Just curious. How high will a stock slant six, 225, mechanical cam engine rev? Is it limited by cam size, valve springs...etc? Thats your experience?

Pretty much a 'stock' 70's slant will rev to about 4k before falling off (assuming you can get enough carburator and exhaust to get it to spin up there...1 barrel cars with stock exhaust barely get up to that...)

Given better components 6200 rpm is pushing the upper limit of the 225 engine...(been there and done that, no valve float on stock springs and valves...not willing to 'try and wind it' to 7000...)

-D.Idiot

Two barrel carb will give you another 500 RPM. These enignes are really happiest at 5K and below. Better eshaust and a 2 bbl will take you to 5k. You can get them higher, but they are long stoke, small bore engines. I think their closest relative is those big tractor trailors that go up and down the highway. Most of them have inline deisels in them that never wind up very high at all. They are torque motors.

Sam

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Sam, How high does your motor rev? What size cam do you have?


I'm getting only about 4500 out of mine. I switched to 340 valve springs bt would have expected a little higher with a 4bbl and turbo.

With regrinded cam (272 0,420 110) stock springs, shaved 0,100 Dutra dual 2 1/2" exhaust and Holley 1920, gives no more power over 4200rpm. But she runs very good up to that.

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Lasse

Signet -66 225
Holley 600 Offy-5270 Dutra Dual,regrind. cam 272 0,420 110, head shaved 0.100 slight.ported
MSD6A
A904
7 1/4 3.23

I am running a 465 holley, headers, a mild cam, 0.100" off the head, ported head, 904, 8 3/4 w/ 3.23's, I can get 5,000 rpm out of her but she is loosing power after 4600 rpm. 4600rpm in drive is about 117mph on my speedo.

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I can only get 4500 out of mine with 340 valve springs, 600 dp and a turbo

Mine pulls hard to 5300 and pulls pretty good to the rev limiter which I have set to 5800rpm.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

Mine rev'd up to 5000rpm with no prob stock motor clifford 3 into1 headers 390cfm holley 4bbl clifford intake with stock size tires stock gears. BUT now with 15' rims and 255/s in the back it seems it has a little trouble gettin to 5000 grand i suspect timing is off or my gear ratio is just too terrible now.

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My cam is a custom modified stock grind. It is designed specifically for turbo aplication. It has less overlap than a stock cam by a few degrees. According to those with turbo slants I have talked to or heard about , their engines work best at low RPM's. They not only produce the best power, but stay together longer when held below 5K. This includes the Drakes and Cameron Tilley. I did not talk directly to either of these guys, but have read their posts, and talked to people who have talked to them directly. Put a big cam in, and you can get more RPMs of of them as Bren demonstrates, and I would think there is nothing wrong with that. I don;t remember how high Dart270 winds his engine, but I think it is higher than 5K. His cam is definately a racing grind,considerably more lift and duration than stock.

Sam

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250 @ 0.050", 0.510" lift. Ported head. Naturally asp. Pulls strong to about 5700 with my current combo. Previous combos (cam timing, headwork) pulled well past 6000, but I've only tried 6200...

Lou

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Home of Slant6-powered fun machines since 1988

Once I was "brave and stupid" I had my car set up with 5.38 gears (1/6 mile) and wanted to see where the engine would stop pulling. 1/4 mile track and just kept going, after the 1/8 mile. Never did stop pulling. It did slow accelerating after 6,000, but went thru the traps at 7200 rpm. Remember I have a 170 (shorter stroke) and nitrous, so it will get more oxigen and fuel at higher rpm then a N/A motor.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Thanks guys, that helps.

We haven't tried a drag strip run, just runs down the street. Our's pulls strong up to 5000. Bored .060", offy 4bbl intake with a 390cfm carb, mild comp cam (can't remember duration off the top of my head), stock exhaust manifold (soon to be changed).

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Linder Tech.com
Bubba's Trailer Park

If you have a typical 2.76 rear gear about 4800 rpm on a stock engine. Thanks Ron Parker











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