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Discussion Starter #1
Is there any reason I shouldnt be able to rev to 7000 rpm on a 347, carb, AFR 185s and a custom FTI cam? What would hold me back? Thanks-Dan
 

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You'll float the valves first.
 

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there is alot of factors in there.

valve ramp rate
weight of valve train
rocker girdle?
...
 

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Discussion Starter #7
what about others with same combos? AFR 185s with the spring upgrade, stock lifters and custom cam? surely someone has the exact scenario, i know its a popular setup..thanks for the help though
 

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I have not experinced it myself but a buddies ride did experience lifter colapse around the 64-6500 range.
 

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Discussion Starter #9
The reason I was asking is since I was doing an all new setup, and I was reading in 5.0 about Robin Lawrence using stock lifters in his R/S car hitting 7000. I thought the cam grinder would just make the cam to peak that high since i should have the rest of the parts to accompany it. What lifters would be recommended then?
 

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With a high rev hydraulic cam and valve train from FTI or AFM, it will be no problem. I'd also run the titanium lifters/locks for insurance. Ask them what oil pump to run with your setup.

Unless you have a well balanced engine, I think you will eventually run into main bearing wear, but I'm no expert, so ask Ed or Anderson.
 

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Do you really believe those are stock lifters in that R/S car? They may be stock bodied but I can almost guarantee they have been modified ( IE change plunger spring, modified oil passages, etc).
 

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According to the NMRA rules, those Pure Street and Real Street cars are supposed to have OEM unmodified lifters. This would be a relatively easy thing to inspect, so I tend to believe they are unmodified.

AFM and FTI sell those cams for the OEM lifters, and if they didn't work, no one would buy them again, and word would get around. I think the key is the lobe profiles to accelerate slowly into big durations/lift. These high rev cams probably make less power at lower rpms than a cam with real agressive lobes that will float the valves by 6400 rpm.

P.S. I like your priorites man. I'd chose the 460 over the brunette any day. Hell, I'd run over the brunette with the 460 and laugh all the way to bank about it. I'm never marrying my wife again! I've learned my lesson :)

Just kidding.
 

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466coupe said:
Do you really believe those are stock lifters in that R/S car? They may be stock bodied but I can almost guarantee they have been modified ( IE change plunger spring, modified oil passages, etc).
I believe. Were you there when the motor was built? I was. They are stock, unmodified Ford lifters, just like what is in my 347 that revs to 7800 with the AFM N-113 and Ti retainers and keepers. Rick Anderson's 347 revs to 8200 with the only difference between his and mine being he has Ti intake valves (I ran out of $$).
 

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466coupe said:
Do you really believe those are stock lifters in that R/S car? They may be stock bodied but I can almost guarantee they have been modified ( IE change plunger spring, modified oil passages, etc).

Hey

THey are stock replacement roller lifters. I got them from Car Shop in Moline Illinios (in the article)

They are no different than any other lifter.

Marc is correct, The NMRA did a teardown of my car at the race in Dallas. In that teardown they removed and took apart a lifter. It was found to be 100% Stock and legal.

A lot of time testing on the dyno went into finding out how to make this combination rev. Last weekend I was spinning it past 7500 RPM.

Call Rick Anderson at AFM. He should be able to help you out.

Robin Lawrence
 

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Building a 347 that spins to 7K would be easily acheived. There are plenty of cams (hydraulic or solid) that will get you there. A ported Vic. Jr. manifold, 750 CFM carb, 1 3/4 headers, 11:1 compression and your AFR heads should get you an easy 500+ hp at the flywheel. I believe the limiting factor would be the stock block. A 347 will create more stress loads on the block than a 306 turning the same rpm.

Using lightweight pistons, rods and crank would help the block last longer, but would you want to spend big money on the rotating assembly and use a wimpy stock block? I'd recommend getting an FRPP or Dart block with that CID and rpm.
 

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If you're serious about this rpm range and you're not limited by rules in a certain racing class, use a custom grind SOLID roller cam and don't worry about collapsing the lifters.

The newer "street roller" type profiles will allow decent valve train longevity (if you wish to drive on the street), but will eliminate the high rpm problems associated with hydraulic roller lifters. These street solid profiles with milder ramps will typically produce 20+ more HP than a hydraulic cam of equal .050" timing, just from eliminating the lifter collapse associated with high spring pressures necessary at high rpm (as well as other hydraulic gremlins). There's very little more noise than a hydraulic performance grind, and with good components and proper setup, you don't need to adjust them constantly like we had to years ago. This is the way I'd go if I were serious about 6300-6500+ rpm.

