Ford 302 engine flow: Matching parts for street engine

In reply to NOHOME :

Know anybody with a Mustang about the vintage as your engine? Take it for a test drive and see how it behaves compared to your expectations. You've built a car similar to a Mustang, probably a lightweight one. If it meets your expectations then compare cam specs to the Explorer cam and mimic the Mustang as best you can. That 302 has a larger bore than an LS of similar displacement and a shorter stroke. With those bigger valve heads it ought to rev at least as willingly as an LS. I think the right cam will liven it up a bunch.

Yeah, the 670 is way too big for the 302, but you should be able to add some reason to it with jetting adjustments.  The rubber float bowl gaskets can help with this . . .

The "alphabet" cams generally suck--the designs are just old school, and they trade terrible driveability (pointless loping/surge) for high-RPM horses, and not very many at that.  My last dance with an e303 and a T5z led to my first LS/6l80 swap, which made me very happy.

My last small Ferd intake experience was with the Edelbrock Performer RPM (1500 RPM base is stated, I think), which pretty much resulted in no power (lack of street torque) below 2000 RPMs--this was on a 340HP Ford Racing crate engine.  It ran well enough, but it was frustrating, especially with the cam surge at low RPMs.  It pretty much just resulted in a car that I wanted to abuse constantly, which was no bueno living on a steep gravel road.

I typically undersize carbs a little, but as long as you're not getting midrange wussy-ness on the new combo I wouldn't stress about it.  This is another place where people focus on peak numbers from dyno results.  Heck, an 850 cfm might give you 3 more hp at 6000 rpms, but if you don't pay attention to what it did at 2500 rpms you're giving up drivability and acceleration.

Run the 670 properly tuned.  If the low RPM velocity sucks, try a Qjet or a 600 cfm

Thoughts on the Edelbrock top end kits? They seem pretty comprehensive and I expect properly matched?

They run about 3k Canadian and if I sell the Fitech and all that I have on the engine now, might be the most cost effective path forward compared to trying to toss another series of darts at the solution.

Instead of throwing 3k at it, why not try a hundred or two and see if you like it. Toss a 5.0 HO cam in it, probably get one for almost nothing, dial the tune in, and see what you think. That should move your powerband up a little but not completely kill bottom end. Ignore the intake for now and see what happens.

Ive got a bunch of friends that were way into 5.0s and I have seen these things run good with all kinds of weird setups, from custom cams to stock 5.0 cam, e7s to aftermarket heads, and stock efi manifolds to carb stuff. It was always pretty east to get like 260whp from them using whatever cheap parts were laying around, then with a little more work matching part correctly you could get to like 290whp, after that you started spending real money on nice parts. I assume this is in a lightweight car and even 260whp would be a riot.

Is it a power problem? As in it just doesnt make enough power. Or is it a power band problem? As in it doesnt make power were you want it.

If its a power problem, Id bet its a tune problem, or something is hurt, but Id lean towards tune. It took a friend  of mine a lot of tweaking to get his Holley topped 350 pretty close, then he broke down and paid a professional and it was a completely different car. Another friend who is a big holley guy even admits even though they are his preferred carb they take him quite a while to get just right. I will say the classic mustang guys swear but the edelbrock 600, and anecdotally they say they run great or real close to it right out of the box.

If its a power band problem, it could still be a tune problem, but if thats straight then you might look to the cam. I always enjoyed the 5.0s more with a bigger cam in them, I like my NA V8s to be kinda peaky. With the explorer cam torque falls off a cliff around 4K and isnt what I would consider a nice powerband on a fun car.

In reply to Opti :

Light car I would say. 2700lbs or so.

The clue is that it feels lazy out of the hole with what should be a low rpm torque cam. Certainly wont light up the tires without a lot of provocation ( not my style) Despite that, it gets worse mileage than an actual explorer.

Have you checked your ignition timing? A timing light can be had for $30ish, and if your timing is retarded, it can kill a ton of power and fuel economy.

Id definitely look at the tune then

Lazy out of the hole, no guts to it without what sounds like some RPM and full throttle, and 14 mpg keeps me thinking tune or component malfunction as well.  

And I'm still confused on people suggesting a street-oriented 670 Holley is too large when Ford themselves were using 600's on this same basic engine when they last used carbs from the factory.  I guess if there was a loaner 450cfm four-barrel that fell from the sky, that swap might be a data point to add to the case, but the 670 doesn't sound that out of range to me.  Not enough to cause the described issues.

