latest results on overheating engine

[robert1]

Is there a spring in the bottom hose?

[ZIGGY]

Is there a spring in the bottom hose?

And is it secured so that all the coils can't migrate to one end of the hose?

[mike22l]

We use a soft hydraulic hose and they are the cadillac. Impossible to collapse. Real nice piece. I run them on all the engines at the track.

I did take the wter pump off today and removed the back cover from it and it looks fine.

I still put my new Stewart stage 3 pump on though. Nice pump

I'm "leaning" towards ther fuel delivery now.

We are changing the fuel pump with a know good one and replacing all the carb gaskets and spacer gaskets.

Cleaning out the fuel filter today and found out he had the filter it backwards. He banged it on the car and a bunch of crap fell out of the center of the tube style filter...At least he had the spring inside it pushing the filter the right way....So maybe he was restrcting flow and running lean up top since alot of crap came out of it? Replacing it anyways with a new one and making sure its installed the right way.

[Unkl Ian]

IIRC, the filters flow more in the right direction.

[mike22l]

I agree a 100 percent there. And they dont plug up as easily....The guy is a little embarassed.....

[mike22l]

Well, we went out saturday and my guy was going for the pass to win the feature but the guy seen his nose and pushed him down and spun him out...guess we should have gone by him faster.

I did find a problem though. I checked the timing at 3000 and it was right on 34 (proven at dyno) I then reved it up to 3800 and the thing advanced to 48! Its a brand new DUI installed at the first of the season. I swapped it out with another new DUI from another build and the thing held its total timing at 34. It had total timing at 2700 and held it there even at 3800. I though great1 Theres our problem. Too much timing after 3000 (since thats the RPM I always set my timing at).

We fixed the fuel filter backwards problem and I cleaned the 4412 carb and also installed a new Stage 3 stewart pump along with the new distributer.

I kept an eye on that stupid yellow overheat light as he went by and at lap 15 it was on! He came off the track after the race was done a little over 230. Damn thing.

A new symptom though. At mid to end of track the engine had a miss in it and it was popping now and then. We didnt lose any water.

Im thinking we are running out of fuel which is causing a lean condition. I also jetted his carb up 4 points! 76's turned into 80's. For last nights race. We always ran cool with 76's

I checked the plugs after the race and we are still lean in the back or getting too hot.

Im going to try checking the timing with another light before changing out the fuel pump. (Thanks to Dave at Propower)

Thanks, Mike

[mike22l]

Any more opinions?

[PbFlinger]

Hi Mike. You asked for ideas so here are some. Some of these are simple, and I don't mean to insult your intelligence by suggesting them; but hey, everything is simple once you find it. All of these have put me on the trailer, slowed us down, or made us invent new cuss words.

Something simple here as far as the front/rear fuel distribution goes (which you have probably checked): have you had somebody mash the throttle (with the pedal) & made sure the carb is fully opening? Canted butterflies can cause odd things with mixture distribution.

As far as the rear cylinders getting hot goes here is something that happened to me (doubt it's your problem, but who knows?). I rebuilt a 400 Pontiac for my DD. It would idle cool all day, but get hot on the highway; seemed like the rear cylinders were worse. New radiator, new pump, new hoses, with/without thermostat, yada yada (didn't do it before). Finally pull engine & tear down. Evidently some kid at the machine shop was learning to install freeze plugs; it looked like a freeze plug dealership inside the block. He had driven numerous plugs in too far, couldn't figure out how to get them out, and just shoved them to the side (inside the block). Evidently it caused enough flow restriction at speed to make it overheat. That was 28 years ago (wow), have installed my own ever since.

Stuff that has caused me fuel delivery issues over the years:
1. A plastic mesh screen on a tank pickup that had the "wires" swell up, causing the thing to look fine but restrict flow.
2. A hidden length of rubber fuel line that had swelled up & gone noodle soft, hidden inside a conduit running through the car. We think it was sucking shut like a radiator hose. It was in there when we bought the car, and there was hard line coming out both ends of the conduit; we thought it was hard line all the way through. Compressed air would blow through it just fine. Like to never found that one.
3. The vent hole in the top of our fuel pump had gotten closed off solid with mud. It would still pump but not much. Worked fine after we cleaned the hole out.
4. Lightweight composite fuel pump pushrod wore down on the cam end, shortened it up to where the pump would barely work.
5. Fuel pump pushrod gnarfed up & dragging in bore from too long of a bolt in the front block hole.
6. Mud dobber construction crew filled our tank vent hose with high strength cement (between Saturdays).
7. (One) zip tie holding rubber fuel line to frame on suction side of pump too tight (duh).

Iust some ideas from experience, maybe one can help you or somebody else.

[roadrunner]

How about a dodgy temp sender unit/gauge

[Matt Gruber]

power valve? vacuum will get high at high revs and close it, leaning it severely. probably need a 10.5 PV

[mike22l]

All Lines look great and clear.
Vent on tank is fine
Pickup in tank is fine.
The thing has an overheat light and a temp gauge which reads 230 and the light comes on then. Just fyi roadrunner.
I am going to check the puchrod when i change the pump

good stuff though. Keep it coming

Thanks guys, MIke

[robert1]

230 after a race in this heat is not that bad. One of my guys is running 230 and I told him if it doesn't get any hotter than that there's nothing to worry about.

[mike22l]

Well, I know its not that bad but when it has always ran no more than 200 on a hot muggy night somethings up.

His one night was a low humidity cool night at 70 deg and he finished the race at 230. His plugs in the back looked like they were fighting a lot of heat.

It that temp he would normally be coming off at 180 not 230...50 degree difference all of a sudden.

Appreciate the input though. Any thoughts on troubleshooting

Thanks, Mike

[rfoll]

Have you dipped the water temp sender in boiling water to verify?

[PbFlinger]

You mentioned misfiring under load; here's something that happened to us a couple of weeks ago. We were normally running about 6800-6900 at the end of the straights on this track. During our heat it would barely get up to 6400 & was misfiring a little. We ran the same set of plug wires (10mm) all last year & part of this year. They were getting pretty beat up & burnt so my friend who owns the car had made up a new set of 8.5mm's, and put some protective sheathing on them that had a metallic looking outer layer. They went on the car several weeks ago, right before a bad crash sidelined us for a while, so we kind of forgot about them; this was the first time we really raced with them. We were in the pit with the car running trying to figure it out when fortuitously our generator quit & we lost the lights. You guessed it, lightning show around the wires. We cut all of that sheathing off & it went right back to 6900 & smooth during the "A". Quality wires properly made.

We briefly had an engine temp issue earlier this year. Expecting a muddy night we had made a screen for the radiator (regular house screen). Came in at 230 after the heat, normally runs 190 or so. Not as muddy as expected, took screen off, came in at 190 after the feature. Wouldn't have guessed it that restrictive. Did it before with no probs, but with a different fan/shroud setup.