In my quest for getting the power out of my F-350 400 engine, I have been seeking information. The engine has 93K miles on it, runs well, and shows no sign of problems other than being a California smog engine. I am in the process of installing a mechanical oil pressure guage to check out the bottom end, and have a Cloyes double roller cam gear/chain set to bring the cam to TDC instead of retarded 6 degrees, and plan on finding a header/ exhaust system to improve flow. I was told by a mechanic that this engine has two piece valves that tend to come apart after the 100K mark. Is this a problem I should worry about? Probably aftermarket aluminum heads would cost little more than rebuilding these heads to prevent the possible problem, but the added cost will move the finish of the project out a while. If the heads/ valves problem was exaggerated, I wouldn't have a problem using these heads. Any solid info would be appreciated. Thanks

 

I wold say these valves are more prone to coming apart at high RPMs verses high milage and the 400 really doesn't like RPMs any way. I don't think the stock valves are near as bad as their reputation, but some times its better to be safe than sorry. What are you doing with this engine? If you are running a stock cam and intake/carb I think you will be fine the power band will still be low. Plenty of these things have been running for 30 years with out breaking a valve. I have switched every motor I have every rebuilt to single groove one piece valves but I am paranoid about such things. Really its up to you and how you thing you are going to run this engine.
-Johnboy

 

Thanks for the reply and help. I intend to keep the milage low, probably 5,000 miles per year, most of it highway. I have never taken the engine over 3900 rpm, and then only when down shifting. On the highway I have usually kept it at between 2400 and 3200 rpm. I intend to put on 35" tires [or so] to keep the highway rpms down to around 2500. I may try for a Edelbrock 4bbl intake as was recommended for better gas milage. I will also port the distributer directly to the engine vacuum to avoid the smog delays with the carb and EGR porting. If I need to change out the heads, I will go with aluminum after market heads, but I would just as soon keep the expense to a minimum so I can afford more gas.

 

You don't want to plug the dist. into a direct port vacuum source. You would want to plug it into the port on the side of the carb.

 

you can run manifold vacuum but the canister on the dizzy needs to be limited to around 12*, it'll pull maybe 60* or more if it's not limited

 

I think Ethan meant he's gonna bypass the temp switch.

 

I have been reading my factory manual, and in the smog section it indicates both the carb and the egr have spark advance delays and retardation to pass emissions. How do I port the distributor to get standard spark advance? And do each of you agree that the two piece valves are OK? Thanks for the help.

 

stock 2 piece valves are NOT ok unless you're looking to scrap the engine at some undeterminable point in the future.

here's a rundown on how to set up for manifold vac advance
Cleveland Links!: How I use manifold vacuum for advance (posted here so I can find it)

here's a rundown on how to set up your mechanical advance, Ford point distributors are the same below the breaker plate, don't miss the second page
Duraspark_distributor_recurve_instructions_index

 

Thanks for the help- so I should start saving for the aftermarket heads, as rebuilding the stock heads would cost about as much.

 

You can but 1 piece stainless 1 groove intake valves(Milodon)at Summit all day long for $85.00 for a set of 8.You can get the exhaust valves for $90.00 a set.Even with new retainers,locks,seals,and guides you will be way ahead of the price of aftermarket cylinder heads.My .02.

 

Thanks for another perspective. I wonder if I could rent the tool to re-cut the seats- R&R heads and new valves would be a waste without doing the complete valve job.