Howdy. I'm new here. I recently started a '59 F100 project; got it with no engine or trans. Today I spotted a complete 4.9 EFI engine/M5R2. Here's where the question is. I have a 300 intake/exhaust and a head that I think is from an '85. These were gonna go on a '65 that got totaled. Will these parts fit on the EFI 4.9? I thought I'd ask some experts before I waste any money. Thanks

 

The 85 parts will physically bolt on the EFI engine. There are a couple things that are different though.

The EFI engines have small combustion chambers ( around 68cc ) in the head and large dishes in pistons. The 85 head has large combustion chambers ( around 76cc ) . The EFI head also has fast burn combustion chambers.

So if you want to run the 85 parts on the EFI engine you can but the head will lower the compression ratio by around 0.5 ( if it ha 8.8:1 compression it will drop to 8.3:1 ) . And with the carbed head you will need more total timing to compensate for the regular combustion chambers. If you want to convert the EFI engine to run a carb you will also want to swap the distributor to a Duraspark II style.

 

Of course you could have the carb head shaved a bit to compensate/raise the c.r. where it should be.

There is no opening for a manual fuel pump on the EFI block. The bolt holes are there, but you have to drill/grind an opening if you want to use a manual pump. Shavings in an engine ....ouch!

 

That would be a pretty massive cut on the head wouldn't it? A 240 head would be a better choice. No compression lost and standard chambers. Either that or change pistons $$$$.

You are right about the fuel pump but you get around that by running a low pressure electric pump.

 

I believe the big alternator/air pump bracket on the passenger side of the FI 300 would actually prevent you from bolting on the older log style exhaust manifold. I think the only way to put a log exhaust manifold on a FI block is to change the FI serpentine belt over to the older V belt and brackets. Or do a buttload of grinding on the alternator bracket. I could be wrong here. I'm only going off things I've noticed visually but not tried.

 

Good info so far, thanks. Sounds like I may be better off either using the stock manifolds or maybe going to an Offy intake with a 650 carb on the EFI head? Going away from the serp belt isn't a problem, if I could find/make a pulley to put in place of the air pump.

 

If it is an efi block, then it should have the efi exh. manifolds.

I don't think it would take that much shaving of the head to gain back the .5 . Of course you would have to cc the chamber to find out for certain, but I would guess a .030 off, or close to it.

 

Run the stock EFI exhaust manifolds with an Offy C-series 4V intake. The dual EFI exhaust manifolds are like cast iron shorty headers and they flow much better then the carb'd exhaust manifold does. For a driver I prefer the Edelbrock 500 or 600 cfm carbs. Just for reliability and simplicity. They are much less likely to leak fuel then a Holley.


He'd need to loose 8cc's per chamber to make up the difference. Personally I prefer to cut as little material from the block and head as I can get away with. But I'm just paranoid about that stuff.

 

It seems there are two different Offy intakes for these engines? I'm more interested in low end torque as this will be a working, pull big stuff truck.
If a stock carb intake will fit with the EFI exhaust I may consider that as the price is right. If the engine passes a leak check I can't see pulling the head. I wasn't sure if I'd need to use the older head with the EFI engine.
BTW I'm a Holley guy. I won't hold your love of Edlebrock carbs against ya.

 

The Offenhauser DP intake is a waste of money. I've ran both and I will never run the DP again. It does nothing except restrict air flow. The C-series makes great low end torque but also doesn't restrict mid and top end power.

The stock intake and carb are very restrictive. If you don't want to run a 4V you can run the Offy C-series and just add a 4V to 2V adapter and run a 2V carb on it. But don't do that with a DP intake. You can run the stock intake/carb if you want to. You will need to do a little fabricating to keep a working heat riser though.

If there isn't a problem with the EFI head ( like a crack ) I'd just run it. They have a valve shrouding issue but in a truck I don't see that being an issue. You will want to swap in a DSII distributor and you will want to take some of the total timing out of it because of the fast burn combustion chambers. That just requires a little tuning( re-curve ) to the mechanical advance in the distributor.



Hey I'm not a Holley hater. But on a daily driver I have found the Edelbrock is a better carb with a much smaller chance of leaking fuel. I've ran Holleys on a 300 and every one of them eventually starts leaking gas from the fuel bowls. And on the 300 when it starts leaking gas it drips right on the exhaust manifolds. Not a good situation. That being said I will be running a QFT Holley E85 blow thru carb on my truck.

 

I've never run the DP but the truck didn't lose anything down low with the C intake. No loss off the line and at least 1,500 more rpm up top.

AB has one of each, what say ye Justin?