Need help with small block purple cam...

[pistol_grip_polara]

ok, I know I am not the first with this problem, but everyone's motor is different. I have done a lot of reading and think I have it narrowed down...

I have a 64 polara 2-door, with a 73 360 and a 64 4-speed. brand new mopar 360 11in flywheel with new clutch set up. The rearend is a 68 b-body 8 3/4 with 3:23 sure grip, running 245/60/15 all around. running headers with 2 1/2 collectors with 2 1/2 pipes with flowmasters and 2.5 into 3in tips

I am going to be finishing up my motor but need to order my cam. I got it already punched .030 over, but someone left some water set in the cylinders so it is now .040 over, brand new sealed power pisonts. (part number is at home) i do know they have a slight dome and have valve reliefs (not the flat tops). I will be running and oil windage tray, as well as a high volume pump. The heads I have are a set of 71 340 x heads, with 2.02 intake valves, freshly redone with new guides, 3 anlge valve job and very mild port work, (mainly just some cleaning persay). Running a set of early 273 adjustable rockers, (waiting to order proper pushrods depending on cam) The shop that has my motor, said he can deck the block.

My question becomes, if i deck the block and the heads are milled .010, what is that gonna do to my compression? planned on running the fel-pro gaskets but have read that the mopar brand ones actually have a more correct bore and a better crush thickness..

with the research I have down, i believe the best cam for my build would be the
P4120233AE: .508/.508 lift 292/292 duration 248/248 duration @ .050 centerline of 108 2200-6500 rpm

I have heard that cam is a dog without at least 3:55's but with my motor and a 4-speed would i be ok?
or would the
P4120231AE: .484/.484 lift 284/284 duration 241/241 duration @ .050 centerline of 108 2800-6200 rpm

I think im narrowed down to those to options, leaning more towards the .508 lift ..

any help would be appreciated. I hate to buy it and not like it.

 

[lewtot184]

personally, i wouldn't use either of those cams in a big car with a small engine; especially not the 292. be sure to check your retainer to guide clearance and coil bind on anything that has more lift than stock with factory iron heads!

 

[pistol_grip_polara]

can i ask what would be the problem with either of those cams in that engine, in that car? did not think of the car as that big, the stock '76 360 in it now with 4bbl and hedders moves the car really good, even being wore out...

 

[RustyRatRod]

Both of those cams are incredibly big for your engine. Both of those cams need a 3.91 gear at the very least and certainly the 508 would need a 4.10. Especially with a 4 speed. Without a torque converter, you lose the torque multiplication that it provides. This is why most manual transmission vehicles come with lower gears. Couple no converter with either of those cams and you have a dog on the street. Even with a decent amount of compression, those cams will not be effective with that gear ratio and a 4 speed. I would recommend something no greater than 236@ .050 ground on either a 110 or even a 112.

 

[lewtot184]

can i ask what would be the problem with either of those cams in that engine, in that car? did not think of the car as that big, the stock '76 360 in it now with 4bbl and hedders moves the car really good, even being wore out...

that 292 cam is a lot of cam for a streetable 440, least wise a 360. the 284-.484 is more manageable but still a tuning headache for a small engine big car combo. basically in a nut shell, big hydraulic cams suck in small engines. call some different cam grinders and talk to them, they'll tell you the same thing

 

[Meep-Meep]

Sounds like you are doing a pretty stock build with minor mods, so you don't want a crazy cam. I'd say a slight tweak over the stock 340 cam should do you just fine. As Rusty said, 112 or even a 110 lobe separation is as much as I'd go for a mild daily driver street engine.

 

[pistol_grip_polara]

I appreciate the responses. Engine is still getting machine work done, and need to assemble. Still debating on cam and talking to my engine guy. Part of my problem is that a lot of the car guys i talk to you and am good friends with, are racers. Most of em build their cars for wide open, and don't drive on the street, so they steer me that direction sometimes.

Again thanks for the responses, as they are appreciated.

 

[dvw]

I've used both in small block builds. You won't like the .509 with 3.23. The 484 is much better choice. I would make sure you got the one ground on the tight lobe centers (108 or 110 can't remember, not 114). Its big but with 9.5-1 and advance it to 104 installed it'll make more power. The comp cams 268H is the next step down. I've run the .484 in a stock short block 318 Dart with stock 360 heads and intake,TQ and headers,stock torque convertor,4.10. It would run 14.0@100 thru the mufflers all day.
Doug