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Discussion Starter #21
Well lets talk about the performer RPM top end kit I have been running for 20 years on a 351W, taking kids to ball games, driving around town sitting in traffic in the bay area, boulder colorado mountain thrashing and upstate new york country roads. I run several autocrosses a year and every few years I'll hit a track or two.This engine has been on Sears point , Laguna Seca, Thunderhill and Watkins Glen international all multiple times. Never had a valve spring issue BUT I chip at 6k to keep it whole. If you want to run to 7k, I would do some research. For instance, a trip to THunderhill, in the California Central Valley, 2 hour drive there, beat the daylights out of teh car all day in 100 degree afternoon heat, 1.5 hours home then 1 hour in bay area stop n go traffic to get to my home. This is a VERY Streetable system. SO first things first, the idle, this video gives a taste of the idle in the very beginning, its quite appropriate for a respectable mid-life-crisis ;o):

Big Fun

What I like about the system is you get a nice broad range of punch. You can get more HP out of a 351 but the power range tends to shrink and move upwards in the RPM range, my first engine was like that doggy at 2500 starts coming at 3500 neck snap at 5500. Felt doggy at street RPMs. For the street you want good low-end punch because any time you hit the throttle say to change lanes without a downshift, she will step out on you and "feel fast". My first motor would likely beat my existing motor on a drag strip but not on an autocross.

So I say, you can't go wrong with the RPM system with some nice shorty headers and a 600-650 carb which will give nice midrange throttle response.

SO that's my pitch, I've run this car for over 20 years with this system, its bullet proof and has never left me wanting for more and all components are matched right out of the box. Not saying you can't do better, but you can do a lot worse playing catalog poker.

Don't forget you have to divot the pistons with valve relief if you go 202 valves. Otherwise, if you are building the motor get the right pistons with valve relief.

Good luck!
thanks for this... that’s massively helpful, the car looks like it performs and sounds really good in the video.. and I’m still pretty keen on getting that setup .
I’m heading down to my local engine shop this week to pick up the bits of the bottom end and the cam .. so will see what they say also .

If you get heads with 64cc combustion chambers and flat top pistons with valve reliefs, your compression ratio ratio will a little above 10:1.
this is really helpful as I’m sure 10.1would be a sweet compression ratio to run, I shall look into the heads with a bigger cc as the performer rpms only have 60cc ... what would this mean for the compression ?

Where are you located? I have a very nice rotating assembly for a 351w posted in the for sale section. I am in Ohio.
ahh cheers man but I’m in England. So the shipping would be terrible
 

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Discussion Starter #22
Also my local engine shop stock these Cams also ...

Comp xe268
Comp xe274
Comp xe284

would any of these be any better in terms of performance ? Also big chop on idle 😂
 

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In the Nov 2003 issue of muscle mustangs and fast fords a 331 made 448 hp/445lbft with AFR 185 heads and 10.6:1 compression. The performer RPM heads did 430hp/428lbft with 10.11:1 compression. This was a roller 5.0 block with 331 stroker kit. Shouldn’t be a problem getting well over 400hp if you go with AFR 205 renegade heads and a good cam.

Thanks,
Rob
 

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Also my local engine shop stock these Cams also ...

Comp xe268
Comp xe274
Comp xe284

would any of these be any better in terms of performance ? Also big chop on idle 😂
When it comes to heads, valve springs, and camshaft, you’ll have to look up the specs yourself or trust your engine shop.
Most aftermarket heads come with valve springs with a max valve lift of .550.
So your camshaft lift cannot exceed that.
Also, camshaft lift specs are for 1.6 ratio rocker arms. If you decide to use 1.7 rockers you’ll have to account for the difference.
Personally, I would go with a cam that advertises lift in the .500 - .515 range. That way you can change to 1.7 rockers later if you want.
 

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Also my local engine shop stock these Cams also ...

Comp xe268
Comp xe274
Comp xe284

would any of these be any better in terms of performance ? Also big chop on idle 😂
The dyno numbers I quoted are with a XE274HR cam. They ran 10 different heads in that shootout. The ramp rates will be quite a bit different between the magazine article and the ones for your block since the magazine used a hydraulic roller cam. They mentioned this cam offered “good power without destroying drivability.” A “decent idle and a broad power band.” They don’t mention it being lopey...

Thanks,
Rob
 

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I ran the rpm cam with rpm intake on Dart heads from the 90s. It sounded good, with tko about 19mpg (US gal) and ran almost 12 flat in 69 fastback using 3.5 or 3.7 gearing. This is just to set a bench mark for you. Everyone's opinion of quick vs fast is different. I have an engine with .650 lift on the street now and another limited use at .790 both solid rollers so "streetable" has evolved over the years. Carb vs EFI is another variable of course.

Long story short: Have you considered hyd roller? Its more money, but with a good set of heads like 11R or P38 you can have vacuum, idle of choice and easy 550hp on street. Only real money is cam conversion, 351w bottom end will take 500+ no problem with any aftermarket piston. With good heads a little stall and appropriate heads, you can likely drive 10:1 on street just fine. LIke said above: less heads will require more cam timing and therefore effect driveability, and limting one self to hyd flat tappet again will necessitate more overlap and cam timing for same lift and performance. Just a few thoughts to toy over. The conversion is NOT hard.
 

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Oh and I have the XE268 in a Corvette and a 32 Ford in the hyd flat tappet iteration . Both great drivers, but not spunky and sound pretty mild. Vette has Jeg's heads and runs a meager 13.2. I would use the analogy of a fast road cam in British terms on my MGB. Noticeable over stock.....kind of like the way "they should have cam'd it " feel.
 

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70Dan, it is the overlap that gives the lopey idle. And it is the lopey throbbing idle that hurts miles per gallon and drivability. You don't HAVE to choose from off the shelf grinds. You can have a larger hydraulic flattappet cam ground on a wider centerline. You'd have driveability, mpg, and plenty of power. LSG
 
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