Valve lifters…solid/hydraulic/roller tappet/flat tappet?

[blykins]

Excellent point Gary....

I was at Jon's shop back in July watching him disassemble a Mountain Motor with about 820ci of displacement. They turn 7000-8000 rpms without issues.

[blykins]

You know, I've never ridden a motorcycle before, but I can see myself getting into them.

I've also never ridden in an all-original GT-350 either....lucky dog.

[zrayr]

Originally Posted by blykins

You know, I've never ridden a motorcycle before, but I can see myself getting into them.

I've also never ridden in an all-original GT-350 either....lucky dog.

My first "real" job was as a motorcycle mechanic in 1969 After a few years I moved on to other endeavors for the next 30 years. I had thought the recession of '09 put me into early retirement, but out of the blue, a job working on motorcycles materialized. So it's a blast back to the past for me these days.

Z.

[ERA Chas]

Originally Posted by xb-60

I need an update to bring me into “C21”

Welcome to the 21st. Only took 100 posts, seven pages and the very patient, generous time of a couple of the best engine minds on the forum. Narrowly avoided sub-atomic matter theories.
Please now build to your hearts desire Glen.

[xb-60]

Originally Posted by ERA Chas

Welcome to the 21st. Only took 100 posts, seven pages and the very patient, generous time of a couple of the best engine minds on the forum. Narrowly avoided sub-atomic matter theories.
Please now build to your hearts desire Glen.

C21, eh? Thanks Chas. 100? Hadn't noticed, but doesn't time fly when you're having fun?
Cheers,
Glen

[olddog]

I have a 347. Cam duration is I/E 236/242 @0.050" lift is 0.555/0.575" LSA is 106 or 108. All this is from memory. It has Edel performer RPM heads. Gasket match appears to have been done to the ports. It has Mass Flow EFI, which is a Edel Victor Jr single plane intake with injection bungs welded into it. According to desk top dyno programs it should be in the 400 to 450 hp range, but I feel it is more like 350-375. I need to chip the EFI and work on the tuning. I'm quite sure there is more in it.

By the seat of my pants, it pulls strong all the way to the rev limit of 6500. A 302 would have the same mean piston speed at 7400 rpm. I would say it is close enough to maximum torque that I cannot feel any difference by 2500 rpm. Again a 302 would be there by 2800.

The cam does not smooth out until about 1800 rpm. That would be about 2040 rpm in a 302. Now do to the tuning issues mentioned, at light load lower rpm it is pulling in too much timing. It may smooth out a little sooner if properly tuned.

I have a TKO-600 transmission with the 0.62 5th gear. I had a rear end ratio of 3.5:1 and just changed it to 3.89:1. I like the lower gear ratio much better, all the way around. However I would hate it with a 4 speed, as 60 mph is just under 3000 rpm.

I can be in 5th gear at 1500 rpm and can accelerate up the steepest hills I can find, with ease. So the low end torque is not bad.

So in short, my engine with a 3.0" stroke should be fairly close to what the OP is wanting. I think it would be workable.

I do think the gear ratio he mentioned is way too steep. I would shoot for about 2500 rpm at 60 mph, to keep the noise reasonable. Maybe a little less, but this is going to kill performance. I would strongly recommend a 5 speed. Gearing is going to make a big difference for this engine. If you gear it too steep, it is going to be a dog!

I have no hint of valve float at 6500 rpm, but I seriously doubt it would turn much more. It does have aluminum roller rockers. You will have to have good stuff to get to 8000 rpm.

If you go to a 4.125 bore aftermarket block, that should help the torque a bit, and it will improve breathing on any head by un-shrouding the valves. 321 cubes isn't all that far short of a 331. This should make you happy. When you see some of the 5.0 blocks that have split in two, a better block is a great idea for turning 8000 rpm.

[zrayr]

Originally Posted by olddog

"...............If you go to a 4.125 bore aftermarket block, that should help the torque a bit, and it will improve breathing on any head by un-shrouding the valves. 321 cubes isn't all that far short of a 331. This should make you happy. When you see some of the 5.0 blocks that have split in two, a better block is a great idea for turning 8000 rpm.

some great advice when you are going all out for horsepower & rpm in a SBF engine, or just want to over-engineer the reliability factor in a mild build-up.

Z.

[olddog]

Air flow is what makes Hp. Well actually gasoline, but you can only put in the amount of gasoline that you have air to burn. Air fuel ratio has to be right.

The head is the largest factor limiting air flow. Exhaust and intake restriction can make a good head useless, so they too are very important. So these three in unison, pretty much sets the upper limit on Hp.

