as the base line and adjust as needed.
I changed my timing from 29 to 30* (Yesterday) and noticed an increase in CHT getting higher. NO real noticeable perfromance changes. FWIW

found it:
350-375F
These temps are standard for a STOCK engine with a stock cam at cruise speed, if it is properly tuned. Generally, if you are cruising at these speeds, as soon as you hit a hill you'll see a spike to a higher level, approaching 400F. If you experience temps of 375 in 5th gear, you may be doing the engine an injustice by keeping the tranny in 5th, hitting a hill with a shift to 4th will keep load off the engine and that reduces engine heat and increases cooling fan speed- 4th gear is a friend to stock engines.

If you see temps in the 375 neighborhood constantly you'll be having to reduce the intervals between valve adjustments to maybe 3K miles due to the extreme heat cycling the engine and valve train parts are seeing. Engines that cruise at 375 are generally out of tune or may be misconfigured creating more heat.

http://914world.com/specs/JakeRabyHeadTemps.php

[FlacaProductions]

@rfinegan - that's exactly the piece of "Jake info" that I was referring to as my reference for CHT temps.

Just not sure what could be "out of tune"

Just scoped under the tins and as near as I can tell it's really clean and clear. Oil cooler fins look good as well. All rubber seals are present.

Fuel - running mid-grade standard pump gas on this load. Seems to my butt dyno that I get a performance boost from "Pure Gas" no-ethanol flavor served up down the road that I frequently run but I can't recall what the temps have been.

I'll do my best to burn this tank off asap and do a refill with "the good stuff" and see what I find.

I'm thinking a small timing bump or two in the correct way might be the answer.

[914_teener]

I'm thinking mixture at part load and fuel pressure with the Raby cam.

[Geezer914]

How is your oil pressure holding up?

[FlacaProductions]

I'm thinking mixture at part load and fuel pressure with the Raby cam.

I don't have a fuel pressure gauge at the moment - i'll get one in there.
oil pressure is great - warm idle at 20, cruise at 60.

Mixture: MPS is a 0280100041 but has clearly been opened as the outer screw are marked w orange paint and there is marked in sharpie: 74-762.0

[emerygt350]

You could try a thinner oil, go to a high quality 40 weight. You will get more volume and with that oil pressure you are doing fine. Remember these are oil cooled motors too. Oil doesn't help the head much but it can help a little.

Do you have an AFR? I would suspect lean mix at cruise is probably not helping. Does your 74 have a vacuum advance? Some do, some don't. If it does, disconnect it and see if that helps.

[FlacaProductions]

@emerygt350 No AFR although I'm familiar with them coming from the 944 Turbo world. AFR paves the way for tuning via MPS adjustment - correct?

Just switched to the DT50 from VR1 after reading others experience with lowering temps.

How do I tell if I have a vacuum advance? I have two nipples on the advance can - one has a hose (that I disconnect and plug when timing) and the other (on top) is open and without hose.

TPS have anything to do with mix at cruise?

[914_teener]

I'm thinking mixture at part load and fuel pressure with the Raby cam.

I don't have a fuel pressure gauge at the moment - i'll get one in there.
oil pressure is great - warm idle at 20, cruise at 60.

Mixture: MPS is a 0280100041 but has clearly been opened as the outer screw are marked w orange paint and there is marked in sharpie: 74-762.0

You didn't say what CR Brad set the heads at. Really critical to know. Hopefully around 8.5:1 or so IIRC.

Check the FP first...you can get one at HF along with the vaccum gauge there. Cheap.

Then...should should check the part load mixture and the only way to check that is underload...from the sound of it without checking the other stuff assuming it's good...going lean. You can get the Innovate wide band with the clip for a bung or tail pipe to check the mixture under part throttle.

Check everything else first though before you start messing with the MPS.

Edit: You can go to a dyno...but $ and have a wide band with you. Might be worth it just to find out without buying the equipment.

[914_teener]

@emerygt350 No AFR although I'm familiar with them coming from the 944 Turbo world. AFR paves the way for tuning via MPS adjustment - correct?

Just switched to the DT50 from VR1 after reading others experience with lowering temps.

How do I tell if I have a vacuum advance? I have two nipples on the advance can - one has a hose (that I disconnect and plug when timing) and the other (on top) is open and without hose.

TPS have anything to do with mix at cruise?

So just read this....really important to have the right hoses going to those two cans AND that they don't leak.

