[prexford]

I did a compreesion test (warm engine) today on my 1971 formula 400 and noticed oil on the #4 and 6 spark plugs. The plug tips were a little black, evidence of oil. The pressure test showed all cylinders at 150 psi...even 4 and 6. Could this be the guides or is this normal for a new rebuild? I have moly rings.

Also noticed the car is running hot only at highway speeds. Stays at 160-170 at idle or low speed driving. I do have an oversized cam on my low compression (8.2-1) 400..it a rasm air IV. I plan on changing it out...do you think this will correct the overheating on highway?

[Half-Inch Stud]

Try a different carb (like a leaner carb) and see if the CYLS' oil cleans-up.
Also, the diff carb will likely run a diff Highway temp.

Worked for me.

I gots 4 diff Q-JETs on in the past week & gots 4 diff result.

[mikejub]

Is the engine blowing any oil smoke out the exhaust? Need to add oil regularly?

Personally...I think you should do a leak down test on those cylinders. If oil is getting in there...could be be rings, guides, valve seals, or head gasket. Leak down test required to narrow it down.

I've got the same problem...but on #5...and will test shortly.

[hpp]

How do you do a leak down test?

[prexford]

I'm using Royal Purple synthic oil. Do you think this could be the cause if oil is leaking down from the guides? My heads are fresh rebuilds with all new guides.

I did have a head gasket leak during my rebuild and re-torqued the head bolts to correct the situation. I'm currently used cylinder cleaner through the carb to clean the valves ( i also cleaned the spark plugs) to see if the oil was from the head gasket during rebuild.

So to summit and look up their leak down test tool. Their you can down load their instructions on how to do a leak down test.

[GT182]

Originally Posted by Greg Reid

Here's a great page explaining the operation and even shows you how to build one. I bought one on eBay for about $50.
http://www.xs11.com/tips/misc/misc3.shtml

Check Greg's link to make your own leakdown tester. How to run the test is there too. Good luck Prexford and I hope it ends up ok.

[critter]

How many miles on the motor? if it's less than 500, go drive the snot out of it and get the rings to seat. Then do it your test again.

[prexford]

I might have 300. I have moly rings; will these take loger to seat?

[performerrpm]

i always thought black was just a rich fuels mixture and oil was whhite ashy or flaky lookin just about everytime a carb has ran rich or loaded my plugs turned black try just making sure the plugs are getting good fire before getting to worried

[prexford]

I did a leak down test today; on a cold engine I heard it leak through the rings. Then I warmed up the engine (per instructions) and it seemed to pass. Still heard air but it stayed in the "safe" zone on the air guage...if there was any leakage it would still be through the rings. Can you guyws help me with 3 questions?

1. This is a new engine rebuild with moly rings. Do moly rings take long to seat? I may have drove it 150 miles, but have atleast 10 hours of drive way idling.

2. when I did the leak down test, I had my wife turn the ignition until both rocker tips relaxed off the springs. I figured this meant both valves would have been closed. I could push down on the back of the rockers and see the tips were off the springs. Does this sound correct?

3. could the oil in my spark plug holes be from my over sized cam that has too much overlap?

Thanks for your help

[kisertl]

My way of thinking is you don't have a problem until you seat the rings and put 5k miles on it, if you still have the oil problem, if it is a problem then start looking for problems in the head gasket, valve guids and rings. Take a tip and puts some miles on it. the heating thing sounds to me like the radiator needs professionaly cleaned, Does it start to heat up sitting in traffic at idol for a long time? Low rpms less heat radiator works fine, high rpms more heat radiator isn't convecting properly.
let me know what you find out
terry

[77TA]

If your running a PCV disconnect and drive it around and re-check... mine sucked oil something fierce with the PCV in the valley pan.. after market KRE POC....

[GT182]

Heating up could also be a bad or stuck thermostat Kisertl. Or even something inside the engine got plugged up when it was put back together..... it does happen no matter how careful one is. But hopefully you,re right and it's the radiator.

[kisertl]

I found that when it heats up at fast speeds and cools down at slower speeds it's the rad. I picked up a YH 428 that I was told had low miles (under 100k) and it had a heating problem, what I found on tear down was who ever replaced the water pump didn't install the divider plate.
they never let it overheat and I got a perfect motor for pennies.

[LouisianaGuy]

Ya need to take the water pump and divider plate off and put the divider on to the back of the pump and look at the clearance between the plate and the pump vanes...if its more than about .060 thou or so take the plate and hammer it down around the opening a bit to close the gap some what....had same heating problem as you at high speeds...did this one modification and car never gets over 180...usually has hard time getting to 180 now LOL....just make the plate closer to the pump vanes...and if you are running a stamped steel bladed pump...loose it and get a cast iron impeller pump it helps also...they are cheep at NAPA.....
Mike

[prexford]

I have a new aluminum radiator, new water pump, modified divider plate. I think it's over heating because of my 041 ram air IV cam selection on a low compression 8.2-1 car. It's just not dialed in. Going to a Summit 2801 to see if this corrects problem.

[LouisianaGuy]

Humm....what kinda RPM are you running at highway speeds.
you may wana try an XE Comp cam, they are designed to work well in low Compression motors....have one in my 455 and its pretty nice...running about 8.2-1 compression right now with this cam and car seems to like it...Im stepping up tho.
Mike

[prexford]

at 3500 im at 210 temp with 160 themostat. anything below 3500 temp rises to 225. Can idle all day long at 160 in the drive way. I'm going to a Summit 2801 cam. Thought about the XE, but really wanted to get back close to stock or little above to try and settle this heating issue once and for all.

[Goin' Topless]

It sounds crazy, but you might want to go to a 180 thermostat. I had a 160 and in one of my Pontiacs (70 LeMans) years ago and it ran hotter than the 180. I think it had to do with the 160 'stat opening too much and too long that it wasn't giving the coolant a chance to cool off and the heat bult up. What you described is what happened to me.

[prexford]

I tried putting in a higher themostat; 180 and 190. Same results happen with the 160 except idle temp is now 180/190