New cam and heads for original 273?

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OriginalDart

OriginalDart

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So the timing gears crapped out on my 69 Dart 273 at 107,000 original miles two weeks ago. Valves are bent, pushrods bent, cam gear now perfectly round its a mess. I know i could get my heads rebuilt, in fact there's a great machine shop nearby. But maybe this is my opportunity to upgrade! :D

My engine is %100 stock but i was thinking about getting a slightly more aggressive cam and new heads. I have a couple questions...

1. Can someone please explains cams simple for me??!!?? Once people start talking about diration this and lift that with all the different degrees i start getting confused and have relapses of math class

2. Aside from trying to throw some slick new aluminum heads on it, whats my best bet with the heads? Rebuild stock? Rebuild with bigger valves? Will 318 heads fit on the 273

I need all the help i can get :)

TheOriginalDart
 
Yes, 318 heads will work on a 273. I would look for a set that has a casting number that ends with '302'. I say this because they are a great upgrade for 273s, and lots of cars from the early to mid eighties had them. Next for a cam I would look into something very mild, like let's say no bigger than the specs of the lunati voodoo 60401. Do you already have a four barrel intake and carb? What about exhaust?
 
With stock bore without notching your gonna have to stick with 273/318 heads and valve size which is fine because they handle 300+hp stock, closed chamber would be the best choice so 85 318 and up 302 heads or earlier 273 heads. As for cam I would get to wild a high lift 262.
 
The 302 heads are good, but watch for the high spot that hits the driver side exhaust manifold near the #7 cylinder. I broke 2 stock early A exhaust manifolds not realizing the heads have a high spot that needed to be carefully ground down in order for the manifold to fit properly. I have the 302 heads and a crane 268 cam in my 318 and with an edlebrock 4601 carb and performer intake. I really like the lopy idle I get. Good power. In fact my 2 year old clutch cant really handle it. I am going with a stage 3 or 4 clutch and maybe an hydraulic throwout bearing pretty soon. Too much slipping when trying to do a burnout..
 
If you lost cam lobes you may want to pull the motor apart and clean all that metal out. Im sure the oil pump has sucked some up and sent it every were.
 
I cant help with your heads question, but Dad and I put a comp cam and lifter kit in his 67 cuda, 273 4bbl. We also added a dbl roller timing chain/gears and new springs/ with retainers. Make sure you get the proper keepers(10*) with the retainers....it set us back a few days trying to figure out why the old keepers(7*) would barely hold the valves. Oh ya if you are going dbl roller you have to specify that as you will only get a single roller in the kit. Im kinda unsure on the terminology with cams, but duration relates to how long the valve is full open, and I believe lift is simply how big the lobe is or how much it lifts the valve.
Here is the comp cams link
http://www.compperformancegroupstor...e_Code=CC&Screen=PROD&Product_Code=CL20-246-4
 
You guys are all on the right track. Your stock heads can be rebuilt and they cam be lightly ported or port matched to be more efficient. The 302's already have hardened seats so you're good for todays unleaded fuel. There's lot of cams out there and mild is what you want. Like 273 suggested, a cam with duration no bigger than 260 will work fine. I would also suggest pulling the pan. (thanks Adam) Look at a couple bearings and clean or replace the oil pump and pick up as needed. Let us know what you find. tmm
 
Thanks guys! That info is really helpful. I have the engine down to mostly the block right now. When i pulled the pan there were a couple small metal shards that i assume came from the timing gears. I say this because the cam and bearings looked unharmed. I'm taking the heads to get looked at tomorrow but i want something with a little more 'umff' so i might inquire about the 302 heads. Now what about the rockers? Should i continue to use the stock ones?
 
Cam Terms explained, at a basic level, for the novice in order to help choose a cam. Once armed with this basic knowledge, choosing a cam is easy and. An be done without a fear of screwing up badly.

Duration:

The amount of time the valves are open. The larger the number, the longer they are open. The longer there open, the bigger the breath it will take in or out.
When the duration is increased, the power. And of the engine moves up in RPM.

Duration is measure in 2 ways. Advertised and at .050, in which is when the cam begins to open the valve. When the valve opens to .050 lift height off the seat, that measurement is taken. This makes the cam look smaller to a degree.

Choose you camshaft based on the operating RPM as described by the manufacturer first.
Your cruise RPM should be in the lower part to middle of the rated RPM band of the cam.
This RPM must have matching parts such as intake, compression, carb, stall converter, rear gear ratio and the cars weight.

Also note that what a cam does in a large engine will act more radical in a smaller engine.

Lift: the amount the cam lifts the valves in theory.
(due to worn, inaccurate valve train parts, the lift stated may not actually be the lift you get. Also In addition to the geometry, valve lash for non-Hyd. Cams, full lift may not be realized.)

Overlap: the amount of time both valves are open.

Centerline: the lower the number the more of a choppy idle you will have and the harder time you'll tuning it at idle. Most performance cams are set at 110 which will give you that muscle car chop.

There, your armed with some knowledge, now go open up a cam book and poke around.
 
What these guys said....and I have the perfect intake manifold for you up for sale in the classifieds ;) Edelbrock LD4B!
 
OriginalDart said:
I'm taking the heads to get looked at tomorrow but i want something with a little more 'umff' so i might inquire about the 302 heads. Now what about the rockers? Should i continue to use the stock ones?
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One thing I should mention is the compression bump you'll get by installing closed chamber heads is small not saying not worth doing just $$ per HP ratio not very high, the rule of thumb is for every one point in CR bump say from 9:1 to 10:1 is worth 4% hp increase on a 300 hp engine that's 12 hp increase.
 
The 302 casting heads have about the same size and shape combustion chamber as the 64-67 273 heads so compression stays the same. The ports are slightly larger and a bit different shape. They flow a bit better than the 273 heads do and also have hardened valve seats which makes them unleaded gas friendly. tmm
 
OriginalDart:::Valves are bent, pushrods bent

You all have the heads covered and the disassembly and cleaning out are a must in my opinion..........But, am i the only one curious about the condition of the piston tops?
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The piston tops have what looks to be 43 year old carbon build up. Except where the valves touched, that area just looks like some of the carbon was knocked off. There's no scarring or pitting or anything else that stands out. I thought about at least replacing the rings but it doesn't fit my budget or my time schedule right now, this is my daily driver and i need it back! Plus the motor wasn't smoking, the oil didn't smell like gas...what's your opinion?
 
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