By the way, it isn't necessarily mandatory to turn that 347 to 7000 rpm to get a bunch of performance from it. You'll get more peak horsepower, but the AVERAGE power might be no better than a well-matched hydraulic combo turning 10% less rpm. Custom cam grinders (that know what they're doing) won't always get you a lot more peak HP, but they'll deliver a broader, wider power band that is more fun to drive...and will arrive at the other end of the track more quickly than an overly peaky engine. It's your motor and your choice, but it would be wise to talk to your chosen cam grinder/engine builder and listen carefully to their advice once they understand your goals.

Steve A.
 

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a few ques real quick

could a semi-stock 302 rev to about 6, 6.5-7k? i like revving it up a little higher, giving me more time between shifts. im trying to keep costs downs, but i still want to have some OK power at higher rpms. i don't like to short shift. so i was thinkin i'd hone out my block, get new rings and bearings, clean it all up. get new cam, new rods, and some TF heads. but i'm wondering with what cam and heads and intake i could be able to rev up to atleast 6,000 rpm? and would i have to worry about my bottom end with this? i'm not expecting too much hp, trying to cut costs but still have some fun and do body work to it. also, i don't want to put too much money into the block because i later want to build a 408 carbed turbo motor. thanks for any advice.

ryan
 

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Re: a few ques real quick

blurr said:
could a semi-stock 302 rev to about 6, 6.5-7k? i like revving it up a little higher, giving me more time between shifts.
A near-stock shortblock can be revved into that range; the higher you go, the more you sacrifice reliability. The main factors in high rpm reliability are adequate components, excellent machine work, and careful, patient, knowledgable assembly ("blueprinting"). The oiling system becomes more critical as rpm rises, as well.

Revving the motor higher may, but will not necessarily, give you "more time between shifts." The PERCENTAGE of rpm drop between each gear will be the same with any motor combo, as the transmission ratios control it...not the motor.

Granted, the high rpm engine will have more absolute rpm change between gears. With a T-5 that's 2.95 1st gear, 1.94 second, 1.33 third, and 1.00 fourth, the rpm drop between shifts is 34% on the 1 - 2 shift, 31% on the 2-3 shift, and 25% on the 3 - 4 shift. If you rev your motor to 7000 rpm in each gear, the rpm drop between successive gears will be 2380, 2170, and 1750. Obviously, whatever the rpm drop is, that's how many rpm must be gained to hit redline and shift to the following gear.

Compare those rpm drops to an engine that uses a 6200 rpm rev limit. Shifting at 6200 rpm, the rpm drop between successive gears will be 2108, 1922, and 1550. So, comparing this to the other motor, revving all the way to 7000 rpm only gains you, between each successive gear, 272, 248, and 200 rpm.

A properly built 7000 rpm combo will likely produce more peak horsepower than a 6200 rpm combo. The torque peak, and possibly spread, however, is likely to be higher on the 6200 rpm motor. That's a fancy way of saying the 7000 rpm motor may be more "peaky." Yet, we're asking the 7000 rpm motor to operate (on average) in a 250 rpm wider powerband than the more torquey 6200 rpm motor! So, the 7000 rpm motor will sacrifice some pull right after the shift compared to the 6200 rpm motor. The 6200 rpm motor sacrifices a few HP right on top to the 7000 rpm motor.

Bottom line, with only 250 rpm average difference between shifts when revving to redline, and with that offset by the greater peak torque of the 6200 rpm mill, you're going to see very little difference in "time between shifts."

Most of the time, the 7000 rpm motor will win an all-out drag race because the additional rpm range allows the transmission gearing to apply more torque multiplication to the axle, farther down the track. Average torque at the axle, assuming traction, wins races.

On the other hand, in real-world street driving where, whether any of us want to admit it or not, the great majority of hours that the motor is running is below 5000 rpm...the 6200 rpm motor will outperform the 7000 rpm unit. Stoplight to stoplight, the torquey motor wins more often...and is MUCH more of a pleasure to live with on a day to day basis.

My point in all of this is that the incremental gains above about 6000 rpm are relatively very expensive and exact substantial penalty on other practical matters like reliability, tractibility, fuel mileage, etc. You get a lot of pain for a little gain. If that last little bit of ultimate peak HP is what matters most to you...go for it!

On the other hand, if you stay around 6000-6200 rpm, you can take advantage of moderate cost, high reliability, low-maintenance components (hydraulic roller valve train), maintain great drivability and efficiency...while sacrificing very little in ultimate performance.

Choose your weapon!

Steve A.
 
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