1970 383 HP Engine Help / Cam Install

[NewRevNorton]

Over the weekend I installed one of the infamous 484/284 purple camshafts in the 383. This engine was given to me disassembled and I was told all of the parts to reassemble it were included. All went very smooth as we used the 555-20462 Jegs timing set but there was no thrust bearing or plate in my included parts to go in between the cam and the block. This is my first Mopar build. Is there not a plate or anything that sits in between the cam gear and block? It didn't look like the cam gear was grooved for one but I want this assembly to be correct. Right now it is only cam, cam gear, washer, cam bolt, then timing cover. On the crank side it was crank, gear, oil shield, seal, then harmonic balancer. Thanks for any input.

 

[NewRevNorton]

Bump!

 

[mattsinger]

there is no thrust plate for the cam...only on a small block

 

[RustyRatRod]

That's like a ton overcammed for an otherwise stock 383, too.

 

[YY1]

Be sure to degree it as per the MP instructions, using the offset bushings, and it will be fine.

Apparently there are two different 284/484 grinds, and that makes a difference as well.

 

[NewRevNorton]

Be sure to degree it as per the MP instructions, using the offset bushings, and it will be fine.

Apparently there are two different 284/484 grinds, and that makes a difference as well.

My set up is a single bolt. Aren't the offset bushings for the 3 bolt designs?

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That's like a ton overcammed for an otherwise stock 383, too.

HP 383 and fresh 651 heads with upgraded valves, new erson springs rated for .550 lift, KB pistons, aluminum intake... I thought that cam would work just fine friend.

 

[mattsinger]

which intake are you using?. Do you know what the compression is?
you will be fine with the cam

 

[RustyRatRod]

If the engine has a stock compression ratio, running that camshaft will have the dynamic compression ratio almost in the 5's compression wise. That camshaft is way too big for something with stock compression. It has 241* @ .050, and the intake closing is at 70* ABDC. Go ahead and run it if you really want a wheezer.

 

[MoparMitch]

Would a Comp XE274H been a better choice??

 

[RustyRatRod]

Would a Comp XE274H been a better choice??

Yeah much better. But this would be better still:

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=716&sb=2

Of course, I am under the assumption the rest of the engine is stock, including compression and whatnot.

 

[NewRevNorton]

Requires machining on cylinder heads.
Stock springs cannot be used.
Includes special shafts & spacers.
Special 10º locks, 1/2 2 groove, 1/2 set 4 groove.
Single groove use part #612-16.
Adjustable valve train required.
Pre 1968 use 824-16 lifters.

The noted requirements for that cam in the link that you sent does not describe a stock engine at all... Would you recommend I just ignore these suggestions by the manufacturer?

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which intake are you using?. Do you know what the compression is?
you will be fine with the cam

The compression will be roughly 10:1 for this build. That advice on the cam is what I have seen from just about everybody I have spoken too. I am not racing so I'm definitely not looking to pinch every fraction of power possible out of this engine. Just looking for a good streetable cam that works well with my 2000 stall and sounds nice at idle.

 

[RustyRatRod]

Actually, yes. Ignore them. Because all of those footnotes are not for every part number there. The 911-16 spring will work with stock retainers locks and valves. In fact, they will probably set up at or very close to the stock installed height with zero mods. Did you even bother to read what all of those footnotes are for? For instance, do you plan on running the comp cams rocker arms? Probably not, so ignore "Includes special shafts & spacers". Since the 911-16 spring is a very mild close to stock single spring, you can also ignore all of the rest, as NO machining of the heads is required, and NO adjustable valvetrain is required. Those footnotes are there for the other optional part numbers. They will not apply to what you are doing. That cam is miles smaller than the Mopar 484. It does not require any of that, so why would a smaller cam?

Requires machining on cylinder heads.
Stock springs cannot be used.
Includes special shafts & spacers.
Special 10º locks, 1/2 2 groove, 1/2 set 4 groove.
Single groove use part #612-16.
Adjustable valve train required.
Pre 1968 use 824-16 lifters.

The noted requirements for that cam in the link that you sent does not describe a stock engine at all... Would you recommend I just ignore these suggestions by the manufacturer?

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Hay, run the cam you want. The Mopar cams are proven. They are also 40 plus year old designs. Something to keep in mind. Now, if you are going to BLUEPRINT compression at 10:1, the 484 will work pretty good. But if you are just bench racing 10:1, like most people, then I strongly suggest against it. Even the stock 10.1 383 HP engine was doing good to actually blueprint at 9:1 because of Chrysler's terrible machining tolerances regarding deck heights and chamber volumes. So unless you're really AT LEAST at an honest 9.5:1 or higher, that 484 is going to bleed of cylinder pressure like a two dollar hooker.

 

[YY1]

Agree the 284/484 is an old school design.

Disagree it is "too much cam" for that motor.

That's what everyone told me while I was building mine (around 1989-90), but it ran great in my 70 Super Bee with stock converter, simple trans drill gere, remove ball, use green clutch, trans rebuild, and 3.55 gears.

Hung with the lighter 5 liter mustangs with their 3.73 gears, and beat nearly all of them.

I think the trick was degreeing that cam. The offset bushings require you to drill out the index hole (single hole gear) and put the bushing in it's place, changing the position of the hole. Read up on it, it's worth it. There's a link to a good article here somewhere.

I also ran a torker intake, another "no-no", but I think it actually helped that combo.