Eventually the valve size limits the heads flow regardless of how good the ports are. Ultimately the bore limits the valve size. Therefore in the end the bore diameter defines the ball park the engine will be in.

The stroke (within a practical range) is meaningless, when it comes to peak Hp. However the torque, is a whole different thing. The shorter the stroke the higher the rpm where the peak torque is made, and conversely the longer the stroke the lower the rpm where the peak torque is made. Also the shorter the stroke the higher the rpm where the peak Hp is made.

Since the Peak Hp is the same regardless of stroke, the short stroke engine will make less torque than a long stroke engine. Experiments have been ran on a lab engine, where the only variable that was changed was the stroke (2", 4", 6" strokes were used). The peak Hp was the same in all three strokes and occurred at the rpm which gave the same mean piston speed. In other words, the 4" stroke hit its peak at 1/2 the rpm of the 2" stroke and the 6" stroke occurred at 1/3 the rpm. Likewise the 4" stroke made twice the torque and the 6" stroke three times the torque of the 2" stroke.

Playing with valve timing is a rob Peter to pay Paul game. It can move the torque curve up and down the rpm scale, but you always give up torque on one end to get a bit more on the other. The better the heads, intake, and exhaust allow an engine to breath, the less games are needed by the cam.

So the old engine muscle tended to be big bore and short stroke, to allow bigger valves. Canted valves, and Hemi heads was a way to cheat the bore and get bigger valves.

Bottom line: a 289 or 302 can make as much power as a 347 (even a 427W). You have to spin it faster, and it will make less torque, but it will make the Hp. However you do have to gear it down to run the same speed at the higher rpm, in order to have the same performance from the cars perspective.

[zrayr]

very nice post olddog.

Z.

[xb-60]

Agreed. An excellent description. And the good thing about these cars with the power/torque available and the weight of the cars is that there are significant enough margins in the power and torque figures to allow compromise to either to achieve the required goals.
Different story of course if you're chasing ET figures, but we're not all doing that.
Cheers,
Glen

[blykins]

Well, I disagree about the cam timing "games" and about the bore determining the ballpark the engine would be in. I'm also curious as to what lab engine was used, that allowed a difference in stroke by 2" increments.

I play the cam timing game on every engine, not necessarily trying to move hp/tq curves around, but trying to clean up the bottom end manners on street engines. Advancing cam timing helps attain a clean idle, more vacuum, better throttle response, etc, etc. Even on heads that flow over 400cfm, I play that game...

As for the bore determining the ballpark, we have to watch what generalities we use. Remember, the Cup guys are making 900 hp with a 4.125" bore. That is very small compared to the 4.360-4.600 bores of a factory and aftermarket 460 block, and extremely small compared to the Mountain Motor bores.

However, XB, what he said really doesn't help your mission statement. His last sentence is true, especially about spinning it faster and getting less torque. That's what happens....the higher the hp peak goes, the less torque and usable power you get. Adding displacement and stroke helps that because it makes the torque curve broader at lower rpms. Taking away stroke makes the engine very peaky and you get nothing down low.

We were discussing the VTEC engines the other day.....remember that those engines are zippy, but the transaxles also have 4.4:1 final drive ratios and overdrive gears.

[xb-60]

I would be quite OK with spinning up a 289 or 302 faster and 'compromising' on torque. And if my proposed gearing doesn't work adequately - and I agree, it would be very much a compromise - then a diff change isn't the end of the world. The way I see it, there's so much more to a Cobra/replica ownership than just bare hp or torque numbers, or acceleration figures (or even max. rpm figures!). There is so much that has to be a compromise because the basics of these cars comes from a design rooted in the '50s and '60s. These are cars that don't have a roof even....the driver is so much more in contact with the noise, the smells, the feedback. To me, speccing an engine for torque on a Cobra replica is like speccing in power steering and air-cond. and a really quiet exhaust.
I'm on somewhat of a learning curve here and I am actually sponging up most of what I'm reading, and I appreciate all comments even if I don't automatically agree with everything presented.
Cheers!
Glen

[blykins]

I agree. You don't need as much torque in a lightweight car. I will encourage you to get some common Cobra curb weights, as everyone tends to think that a Cobra weighs about 2000 lbs. Some of the kits, especially when you add in a full tank of gas, driver, etc, will hit closer to 3000 lbs.

Let me remind you that I've never stressed a high horsepower or high torque engine. What I have stressed is that you forget about picking a random rpm number that you want to achieve and concentrate on making the car usable in the rpm range that you will be in the most.

You can not have a 289/302 that will have great manners and power at 1500 rpm and still make peak horsepower at 7000 rpm. It's just not going to happen.

