2F with shaved head and Sniper vs 2FE (1 Viewer)

[Seth S]

I've got a decent opportunity to pickup a 3FE with harness and computer from a mudder with a parting 80. I was planning to either build a 2FE for my truck...but more recently I was thinking of just doing rebuilding the head and having it shaved to bump the compression up a little and then run a sniper TBI. I picked up a set of 3FE exhaust manifolds already so I can get rid of the restrictive 2F exhaust manifold.

So if wiki is correct an 80' 2f is 7.8:1 compression and a 3FE is 8.0:1 compression. I haven't done the math but gut feel seems like a small amount of shaving on the head could bump the compression to the 8 territory.

So I've been reading through all the 2F, 3F, 3FE, 2FE threads in the archive however pretty much all of those threads were in the time before the proven TBI systems were in existence. So I'm wondering if I'm better off just working my 2F head a little and putting the sniper on. All my brackets stay the same and other than the sniper wiring nothing much changes on the truck. I can aquire the 3FE engine and wiring for less than the sniper unit but then its a fair bit of work to build up a 2FE and will be a bit of down time.

thoughts (braces for tidal wave of opions )

 

[John McVicker]

For me, simple is best. As described, I would opt for your thought on reworking your own head & put on the Sniper. Much less work...and you will ‘know’ exactly what you have.

 

[Seth S]

For me, simple is best. As described, I would opt for your thought on reworking your own head & put on the Sniper. Much less work...and you will ‘know’ exactly what you have.

thats pretty much where the rational part of my brain has been leaning. I suspect the 3FE head on the 2F block results in a higher comp ratio than either the stock 2F or 3FE and combined with the fuel injection and long runnered intake and better flowing exhaust manifolds is why the 2FE does so well. but I suspect a worked 2F head, a 3FE exhaust manifold, and a sniper will be pretty close.

This is the best explanation I've seen out of the various threads:

The strength of the 3FE is in the top end. The head has a tighter combustion chamber, the exhaust ports are bigger, the intake manifold and exhaust manifolds are both a more smooth flowing design than on the 2F, and of course you have a multiport fuel injection system, with all the engine management and fuel mixture benefits that come with it.

Benefits of 2FE

What are the benefits of a 2fe? Its fuel injected which is one benefit. What else?

forum.ih8mud.com

 

[FJ60Cam]

A lot of the awesomeness of the 2/3FE comes from putting the smaller 3F combustion chamber on the bigger 2F bores. Will be well over 9:1 CR. Up to 9.5 depending on your piston size (maybe, haven’t done the math in a while.)

 

[FJ60Cam]

The Sniper is 10x easier though, and has woken up every 2F I’ve put one on, even without any engine mods.

It doesn’t have multi port injection obviously, but todays engine management is light years better than 30 years ago.

 

[Seth S]

A lot of the awesomeness of the 2/3FE comes from putting the smaller 3F combustion chamber on the bigger 2F bores. Will be well over 9:1 CR. Up to 9.5 depending on your piston size (maybe, haven’t done the math in a while.)

Ok, so thats a big jump in CR. wouldn't have much left of a stock 2F head after shaving it for that much CR bump. But I suspect even geting a 2F up to 8.5:1, running a better exhaust manifold and a sniper would be a vast improvement over a stock 3FE or a stock 2F. Good chance I'll pick up the engine anyways. Its nice to have options and I have other projects I can use an engine in.


This is how people end up with LS conversions

 

[FJ60Cam]

We’ve been doing low 9 CR’s lately (but with a more aggressive cam and some nice valves & seat work) and have been getting away with cheap gas and timing still above stock.

There’s room to mill more off if you’re willing to run premium.

 

[RockDoc]

I've got 2 2FEs now and like them both. I think if you have the parts on hand, and especially if it's going in an original 3FE truck the 2FE makes sense. I have no experience with the sniper or other aftermarket setups, but I would think that is the way to go starting with a good 2F truck.

The 2FE will give you a nicer intake manifold and multiport, but I suspect the more modern (and tunable?) control on the sniper will balance or better those benefits for all but maybe high revs.

