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#1
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When I rebuilt the 383 in my '69 RR, I used 516 heads with 1.74 exhaust valves, flat-top (9:1 nominal) pistons, 1-3/4" headers, a Weiand Action Plus manifold, and the 3310 Holley. I have dual 2-1/2" exhaust with crossover. The actual compression should be in the 9.5:1 range because of the closed chamber heads. The cam I am using is a single pattern, 218@ .050/.458 lift. From what I have been seeing it looks like this is a pretty wimpy cam especially for my engine combo... am I right in this assesment? I have been thinking about the 284/484 MP cam or possibly a Hughes with similar lift but slightly lower duration like the 1423 or 1923. This car sees 95% street use but I would still like to get high 13's in the 1/4 by simply swapping my gears for a day at the strip if necessary. Right now I have 3.23's with 28" tires (275/60-15) I know this kills my ET's but works great for highway acceleration (I can go 100 in 2nd gear which is cool for impressing my friends). I don't want to go too high duration because of the current gearing but still would be interested in improving performance via cam swap if possible...
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#2
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That cam should be produceing alot of torque for you. Its the gear ratio & tire combo that hurts of the line performance. Whats the stock tire size for the car?
And your at 28 inchs now. Thats a lot of tire. Also, tou did not mention your intake valve size. That will have an effect on how things work to. A cam would help performance. But not of the line. Your combo looks good as is. Swaping in a cam of those sizes with what you have, looks like it would still work OK. The purple cam @ 284 will need alot more gear to run proper. |
#3
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DROP DOWN 27 OR 26.5 IN TIRES!
Dropping down to a smaller tire would help. make em more like 3.40s, Is that the Blue Racer Wolverine cam? My dad has that in a '70 Charger w/ 440 and it runs AWSOME! ok, mid 13s w/ a stock stall converter isn't "AWSOME" But it makes hella-lotta-tork! He is gonna take it out and I was considering dropping it in my 383 w/ a similar intake and ported '516s w/ similar CR and same valve sizes. Ifigured it would run awsome. But I would be running 3.55s w/ 27 in tire or maybe 3.73s w/ 28 in tire. I have also considered the use of a 3.23 gear/25 in tire/ low gear set from mancini. You might want to consider the low gear set also. 2.74 from 2.45 first gear. I think they are $350 but that should really wake up the performance in first gear. If you did change cams, I would look to Hughes, give them a call. They are very knowledgeable and should be able to get something that would be just perfect. If I were you I would look at gettin some head proting done. If you stay w/ stock size valves and just have a simple port and polish job done by a local machinist, you could probably pick up 40 HP. Thats what I would do. head porting and 26.5 in tire. you could still probably do 85 in second. Or you could just drop in the low first. still would have the 2nd gear/ 100 MPH
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#4
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I'm runnin' a stock 2.08 intake valve. I'm looking to change cams to something that won't hurt my off-the-line performance much but will wake up my freeway acceleration; this car is used mostly for freeway cruising hence the 3.23's and 28 inch tires. I have considered changing to 26 inchers (stock diameter) for better short term acceleration but again, since it's mostly the 40-90 MPH type run I am looking at I am thinking a little more cam would help. I'm not concerned about off-the-line and 1/4 mile at all really. If I were I would seriously consider 3.73's or 3.91's. Then again decent low-RMP grunt is nice... the only way to get decent performance both ways is generally with a fast lift cam. The cam I am running now is a "Chevy" pattern cam (from CPP), which is why I was wondering about a Hughes or MP part so I can get more lift with the same duration. I am planning on pocket-porting the heads with the MP templates eventually. The responses I have gotten indicate that my cam has a good duration for the gear ratio/tire diameter I've got, so should I stick with the same duration but simply higher lift?
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#5
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A change to 1.6 ratio roller rockers would fix that and would be a change that would work well on any motor and with any cam. You are also making it more durable. I think the 26 in tire would do wonders in the 30-90 area as well. Duration won't do you much good.
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#6
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That was my other option... similar difference to swapping in Hughes but much simpler, also reduces friction for more HP and longer life. Where can I get a set? Are they only in the MP catalog, or do lots of people make them? Any reccomendations for which ones to get?
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#7
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Goose, Is that a Blue Racer or Wolverine cam?
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#8
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I dunno anything about the cam really; when I rebuilt the engine I got the rebuild kit from CPP, and asked for a cam that would give similar performance to the original 383RR cam. They said they had a cam rated at 218@050 with a .458 lift that would give similar performance, and that's all they said. I know nothing more, sorry! You do have me curious now though
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#9
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You can get roler rockers from Comp cams, Crane, Harland sharp and others I'm sure.
Comp Cams sells a kit that bolts on. I think Crane does as well. Look in a jegs for it. |
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