An engine that makes peak horsepower at 7000 will not only require a 7500 (or higher) shift rpm, but the camshaft required to make peak horsepower at that rpm will pretty much insure that you won't have much at off-idle rpms.

Again, I'm just trying to help.

[zrayr]

Originally Posted by blykins

"................. You can not have a 289/302 that will have great manners and power at 1500 rpm and still make peak horsepower at 7000 rpm. It's just not going to happen.
An engine that makes peak horsepower at 7000 will not only require a 7500 (or higher) shift rpm, but the camshaft required to make peak horsepower at that rpm will pretty much insure that you won't have much at off-idle rpms. ......."

not trying to be constantly argumentative, but........ you don't need much power at 1500 rpm in a lightweight car. A stock Hi-Po flat tappet cam in a 289 K code engine will be quite happy idling at 900 rpm and pull cleanly to the maximum power rpm which is 6000 to 6500 rpm. With just a little head work you can get usable HP beyond 6000 easily, and up to 7000 (or more) is not difficult to achieve.

If the OP wants a 7000 rpm engine, then it seems that once opinions are voiced in the negative, it's would be helpful to set aside any reservations we might have and offer concrete ideas on how he might proceed.

That's why I suggested earlier that he should build a 289 FIA dead-on replica, and then drive the snot out of it. Once he's done that, he will know what, if anything. he will have to change in order to have the car he envisions.

Z.

[blykins]

Z,

It's not all about how much power you make down low, it's about how easy the engine will run and cruise down that low too.

From his description, he's wanting an engine that will cruise around right off of idle but then make peak horsepower at 7000.

There is a difference between making *some* power at 7000 and making *peak* power at 7000. If you just make *some* power at 7000 and the peak is much lower, then there's no use at all in straining the engine and putting undue stress on it at that rpms. Just because you can see 7000 on a tach doesn't mean that you haven't lost 50-75 hp by the time you get there.

I've given many concrete options for him in previous posts. And again, I'm not trying to be negative, but I'm trying to offer advice that comes from experience.

I agree with you 100%. I think it would be more worthwhile to put the peak down lower, say 6000 rpm, then see how the car behaves that way. If it's not suitable, then parts can be swapped.

[olddog]

Originally Posted by blykins

Well, I disagree about the cam timing "games" and about the bore determining the ballpark the engine would be in. I'm also curious as to what lab engine was used, that allowed a difference in stroke by 2" increments.

I play the cam timing game on every engine, not necessarily trying to move hp/tq curves around, but trying to clean up the bottom end manners on street engines. Advancing cam timing helps attain a clean idle, more vacuum, better throttle response, etc, etc. Even on heads that flow over 400cfm, I play that game...

As for the bore determining the ballpark, we have to watch what generalities we use. Remember, the Cup guys are making 900 hp with a 4.125" bore. That is very small compared to the 4.360-4.600 bores of a factory and aftermarket 460 block, and extremely small compared to the Mountain Motor bores.

However, XB, what he said really doesn't help your mission statement. His last sentence is true, especially about spinning it faster and getting less torque. That's what happens....the higher the hp peak goes, the less torque and usable power you get. Adding displacement and stroke helps that because it makes the torque curve broader at lower rpms. Taking away stroke makes the engine very peaky and you get nothing down low.

We were discussing the VTEC engines the other day.....remember that those engines are zippy, but the transaxles also have 4.4:1 final drive ratios and overdrive gears.

Bill the lab engine was a single cylinder, designed for experimental work like this. I believe it was a flat head design. The professor that wrote the book I am referring to had formulas for calculating power and fuel consumption for every type of internal combustion engine know to man. Radial air craft, turbine, diesel, 2 strokes, and even two pistons running in the same bore. It was interesting.

I do not 100% believe everything that was written. The book was written 60 years ago and a lot of things have be invented and learned since then. However a lot of the fundamental theory has not changed. I played with desk top dyno programs for hours testing this guys theory and they all seemed to prove out. Granted that is not a real engine, and my running computer simulations does not match up to your real world experience. Truthfully I believe you have given great advise here, and I would personally go for more stroke and less rpm.

The guy is set on building a short stroke engine, so I gave him the information I have that might help him.

Some personal observations over the years. I have seen some 289 Ford and 283 Chevy engines eat big blocks alive back in the day. There street manors sucked. In the early seventies we could stroke a 400 sb Cchevy to around 460 cid. Nobody (bar a few mega dollar race teams) could figure a way to get them to breath. It was a waste of money, and we were de-stroking them with a 350 crank and rods.

Today there are great heads everywhere, and strokers are the rage. Before there were good flowing heads, it was a waste of time.

