302 vs 351w

[Orangecrush]

The compression test shows less than 100 psi for the 351w (when cold). I guess that means it's time to rebuild or replace. Now, I spent tons having brackets fabricated so that the A/C would bolt up and work with all the other accessories.

To make sure everything just bolts right back up, can I buy a crate 302, or do I need to stick with the 351w? I don't recall??

Also, how much torque can the c4 handle? I've got lots of options but don't want to break the tranny.

Thanks!

 

[Scott Andrews]

The compression test shows less than 100 psi for the 351w (when cold). I guess that means it's time to rebuild or replace. Now, I spent tons having brackets fabricated so that the A/C would bolt up and work with all the other accessories.

To make sure everything just bolts right back up, can I buy a crate 302, or do I need to stick with the 351w? I don't recall??

Also, how much torque can the c4 handle? I've got lots of options but don't want to break the tranny.

Thanks!

Before you rebuild the 351, you should do a leakdown test (See attachment). THis will tell you pretty clearly what needs rebuilding. My 73 302 had ZERO compression on two cylinders. It was leaking into the exhaust and not the crank case, so I pulled the heads. As suspected, major burned valves. In fact, the heads had not had valve seat inserts installed, so, running unleaded gas the exhaust valves were slowly working their way right through the head! I had some olde 3023 heads in my shed, so I had them refurbished (new valves and seals), and that was it. Does it blow a lot of oil smoke? If not, then it is probably just the heads.

The C4 is pretty strong. I think it can take over 400 Ft-Lb of torque. Check the TCI web site.

S

Leakdown_Test.ppt

 

[Orangecrush]

Before you rebuild the 351, you should do a leakdown test (See attachment). THis will tell you pretty clearly what needs rebuilding. My 73 302 had ZERO compression on two cylinders. It was leaking into the exhaust and not the crank case, so I pulled the heads. As suspected, major burned valves. In fact, the heads had not had valve seat inserts installed, so, running unleaded gas the exhaust valves were slowly working their way right through the head! I had some olde 3023 heads in my shed, so I had them refurbished (new valves and seals), and that was it. Does it blow a lot of oil smoke? If not, then it is probably just the heads.

The C4 is pretty strong. I think it can take over 400 Ft-Lb of torque. Check the TCI web site.

S

You're right! It burns NO oil. There does seem to be a good deal of crank case gas (if I just pop in a breather in the valve cover, rather than PCV, you can see a "steam" coming out, even at idle. I don't know if this is normal or not). However, it burns no oil and does not smoke at all. The exhaust is nearly invisible, even under load. Therefore, I may suspect that the valves are not sealing. This may also explain why the truck basically won't start when it's cold out. Could something like this also contribute to an overheating problem? (GIANT aluminum radiator and fan and shroud but still get hot over time). You may have it.

If it were leaking around the rings (which would mean FULL rebuild or replace), would it definately be burning oil and smoking blue out the exhaust? How much weight should I put on the fact that I can stomp on the gas and still the exhaust is clean (well, maybe a little black but that's fuel). Can I take this fact to the bank pretty much that the bottom end is in fine shape?

Finally, what heads should I buy considering low-end torque and driveability is the goal? To keep the compression at 9:1 or so, what combustion chamber volume??

 

[Scott Andrews]

Did you read the powerpoint? It describes the leakdown test.

I suspect it is just heads,. The early SB Ford engines did not use hardened valve seats, and using unleaded gas cases them to erode, so you burn valves, and lose compression.

Depending on your budget and needs, you can probably find some serviceable used heads for under $400. A rebuild (if it is possible) will run about $800 to $1100 depending on the situation and the rebuilder. New aluminum heads will set you back about $1300-$1500. I used ALuminum Edelbrock head on my 65 Mustang. They were very very nice!! I opted not to use them on the Bronco, however, because of the higher operating temps due to lower speeds. Personally, I woud find some iron heads, get them ported and have the valves done. Replace the timing chain with a double roller, and get a high volume oil pump. Flush the radiator and look for crap in it, and check the watrer pump. Use ONLY Permatex Hylomar when you do the reassembly.

Hard to say about the overheating. Have you checked the thermostat and water pump? I'd check those first. If the radiator is older than abou t2-3 years, then I'd have it boiled out by a qualified radiator shop that knows aluminum radiators. Some phosphate based coolants actually corrode aluminum, so it may be that inside, that giant radiator isn't so giant. I also have several old BMWs. These have aluminum heads, and BMW is VERY particular about the type of coolant to use. Everyone on the BMW boards swears by BMW OEM coolant cut 50% with water (it's blue). The worst thing you can do is to mix coolants since that can cause them to generate sludge.

I would drain the entire system, flush it with some sort of cooling system cleaner (but not phosphate based), refill with a good coolant that is OK for aluminum, and try that with the rebuilt/new heads.

HTH

S