400 with Dis question
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400 with Dis question
I have a rebuilt 400 in my 78 F250, the guy I had take it out and take it to get it rebuilt said he had the heads worked to get a little more compression. What compression would I have getting that done? Also he returned it back to me with the vacuum advance disconnected. Said it would run better that way as the timming doesn't change. This doesn't sound right to me. Please help.
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Joined: Aug 2001
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From: Delaware
Originally Posted by 69BigblockFord
I have a rebuilt 400 in my 78 F250, the guy I had take it out and take it to get it rebuilt said he had the heads worked to get a little more compression. What compression would I have getting that done? Also he returned it back to me with the vacuum advance disconnected. Said it would run better that way as the timming doesn't change. This doesn't sound right to me. Please help.
If he had the heads milled, it will boost the compression. On a 400 that is not a bad thing to do. Although there are better ways to boost the compression, milling the heads is probably the cheapest. Without knowing how much he removed from the heads, it is impossible to determine the actual compreesion or compression ratio.
As far as disconnecting the vacuum advance is concerned, that is not desireable. The vacuum advance advances the timing when it is needed for power and fuel mileage.
Did this genius do anything else, like disconnect the EGR valve?
Does the motor ping?
Or did it ping before he disconnected the vacuum advance?
Try to find out what was done to the heads, or how much they were milled.
