v8 cooling & tuning

[914GT]

What advice, if any do you experienced V8 owners have for me when it comes to engine tuning and recommended temperatures? It looks like my engine wants to run around 200 F around town and extended idling. I've let it run fast idle about 2200 rpm and it seems to hold about 200-205 degrees with a 100 F outside temperature. I've got my fans turning on a little lower so the engine temp doesn't 'overshoot' and get too hot too quickly. I'm running full vaccum advance on the distributor.

I'd like to drive it to work, about 12 miles mostly highway, but still don't have full confidence in it. I had a hose pop off in town the other day but I've now reworked all the fittings so that should not happen again. It's a real PITA when that happens.

I've got a 180 deg thermostat but I'm sure it's a regular type, not high flow. Should I get the high flow (Mr. Gasket) type to be on the safe side? What is the maximum temp I should be getting worried about and pull it over to the side of the road? Should I run full vacuum advance or ported vacuum? I've got a 2500-5000 rpm curve cam advanced 4 deg. Am I worrying too much? It sure is fun to drive but still at stage it makes me nervous.

[marks914]

Hey
Is your car running 200-205 when you are idiling? That seems high, I run my fan thermostat at 190-195. What is your temp on the road, when the car is moving? The best way to find out how reliable your car is is to do it the way I did... Put your toolbox in the trunk and drive it. I have put 8000 miles on my 72 v8 car in the past year.
I tune my car in the same manner as a normal SBC, stock timing and all. Seems to work best.

What conversion parts did you use? Desert hybrids is in your area, thats where I got my stuff from. What radiator are you using? I use a 85 corvette radiator and fan. My temps around town are 180-190 all day long and it gets around 205 at 80-90 mph on a 90 degree day here in detroit. That $150 radiator and fan sure was alot cheaper than that $900 unit from that other place.
Any other questions, feel free to ask.
Heres some pics of my car

http://hometown.aol.com/jtronika1/myhomepage/artgallery.html

Mark

[914GT]

Mark, I drove it around town in stop & go traffic a couple weeks ago with temp in the 90s and no problems. Engine temp running 190-200. Then last week I took it out one evening and I only got a couple miles from the house and blew a hose off. That shouldn't happen again after the mods I did to my fittings. I've never had it overheat and boilover. Last Sunday I just let it run for a half-hour out in the heat (100F) and it was holding a little over 200F at fast idle (2200 rpm).

I don't know my temp yet on continuous highway driving. Like you said, load up some tools and take some water and go for it. I think I'm all right but just gun shy. I have my AAA card just in case. Just got my insurance card in the mail yesterday so I'm legal now.

I got a lot of parts for DH. He sold me a nice radiator and fan shroud at a good price. What is different from everyone else is my electric water pump setup. That is all my design. If I could do anything to improve the cooling system, it would be to have larger return line from the radiator to improve flow. Currently I have 3/4" steel pipe both ways under the car with 1" sections of hose to the radiator and engine.

Thanks for the comments and letting me know what temps you normally run at. You have a nice looking car. I think you posted some pics of it a few weeks ago if I remember correctly.

[1bad914]

Mark,
You have a PM.

Randy

[John2kx]

Guy,

Your engine temperatures look normal. 200-205 at idle with your ambient temp. is GOOD. Your building allot of heat at 2200 rpm with the car motionless. This should reduce a bit above 45 mph where the fans really don't help at all but the continuous movement of air through radiator really remove heat from system.

Not sure how much time you spent burping air from your system prior to blowing that hose but it takes a few days of driving/purging air any time you introduce air into system.

I use the Mr. Gasket thermostat only because a normal t/s did not cool my car. There are many variables that come into play here. The type of engine has allot to do with it. A higher output engine makes more heat. It looks like your t/s is doing the job.

Where you have your water sendor located will make a difference in what you see on your temp. gage. 180-220 is pretty normal for a chevy v8. Just watch your gage after you've spent time purging air and see what is normal for your system. If your temp. is high (+225) or bounces up and down from 180 and then back to 225 or higher, you've got air in system at a minimum. There are many other things that can cause high temperature but I'd concentrate on the simple things first.

