Advise on Ford 302- 331/347

[zarpoxx]

Hello

I wanted to know your opinion about the following topic:

I have a cobra with a 302 ford engine (1971), with edelbrock intake (dual plane), holly 650, and little else (stock pistons, stock camshafts, stock heads).

I wanted to increase the performance of the engine (supposedly gives 324 hp, I don´t dyno the engine, so it is a estimation that the seller told me), and wanted to know your opinions about what elements to install keeping in mind that in the future I will want stroke to 331 or 347.

I know I want to buy AFR heads (I know that if I were not to do stroker the best would be 165, but I wanted to know that you advise me in order to be able to serve both the 302 engine and the future 331/347 if it is possible.

Camshafts that are worth for both applications? (model or specs if it is possible?)

My current status is:

Differential 3.31
Gearbox tremec T5 (first of 2.95 and fifth of 0,73)
15 "wheels (215/60 15 and 235/60 15)

The use is 100% street (mountain ports and sports driving)

I would like it to go up to 7,000 rpm and have torque from below (say 1500 rpm - 6500 rpm, but could reach 7,000 rpm)

I would like to get in the 302 configuration up to 400 hp at least to the flywheel.

I would like to arrive at the 331/347 up to 500 hp at the flywheel.

Thank you so much for your opinions, are much appreciated

A greeting from Spain!

[bwdz]

1971 the 302 put out 210 hp in the Mustang (if that is where your engine is from, it put out less in other cars) That 210 hp was rated the old way meaning not SAE so to compare it to the way engines are rated today it was about a 160hp engine. By changing to a 4 barrel carburetor and aluminum intake and you probably have better exhaust than factory you are probably in the low 200hp range. I used to dyno lots of Mustangs back in the 90s and a "hot 302" with good heads and a nice roller cam got around the 300hp mark and more if it had high compression ported aftermarket heads etc..
What I am saying is that you are around the 200hp mark, if you start making 300 you will feel like you just turned your car into a Ferrari. Get the AFR heads if you want but I would just build a new engine in the garage using a roller block from a later model and not use that old block to build a new engine. This way when the other engine is complete just sell your old one and install the new one. Seeing that you mention you are in Spain it is probably not as easy to find a roller block as they literally lay around in garbage piles here in the states but I would not throw those great heads and stroker kit on that old block as you will only spend a fraction of what you spend on those other parts on the newer better block.

[zarpoxx]

Good point of view, bwdz.

You are right with the less possibility to find a newer ford engine here, but not impossible. I will check this option.

But I really surprise me it you said about the real power of my engine. Really a new engine from 1971 in power terms is only 160 HP? It is the first time I read something like that. I am not saying you are wrong, only is very rare to me.

I am a Porsche lover, and when you drive a 911 from 1978 (911 SC) with 188 HP (Theory) you feel every horsepower in your pants, with no less power or something like that. Maybe it is because there are European horses (din) but the horses are in the engine.

When you said to buy a newer engine with roller block, from what year?

Thank you for your reply

[bwdz]

Originally Posted by zarpoxx

Good point of view, bwdz.

You are right with the less possibility to find a newer ford engine here, but not impossible. I will check this option.

But I really surprise me it you said about the real power of my engine. Really a new engine from 1971 in power terms is only 160 HP? It is the first time I read something like that. I am not saying you are wrong, only is very rare to me.

I am a Porsche lover, and when you drive a 911 from 1978 (911 SC) with 188 HP (Theory) you feel every horsepower in your pants, with no less power or something like that. Maybe it is because there are European horses (din) but the horses are in the engine.

When you said to buy a newer engine with roller block, from what year?

Thank you for your reply

In 1972 they changed the way they rate horsepower to SAE or Net hp. Basically the engine prior to 1971 were rated with no accessories such as alternator, power steering etc.. They ran optimized headers with no exhaust and very hot timing to get it to a maximum output. After 1971 they changed to testing the engines in factory tune with accessories and exhaust system so the rating would be accurate with exactly what the engine put out as it was installed and tuned for the actual vehicle it was in. Essentially the same engine that in 1971 was rated at 300 hp when tested as installed in the vehicle only put out about 225 hp or so. This is the way engines are tested today which is why I said the 1971 engine was really only about 160 hp. You have to compare the numbers equally, so if you took a 1990 Mustang which was rated at 225 hp and took off the accessories and ran open long tube headers and maxed out the timing there is a chance that it would make close to 300hp and that would be the old rating but 225hp is much more true to what it actually put out. The roller blocks started in I believe 1985 in the Mustang H.O. A roller block means that the camshaft uses roller lifters instead of flat tappets. This gains a little power from reducing the drag of a flat lifter against the camshaft lobe but also allows for steeper cam lobes opening up the valves quicker. These blocks are the standard for most modern 302 builds. The core charge on these blocks is not much so I would recommend just buying a complete short block that has already been machined and clearanced for the stroker kit you are running.
PS, I love Porsche as well, new and old. Currently there is a Boxster in my garage

[blykins]

For a street engine, I would highly advise against having an engine that makes horsepower at 7000 rpm. These engines are not modern fuel injected pieces with variable cam timing. If you cam an engine to make horsepower at 7000, you will be extremely disappointed at 1500 rpm.