It was kind of a bitch to find and dial in a carb, and the motor did feel like- the faster you went, the faster it wanted to go- if you know what I'm trying to say...but was street driven daily on 89 oct and got 93 on friday nights.

Is there better available now- I'm sure, but mine was fun.

 

[RustyRatRod]

A properly matched camshaft will not need much if any degreeing in from dot to dot. This is why the camshaft industry grinds cams with 4* advance built in. Because most everybody overcams their engine. Why choose a camshaft and then advance it 4-6 or more degrees to make up for a poor cam choice? It simply makes no sense to me. Plus, when you add that 4-6 degrees to the already ground in 4 degrees, your cam timing suddenly becomes 8-10 degrees advanced. Entirely too much. Just because your engine "ran great" with your combo, doesn't mean another cam chioce couldn't have unlocked as much as 50 additional HP. Again, unless the OP's static compression is a blueprinted 9.5:1 or greater, that 484 is entirely too much cam. It's not a question of band aiding with advancing cam timing to make it run better. It's a question of having the wrong cam to begin with. Go ahead and build it. It'll sound good.

 

[ga66mopar]

I used that cam in a 70 roadrunner back in the early eighties. It was basically a stock 383 with headers, intake and a small stall. It ran pretty strong but it also had 410 gears. I didn't think that cam was all that large. I probably wouldn't run it today with all of the improved cam designs but I don't think you would have any problems. The 509 cam would be too large.

 

[RustyRatRod]

Look at the duration @ .050, the LSA, intake closing and the overlap. None of those specs are really that drastic, but all of them together mean that cam will bleed of a lot of needed cylinder pressure in a street engine with below about 9.5. The intake closing is rather late though....maybe if it was 60 or less, it wouldn't have such an impact. It really needs 10-10.5.

Intake Duration, Nominal	284°	Exhaust Duration, Nominal	284°
Intake Duration @ .050”	241°	Exhaust Duration @ .050”	241°
Intake Lobe Centerline	108° ATDC	Exhaust Lobe Centerline	108° BTDC
Lobe Separation Angle	108°	Overlap	68°
Intake Opens	34° BTDC	Exhaust Opens	70° BBDC
Intake Closes	70° ABDC	Exhaust Closes	34° ATDC
Intake Lift	.484"	Exhaust Lift	.484"

 

[coloradodave]

A properly matched camshaft will not need much if any degreeing in from dot to dot. This is why the camshaft industry grinds cams with 4* advance built in. Because most everybody overcams their engine. Why choose a camshaft and then advance it 4-6 or more degrees to make up for a poor cam choice? It simply makes no sense to me. Plus, when you add that 4-6 degrees to the already ground in 4 degrees, your cam timing suddenly becomes 8-10 degrees advanced. Entirely too much. Just because your engine "ran great" with your combo, doesn't mean another cam chioce couldn't have unlocked as much as 50 additional HP. Again, unless the OP's static compression is a blueprinted 9.5:1 or greater, that 484 is entirely too much cam. It's not a question of band aiding with advancing cam timing to make it run better. It's a question of having the wrong cam to begin with. Go ahead and build it. It'll sound good.

Rusty: Where is your information coming from? Honestly, do you think that all the independent cam manufacturers got together and conspired to grind their cams 4* advanced because their customers don't know what their doing? And the comment about little or no degreeing? You either degree it in to check the opening and closing events or you don't. I can't count how many cams from various manufacturers including Isky, Crane, Comp-Cams, Lunati, General Kinetics, Mopar, GM and Ford I've degreed in and never found that they ALL were 4* advanced. They are all over the place due to manufacturing tolerances. When you add after market parts to the mix it becomes necessary to degree it in if you're going to get the performance you paid for. I wish you wouldn't put this stuff out there. A lot of guys read it and take it for the absolute truth, which it definately is not.

 

[RustyRatRod]

My information comes from almost thirty years building engines. Call Comp, Crane and any other cam maker and ask them how much advance is ground in. It's a common known fact. Of course you never found them to be 4* advanced. Because of the tolerances in machining in timing gears and chains and keyways in cranks. There's no conspiracy involved. It's an industry wide practice to give more bottom end performance. Hell, I thought everybody knew it. It's been bounced around every single major magazine for years. The internet is your friend. Don't take my word for it.

 

[NewRevNorton]

Battle of the gold members... Sorry to start a feud guys. A lot of the talk even in this post still seems foreign to me but I am learning for sure. I have always been satisfied with Howards Cams in the past but being my first Mopar build I really just wanted to verify I was not missing a Cam plate of any sort and make sure I made wise choices on my performance upgrade of a camshaft. I imagine time will tell but the 484/284 camshaft is already in! No turning back now!! Sadly enough, all of this really just makes me miss the simplicity and fun in building these classics.

 

[coloradodave]

My information comes from almost thirty years building engines. Call Comp, Crane and any other cam maker and ask them how much advance is ground in. It's a common known fact. Of course you never found them to be 4* advanced. Because of the tolerances in machining in timing gears and chains and keyways in cranks. There's no conspiracy involved. It's an industry wide practice to give more bottom end performance. Hell, I thought everybody knew it. It's been bounced around every single major magazine for years. The internet is your friend. Don't take my word for it.

Common known fact? All I can say folks, is if you read something on a forum, before you make a decision based on that information, do your own research with the manufacturer who makes the product before spending your money...