With my estimated 400hp engine, I see 170-180 gage temperatures on the highway at 70 mph with a/c on with 90F ambient. 160F on my early morning drives to work and 190-210F while stuck in traffic.

You'll also note that when changing from highway driving (constant rpm, making lots of heat) and then dropping into town with several red lights, your cooling system is really being put to test.

Before you write this off and think everything is normal, what kind of gage are you using to measure water temp.? I would not rely on one of those $20 POS available at your FLAPS. If not a good VDO recently calibrated by someone like North Hollywood, I'd spring for a middle priced Auto Meter and install sender at intake manifold.

BTW, congrats on getting your car on the road!!!

John

[914GT]

John, that's some really useful information. If I did not have a hose come off I would be having no concerns. The hose problem was stupidity on my part. It was the hose right off the manifold expansion tank where I had maybe a 1.5" long piece of 3/4" smooth pipe, then had it double-clamped. I should have known better. I don't even think I had the clamps very tight. I replaced it with about a 3" nipple, threads on the end then cut concentric grooves into the pipe for the hose to bite into. If I could find the right size hose barbed fitting I'd go with that.

No air in my system, the sight tube on the expansion tank is full. I don't hear the water pump passing air with engine off. I think I will go with the Mr. Gasket thermo per your recommendation just for margin. My temp sender is a stock Chevy sender in the left front head. I recalibrated my VDO oil temp gauge to work with it. I calibrated the gauge by placing the sender in contact with an adjustable tip soldering iron, and placed a calibrated digital temp sensor onto the sender to monitor its temp. I placed tick marks on the VDO at 10 deg increments from 150 up to 230.

I did the fast idle test in the hot sun to try to stress it. If a hose blows off I want it happening at home and not a few miles from the house. I'm going to take her out on some errands today so wish me luck.

[sean_V8_914]

congrats Guy!!! Being cautious is a good thing. I like the toolbox test idea. Perhaps go climb that mountain to the south of you, down by Green Valley as a test. Climbing mountains will make it generate heat. I solved most of my high temp issues simply by sealing off the input air to output air flow around the radiator. the cooling air flow was stalling at about 65-70 mph. it runs 200-210 on the freeway (8 east up the mountain goinfg to AZ) 185-195 around town. The next AX will be a good test. my engine still gets filthy really quick. under teh car is higher pressure than behind teh rear window

[914GT]

I drove it around town a while ago, about 100 deg out (supposed to hit 104). Stop and go along with straight sections where I could run 50 mph for a few minutes. The good news is I made it back home. The bad news is there were a couple times I had my doubts.

Not once did it get too hot, it went a hair over 200 toward the end of the trip and no higher. But I had two other 'anomalies' occur. After the first stop to pick up some tortillas, the starter did not engage, like the solenoid not throwing out properly. Starter motor made an irritating grinding, scratching sound and would not turn over. I get out, look at the starter. Bolted up tight, wires on ok. I get back in and it starts. This is a brand new IMI hi-torq starter with a new flywheel. What the hell?

After my second stop, it starts ok. Head back home and just a short distance away from home it dies pulling away from a stop sign. Like it's out of gas. So I suspect my gas gauge stuck which reads 1/4 tank. Open the hood and gas cap and see gas in the tank. Get back in and cranks a bit, then starts. Takes me the rest of the way home. The only noticeable thing wrong is idling fast, and can see my throttle cable holding it off the idel speed screw a bit. My return spring bracket just needs to be pulled back a bit more. But I don't know why it died. One thing I should change is I have my fuel filter on the inlet side of the pump and not between pump and carburetor. I don't see why did would cause the problem.

Guess I'll take that starter off and go through it. Then move my filter, maybe even pull the carb off and go over it again too. Seems I'm being annoyed by nitpicky things but they are troublesome enough to take the pleasure out of driving this car. I'll be so happy to where I can trust it. Not quite there yet.

I'll edit this due to an afterthought - do you think I need another relay for my IMI starter? I have a new ignition switch, but maybe I'm just barely getting enough voltage to the solenoid to throw it out?

