347 stroker and EFI

[CJ who???]

I just saw a post with somebody asking about a 331 stroker but didn't want to hi-jack.

My buddy's dad was a college professor for 35+ years in engine rebuilding. He's been retired for about 20 years and helped me re-build this engine. Anyways, they talked me into a 347 stroker and I actually had the kit ordered. The next day I got online and ended up on tons of Mustang sites, and that's what got me to change my mind to keep it basically stock. The engine is bored .030 over, very low rpm. cam for EFI 5.0's, new valve springs etc.

Question is; If you go with a 347 stroker, does it work with the stock EFI stuff??
I know you can't totally go with what the Mustang guys are saying because they're after more top end hp., us Bronco guys are usually looking for low end torque.
I changed my mind because most of these guys with the strokers have changed to 24 lb. fuel injectors, bigger TB and MAF and also re-calibrated the computer. They also say that stroking a Ford with out upgrading to aluminum heads and better intake (I have the 96 Explorer gt40 intake and heads) the engine can't breath and you're wasting your money. My buddy and his dad say " you just need to upgrade that stuff for high rpm, you'll be fine with the stock efi stuff at lower rpm's and this 347 would be a stump puller". They're still telling me that I should have gone with the stroker, but I thought there was way to many other things that I'd need to change.

What do you guys think ???

 

[rustbucket]

You'll be fine. You and the Mustang guys are looking for two different things. The 351W/5.8 uses 19 lb injectors. It's all about matching the components. The intake, heads MAF and throttle body only become restrictive at high rpm's. Your setup will allow for good air/fuel velocity (vacuum) into the combustion chamber, which will give you good torque. As you increase the size of the cam and intake components/heads, you reduce the velocity at low RPM's, so torque suffers down low. But, as the RPM's increase, you will have more air volume to feed the beast. The larger injectors are then needed to allow for proper air/fuel mixture at the higher RPM's when the engine is sucking all that air. Chose a cam first, and that will tell you what intake and injectors you need. If you're using a stock or mild cam, you'll be good.

 

[red hot71]

I find your post of a lot of interest,I went through the same problem about 12 years ago when I was buying parts. The advice I was getting was bigger and bigger,and it was breaking the budget. What I wanted was 347ci that made its max power at about 5000rpm. I think that your friend and his dad are on tract, those mustang guy's don't have a clue on what works off-road. In the end I sold my fuel injected stuff and went carburator, but remember this was 12 years ago and the aftermarket has caught up and its easier today then it was then. The biggest problem I find is everything is based on a 302ci how does adding 45ci change the final numbers,or does it? Most on this site will tell you to go 351,but 351's don't fit like a 302 base motor. In the end I think the stock fuel injection and heads you got should work just fine,maybe a cam change such as comps 35-413-8 it's rpm range is from 1200-5200rpm's, I think it will give you the stump pulling power you're looking for.

 

[broncnaz]

I kinda agree with the mustang crowd as far as using good heads on a stroker dont have to go overboard but they need good heads or your just choking the engine down even low RPM type builds. I'd go for something with 1.90/1.60 valves thats a good increase over stock and not to big for a low RPM engine. I run 2.02 valved heads on a 302 and think its fine I might be losing a little lowend but I really dont notice it. by running good aftermarket heads you can gain up to almost 100HP over a set of stock heads. In most cases I'd expect a gain of around 40-50 HP just from the heads.
There's not a stock ford head that is worth putting on a stroker IMO. Camshaft really dictates the power band and good heads will actually allow a slightly higher powerband without loss of lowend.
As for the rest I think you could get by with stock type manifolds and such as your not looking for max high RPM power.

 

[fungus]

A buddy of mine in Norcal runs an EFI 347 w/ GT40 heads/ upper/ lower intakes. He does have a custom tune to optimize the setup but its not "required". Pretty sure he's running 24# injectors and he's got the Comp 35-308-8 cam which is a low end oriented cam. He can idle up inclines that'll make your eyes water without even touching the throttle. Just proof that it can be done. He DID say, however, had he to do it over again he wouldn't have invested the $$$ into the GT40 heads and just gone w/ some nice alums! Most cams that'll really optimize that stroker require stud mounted rockers so you'll have to have the pedestals machined for studs. You could build the 347 now with the components you've got and always upgrade things later (heads, injectors, MAF, TB, custom tune) as time and money allowed.

