I bought the block from a salvage yard and took it to the machine shop where they hot tanked it and magnafluxed it and then bored it .020 over stock. I talked with the machine shop today and they said that if a cylinder was cracked next to a water jacket it would show up in the compression test and I would have coolant in the oil or steam blowing out of the exhaust. Which I had neither signs of when the motor was running. I did some reading on the web after doing a google search and the best scenario I could find was the one you said where if the heads were cracked it would cause exhaust gases to build up in the coolant system and the other is if the were air pockets in the coolant system that would cause it to overheat as well, but didn't mention anything about pressurizing the system.

If you start a vehicle cold with the radiator cap off, you should be able to let it run until the thermostat opens with out the water flowing out the radiator cap opening right?

 

I have heard the these 302 (as well as other engines) can become air locked around the thermostat and that it is a good idea to drill a couple of 1/8" holes in the outer metal rim of the thermostat to prevent this problem. My 302 actually has a pipe plug in the thermostat housing that can be used to vent any air above the thermostat. If the thermostat is air locked it won't be able to open or it will be slow to open because the hot water can't get to it to make it open.

 

In answer to your earlier qustion Dave, don't coat the head gaskets with anything. Good quality modern head gaskets such as the Fel-Pro blue need no other coating, that's old-school stuff.

 

Cujo-I have heard of those "fail safe" thermostats, but I could not find one for my Bronco anywhere. But dont they have like a little one way valve in them so the cool water doesn't flow into the housing? It seems to me if I just drilled a 1/8" hole in the rim the cool water from the radiator would flow into the housing and mix with the hot water and never let the thermostat open.
If I take the heater hose loose just before the heater core will that let the air escape as I fill the system?
Dan- thats what I thought, one of my performance 302 books that I have recommended it but it was published in 1980.

 

I don't pretend to hold a candle to what you guy's know about engines. I've been keeping up with what's going on, because I hope to rebuild my 91' 302 some day. I did deal with an overheating problem for a whole summer changing the water/antifreeze probably 10 times. I had heard about the vapor lock, I never had any problems with that. I just let it worm up with the cap half on, and kept adding water till it was full. It usually took about 10-15 min. depending on outside air temp. I'm confused how a radiator with a 8-14 lb. cap can let the hoses get hard as a rock. Even if the pressure is coming from the cylinders, shouldn't the cap let go before the hoses get that hard.

 

I don't know about the "fail safe" thermostats, but the practice of drilling an 1/8 inch hole to allow air to escape is commonly done on many makes of vehicles. I am a member of Chevy, GMC, and Pontiac forums as well as FTE and I seen this type of fix listed in all of them, so it must work. I will be doing this modification on my thermostats before I install them.

 

If you use a Ford Motorcraft or a MotoRad Failsafe thermostat they dont need to be drilled as they have a vent hole in them with a plug that seals it as the coolant pressure rises. I install mine with the vent hole twards the top.

 

Well I am going to give it a shot. I'll let you know what happens.

BigRed- thats a good question, I have a 15lb brand new Stant radiator cap on mine and it has not yet let any of the pressure release into the overflow tank.

 

Maybe just for the hell of it, get a 8 lb. cap and see what happens.

 

Boyd Coddington had the same problem with a Ford small block on "American Hot Rod"...they even put a vacuum pump on the radiator neck which was supposed to bleed the air out of the system. If it can happen to them I guess it could happen to anyone

 

I have an update: Pulled the cam and sure enough, #7 and #5 lobes are wiped:




Is it typical for assembly lube to gather around the pickup tube like this? Will it eventually dissolve?


And there is some fine scratches on the piston skirts and piston walls, you can't feel them but you can see them, these normal as well?


I also have 2 questions before I start assembling this thing:
1. If I use a wheel cylinder hone to clean up the lifter bores, should I use oil or do it dry?
2. Can I take off one of the Main and Journal caps to look for damage from the metal shavings and still be able to use the same bearings if they are good?

