crate engine question

adamsgt said:

im planning on buying a crate engine. im looking for opinions on the pro's and con's of a 347 vs a 331. its going to be street driven, and will also see frequent trips to the drag strip. also with a crate motor im wondering if i should go carb or EFI

Click to expand...

If you do a search you'll find years of info on this.

The only difference between a traditional 347 and a 331 is the stroke. The 331 has a 3.25" stroke and the 347 has a 3.4" stroke. There was this rumor that the 331 has much higher longevity because of it's less aggressive rod angle. Maybe 20 years ago...

I have two 347s and a 331. Unless you get a really good deal on a 331 I don't see why you'd want it. The cubes alone are very easily worth 20 hp.

As far as going carb why? Unless if you're going really extreme, and want to redo the entire fuel system, there is no reason.

giddyup306 said:

If you do a search you'll find years of info on this.

The only difference between a traditional 347 and a 331 is the stroke. The 331 has a 3.25" stroke and the 347 has a 3.4" stroke. There was this rumor that the 331 has much higher longevity because of it's less aggressive rod angle. Maybe 20 years ago...

I have two 347s and a 331. Unless you get a really good deal on a 331 I don't see why you'd want it. The cubes alone are very easily worth 20 hp.

As far as going carb why? Unless if you're going really extreme, and want to redo the entire fuel system, there is no reason.

Click to expand...

Words of wisdom, right there.

Dittos on the induction system - I would stay with the EFI - part with a couple hundred bucks for a dyno/chip burn.

DonMaximo said:

part with a couple hundred bucks for a chip burn.

Click to expand...

That's like throwing money in the garbage, especially so on a NA engine.

A chip rarely if ever can beat the stock computer for hp or driveability on a NA combo.

Giddyup is right, go with the 347.
Forget the carb, there is a dozen reasons why.

Consider a few other things when you do the engine, such as what you are going to do with it.
Daily driver?
Plan on a power adder in the future? A good 347 can push a stock block to 75% of it's capacity for power, so if you plan on using a power adder, plan on a better block, because a supercharger will easily exceed it's limit.

If you don't plan on a power adder, no point in spending a ton on the internals, they all handle basic 347 power levels.

The stock EEC only knows about 302 cubes, 19# injectors, a factory MAF, etc etc etc

How would you suggest you plug a 347 into that stock EEC (computer) and have it run correctly ???

Personally, I've used a Binary Editor, wide-band O2, Moates Quarterhorse, and DataLogging in order to get my 347 in good working order.

I could have saved hours and $$$ had I gone to a dyno for a chip burn.

I just happen to be interested in learning how the Ford Fuel Injection system works, otherwise I would have exercised my own advice and had a chipped burned.

DonMaximo said:

The stock EEC only knows about 302 cubes, 19# injectors, a factory MAF, etc etc etc

How would you suggest you plug a 347 into that stock EEC (computer) and have it run correctly ???

Click to expand...

With the right mass air meter, which always was Pro M or Pmas, and now the Abaco DBX. Same way it's been done since the maf mustang was introduced in 89 (88 in cali).

I've personally seen cars on the dyno make 650rwhp, no tune or chip.
There's even guys here that suggest they've seen in the 700's at the wheels.

As long as the meter calibration (flowed meter, NOT a C&L) matches the injectors, you are good to go.

If you little to fiddle with the computer stuff as a hobby, that's cool, but it's also unecessary.
I've seen it tried on the dyno many a time, stock computer vs chip or programmer, and the stock computer is victorious just about every time.

Sir,

I respectfully disagree with your advice and I'll attempt to briefly explain my point.

AdamsGT, who started this thread, indicated the car would be street driven. In addition, the subject has to do with choosing between a 331 vs 347 engine.

The typical/most popular EFI solution is to use Ford's EEC-IV. The Adaptive capabilities of this computer would support the operation of a stroker motor (331/347), but it's civility and behavior will MOST CERTAINLY be different from the stock 302.

I have pulled the following text from a website devoted to Ford EFI.

*************************************************************

What does modifying the EEC tune give you? The #1 thing it gives you is the ability to make a moderately built 347 stroker run with near stock manners on the street. You can usually improve fuel economy, rid annoying lean tip-ins that make takeoffs rough, calm hunting idles to let you run a much lower RPM idle than would be possible with an OEM tune, and cure conk-outs on RPM-drops as you approach a stop sign/light or declutch. There's other issues you can often face while just driving that would be annoying like tip-out bucking. Automatics can also have issues where they want to conk out as soon as you put them in gear if you don't manually tune the idle screw up. Not every vehicle is going to display every one of these issues. But if you have any of them, these are the things that can be tuned out to make a beast-of-an-engine tame enough to drive on the street without headaches. As long as the cam isn't over-the-top aggressive and there aren't other mechanical issues, you should be able to get decent driving manners out of most any SBF build.

Having the ability to tune also gives the the opportunity to play around in the spark tables to see if you can save some cash by going with lower grade fuels. Most people with builds that rely on the OEM tune just accept that the engine will live on 91/93 octane premium. However many people find that with the right tweaks, they can get near the same power and run lower grades.

And with a tuning solution, a dyno operator can find the optimal spark table for your engine to maximize the fuel you are burning. The stock curve is best for a stock engine given Ford's goals for the engine (longevity, emissions, etc). But even the OEM spark tables aren't necessarily ideal for the individual. You can usually find places all within the RPM/Load map where adding some spark here or pulling some spark there improves things even on a stock engine. And with a modified engine, it's pretty much a guarantee that this will be possible. This becomes especially true with boosted applications.

So bottom line, you get what you pay for. If you are only racing the car up and down the track and you aren't getting paid, then run the stock tune or better yet, do as someone else suggested, just run a carb. It's a lot cheaper and simpler. EFI gives you flexibility in engine tuning that goes beyond what a carb and vac advance can give you. If you deny yourself the ability to use it, then you are better off with a carb and simple distributor. However if have a moderate build in a frequently driven vehicle and you want daily-driver manners and some sentiments of fuel economy from it, then that's where a tune is going to be much appreciated.

**************************************************************

Again, my recommendation would be to go with the 347 and have the EEC tuned for that engine ($350) and Adam will have a car with great street manners and many more HP for the adrenalin boost !

I greatly appreciate having a venue in which disparate opinions can be expressed !! Sincerely...

-D

Don, dyno tunes with a chip are not $350, more like $750.

I've had alot of different parts over the years and have seen them all in person at my buddies shop, and a 347 built for the street is comprised of different parts than one built for the track.
Stay away from huge cams and large intakes and the only difference between a 347 and a 302 is that there is more power when you are on the throttle.