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gt40 heads on 302 speed density motor


mikeE72

Well-Known Member
V8 Engine Swap
Solid Axle Swap
Joined
May 29, 2008
Messages
125
Vehicle Year
1988
Transmission
Manual
anyone run a set of gt40 or gt40p heads on a 86-88 302 speed density motor. i know most people pick up a good gain in power and ive got a chance to pick up a set of gt40(p) heads for my truck for 300 and they only have 35000 miles on them.my one concern is that ive heard of the speed density motors responding badly to almost any mods. any help is appreciated. and thanks in advance
 
I run/ran GT40 heads on my truck. My truck was Speed Density for a while, the heads cause no problems.
It's camshafts that can cause issues with Speed Density, and the reason for that is the MAP sensor. It references intake manifold vacuum, which is typically reduced at idle with an aftermarket cam.
(With a Mass Air system, the vacuum source is removed from the MAP, now BAP, sensor- It now references barometric pressure, not manifold pressure. Same sensor, though.)
 
Thanks man and how do I get the v8 rbv banner like you got vie had a v8 ranger for 4 years or so now.lol. And again thanks I did some digging last night for a long time and came to the same conclusion. Just wanted to make sure.
 
Look for "group memberships" on the left side of your user control panel.
 
If it had E6 heads originally the engine didn't valve reliefs in the pistons. That will likely cause piston/valve interferance, especially with a different cam.

If it has been rebuilt (20+ years later) it is anyone's guess what was put back in. Either find a buddy with a borescope or you are going to have to do an exploratory and pull the heads.
 
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