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?

 

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.

 

Wow, wasn't even thinking about the valve covers but I put on tall ones to clear the roller rockers. I reckon it's probably worth it just for the clearance.

 

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.

 

It's weird that they don't do anything in an EFI vehicle, I've seen guys pick up 20hp with carb spacers. Must be a fuel atomization thing.

 

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.

 

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

 

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.

 

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.

 

Paul, do you use a ball peen or claw clearancing tool?

 

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.