One is for spark retard and and the other is vac advance. Vac advance hose is ported vaccum and retard daiphram is manifold vaccum. REALLY important that these don't leak and function properly otherwise your timing will be off.

Ask me how I know. I found mine leaked and was doing the same thing...running hot but running ok. So ditched the stock dizzy for 123...no more issues.

[rfinegan]

I'm thinking mixture at part load and fuel pressure with the Raby cam.

I don't have a fuel pressure gauge at the moment - i'll get one in there.
oil pressure is great - warm idle at 20, cruise at 60.

Mixture: MPS is a 0280100041 but has clearly been opened as the outer screw are marked w orange paint and there is marked in sharpie: 74-762.0

This is the pressure I have seen on my gauge too ( T4 OIL PUMP) CURENT BUILD Looks Good to me

[emerygt350]

Getting yourself a 123 is a great way to eliminate lots of gremlins. Can't recommend enough. 74 (late I believe) kept the retard and lost the advance. Since your idle is a little high, I suspect something might be up. Your throttle will have 1 port facing the rear of the car or 2 small ports on opposite sides. One is giving you 'manifold' vacuum (the rear facing), the other is just above the butterfly. That is the one that only pulls vacuum at cruise and is the advance. A late 74 should only have the manifold vacuum and that should be going to the ... Inside? can. Can't remember now. Others will know.

[FlacaProductions]

@914_teener - Correct - CR is unknown to me. I can check with brad but it was done under previous ownership (actually one before that....)
Will be working on checking fuel pressure asap.

To be clear: I am NOT messing with MPS.

I would like to see what the mixture is so the Innovate suggestion might need to happen.

I’ll give a rundown on what my dizzy/hose connections are but a 123 may be a good option.

@emerygt350 - late ’74 - yes.

[brant]

Do you have an AFR? I would suspect lean mix at cruise is probably not helping. Does your 74 have a vacuum advance? Some do, some don't.

Bingo!
I’ll read the rest of the thread
But even a stock MPS is too lean with todays fuels.
Richen the fuel. Verify with AFR
And I bet your head temps drop

[Olympic 914]

I know you don't want to mess with the MPS

But maybe you could borrow another one from someone with a similar engine just to try it out.

Or have someone test yours with a LCR to see where it IS set.

[FlacaProductions]

ok - lots to things to work on here - i really appreciate the input.
I only have thru Saturday on this trip and it's not just a 914 trip but I'll get started.
@Olympic_914 - I'm not against messing with the MPS if it'll help or is "the answer" - I'm mechanical but with a fairly limited tool resource.

First thing is fuel pressure - ideally, i'd find a way to T off the fuel rail port.

[Porschef]

Just throwing in the ring some echoing comments, these are all good points that have been made. Pardon any redundancy.

In order, the three best things that have helped tune the engine (IMHO) for me.

1. By far, the 123 distributor. I had the stock 205A that I messed with, adding Pertronix, lubing, etc., but was never able to get it right. Close, but adding the 123 was totally game changing. I was very hesitant to spend the $$ but it was well worth it.

2. AFR gauge. Yes, it’s easier to make air/fuel adjustments with Ljet (I never had the pleasure of messing with an MPS) but it’s obviously doable. Getting that mixture right is so important on air cooled stuff.

3. CHT gauge. I like being able to keep an eye on what’s going on. Do my best to keep temps under 375°, no guessing involved. Mount the sensor under the #3 plug. Dakota digital gauge is great. Make sure all tins/seals/grommets are as they should be.

Fuels today do suck, I can’t get non ethanol here.

I do have a fuel pressure gauge, but again, once it’s good, it’s not really necessary.

I now run regular gas, no pinging, with very satisfactory performance.

Hope that helps. (IMG:style_emoticons/default/beerchug.gif)

[FlacaProductions]

@Porschef - Thanks for this.
I'm taking all-comers - unfortunately, I only have 914-time in short bursts.

123 - I've added a pertronix in the last year and it smoothed out the idle but nothing earth-shaking. Glad I did it though - no points going forward at least.

AFR - yup. I think in the long run, this happens.

CHT - yup. I have a dakota and it's been the indicator that has lead me to this point. I'm sure it saved me since the oil temps look good.

I can get non-ethanol here so that's going to be the requirement going forward. This tank is 10% ethanol which can't be helping but no pinging.

Off to NAPA to figure outa fuel pressure setup.