[sean_V8_914]

I use a stock starter with a $4 Ford style relay. I have had 5 914s now and 3 of them needed the "helper" relay. the ignition sw contacts just dont seem to hang in there. I have never had a new ignition switch. You are not being nitpicky. the starter thing would need to be fixed IMO. same goes for the carb issue. a Chevy should run smooth and reliably for many years. my Chevies never stalled when properly tuned. does the exhaust smell clean? is the bendix drive shaft lubed?

[914GT]

Sean, I'm pulling that starter off this weekend to check it over good. Maybe just needs some lube, I did nothing to it but take it out of the box and bolt it on. I'll add the relay while it's out. I think my new ignition switch contacts could be burned already.

Exhaust is fine, no unusual odor or appearance of unburned fuel. But the volume of exhaust gas out each muffler is huge compared to the dual exhaust on my 350 Chevelle. I can reduce this my advancing the timing way up. But it's an amazing difference that I believe due to the head porting and cam profile. I'm almost wondering if the Edelbrock carb is too small and affecting low speed idle. But revving it up it's smooth.

I fixed two other things this afternoon. My turn signals were staying on after turning, and my odometer didn't work. Got those two bugs taken care of.

[sean_V8_914]

a small carb would run smoother at low-mid rpm. please describe more in detail the characteristics of teh problem. If I can help, call me. I got a 750 cfm you can borrow to try it out. It's allways fun to play with it. Itint that really why we own these beasts? My car ran MUCH Stronger with that carb but gas milage was in the dirt. What carb did you say youre running?

[John2kx]

Guy,

It sounds like your getting there. You have performed major surgery and this is all part of getting a converted car on the road. We all have little things to tweak the first hundred miles or so.

I too had a bad IMI starter. Worked fine when cold but would not do anything when engine was at operating temperature. Spent weeks troubleshooting bad connections before vendor was convinced starter was bad. A replacement cured the problem and followup with vendor revieled original starter was indead bad. I would not "lube" that starter or add another relay. Something else is wrong.

Just my opinion, but I'd have the air/fuel ratio checked with car on dyno just to ensure you don't fry that engine by running too lean. Hard to tell by ear but the device used to test air/fuel can measure from idle to red line if used in conjunction with a dyno. May cost you a hundred dollars but good insurance you don't kill that motor due to a lean mixture. As my mentor says, "run it lean once, run it rich forever". I run a 600 cfm Holley and had my engine builder (Wild Bill in Ca.) bench flow carb. Testing on dyno indicated air/fuel ratio was perfect from idle throughout rpm range and carb required NO tweaking from day one or in the past two years of operation.

I'd also opt for another water temperature measuring device. Your home calibration may have worked but another $100 or less here would be good insurance in protecting that motor from overheating. Heat is usually what kills these converted cars and the cause of most headaches associated with operating one. It looks like you've spent allot of time/money on your conversion and I applaud your efforts. One more gage is good insurance. What I have as indicators for my $6000 engine is two gages (one mechanical, one electric). One of the senders is a dual purpose with one prong that trips a idiot light. Another $2 device that shows radiator fan on/off status (available at radio shack and wired directly to fan power supply). If this one trips while on the highway, it is a good indication something is wrong. As you can see, I take water temperature pretty seriously and don't rely on watching gages continously. Lost a engine years ago due to lack of idiot light. Long story, but a expensive lesson. Seem to remember having the heads pulled 3 different times due to cracks or failed head gaskets. Engine ended up being toast after spending over $2500 in attempted repairs.

I hope the electric water pump works out for you as it is a simple way to cool engine. My emphasis on adding more temperature indicators is due to the long term reliability issues with these pumps. You may have a winner but the added insurance is worth it no matter what kind of pump you run.

Keep an eye on those cv mounting bolts if you've just reinstalled them. This was the first thing that put me on the side of road with blanky out and tools scattered. A couple of retorques was all that was required during the first 500 miles and what the folks at Renegade told me to expect.

Have fun with that beast and keep us posted.

John

[914GT]

I appreciate all your good suggestions. I'll check those CV bolts again. And install a second temp sender. What I really could have used is something to detect loss of coolant. A temp sender won't tell you a hose blew, but you either smell it or see the vapor coming out somewhere.

