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explorer 4.0 ohv intake manifold / throttle body mods

1991 sploder

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Wondering if anyone has swapped out their upper and lower intake for a better one or put a bigger throttle body? If u guys know exactly what works it's for a 1991 maybe a Ford van has a similar fit but wider...
 
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410Fortune

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port polish and gasket match
with the metal intakes you can do that
Also run a spacer between the upper and lower intake to keep the heat soak down, cooler air charge = more power.
 
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1991 sploder

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port polish and gasket match
with the metal intakes you can do that
Also run a spacer between the upper and lower intake to keep the heat soak down, cooler air charge = more power.

Thanks for the tips, porting the intakes now...
and I'm going to be looking for a spacer
 
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1991 sploder

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port polish and gasket match
with the metal intakes you can do that
Also run a spacer between the upper and lower intake to keep the heat soak down, cooler air charge = more power.
How far would u go on the porting.... ? A lot of these parts upper lowet+ fuel rail r only 15mm thick I'm leaving 7mm I feel like that's plenty...also should I pull the heads or leave them on? Want to pull them but don't have a good reason aside from porting...if I do am getting headers idk I don't want any heads to crack.
 
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1991 sploder

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Also...looking at it.... The upper intake is scroll style could handle 400+ hp? From my experience doesn't at all need porting...lower intake is single plane.pretty restrictive..needs heavy porting... I really don't think upper intake would do anything at all? Just going with a bigger throttle body....and spacer
 
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410Fortune

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there is for sure such a thing as too much porting
The biggest hurdle with the metal upper and lower intakes is to get a good gasket match on them and as you said some porting in the lower intake
These are not choke points for the 4.0 so there is no need to try and flow more air then the engine can possibly take in

Sven Pruett wrote the book on making power from a 4.0 ohv....literally
I have a copy, I have not seen it for many years, but it is still avail online for sale

going for $100 or more!! holy smokes
How to Build and Modify Ford 60 Degrees V-6 Engines (Motorbooks International Powerpro): Pruett, Sven: 9780879389147: Amazon.com: Books

If I have a good running 4.0 on the stand you better believe I am pulling the heads, timing cover, oil pan....I would re seal the entire engine and replace the timing set and update all of the gaskets, new head bolts as they are TTY, replace the valve seals as well
I have sealed up many 4.0 and doing head gaskets on them takes patience and some know how, but once you get it down then every 4.0 OHV you see in the shop needs fresh head gaskets, lower intake, oil adapter o rings, timing cover, oil pan. etc etc.............. it really can buy you another 200-300K miles on these engines
 
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1991 sploder

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Thank you, Yea one on there is 205 lol I'm going to look into that.. I have a chiltons on the way... Didn't even know this book exists might have to order that. Looking for a cheaper copy now.
 
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Jason94sport

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BBK's TB I had good success with. Not sure if it's made still.. Good for much better throttle response. Had 1 on all my 1st gens.
 
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