EFI plenum spacer
Thread Starter
|
Postmaster
Joined: Mar 2005
Posts: 2,949
Likes: 6
From: Earth
EFI plenum spacer
Anyone using an aftermarket EFI intake with a plenum spacer? How much difference do they make with EFI vs. a carb? For that matter, what about with a 5.0 truck intake?
I just ordered a Typhoon 5.8 lower and have a Performer EFI upper. I know I can easily fit one 1" spacer under the hood of the truck. Worth the $75?
I just ordered a Typhoon 5.8 lower and have a Performer EFI upper. I know I can easily fit one 1" spacer under the hood of the truck. Worth the $75?
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Slightly longer runners should make a difference.. but it will be hard to detect I bet. It may even be necessary for TB clearance over the fuel rail or valve cover... I don't know because I'm not that close to mocking up my 5.8 yet.
Moderator
Joined: Jun 2003
Posts: 3,548
Likes: 71
From: Calhoun GA
You wont notice any difference with a spacer. Most people need to install a spacer if they also have tall valve covers, and in some cases, the tall valve covers are needed to clear aftermarket roller rockers.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Yes it's a fuel atomization thing on carb and TBI motors. A plenum spacer on a long runner design like these trucks have will affect the TQ curve but it's going to be pretty small and hard to feel, it takes a 3" or 4" difference in runner length before it really becomes noticable from the drivers seat. The Edelbrock Truck upper is about 4" longer than the stock truck upper for example, and the Victor series intakes are 3-4" shorter than the Performer series. Both of these shift the powerband 800-1000rpm up or down.
Senior User
Joined: Jan 2004
Posts: 299
Likes: 0
From: Mt. Home, ID
Do you guys know of anyone that makes a spacer for the stock 5.8 intake? I can't seem find one with any searches. Without the taller valve covers my next option is modifying the stock ones. I just picked up a set of roller rockers for mine.
Mike
Mike
Trending Topics
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
All you should really need to do to fit the rockers under the stock covers is clearance the baffles for the oil fill and PCV. I have put these on Mustangs with the stock cast aluminum covers which are a little shorter than the steel truck covers.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Moderator
Joined: Jun 2003
Posts: 3,548
Likes: 71
From: Calhoun GA
A stock mustang valve cover will clear aftermarket roller rockers, however, the oil fill tube may need to be modified slightly to clear a stock F-150 upper intake; you can use a little heat and bend it since the neck itself is steel.
Try putting your stock covers on first, some aftermarket roller rockers will work with the stock truck VC's.
Try putting your stock covers on first, some aftermarket roller rockers will work with the stock truck VC's.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Diesel/hydraulic powered BFH. 
Actually you would be surprised how restrained I can be at times... my favoite tool for this type thing is a dremmel with a cuttoff wheel installed.
Actually you would be surprised how restrained I can be at times... my favoite tool for this type thing is a dremmel with a cuttoff wheel installed.
4wd Low
Joined: Mar 2024
Posts: 12
Likes: 1
Plenum 1” Billet Spacer VIN: H, HO 1988-1997 F-350, F-250 Fits Felpro MS 94176 | eBay
and shop online is
Items for sale by reapercustoms805 | eBay
plenum doesnt touch 'firewall' after install YOU MIGHT WANT TIG WELD IT TO PLENUM, im too worried about vacuum leaks through too many gaskets on either end of spacer !!!!!!!!!!!!!!!!!!!!!!
Trailering
Joined: Dec 2024
Posts: 15
Likes: 0
here i bought a while back they're good quality billet
Plenum 1” Billet Spacer VIN: H, HO 1988-1997 F-350, F-250 Fits Felpro MS 94176 | eBay
and shop online is
Items for sale by reapercustoms805 | eBay
plenum doesnt touch 'firewall' after install YOU MIGHT WANT TIG WELD IT TO PLENUM, im too worried about vacuum leaks through too many gaskets on either end of spacer !!!!!!!!!!!!!!!!!!!!!!
Plenum 1” Billet Spacer VIN: H, HO 1988-1997 F-350, F-250 Fits Felpro MS 94176 | eBay
and shop online is
Items for sale by reapercustoms805 | eBay
plenum doesnt touch 'firewall' after install YOU MIGHT WANT TIG WELD IT TO PLENUM, im too worried about vacuum leaks through too many gaskets on either end of spacer !!!!!!!!!!!!!!!!!!!!!!
By chance do you know what bolts you ended up using for this?
Last edited by hotrod_lincoln; Oct 24, 2025 at 09:56 PM.
4wd Low
Joined: Mar 2024
Posts: 12
Likes: 1
i went with zinc steel bolts standard tool hex top with the extra width of the plenum spacer , go with some nice expensive ones. if its too long use angle grinder. i dont recall exact measurement.
Turned out to be a warned out bushing inside the distributor , which lowered the windows on the Hall Effect Sensor which inturn didnt detect the open windows inturn didnt command the tfi module to command the ignition coil to fire . I figured this out with a Toledo Ignition Spark Tester Box Type - 302165 . But in my haste when i replaced the Distributor i didnt make a marking on the timing reference to the block and lost my Timings. so now i have to do a timing correction reset to valve on vacuum-up cylinder . i must take of the plenum again to get remove rocker cover. I did it the correct way without taking the rocker cover but it wont start. So i will need to spot the valves when both are open to get a more accurate Top Dead Center (TDC) instead the marking on Harmonic balancer. IN TURN STORAGE FOR MY XLT until i get the SPACER TIG WELDED TO THE PLENUM just too much **** to remove and re-install .. glad the spacer worked out for you ,
Turned out to be a warned out bushing inside the distributor , which lowered the windows on the Hall Effect Sensor which inturn didnt detect the open windows inturn didnt command the tfi module to command the ignition coil to fire . I figured this out with a Toledo Ignition Spark Tester Box Type - 302165 . But in my haste when i replaced the Distributor i didnt make a marking on the timing reference to the block and lost my Timings. so now i have to do a timing correction reset to valve on vacuum-up cylinder . i must take of the plenum again to get remove rocker cover. I did it the correct way without taking the rocker cover but it wont start. So i will need to spot the valves when both are open to get a more accurate Top Dead Center (TDC) instead the marking on Harmonic balancer. IN TURN STORAGE FOR MY XLT until i get the SPACER TIG WELDED TO THE PLENUM just too much **** to remove and re-install .. glad the spacer worked out for you ,
Last edited by hurr1cane; Oct 27, 2025 at 11:56 AM.
Thread
Thread Starter
Forum
Replies
Last Post
4x4man514
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
4
Sep 20, 2015 10:57 PM
joey390burnout
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
10
Aug 20, 2010 11:52 AM
jerg_064
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
5
Mar 3, 2008 08:45 AM
FordPerf300
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
2
Sep 7, 2004 04:37 PM
restorit
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
8
May 29, 2002 11:32 PM