I originally had a Carter AFB 600 cfm carb, but swapped it for the newer Edelbrock 600 off my Chevelle. Looks nicer. But my idle has a slight 'hunting' on the rpm's which does not even out completely with either the mix screws or timing. May be something internal to the carb I need to chase down. Well I'll eventually get it right. What's funny is I'm still fixing things that have nothing to do with the V8 conversion. Sooner or later I will get them all. But maybe not, after all this is a 914!

John, the dyno check sounds like a good idea considering the modifications to my engine over a stock 350.

[Rotary'14]

Hi Folks,,

Just my .02 on the temp issue. When I ran electric guages in my first rotary 914 (we have temp issues like you V8 guys) I eventually discovered that all my guages readings were affected by high amperage devices coming on,, causing the voltage of the entire system to vary just enough to throw the guage off. I know headlights made my guages read about 10 degrees higher. I'm sure some powerful electric fans will do the same. Perhaps my car's electrical system wasn't grounded well, but it's also some thing worth investigating because this could be affecting your car too.

-RM

[John2kx]

RM,

I've tried no less than 5 different water gages on my car and found differences in the way mechanical vs. electric work. Same goes for the cheap vs. higher priced electric gages.

This is what I have observed:

Cheap ($20) gage I purchased at my FLAPS electric read pretty close to 180F all the time once engine was up to operating temp. I used this one until my my recalibrated VDO came in from North Hollywood.

The high dollar VDO read higher than the $20 unit in similar conditions and did seem to change according to heat load produced by engine. Testing of the cheap gage in water with infared showed calibration to be off at 180 and very slow to respond as temperature was increased or decreased around 180F. That one was added to paper weight collection. I don't see any change in my electric VDO gage as accessories are turned on to include lights, radio, radiator fans and a/c. I'm running a 100 amp GM alternator and ALL grounds in electrical system very checked/cleaned during assembly of car.

A mechanical Auto Meter was added as a backup and found to show temperature changes immediately as compared to any electric gage I have used. The fast response is a little scarey to watch until you get used to it. I find this one to be the one I trust more so than any other measuring device on my car.

Veryifying calibration is a must but I'm in the air about response time between mechanical and electric gages.

John

[914GT]

I took a voltage measurement on my starter solenoid this morning. I was curious how much drop I'm getting thorugh the ignition switch (new) and the stock wiring. Measuring at the IMI starter between the battery cable (disconnected at the starter) and the solenoid terminal, I have a 3 volt drop when cold. This decreases to about 2.8 volts with the starter in the on position after several seconds, due to the solenoid winding resistance increasing as it heats up. So, the solenoid voltage can get as low as 9 volts due to wiring losses. I'm putting on the relay as this will get me nearly full battery voltage and takes the stress off the switch.

RM is right, the stock wiring is undersized and voltages vary with load changes. I've got my engine stuff all running on a separate new wiring harness with relays controlling everything directly off the battery. My VDO gauges still use the stock wiring for the 12v though. I notice the voltmeter jumps around with brake light and backup lights. I haven't noticed any variation on the temp but it could be happening, I'll check that. When on the workbench I didn't see too much effect on the temp gauge by varying the +12v a few volts (using a lab supply). But it is worth another look.

On my alternator, I moved the sense line off the alternator's +12v output terminal by running a new wire over to the terminal strip that feeds the rest of the car. This regulates the voltage a little closer to the loads.

I'll post back later after checking the VDO temp gauge with different lights and accessories turned on.

[sean_V8_914]

thanks John. my car came with a VDO clibraTED BY Norht Hollywood but I will chech it on the stove to be sure.

[sean_V8_914]

GT deck lid: does anyone have any experience with these? any observations with regard to engine temps?

[sean_V8_914]

what is considered TOO HOT for a Chevy? 230? 240?

[914GT]

Well the console wiring +12V doesn't cut it. I put a resistor (potentiometer) in place of the head sender and adjusted it to 200 deg mark on my VDO. Stepped on the brake - slight change. Put trans. into reverse (back up light) - also slight change. Turned headlights on - temp went up about 10 degrees. So RM, you are right on. Not that I'll drive this car at night much, but still I don't want the gauges affected by volt. drops. So now I have to run a new +12V wire from my main terminal strip by the battery up to the console. Might as well run wires for another gauge or warning light while I'm at it.