351w efi flat top pistons?
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From: arizona
351w efi flat top pistons?
will be rebuilding tired 351w in '89 e350 sometime soon. want to put comp cams 35-255-5 speed density cam for a bit more power, and port the heads.
1) when i replace the pistons, should i shoot for more compression by possibly going with flat tops? or would that be a problem for the computer? will the speed density need tuned? if so, how is it done?
2) also, there is a lot of talk about maf conversions. it seems that the topics revolve around a truck or car. what about a van conversion? is it worth it? the van is used for pulling a 5000# trailer and has an aod with shift kit from a e150 302 and a 4.10 rear gear. could definitely use more power. lotsa mountains around here. i want to keep the efi because of the big elevation changes it sees.
1) when i replace the pistons, should i shoot for more compression by possibly going with flat tops? or would that be a problem for the computer? will the speed density need tuned? if so, how is it done?
2) also, there is a lot of talk about maf conversions. it seems that the topics revolve around a truck or car. what about a van conversion? is it worth it? the van is used for pulling a 5000# trailer and has an aod with shift kit from a e150 302 and a 4.10 rear gear. could definitely use more power. lotsa mountains around here. i want to keep the efi because of the big elevation changes it sees.
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Joined: Nov 2003
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From: vancouver bc
alright dont go for the flat tops, 351's ping like crazy with them, unless you want to run premium gas. stock replacement is just fine. if the motor is anything but stock and you want to run speed density injection you will need a custom chip to make it run right. maf is realy nice, i converted my truck from carb to maf out of junkyard parts. stock mustang maf will run just about anything up to 350 hp without any tweaking or injecter changes, anything over 350 hp and you gotta change injecters and do a bit of computer tweaking. but anyway, dont get the flat tops!
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From: arizona
thanks for the reply. when going to maf using mustang parts, what about the plumbing aspect? in a van, youve got a really different intake, filter, and hose plumbing. is there a problem locating the the maf meter?
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Joined: Nov 2003
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From: vancouver bc
it would be a little tougher to plumb in a van but it can be done. you have a twin bore throttle body and you need to get that into one tube to conect to the maf, the easyest way to do this is to get a part from ford (only thing i couldnt find in a junkyard) its just a black plastic y pipe with some tubes coming off of it, two tubes connect to the throttle body, go to the y pipe and come out as one larger one, i a have a big rubber tube connected to that, then the maf sensor, then just a pipe with a cone filter on the end. this is a very involved conversion but can be done, check out fordfuelinjection.com
Fleet Mechanic
Joined: May 2004
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From: Montana
I would get whatever pistons get you 9:1 compression. I think stock is a bland 8.5:1 if memory is correct, Im doing this build with edel intake and heads....I was told it should work without MAF.
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