Lou64

Ok, on to the next set of problems with my 350 crate engine (I thought these were plug and play?). I have like 5 miles on it so far. I did a compression test today with the engine at about 90 degrees and got compression on all cylinders in the 115-125 range. Driver side plugs were fine, BUT the passenger bank of spark plugs were a bit weird. #2 was fine. #4 was slightly dark, maybe 4 out of 10 (10 being completely dark and fouled). #8 was a bit darker than that, maybe 5 out of 10. #6 however was atrocious, 10/10, carbon deposits crusted on it terribly. I mean this engine hasn't probably ran more than an hour in its life thus far. Advice?

I am also having these other problems:
1. Running super freakingly hot. Think I should remove my radiator and have it flow tested, I'm thinking it's original.
2. Along with that my temp gauge isn't working right. I put an IR gun on it at 90 degrees and the temp gauge said about 230. The sending unit is brand spanking new. Common problem? Fix?

SDVette

Hi Lou,

I'm surprised no one has jumped in on this yet.. so I'll give you a few ideas, and a bump to the top!

With compression numbers looking normal, I think you have to suspect a spark problem. To be fouling plugs that badly in 5 miles, something has to be out of whack. Tell us about the ignition system...... New wires, cap, points, etc???

Also, is it using any oil?

Regarding the heat... I think it's pretty common for the repro senders to be off - but maybe not as much as you are seeing? +140 degree error?

And are you REALLY SURE it's truly running "freakingly hot", or just indicating that on the temp gauge?

Westlotorn

Lou, very sorry for the headaches you are having. I think this may be where someone needs to come in and advise you on scene. Someone with experience, not your neighbor that worked on cars when he was a kid. Talk with locals that might know a good experienced mechanic with a well rounded engine background. With those low compression numbers I am afraid you may have something else going on.
Maybe someone on this forum can hook you up.
Heat can destroy a brand new engine quickly. So can a bad tune. Better to rule things out and save your investment rather than guess. I really hope it is not to late already.
Sorry but that is the way I see it. Even if heat damage is the cause of your low compression you may only need new head gaskets and that is pretty easy on these old engines. May want to drain the oil and cut the filter open and search for any metal that does not belong in there. Just ruling things out.
When I was a much younger I made the mistake of installing 350 heads on a 305 with the smog dished pistons in it. The combo was probably 7:1 compression, even that engine made 120 PSI on a compression test. I thought I was going to gain power with the larger valves. Hey I was only 22 and thought I was doing the right thing to make more power.

Lou64

Well this is an 8.5:1 engine, so it ain't gonna be very high. Plus the cooler temp on the test accounts for some of that as well. I'm supposed to be taking it to Ernie at Willcox pretty soon, but he is way backed up. I'm thinking issues might be valve seating, but just guessing.

And yes SD Vette I am sure it is hot, when I pour water on the IM it boils immediately, and the air cleaner is too hot to touch. I know timing being off can cause excess heat, but I know I am good there.

And I have just changed the oil a couple days ago and it was clean as a whistle, not gritty, no shards in the filter or anything.

ChattanoogaJSB

Just to be clear- ignoring your cars temp gauge, your IR gauge said 230? Someone will chime in yes or no, but I would think 230 degrees is HOT certainly but not hot enough to permanently damage anything in the short term, assuming that has been the max temp reached. You could have a lying sending unit, absolutely, but I would trust the gun. You can also take ohm readings at the sending unit when the engine is at ambient and then at know running temps as per your IR gun and compare them to the lbfun chart (the search function will find that quickly I'm sorry I don't have a link)

Westlotorn

Just a thought on this new engine install, was the air purged from the system? With the front end higher than the rear end remove the thermostat cover and make sure there is not an air pocket trapped in the engine.
When filling a block with coolant it is a good idea to fill them slowly and listen carefully for air escaping. If you are hearing air wait till it quiets and then fill some more so you don't trap air. Small blocks are pretty forgiving and purge easy but worth a check.

Lou64

Good call, but I'll also add my original engine was also running very hot before I pulled it. I also need to check the expansion tank. It was about half full when I started, but it was so hot when I got done I didn't want to touch it.

67vetteal

Time for some serious trouble shooting. Your Radiator needs to be addressed before it can damage anything else. (If it is Faulty). No harm investing cash into the Radiator as it is an essential part of your car. Once that is done take one of your good "used" plugs and put it in #6 and add a new plug where you took that Plug from. Why ruin a new Plug? On occasion a new plug will be bad. Years ago we rarely saw a new plug fail but these days it is more common. Run engine up to operating Temp. and using Gloves redo the compression test. I'm thinking 140 PSI is what it should be. BTW, Buy a cheap screw driver magnetizer and Magnetize the end of your Dip Stick. Easy way to look for metal particles in the crank Case. What Oil are you running? I'd change out the Filter now just for the "Maybe" factor. If the plug you install into #6 appears the same you most definitely have identified some sort of problem. Seeing as the Compression in that cylinder is compatible I'd be looking for either a bad wire, excessive fuel dumping into #6 or something weird. Al W.

Westlotorn

A new engine will make more heat than an old fully broken in engine. Sometimes a marginal cooling system that works on an old engine will fail to cool a new engine.
If you ran hot before odds are you have an issue that needs help.