With either the 302 or the 331/347, you can use an AFR 185cc head. It will be a little soggy down low with the 302, but it will be manageable.

The camshaft will dictate where the power peaks and what the hp/torque curves look like. If you are set on a higher revving engine, I would most certainly look at a much lower rearend ratio, like a 3.73 or a 4.10. Durations at .050" of the mid 220's will get you a 5500-6000 peak, which would allow you to shift at 6500. To peak at 7000 rpm with a 331/347, you will need to be in the high 230's, low 240's at .050" duration.

I don't like many off the shelf cams for the small blocks and FE's. The lobes can be very aggressive and generally follow the same 6 degree intake/exhaust duration split as is popular with the SBC crowd. These are all universal camshafts and don't work optimally for every engine family. You can actually lose horsepower by using some of the aggressive cams, such as the XE or XFI series, plus some of them can be pretty noisy.

A 425-450 hp 331/347 would be more indicative of a "performance" street engine. To hit 500 hp and 7000 rpm would require a lot more specialized parts and a lot more detail/skill by the builder.

[1795]

I agree with Brent regarding the decision to go for a build that makes peak horsepower at 7,000 rpm. Unless you are on a race track or in the middle of the plains states on some flat road that stretches for miles with no speed limit, there is no practical application of 7,000 rpm on the street. You would have to be making a real aggressive pass to come close to obtaining 7,000 rpm, or be running a 4:56 rear end.

Go to the second strike website and use the rearing calculator and see how fast you would be going in each gear to shift at 7,000 rpms. It is a lot faster than you think. Then there is the issue of driving for an extended period at 6,500-7,000 rpms, it is noisy and you go through fuel like there is no tomorrow!

It is nice to have bragging rights, but a much more usable and practical build will have peak horsepower in a lower rpm band.

Good luck with your build.

[moore_rb]

well ok, since you asked for opinions...

First- What is your current 302 engine's compression ratio? That number plays an important factor in deciding on whether it could manage the AFR 185 heads, or whether the 165's are a better choice. it is also a factor in determining if your 400 flywheel HP goal is reasonable.

Most stock, street 302's with 9.0-9.5 compression ratios are indeed best suited for the 165cc heads, but if your 302 has 10.5:1 compression ratio (or larger), then the 185 heads would probably work just fine on your engine (and would be one less thing you would need to upgrade when you step up to a stroker engine)

Regarding cams - There are many factors to consider, like: how choppy of an idle can you tolerate? is raw performance the primary consideration, or are you looking for more of a balance between performance and driveability?

for an engine that is primarily street driven, and needs to start easily when cold, you are probably going to be best off with a hydraulic cam, with duration in the high 220's to low 240's (at .050), and lift in the 555-570 range. If emissions and idle quality are not primary concerns, then a lobe separation angle of 112 (or even 110) will help generate a nice, flat torque curve... Something like the compCams XE274H, or the XE284H if you can handle a rougher idle.

A well-tuned 302, with 10.5:1 compression ratio, AFR 185 heads, and the XE284H cam would probably get pretty close to your 400HP goal at the flywheel, and would be a high-revving engine (7000+ rpm)

A similar 302, but with lower 9.5:1 compression, could use the AFR 165 heads, and the XE274H cam, and would probably dyno around around 360-370 HP at the flywheel, and would probably rev up into the 6000-6500 RPM range.

please reply back with your engine's compression ratio, (and the number of miles or km on the engine) so that a better estimation for your engine can be made.

also, a great place to do more research about small block Ford Windsor engines is on the many Mustang forums on the Internet. Any engine that works well in a Mustang, will work even better in a Cobra...

[Dimis]

Zarpoxx - Welcome!

Careful asking for opinions. You'll have all sorts of people like me spending your money

The Cheap & Easy (Easier) fix, to get that kick in the pants feeling it seems you're seeking is to change your rear end. ie: something over 3.50 and up to 4.11.
The "negative" is the car will be working at a higher rpm range whilst cruising, but if you're chasing a 7k RPM engine build you probably prefer that.

