1968 383 road runner camshaft question

[Scott Kiger]

So my 68 road runner that I’m restoring came with the original numbers matching engine already rebuilt and assembled. I verified everything with the bore scope and she’s new. I was told it was built back to stock specs. How will the camshaft sound is my question? Not looking for a ton of power out of it as I have other rides for that. Looking for a cruiser that sounds good with this one.

 

[Runcharger]

If it truly is stock compression and camshaft it will have a fairly smooth idle. It will work well with the stock 383 magnum convertor if it is still there as well. It is really easy to screw up a 383 rebuild with too big of a camshaft and lousy compression ratio pistons.

 

[biomedtechguy]

Not for your described purpose, but I know how well my best friend's 70 Roadrunner 383 4 speed car ran with shade tree mods: Aluminum intake, 750 or 780 cfm carb, headers, cam, valve springs, and especially the rear gears. He ran from a 4.3X to a 3.90 in the 8¾ and that really helped a lot!
Solid mid 13s street tires car. First gear was a lot of noise and tire spin, but it really got moving, and 2nd gear is when he would usually pull ahead of the guy next to him.
I'd try a 292°/.509 cam in a 383 with supporting parts in a heartbeat!

 

[Cranky]

You know you can plot the lift and duration with a dial indicator and a degree wheel. Yeah, it's a little bit of work but you can do it without pulling the heads and then you will know exactly where the cam is degreed at.....

 

[Scott Kiger]

It’s going to be an OEM resto. Engine is original from the carb to the oil pan as it came in the car. It’s an early 68 four speed post car that was ordered with A/C so it’s a pretty rare bird. Didn’t come with power steering or power brakes but I have considered adding steering just for drivability

 

[Cranky]

It’s going to be an OEM resto. Engine is original from the carb to the oil pan as it came in the car. It’s an early 68 four speed post car that was ordered with A/C so it’s a pretty rare bird. Didn’t come with power steering or power brakes but I have considered adding steering just for drivability

I remember back in the day you would hear and see a few 'freak' cars.....cars that ran really really good vs the most of them. Back then, street tires were at a minimum at best for traction. Heck, I had G60's on my 66 Belvedere with a mild 383 in it and had no problem boiling then and the car only ran mid/high 14's on borrowed slicks. Anyways, there were a couple of guys when asked what they did to their cars they said nothing and that 'dad' bought the cars for them and they knew nothing about the mechanics of cars and didn't know how to 'manage' the power. I'm thinking these 'freak' cars came from the factory with all the tolerances in the right place and if you don't know, the tolerances for all the big 3 were all over the place unlike the cars of today. There were many new cars that ran like crap right off the dealer lot and the dealer mechanics couldn't do squat for them. So, that said, having the cam in the 'right' place makes a big difference so long as the rest of the build is right.

I remember dad buying a brand new New Yuker in 69 that was almost a total lemon....except for the 440 and trans that was in it. Even though it was supposed to be a 350 horse passenger car engine, that thing ran very hard!!! Yeah, dad made a couple of mistakes in letting me drive it a time or two lol. Too bad dad didn't wreck the car so I could talk him into buying it back from the insurance company so I could snag the engine and trans. Oh well.

 

[Budnicks]

1968 the RR Engine 383/335hp camshaft
(HP 383/335HP & 440/375HP, 1968-70 same cam)
IIRC off the top of my head cam spec.s if acually what was used
Hydraulic flat tappet, M/P 264* dur./0.464" intake & 268*dur./0.468" exhaust Gvl
The camshaft should have a slight/choppiness
bucket tee-bucket tee-bucket tee-bucket tee, a lil' rumble to it,
with the factory HP 68-70 Manifolds & the OE 2-1/4" w/h-pipe & dual exhaust
thru Hemi turbo muffs, w/tailpipes out the back

those pistons/with big valve reliefs, don't look like 'stock spec' either

While you're at it, a nice set of 1.6:1 Crane or Isky ductile iron adj. rockers,
along with the appr. style/length ball & cup style pushrods
it'd be like 0.510"in/0.514"ex GVL, using the same camshaft
it'd add a lil' % of duration too, keep the valves open a lil' longer
to sound meaner too
vs the factory 'not so accurate' mass-produced anywhere between 1.48:1-1.5:1 ratios
stamped steel, non-adjustable factory rockers
It would wake it up a bit, and sound a lil' better/meaner too

good luck

 

[haywire 440]

those pistons/with big valve reliefs, don't look like 'stock spec' either



good luck

I agree, not stock pistons.