Thanks!

 

1. Not dry! Use lubrication when honing, always...

2. Yes, as long as you check them one-at-a-time and don't mix them up.

I've never pulled apart a freshly-built motor so I can't say for sure how much of what you're seeing is normal. I would think you'd have some fine scratching of the piston skirts as they wear in, but it should be more of the order of scuffing then actual scratches. Perhaps a little more oil on them during assembly wouldn't have been a bad thing. And I believe the assembly lube would have disolved with a little more run-time. I like to run it for 1/2-hour to an hour, then change the oil and filter with the oil still hot. That should remove the traces of goo and metal. Obviously you weren't able to do that.

Check out Crane's line of assembly lube products, makes for some interesting reading:

http://www.cranecams.com/index.php?s...s&lvl=2&prt=15

Bummer about the cam though...convert it to roller and then you don't have to hassle with cam break-in.

 

Well this time was successful (so far) I did a 40 minute break-in on the new cam without it overheating this time. I did the 1/8" hole in the thermo-stat to vent the air out, don't know if thats what really fixed it or not, but its working.

A few problems I do have that may be you guys can help me with:

1. It was idleing fine in park, but as soon as I put in gear it would stall. I raised the idle from 700 rpms to 900 rpms and now I can put it gear but it kind of hunts for steady idle. I put a vacuum gage on and I'm getting 15" of vacuum at 900rpms.
I took it out and drove it but it definately shifts funny, it shifts in the high rpms, not extremely high rpms, just higher than normal.

2. I disconnected the spout connector and set the timing at 10* BTC at 900 rpms and it would stay steady at the pointer. Turn it off and reconnect the spout and start it back up and the timing mark is way off the mark and not steady, moving back and forth.

I have an idea what may be wrong, tell me if on the mark or not. First, I'm running no exhaust at this time, just the 2 Cats with no tail pipe. I'm thinking because of no back compression this may be causing my stalling and weird shift patterns.
Second, if I am off by 1 tooth on setting the distributor, will that effect anything? Like my vacuum reading? I'm thinking 15" is a little low, should be more like 20" right? Truck runs a little warm but doesn't overheat, its between the "R" and "M" in NORMAL, I'm used to seeing it run closer to the "N" and "O".

 

what cam did you put in it....@.050 and lift....

 

I put a CompCam in, the 31-255-5. Here are the specs:

<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Basic Operating RPM Range:</TD><TD class=overview-c2 width="75%">1,000-5,200 RPM</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Intake Duration at 050 inch Lift:</TD><TD class=overview-c2 width="75%">206</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Exhaust Duration at 050 inch Lift:</TD><TD class=overview-c2 width="75%">212</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Duration at 050 inch Lift:</TD><TD class=overview-c2 width="75%">206 int./212 exh.</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Advertised Intake Duration:</TD><TD class=overview-c2 width="75%">250</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Advertised Exhaust Duration:</TD><TD class=overview-c2 width="75%">260</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Advertised Duration:</TD><TD class=overview-c2 width="75%">250 int./260 exh.</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Intake Valve Lift with Factory Rocker Arm Ratio:</TD><TD class=overview-c2 width="75%">0.462 in.</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #f5f5f5" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Exhaust Valve Lift with Factory Rocker Arm Ratio:</TD><TD class=overview-c2 width="75%">0.474 in.</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Valve Lift with Factory Rocker Arm Ratio:</TD><TD class=overview-c2 width="75%">0.462 int./0.474 exh. lift</TD></TR><TR onmouseover="this.style.backgroundColor='#f5f5f5'; " style="BACKGROUND-COLOR: #ffffff" onmouseout="this.style.backgroundColor='#FFFFFF'"> <TD class=overview-c1 width="25%">Lobe Separation (degrees):</TD><TD class=overview-c2 width="75%">114</TD></TR></TBODY></TABLE>