Build one of each and give us a good comparison

 

[Seth S]

I've got 2 2FEs now and like them both. I think if you have the parts on hand, and especially if it's going in an original 3FE truck the 2FE makes sense. I have no experience with the sniper or other aftermarket setups, but I would think that is the way to go starting with a good 2F truck.

The 2FE will give you a nicer intake manifold and multiport, but I suspect the more modern (and tunable?) control on the sniper will balance or better those benefits for all but maybe high revs.

Build one of each and give us a good comparison

This is going into my 60...so the 3FE wiring has to be figured out. I think the 3FE intake combined with Mega/Microsquirt would be the best way to go because then its a completely standaone harness and all modern efi components....also a lot easier to go to a distributorless ignition. But its also going down the rabbit hole of complexity. TBH though I'd feel more comfortable traveling with Megasquirt than the old 3FE system as there are a myriad of sensors and injectors that can be run with it. And if your MAP sensor fails on a trip you can get one of several versions and just make some adjustments with a lap top. but I digress.

 

[RockDoc]

This is going into my 60...so the 3FE wiring has to be figured out. I think the 3FE intake combined with Mega/Microsquirt would be the best way to go because then its a completely standaone harness and all modern efi components....also a lot easier to go to a distributorless ignition. But its also going down the rabbit hole of complexity. TBH though I'd feel more comfortable traveling with Megasquirt than the old 3FE system as there are a myriad of sensors and injectors that can be run with it. And if your MAP sensor fails on a trip you can get one of several versions and just make some adjustments with a lap top. but I digress.

That would be the ultimate. If I were a younger guy with more static in the attic and fewer draws on my time......

 

[FJ60Cam]

1FZs seem to be picking up 25-ish HP just from switching to modern computing. Seems like the 3FE would benefit even more, at least percentage-wise.

 

[Seth S]

Well there is this

 

[FJ60Cam]

Well there is this

View attachment 2231177

View attachment 2231178

Hold my beer

 

[b56tc]

Just finishing a desmog on my stock 2F, bore .30 and balance, mild cam, headers, deck work, Sniper. Compression predicted 8.3 - 8.5. Just finishing running the fuel lines so I can't comment on a performance difference but boy it is cleaner and appears much simpler.

 

[Mark W]

A nominal 8.1:1 compression in a 4.0 liter engine will rise to 8.5:1 when the displacement is increased to 4.2. If you have installed new .02 oversized pistons in a 2F block then your nominal displacement and compression is about 4.3 liters and 8.7:1 compression.

I don't remember the cc size of the 2F heads I have had cut in the past (usually took the full .1 that the factory says is maximum), nor do I remember the cc of the late model F heads or the dome displacement of the early model 2F domed pistons that we used for the F/2F head swap. In any case both approaches gave me about 185-190psi cranking pressure on a fresh build. A stock 2F fresh build runs about 160-165psi cranking pressure.

If we assume an accurate (nominal) 7.8:1 for the stock 2f, those numbers indicate about a 9.0:1 comp ratio.

BUT, the modified engines all had longer duration camshafts which lower cranking pressure, so for a seat of the pants guesstimate (That I *think* is supported by the numbers I can not remember or find right now) is that the shaved 2F head and the F/2F head swap produced about 9.2-9.3:1 nominal compression.

Mark...

 

[iCruiser]

The Sniper is 10x easier though, and has woken up every 2F I’ve put one on, even without any engine mods.

It doesn’t have multi port injection obviously, but todays engine management is light years better than 30 years ago.

If you are considering the Sniper upgrade, highly suggest ordering the kit from Cameron at Mosley Motors. Everything from the Sniper carb, fuel pump, fuel line and other items required are included. Having this kit option versus sourcing components individually made this upgrade much less intimidating for people like me who prefer paint-by-number projects. Each component in the box is labeled. Just finished replacing the radiator, wp and power sp and rebuilt alternator (done by Mosley Motors too!) for the 37 year maintenance interval. Starting the Sniper project later today. Will keep you posted. I'm slow so might be awhile.

 

[OG SUV]

Icruiser, keep us posted on your install. Should be awesome upgrade when done!