In terms of engines, if you are hell-bent on getting one done, and the budget allows, go get yourself a custom engine built as you want it from the beginning.
Band-aid fixing or part swapping the current engine may end up costing you more in the end, as you chase, swap and redo items to finally get want you wanted to begin with.

Good luck either way and enjoy

[CraftEngines]

We typically recomend the 331ci engine for longivity. We really like the AFR 185 with 10:1 compression and a small hyd roller. We do alot of 224/232 range cams that make good power and are nice drivers. If you would like to turn 7000 rpm you will want to use short travel lifters and a single plane intake. Only disadvantage to the single plane intake is that it will hurt the torque down low (1500rpm). This engine will make 450hp and 425ft/lbs torque. To make 500hp you will have to make this build a little more radical or up the cubic inch, cam, compression, etc.

Thanks
Lance

[moore_rb]

Well, coming from someone who presently owns a small-cube Windsor that does rev to 7000 RPM, and also chugs around town just fine at 1500 RPM/45MPH, and spins 3.31 gears, I (personally) don't think it's overkill at all... JMHO.

It is absolutely overkill for a street driven big block, and it would absolutely be overkill for an undersquare stroker (396, 408, 427) built on a tall deck Windsor block.. I totally agree.

But small cube, oversquare engine designs will rev freely, as long as they're built, blueprinted, balanced, and cammed correctly.

Also- I don't think the original poster is talking about wanting an engine that can spend ALL DAY at 7000RPM; but using that number as a safe redline is very do-able. (again- JMHO)

My engine HP peaks right at about 6500/6600, and the only time I wrap it out those extra few RPM's (in first gear) is when I'm doing a timed 0-60 run, so I can trip the timer before having to upshift to 2nd.

If I don't care about the 60mph time, or I'm doing a timed 1/4 mile, then I'm on the clutch grabbing 2nd, just as the needle is sweeping past 6500...

Now I suppose that if my engine suffers an early termination in lifespan, I may go back and re-think my position on this, but my little engine rev's like a turbo motor, it's making no blow by (my oil level hasn't moved since the day I brought it home) and I love it...

So what if it doesn't make 400 HP? my best timed 0-60 has been 5.2 so far, and with stickier tires, I'm sure there would be a few more tenths to gain in there...wheelspin is still the acceleration limiting factor in my car.

I do agree that a full roller valvetrain is a critical consideration in running such an engine, and I also agree that if the original poster already has plans to upgrade from his current 302 to a stroker, then he is better off concentrating his time (and budget) toward getting his long term engine designed and built correctly, as opposed to trying to throw parts at the mystery motor he currently has...

I also agree with 90% of Lance's (CraftEngines) reply, except:

If you would like to turn 7000 rpm you will want to use short travel lifters, and a single plane intake. Only disadvantage to the single plane intake is that it will hurt the torque down low (1500rpm).

Agree on the lifters, but the Wieand Stealth, and the Edelbrock PerformerRPM AirGap, are both dual plane manifolds that work well in higher RPM street engines - True that they don't maximize HP, but they do offer a great balance of high end power, with lower end driveability... I have the RPM Air Gap on my engine.

As to all the points about having to run lower rear gears with a higher revving engine... That totally depends on the gear profile of the transmission being used, as well as your planned rear tire circumference.

Final drive ratio (in each forward gear), assessed against rear tire circumference, is the real design point, and the rear diff ratio is only 1 of 3 factors in that calculation.

With a 7000 RPM redline (and a programmed 7200RPM rev limit), and 3.31 final drive ratio in 4th gear, my car has a theoretical top speed of 173, which is right inline with the assumption that its real (drag limited) top speed would be approx. 80% of that (or about 138-140, somewhere around 6 grand)

And since I have yet to exceed about 125, I really don't care whether it can go to 138, 148, or 173... 125 is fast enough (for me) to get a quick thrill every now and then...

I also understand that just because something works for me, doesn't mean that it will work for everyone... So do your own research, work with your builder, and make your own decisions.

I'm just offering one person's real world experiences running a small cubic inch V8...

[blykins]

Yes, as stated, there's a big difference between an engine that will "rev" to 7000 and an engine that "peaks" at 7000. You can take an engine that peaks the horsepower at 6000 and it will probably spin 7000 if it doesn't float the valves, but it will probably be down 25-30 hp by then as well.

I'm reminded of all the guys who had the 289 Mustangs back in the 60's.... "That 289 would spin to 8000 with no problem." Yep, it sure would, but it probably quit making horsepower about 2500 rpm ago.

But yes, that's why we all clarified our statements about where the engine peaks and what to expect there.

[zarpoxx]

Many thanks to all for your choices,

I go by parts:

The compression of the engine is the origin, that is, 9.5 so I read that gave the Ford engines that year. The odometer marks only 650 miles, but it is not work so I have no idea how many miles the engine has (two year ago had the same miles...)