 

[Scott Kiger]

Pistons are forged for sure. I was told it was built right. I am aiming to to maybe take it apart and just check everything out and figure out exactly what I have. Gaskets are cheap and they painted it the wrong color anyway. Dang thing is corporate blue. I was told that was the pint the engine builder had on the shelf so he painted it so it wouldn’t rust. Lol

 

[Budnicks]

a 68 383/335hp RR engine
should be the Turquoise color
(not orange until 69)

something along these lines

 

[Budnicks]

the steel org. 0.020" MP/DC - 0.025"-0.027" shim head gaskets
Vs the thicker/hi volume
like the Fel-Pro Blue Perma-torque 0.039" torqued/compressed head gaskets
will lower the compression some, decent gasket, but more volume

The lower volume one, thinner & smaller bore, less volume in cc's
if you can get a gasket closer to the bore size, the better too

With a the 0.020" to 0.025" to 0.027" thick
with a diameter like closer to 4.30" - 4.35"
(instead of the more marketed 4.41" or bigger mass produced stuff)
Smaller & thinner, will give it a tad bit closer to org. 10:1-10.5:1 compression intended too
albeit they aren't cheap
Cometic sells them

Fel Pro Perma-torque blue for 'a generic' one size fits all, all 350cid-440cid BB MoPar
is 4.505" bore x 0.039" compressed = 10.18ccs volume.
$19.77each in stock Summit Racing

So does Mopar Performance/Direct Connection
0.025" x 4.38" bore = 4.938ccs volume. DCC-P5155237
they are like $170-$175+ for a pair, last I saw from MP/DC
hard to find them, maybe Mancini Racing (?)

Mr. Gasket sells them too 4.40" bore x 0.020" thick
0.018" compressed volumes (the thinnest) x 4.45" bore = 4.58ccs volume.
$29.83 each , #1135G
Summit Racing has them right now
no a really good gasket, but low volume/high compression
you need to spray them with copper sealer
& be very careful when torquing them down

IMO Cometic is a better overall gasket...
it's at 4.35" bore x 0.27" = 6.576ccs volume.
They're not cheap $, in stock at Summit Racing C5460-027 $96.54 each

Good luck

 

[Scott Kiger]

Yeah I run Cometic head gaskets on my race engines. They are expensive but they are the best thing going for aluminum heads

 

[biomedtechguy]

I had mentioned the 292/.509 cam, and I know you want "stock" but I ran across a YT channel for an engine builder that does almost all Mopar engines and puts them on his channel for customers, and he uses the "509" cam on most of his builds.
I thought that was really cool and had to mention it.
Carry on!

 

[Mopar Hunter]

I had mentioned the 292/.509 cam, and I know you want "stock" but I ran across a YT channel for an engine builder that does almost all Mopar engines and puts them on his channel for customers, and he uses the "509" cam on most of his builds.
I thought that was really cool and had to mention it.
Carry on!

What lobe separation?

 

[biomedtechguy]

What lobe separation?

Looks like 108. 292 intake/299 exhaust. It's a CompCams stick.
I don't know how that differs from the "old school" Mopar, or in the days I first heard of it Direct<-->Connection Purple Stripe.
One glaring reason why "the 509" cam may have been so popular among "street" guys who do some racing is it having been the "hottest" hydraulic cam offered I'm sure that alone, especially in the era when roller cams weren't really a thing, hydraulic rollers especially, made that a popular choice.