Just registered with your forum today. (lots of great info here)
This is for Doctor Dodge or anyone with cam experience.
1970 Duster 225 w/ Clifford heated intake & shorty headers, 2 1/4 duals w/ x-pipe before 3 chamber mufflers & tail pipes to the rear bumper. Holley 390 4BBL. A904 auto w/ factory converter & gears (276 ??). Just ordered oversized valves from Engnbldr to put into my freshly ported head following DD Guide lines @ dutra.org. Considering comp 264 or erson 270 cam kits.... should I be looking at the RDP erson grinds they have been doing for you guys? Looking to build a upper end street machine that still runs 87 gas and has not lost too much low end torque
& economy. What compression ratio can I target to do this and with what cam? Thank You for time.

i like it, you got a good start

personly while i had the head off for the valves i would shave the head to bump up the compression a little bit even 9 to 1 would be fine for street

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1973 plymouth duster 225 slant six .30 over, erson 270 cam, 9.5 to 1 compression, big valves, headers, and a holley 4 bbl
http://cardomain.com/ride/3135091

hey that thing got a hemi? naw its just a slant six

Im sure Doc will answer you. That being said I would look at the 280/270 RDP cam with(as stated in the above post) about 9.5 to 1 comp. This build is simular to Sandy in BC's mill.
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

The Comp 264 cam is lame in a Super 6.....

You need to do some serious planning to get the performance you want from 87 fuel.

My build is 9.5 static and just runs on 87........because my gears and 5 speed allow me to be in the RPM range to make it work.

Your convertor and gears will not allow your build to work well enough for 87.

Learn about dynamic compression ratios.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Use the Erson cam deal, I just got mine today, and it is beautiful. Comp had some problems with the oil holes lining up?
The cam I would start suggesting would be a 272 intake with a 266 exhaust along the lines of the .465lift and 110 LSA. I run a manual so I could've popped it up to 280, but my compression is only 9:1 which makes me nervous. I run 87 with 34deg total.

Thanks alot for the input so far guys. I have been using the Search and finding more great ideas..... this forum is set up very well. Now I have not heard from Doug or Lou yet, I have noticed that they look at things from many different angles which really gets you thinking. LOU have you tried your 280/270 RDP cam in your '68 Dart that Erson made for you last year? This is what I am leaning towards when Erson gets more blanks in, which might not show up until the end of May. I talked to John Hartman April 30th and this is the latest. He said he e-mailed Doug about it as well.

DARK

I have not tried that cam yet, but a few others have ordered it too. I think Sandy is the first one to have one running and he seems happy? Shoot for about 9.3 to 10:1 comp for pump gas depending on grade you want to use.

Should be a great street cam with a 2600-2800 stall converter. I am thinking I can get it to work well in the '68 Dart with a 2200 converter.

Lou

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Home of Slant6-powered fun machines since 1988

Thanks for the reply Lou. That would be the V8 stall rating from the suppliers since our slants would stall a bit lower? Any preferences or converters to stay away from, I can get Summit parts rather easy. Also what are your thoughts on the GM HEI conversion?

DARK

No, that is an actual Slant stall. You'd need a 3600 V8 stall rating converter. Best to order a custom converter for about $400-450 from a reputable shop like Midwest Conv, or FTI or PTC. Those are the ones people have been most happy with here.

DO NOT spend less than $350 on a new converter. You will be sorry.

GM HEI is good. I have not done it, but will soon as part of my megasquirt setup. Pertronix is the easiest and worked very well on my Valiant racecar with just a stock coil. Not a really hot motor, but pushing 200+ HP and 5500+ RPM.

Lou

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Home of Slant6-powered fun machines since 1988

True! Great cam with at least 9.25 compression. Fat torque curve, good idle and low end.

This cam is probaly as much as a Super6/bbd can tolerate.
Definitly needs gears!

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Yeah....Im the one who destroyed this rare, vintage automobile.....

With-out lower rear end gearing and some extra stall... the 280 / 270 RDP cam would be a bit much for DD street use.

I like mild cams for street cars. The 260 / 244 grind I designed with Erson works well for street performance, stock compression and 87 pump fuel. I have used this cam in a number of engines and it revs to 5000 RPM and it idles at 800... with a responsive torque curve inbetween.
DD

Oh come on! 10:1 compression, 3.91's and a manual tranny will take care of all that, right?!?!?!?



Doc is right, for street and a 'first' build it's better to go reliable and conservative, then work toward 'the dream engine'. You can get more 'fun', keep the mileage with a small amount of mods (upgrade to moderate duration moderate lift cam, upgrade compression-9:1-ish, change rear gearing-3.23ish, change the distributor curve-slightly more aggressive advance, change the carb-one to two barrels, and get a larger exhaust pipe-2.25")...some of these you can install when you can afford them, others like engine compression and cam will be a "I got the engine out, might as well do it all at once" type deal.

-D.Idiot

Thanks again everyone for the input, it's really appreciated. I will continue my research on gears and converters.

DARK