In reply to Cactus :

As mentioned earlier, timing is 14 at idle and all in before 3500 at 33 degrees. 

I suspect the real issue is lazy airflow velocity due to the volume of air in the system. Carb a bit too big, intake port volume a bit big and  muffler restriction out the backside. 

You've got some mismatched parts but the description of the performance makes me think that there's something out of whack with the tune.  What rear gears are you running and what's the transmission?

ET70 head swap, then, based on your logic.  Which might not be incorrect even if I don't agree with it. 

A rolling road dyno session might be useful?

Timing sounds pretty good. Is this thing running real fat?

In reply to APEowner :

3.31 rear gears with a T5 gearbox. 3.35 first gear. 

My car weighs 3260lbs and is a 302/c4 with 3.08 gears. It's a bone stock 69 truck engine down too the 2 barrel carb. Figure 225hp and my car has no issue boiling the tires. There's something broke or really mismatched in your set up. I think you need a bit more cam to make up for the larger heads and 670 carb. 
 

I went from running 12.90s in my old Capri to running a 14.40 because I decided to mismatch parts and a lot of it didn't work together. 
 

as far as the 670 being too big, I drove an 81 marquis with a 750 vacuum secondary Holley on a 302 with headers, performer rpm and a 212/216 cam. Car managed 18 mpg cruising too work and would start and run happily in any weather. Put a bit bigger cam in the car. 

I agree that I don't think it's because the carb is too big.  It may be that the carb is poorly tuned or dirty, but not too big.

I suggest a compression test.... Not to look for a bad cylinder, but I want to see what cranking compression is.  I'm wondering if the 9.5:1 CR isn't really 9.5:1.

Edit to add:  Pull a spark plug and use a wire to get the piston at TDC on compression.  Then look at your timing mark on the balancer.  Not exactly common, but highly possible that your balancer has spun on the rubber and your timing is therefore off.  Also, don't be afraid to add timing.  33 is probably fine, but you might experiment with 34-36 total (15-17 initial)

You could do a top end kit like the one you listed, and yes they're pretty well sorted, but they are maximum cost for not a ton of benefit.  You can do it yourself for under $1000 easily.

I would think if you did some P-heads from an explorer, a proper alphabet cam, and (seriously can't stress this enough) GET RID OF THE TORKER INTAKE, you'd be making 300 hp and 350 tq instantly.

Edit:  I agree that something is off.  A bone stock 302, even in smog wheezer form should make that light car scoot.  I had a 74 Maverick with a bone stock, tiny-cammed, low compression 302 and it was surprisingly quick in that light car.

Cranking compression is around 155. Give or take 5 psi.

If I had to guess, this thing would run maybe a 15 sec quarter while I figured that it should be able to do 13s while still being reasonable to drive on the street. 

Ok, that tells me that the cam isn't excessively advanced or retarded, and it is a logical number for the 9.5:1.

Did I miss where we discussed what the port volumes are on the overseas heads?

Regarding your questions about the valve size and velocity.  At the point where the air flows past the valve, it's a bloody tornado of fury regardless of the valve size.    Increasing valve size is more of a flow support consideration than a velocity situation.  You need enough area/volume in the valve margin (between the valve and seat) to match the flow that the ports and cam are giving you, but generally speaking, bigger valves don't have a ton of effect on how much air gets into the engine.  That is to say - you need enough valve size, but increasing valve size won't increase flow unless the potential is there behind it.  Increasing valve size with a small cam like yours will likely not change much, but increasing valve size on something with big ports and a big cam can really be a supporting mod that helps the flow match the needs.

I don't believe that valve size is what is causing your issue.  I think it's a mismatch of small cam, big heads killing velocity, and an intake that I wouldn't even use as a boat anchor.

First things first... check the little things like balancer/timing and carb tune.  Try two more degrees of initial and see if that perks it up.  Does it have working EGR?  if it's stuck open you could be getting a bunch of exhaust flow when it's not supposed to.  

I agree with Curtis as to the futility of using the Torker intake on this engine.
 

Let me clarify that I think you've got a Torker II intake. I've never seen a Torker, and when I was in the Edelbrock tent at the Gatornationals, the salesman corrected me when I called one a "Torker." 
 

I've only ever heard of one logical application for that intake, in a mid 80s Thunderbird with a 460. The intake was chosen because they needed to decrease some of the low RPM torque and because it fit under the hood.