I do not have any restrictions on emissions or noise, so I have no problems in this regard with the law.

I would like to have a nasty idle sound, for me it is part of the special character of the cobra.

Maybe I did not express myself well, what I wanted to say is that although it is a car that is going to be used on the street (I speak of mountain passes and deserted roads) 100% of the time, I like to do a sporty driving, but not I'm looking for a car that gives the power at 7,000 rpm.

In fact, one of the thousands of things that has fallen in love with the Cobra is its torque at low turns (here in Europe a car with 5 liters of displacement is considered a HUGE engine, I no longer want to value what is thought of a motor Of 7 liters , so my priority is to not lose that good down torque.

That is to say, I would like a motor that goes down at least as it goes now (great for my taste), but it has the capacity to breathe up, since at present I notice that if I stretch it more than 5000 or 5500 rpm it faints (although it can Stretch it at 6.000 rpm I notice that it is very forced). In short, it is not that you want the power at 7,000 rpm (and less if that is going to make it down there is nothing) but have a real use margin up to about 7,000 rpm, although the pontencia delivered it to 6500 Rpm (I do not know if I explain myself).

Maybe bykins and moore_rb have explained better than me. I only want a engine that is capable to reach 7.000 rpm, not to give the peak power at this point.

Bwdz, thank you for the explanation, did not know those details of the old engines.

[olddog]

The factory ford 5.0 block is generally accepted to be at tad on the week side for high HP builds.

You can buy a Ford boss 302 block with a 4.125 bore. It is stronger too.

https://performanceparts.ford.com/part/M-6010-BOSS302

By the time you find a used block, clean it up, bore it, hone it, etc, you will likely have similar money in it.

[Dimis]

Originally Posted by zarpoxx

Many thanks to all for your choices,

I go by parts:

The compression of the engine is the origin, that is, 9.5 so I read that gave the Ford engines that year. The odometer marks only 650 miles, but it is not work so I have no idea how many miles the engine has (two year ago had the same miles...)

I do not have any restrictions on emissions or noise, so I have no problems in this regard with the law.

I would like to have a nasty idle sound, for me it is part of the special character of the cobra.

Maybe I did not express myself well, what I wanted to say is that although it is a car that is going to be used on the street (I speak of mountain passes and deserted roads) 100% of the time, I like to do a sporty driving, but not I'm looking for a car that gives the power at 7,000 rpm.

In fact, one of the thousands of things that has fallen in love with the Cobra is its torque at low turns (here in Europe a car with 5 liters of displacement is considered a HUGE engine, I no longer want to value what is thought of a motor Of 7 liters , so my priority is to not lose that good down torque.

That is to say, I would like a motor that goes down at least as it goes now (great for my taste), but it has the capacity to breathe up, since at present I notice that if I stretch it more than 5000 or 5500 rpm it faints (although it can Stretch it at 6.000 rpm I notice that it is very forced). In short, it is not that you want the power at 7,000 rpm (and less if that is going to make it down there is nothing) but have a real use margin up to about 7,000 rpm, although the pontencia delivered it to 6500 Rpm (I do not know if I explain myself).

Maybe bykins and moore_rb have explained better than me. I only want a engine that is capable to reach 7.000 rpm, not to give the peak power at this point.

Bwdz, thank you for the explanation, did not know those details of the old engines.

Dear Zarpoxx,

I think you have explained yourself very well.
...and the more I learn about your situation and the terrain you'll be driving in Spain, the more I think a rear end ratio change is your initial solution.

Generally speaking our American compadres are exposed more to interstate/hwy/freeway cruising, straight-line dragging and/or circle track work, rowing through the gears isn't necessarily their number one consideration.

If your driving spiritedly through this sort of terrain:



Then you would be better served changing the rear end to something between 3.73 or 4.11 to help launch you out of those corners, and climb to the next apex.



Enjoy

[1795]

Dimis,

I concur. 3:31 is awful steep for climbing hills, unless you want to keep the car in 2nd and 3rd gear all the time. A lower gear ratio would put you in the power band and help with acceleration out of the corners. While it hurts the top end speed, you will never notice it going on those kind of roads.

What you want to do is take a look at the car as a whole when considering what to do. It is difficult to end up with a quality product if you piecemeal parts together. Do not just focus on the engine, but the transmission, rear end and suspension as well. Figure out what would be too costly or difficult to replace, and then try to build the rest around what you are going to keep and make it functional for your environment. There is no perfect car, what you need to decide is what combination will work well for most of your driving. Keep asking questions and do your research. You will get it right in the end. Drive the hell out of the car now and see what you like and what could need improving.