I was going to build a 347 out here but decided to go with a full roller 351. In the end, the 351 will be about $1500 cheaper to build and also preserve more power options for follow on rebuilds if I so choose (393, 408, etc). I had accumulated alot of parts for the 347 build that are now going on the 351 (Edelbrock heads w/ 2.02/ 1.60 valves, Scorpion 1.6 roller rockers, blah, blah). Picked up the F4TE motor for $250 and had it tanked and honed (no overbore). Stock pistons will go back in it and I've got the same Comp 35-308-8 cam (5.0 roller cam) to go in it. 65mm BBK TB (that came w/ the 5.0 I've got), 72mm C&L MAF that I bought for the stroker and an A9L computer w/ RJM harness. Picked up a Lightning lower off Ebay and I'll use the GT40 upper that also came on the 5.0 I've got. In the end, I think it'll be alot better platform and CHEAPER to build as I saved about $1500+ by not having to get a stroker kit shipped out here & machining on the 5.0 block!

 

[Broncobowsher]

What heads and cam will you be running? Something stockish will run stockish. As stated a stock 351 ran 19LB injectors. Not noted was when a 351 gets warmed up a little the 19s are no longer big enough. I will also throw out there that a lot of 351s are running with a stock 5.0 tune and EFI parts. Providing it is all stock, that should work just fine. A 347 is just a touch smaller then a 351.

Problem is when you put some good heads on it, a bit of a healthy cam and intake that can keep up. The 19's will start and drive around just fine, as will the rest of the mustang parts. But I know warmed up 5.0s (cam, intake, heads) that run around town great on stock mustang parts, but on the dyno at the top of the RPM band, they lean out bad. That really matters when you decide to drop a gear and pass that truck just to start getting around and find that the one truck is actually 2 slow trucks and now a car has crested the hill coming toward you. Keep the throttle burried and wind it out. Hopefully not lean it too much during that pass and burn a piston.

 

[vintage bronco]

Well I will chime in my 1995 Lightning P/U has the 351 engine gt40 heads intake ect from the factory and runs a 19lb inj and is speed density to boot so you should be fine, BTW the lightning redlines at 5,000rpm and has very good low end T/Q and plenty of towing power.

 

[av bronco]

Ive got a hibred fi setup on my 427 stroker, 42lb injectors 80mm maf 75mm throttle plate ported victor intake, tieing all this together is a moates quarterhorse and wideband, takes a minute to figure it out but you can tune in real world stuff and once you get the basics the world is your oyster.

 

[itsabronco]

OH MAN !! Are you changing your mind again?? I will take your new parts you change out for the other 5.0 that I have for old yeller.;D Remember, the parts are used now so I get a good deal ! Just messin wit ya !

 

[CJ who???]

Ha Ha !!! No, not changing my mind !!! Just trying to justify keeping it "stockish". My concern was that using the stock Stang 55mm. MAF, Explorer TB., #19 injectors and a Stang A9 computer that all think it's bolted to a 302, when it's actually bolted to a 347.

It sounds like it can work, BUT, to get it to REALLY work, everything else (#24 or even larger injectors, bigger MAF, bigger TB, A9 custom tune) needs to be changed as well. Which is just what I didn't want to do.

 

[fungus]

BUT, to get it to REALLY work, everything else (#24 or even larger injectors, bigger MAF, bigger TB, A9 custom tune) needs to be changed as well. Which is just what I didn't want to do.

That's pretty much the size of it. I picked up a lightly used C&L MAF off CL for 24# injectors AND the 24# injectors pretty cheap as well as both my A9Ls. The 5.0 explorer is a good route to get a 65mm TB too on the cheap. Just keep your eyes peeled and you can find the parts you need very reasonably priced.