First im replacing the intake manifold with a the efi manifolds. I was curious anyone know a vehicle I can salvage a partial exhaust from ? basically y pipe and maybe 3 feet?

Second im using the DP OFFY intake and was curious about the differences between that and the single plane?

Third Holley 390 vs Edelbrock 500. The holley is a lot more expensive is it really worth it ? Does the Edelbrock hurt MPG that much?

Fourth Ignition I was just going to do the petronix in what I believe is the original distributor but I read that the advance kinda sucks is their something else I can do instead? Or maybe a later distributor I can use that isn't that vacuum advance one?

All of this is in a 1966 f100 t18 4 speed 300 motor.

 

The EFI 4.9/300 came in 87 - 96 Ford trucks and Broncos. Any of those could potentially have a six in it. Another option is to just buy the manifolds off of Ebay and then get a Walker 45166 pipe.

The differences are pretty minor. I have two Broncos, both with 300 sixes, and 600cfm Holley 4bbls. One has the C and the other the DP. The DP seems to have a little bit more low end oomph and a tad better gas mileage, it also has a more aggressive sound to it. The C seems smoother and overall more "luxurious". Neither really seems to have a big enough advantage that makes me wish the other had it.
About the only big difference is that the DP is strictly designs for a 4bbl, whereas the C can take anything with the right adapter.

I haven't had a Edelbrock 500 on mine, but I've tried the 390 and was never impressed with gas mileage. I got about 11 - 13 no matter what I did. Switched to a generic 600cfm Holley and, while it doesn't have quite the "snap" the 390 did, I get around 16 - 19 for gas mileage. Granted, I may have just had a lemon carb, since plenty get good gas mileage with the 390, but that's my experience.


I'm not sure on that one. I just used the stock DuraSpark II ignition on both of mine and have been happy with it. Another common setup is to use the DUI ignition.

Best of luck.

 

Really appreciate that a lot of info all at once. Im going to look to score a dura spark 2 from the boneyard or possibly cough up the money for the dui.

I also got my hands on a 4100 1.08 venturi carb rebuilt 1 year warranty and the guys gonna tune it on the car all for 250 plus tax. So hopefully if summit does their job and gets it here fast ill be up 20 - 40 horse by Monday. Once again thanks a lot

 

Here's another option on the distributor if you haven't found one yet:

74 87 Ford 4 9L 300CI i6 Distributor E 150 250 350 F 150 250 350 Bronco New | eBay $48 with free shipping.

I just put one of these in my Bronco with an I6 and it is working great. Magnetic pickup going to an MSD Street Fire Ignition Box.

Dropped right in the block, fit was perfect.

 

You should know: There are big block 1.08's that Ford put on 390's and up, and there are small block 1.08's. These are calibrated very differently. I have used both. You want the sb 1.08. Check the serial numbers on mustang tek dot com.

Good luck. k

 

Wow did not know that but to late as i already have the carb rebuilt in my possession ill have to check the serial numbers when i get home though. Thanks for the heads up.