347 stroker

IMO the Carbed setup should run quicker when setup correctly.
The vacuum secondar is not so desireable, but can be modified to work very well.
There's no mention of a camshaft... that's pretty important.

Any cold weather driving plans? FI really improves driveability in the cold.

EFI > CARB in my opinion.

It is the wave of the future.

If it was not so costly (R&D), the pro guys would shift to it by now. You will see it transition in the near future to EFI and they will get faster.

347

I went back with fuel injection on my 347 and it works great but if i had it to do over i would go with a carb because the injection is so mutch more costly if you do it right you will spend around 2500.00-3000.00 more on the efi.

When I build my motor, it won't be EFI. Just too many electrical things to mess with. And 13:1 CR doesn't sit well with me on FI

bynummustang said:

When I build my motor, it won't be EFI. Just too many electrical things to mess with. And 13:1 CR doesn't sit well with me on FI

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But it does work well with massive amounts of boost? I do not see why EFI would not work very well with 13.0:1 compression. You are just building cylinder pressure with mechanical compression instead of boost. Same difference so to speak. It is all in the tuning. It is VERY hard to get a carb intake manifold to distribute the air and fuel equally to all of the cylinders. While a EFI set-up will always (in comparison) have a equal distribution of the fuel at the very least. A carb sitting on a intake manifold has different length runners to distribute the fuel thru, while the EFI set up has each fuel injector placed exactly the same distance from the intake valve on every runner. The highest H.P engines (piston) in the world are always fuel injected, either mechanical or electronic, they are always fuel injected, bar none.

Well i like the carbs but you do have a point with the EFI. It's not a totally balanced system as you would think. Injector placement not withstanding all the runners are not the same length and do not have the same cross section. Most high HP high RPM motors (like F1) use individual runners. This gives you truly equal distribution as well as resonance tuning.

With that said if you go carb ditch the funnel web and go with a Vic JR. The funnel web, although it is a single plain has a TON of taper and a pretty small plenum that I think will start to restrict the motor as you crest 6K.

True, but the point was fuel distribution would be better at the least. Air distribution is always a concern with any multi runner intake manifold. Spent a lot of $ with Wilson Manifolds once to get a Edelbrock Victor (SBF) carb single plain intake to flow within 1% runner to runner. Had to send them the heads, head gsskets, intake manifold and engine block spec's to get the flow #s right. They did beautiful work (art really) and the engine responded very well to the manifold. Was a 13.5:1 347 cid 200 h.p. shot of Nitrous. Needless to say air and fuel delivery was very important, especially at 8,000 rpm.
Dyno'd a carbed 347 with a Victor Jr, and then put on a Funnel Web. Spent as much time as possible trying to dial in each manifold to make maximum H.P. and in the end after 2 days on the dyno, the Victor Jr. made more H.P. and tq. Especially if you look at average H.P./tq. across the pull. The Funnel Web would have a point here and there where it made more power, but across the curve, it was down 8-10 h.p. and down 15 lbft torque.

8000 RPM 347 yeah baby!!!!

Glad to see there are more people out there that like RPM. The only down side is all the supporting parts are a lot of dough.

A street 347 sounds nice at 6,000 rpm, but man does a high compression 347 sound SWEET at 8,000 plus! Car had 1 7/8" headers, with 3" Dr. gas X pipe going into Spin Tech Mufflers with turn outs just before the rear axle. It made such sweet noise. And when on a chassis dyno the car made no extra power when we ran it with open headers. Was hell a lot louder tho!

Brian@PAR said:

8000 RPM 347 yeah baby!!!!

Glad to see there are more people out there that like RPM. The only down side is all the supporting parts are a lot of dough.

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I would guess that the $ spent to get 800 h.p. reliably at 6000 rpm is pretty much the same as 800 h.p. at 8,000 rpm. To get 800 h.p. at 6k you need a blower/turbo or a but load of Nitrous. To get 800 h.p. N/A you have to compression the hell out of it and spin it 8k or better. The above example is with a SBF. (302 based engine) The 800 h.p. number is much easier to get at 6K rpm if you start out with BIG displacement.

I'd just like to mention static compression ratio has no real affect on a running engine.
The camshaft events are what affects cylinder psi.

The camshaft appears to be for EFI... I have no experience with that setup though.

Going carbed saves you money, and allows you to build a better overall setup with the money saved.
This does not mean carbed is better than EFI or viceversa.

Ok the post is confusing. You are going EFI then. Maybe you meant to say you are not looking for a quick fix. If you were carb is the way to go.

And Bullit my cost reference was to the valve train required and the transmission. For 8K you're looking at a faceplated or proshift trans (I don't do automatics) and shaft rockers with some pretty serious springs. The springs are really chump change but shafts......

347HO makses a good point as well. We look at dynamic CR at .050 and cranking compression. The old school method for getting back the dynamic CR you loose with a big cam is to raise the static CR.

I've got a HR cam in a 306 that develops 180 PSI of cranking pressure. This is a 10:1 motor that runs on 92 octane. Put that cam in a 10:1 347 and I'd need race gas.

i say go EFI. dont have to get all crazy with it, a tweecer will be enough to properly tune a 347. and compression doesnt affect anything as far as EFI tuning. you just have to make sure you adjust fuel and spark accordingly to prevent knock. has nothing to do with being EFI or carbed

obviously less ignition timing is needed with high compression and perhaps more fuel to keep heat down in the cylinder. put some race/high octane gas in the car. then you car start running alot of timing not being so octane limited and then it will start making good power.

to me EFI is alot more precise, carbs and EFI can make pretty much the same max power but the EFI car will drive/start and run smooth every time.

i think its cool to go to the track and see some all out gutted drag cars that are trailered there, run and idle like crap, but run great at WOT and bust of a decent time. then you have some mustang DRIVE to the track in the car, throw a set of slicks on the car, run the same or even beat the drag car, then drive home and have the A/C blasting.

BUT EFI has to be properly tuned to work best (not "calibrated" MAFs on a stock EEC) i mean either a tweecer SCT or custom chip or even a standalone. to actually TUNE your setup. once you get everything dialed in...timing adjustments are as simple as typing in the number in you want, and setting the fuel you want, no messing with springs or weights in the dizzy, no more jets and other carb stuff.

i started tuning on my car and i have had to mess with anything mechanical (related to fuel and spark delivery) i set the dizzy to 10* base and the FP to 39 psi no vac and i havent even touched them since.

old school carb guys will argue to the ends of the earth that carbs are better than EFI but they are wrong, efi all around is a better method of running an engine. IMO all the old school guys are just scared of something they dont understand.

dont get me wrong carbs work great and are pretty simple, for a pure drag car a carb is probably the simplest and best way to go. but for a good driving street car with good driving manners, EFI all the way.