It's a stupid design with conflicting features, being a low rise single plane intake. It makes no sense.   They really are junk.

Curtis's advice to make sure that tune and all of the basics are accurate is spot on. That's never bad advice,  but I'll bet a cheap dual plane like the original Edelbrock Performer 289, Weiand Street Warrior, etc. would transform that engine.
 

An intake swap on a 302 is not a lot of work either. I would do it before replacing the cam, even though you might have to pull the intake again for the cam swap if it doesn't do the job. If you change the cam and the intake at the same time, you won't know which made the difference.

Do you know the volume of the ports? It's possible that the heads are meant for a larger displacement engine and don't have enough velocity, introducing another common parts mismatch. 

As for the carb, as long as it's clean, jetted properly, doesn't have a blown power valve, or some other big problem, it should work fine on that engine. 
 

Swap the intake. Seriously. You can buy a generic dual plane for barely $100.

I've got the older Torker 289 (which I'm told is way better than the Torker II, but still sucks) I'd be curious to know what is about the same height, because I'm very limited in hood clearance.

Also sorry I missed the timing numbers, those seem fine.

I can send you the right manifold for that combo. Just plug a few of the ports as its an EGR performer manifold. I also have a stock 85 mustang GT manifold. That is more what you want with that motor. 

But more than anything double check you carb and AFR if you can. Mine did that when I got it. It was a DOG in the mid range. The carb tuning was just dumping fuel into the motor and it was a mess. I knew there was an issue as my old 85 GT would have toasted the no name wally world tires on it with no issues and I couldn't even spin them. 

I will dig around in the spares pile and see what other intake manifolds might  might be around.

Gotta keep in mind that used parts and dyno access is not thick on the ground and stuff cost twice what it does south of the border. Do dyno guys even know what a carb is anymore?

The balancer timing mark has been verified as it was a concern back when I was fighting to get the Fitech to work. The Fitech fiasco turned out to be a bad AOD, combined with failing HEI style distributor and a small leak in the exhaust on the O2 sensor bank. Originally had an E303 cam but the bad AOD was creating a  low vacuum situation  ( less than 10 inches of vacuum ) and hence the higher vacuum exploder cam was put in place. Took a while to circle around to the AOD being the cause of low vacuum and not the engine itself being the issue. The E303 went to live with someone else so not around to retry.

Be right back, going to take a pic of the intake as it was 6 years ago that I bought it and I might be wrong on the description

Well, no real identifiers on the manifold and its pretty hidden under the carb so not sure other than the air-gap bit

What is more interesting is the plug colors. They are either brown/tan or black sooty without much in between, about evenly divided. 

These are pretty much new plugs and the car has just come back from a good long run where we did not sit in traffic for any amount of time.  Might be some lower end issues after all even though I dont notice smoke out the back when driving.

pres589 (djronnebaum) said:

Lazy out of the hole, no guts to it without what sounds like some RPM and full throttle, and 14 mpg keeps me thinking tune or component malfunction as well.  

And I'm still confused on people suggesting a street-oriented 670 Holley is too large when Ford themselves were using 600's on this same basic engine when they last used carbs from the factory.  I guess if there was a loaner 450cfm four-barrel that fell from the sky, that swap might be a data point to add to the case, but the 670 doesn't sound that out of range to me.  Not enough to cause the described issues.

I had excellent drivability with a 750 vacuum secondary on a 289.  

It's just a 500cfm 2 barrel until the secondaries open...  (A 500 2bbl and a 750 4bbl have the same size venturis and throttle plates)

It is all in the setup.  A small carb with awful atomization and screwed up transition circuits will be a dog everywhere, especially at low throttle.  A carb with good atomization and a well-tuned transition will be a dream even if it is "too large".

I would not run anything but a genuine, 60s/70s era Holley, or a Quick Fuel carb.  Quick Fuel make the only new-production 4150/4160 carbs worth a damn.

Curtis73 (Forum Supporter) said:

And no, GM didn't plumb exhaust gasses to the choke.  Some of them used a tube that had a loop in the exhaust crossover to heat the choke, but they didn't use engine heat to "get the choke off."  They used engine heat as a reference for when the choke should start opening.  It wasn't done "for the choke," it was done to get the runners hot so it could signal the choke to open for normal operation. 

That is a beautifully succinct way to explain the purpose of the choke.  Not for a cold engine, but a cold intake manifold....