As far as the cam game goes, look at the duration and lift that Sean Highland (hope I spelled that right) wrote in his book on the 4.6 ltr Ford. I think he was under 230 duration at 0.050 lift and a max lift of 0.480" at the valve. With ported 4 valve per cylinder heads, he was making good low end torque and peaking the Hp over 7000 rpm, normally aspirated. This is proof enough for me that you don't need to go radical on the cam if the head flows good. Granted a two valve per cylinder head will likely never compete with the 4 valve per cylinder heads.

[roadrod2000]

I have a HIPO 289 powered Unique FIA car with a 4.27 rear axle ratio and a ford motorsports T5. The camshaft is a solid lifter with .560/.512 I/E lift and 244/254 duration at .050. I just looked at a chart comparing RPMs at MPH for both my setup and the one proposed by XB-60 /Glen (3.07 rear and wide ratio toploader). What I find is that my 2nd, 3rd, and 4th gear are very close to the same (compounded ratio) as Glen’s 1st, 2nd, and 3rd , with that in mind this is what I experience driving the car; 1st gear is too low, I can easily get the car moving by starting in 2nd (starts on a hill might be a challenge though ) 2nd through 4th are well spaced and fun, but my jump from 4th to 5th is too much of an RPM drop, at 55 in 4th I’m at about 3000 rpm’s, the shift to 5th drops me to about 1900 and the engine is not happy there, so driving a winding mountain road is a battle between 4th and 5th . On the freeway at 70 I’m at 2400 rpm’s and that works fine for cruising but ideally I want to raise the rear ratio and drop the overdrive ratio so that 4th to 5th is closer. To summarize; the 3.07 /wide ratio toploader combo would probably work well with my car and for how I drive it, but on that hill I would want a slightly lower 1st.

[xb-60]

Originally Posted by roadrod2000

I have a HIPO 289 powered Unique FIA car with a 4.27 rear axle ratio and a ford motorsports T5. The camshaft is a solid lifter with .560/.512 I/E lift and 244/254 duration at .050. I just looked at a chart comparing RPMs at MPH for both my setup and the one proposed by XB-60 /Glen (3.07 rear and wide ratio toploader). What I find is that my 2nd, 3rd, and 4th gear are very close to the same (compounded ratio) as Glen’s 1st, 2nd, and 3rd , with that in mind this is what I experience driving the car; 1st gear is too low, I can easily get the car moving by starting in 2nd (starts on a hill might be a challenge though ) 2nd through 4th are well spaced and fun, but my jump from 4th to 5th is too much of an RPM drop, at 55 in 4th I’m at about 3000 rpm’s, the shift to 5th drops me to about 1900 and the engine is not happy there, so driving a winding mountain road is a battle between 4th and 5th . On the freeway at 70 I’m at 2400 rpm’s and that works fine for cruising but ideally I want to raise the rear ratio and drop the overdrive ratio so that 4th to 5th is closer. To summarize; the 3.07 /wide ratio toploader combo would probably work well with my car and for how I drive it, but on that hill I would want a slightly lower 1st.

Good, thanks, I haven't had many (good) comments on my proposed gearing. It sounds like your 5th gear is a 0.62 overdrive, so your fourth - fifth split of 1.56 is a little different to my third - fourth split of 1.36
Having a high first gear - equivalent to your second gear - is OK, and even desirable. On both of my current cars I often start off in second gear if it's not uphill, and one of the cars, 35 years old, still has the clutch that it drove out of the factory with, so I'm easy enough on clutches even taking into account the second gear starts.
Cheers,
Glen

[xb-60]

Originally Posted by olddog

....you don't need to go radical on the cam if the head flows good....

Good point olddog. There's an article I've come across a couple of times 400 HP 302 ci AFR 165 cc(Stock Cam) about obtaining over 400bhp from a SBF 302 while retaining the stock factory hydraulic roller cam, main changes being heads (to AFR165), by using higher ratio roller rockers, and headers/extractors. Main point is that it uses the stock factory cam. Does that mean that it would retain some manners at the bottom end while delivering at the top end (with the power graph still steep at 6200rpm)?
OK, I've said that my preference is to stay with CI heads for authenticity, but this seems to me to indicate that I could easily stay with a 302
Cheers,
Glen

[Gaz64]

Glen,

That is true up to a point.

A good rule to follow is spend money in the heads, then you can pick the appropriate cam, milder than most would go for.

You can make more reliable power and a better spread of torque with a mild cam (modern grind with less difference between seat to seat & .050 timing) and correctly ported heads,
compared to poor breathing heads and a large cam. You also don't have as much stress in the valvetrain (friction and inertia etc).

The majority of new cars these days have four valve heads for this reason, that is how the factory can offer the flat torque curves the engines have.