[El_Bambino]

Hi all,

long time since I’ve been on. Hope you all are doing well.

I just drop in and fired up my 383 stroker for the first time today!! It’s runs great and hits HARD...but I have some questions!


First off, I’m leaking coolant from one of my intake manifold bolts. Passenger side, second from the front. I pulled it out and put some black RTV on it. Bad move? Do I redo the gasket? Did coolant get in my oil?

Second, at idle I’m only getting about 20psi oil pressure, but as soon as I touch the throttle it rockets to a healthier 60ish. Is the 20 psi at 750 ish idle normal?

Third, what are your recommendations about how to break this motor in? Oil changes cycles, driving style, etc.
This is my first time dealing with a new engine. So far I just put conventional 10-30 with zinc additive and idled it for 10 mins, drove around city block twice. Then noticed the leaks and called it a day.

69 corvette block
Stroked
10:1
XR282HR-10 cam
RPM Intake
Dart SHP 64cc aluminum heads
Hydraulic roller lifters
1.52 Roller rockers

Thanks!!
Matteo

 

[johnwoods]

Hi all,

long time since I’ve been on. Hope you all are doing well.

I just drop in and fired up my 383 stroker for the first time today!! It’s runs great and hits HARD...but I have some questions!


First off, I’m leaking coolant from one of my intake manifold bolts. Passenger side, second from the front. I pulled it out and put some black RTV on it. Bad move? Do I redo the gasket? Did coolant get in my oil?

Second, at idle I’m only getting about 20psi, but as soon as I touch the throttle it rockets to a healthier 60ish. Is the 20 psi at 750 ish idle normal?

Third, what are your recommendations about how to break this motor in? Oil changes cycles, driving style, etc.
This is my first time dealing with a new engine. So far I just put conventional 10-30 with zinc additive and idled it for 10 mins, drove around city block twice. Then noticed the leaks and called it a day.

69 corvette block
Stroked
10:1
XR282HR-10 cam
RPM Intake
Dart SHP 64cc aluminum heads
Hydraulic roller lifters
1.52 Roller rockers

Thanks!!
Matteo

Any bolt going into a coolant passage should be coated with a quality thread sealer/RTV. When you say "at idle I’m only getting about 20psi", are you referring to engine vacuum or actually coolant pressure at the cap?
As far as break-in, that's pretty straight forward. Quality, specialized break-in oil (high zinc) @2500 rpm (steady) for 30 minutes.

 

[El_Bambino]

Any bolt going into a coolant passage should be coated with a quality thread sealer/RTV. When you say "at idle I’m only getting about 20psi", are you referring to engine vacuum or actually coolant pressure at the cap?
As far as break-in, that's pretty straight forward. Quality, specialized break-in oil (high zinc) @2500 rpm (steady) for 30 minutes.

Sorry, when I say 20psi at idle I mean oil pressure. I edited my previous post. Thanks!

my engine vac is only about 10 at idle iirc.

 

[greywolf]

What John said on the manifold bolt.
Oil Pressure sounds about right. 20psi at idle is fine as long as it jumps right up to 60 as the engine starts turning up.
My practice is to run that first run up, stabilize temps and check things over, then shut down and dump that first load of oil. It just cleaned out any rebuild left overs. Also that first load of coolant. Second oil is good for a couple hundred miles, then change it one more time. Just insurance cuz I'm paranoid about any crud that might sneak in during the build up. That build up always takes me too long, working in spare time. And the breeze here in Kansas can blow dust inside a golf ball.

 

[JKCamino]

I use driven BR15-50 break in oil, highly recommended by my builder and many others, 10-30 sounds to light a 20-50 might be better and give you some more pressure, 20 sounds low to me , mine is around 60-80 psi at idle might dip to 40 after it’s been running for a awhile, but if it does increase with rpm you should be ok. A heavier oil with give you some more pressure👍

 

[cyberray]

COMP Cams XR282HR Dyno Results

Dyno results for XR282HR Chevy 350 Small Block Hydraulic Roller Camshaft

www.compcams.com

Duration @ 0.006":​	282° / 288°	Duration @ 0.050":​	230° / 236°
Max Lift w/ 1.5RR:​	.510" / .520"	Lobe Separation:​	110°
Lobe ID#'s:​	3315 / 3316	Intake Centerline:​	106°
Engine Type:​	Chevrolet 350 Small Block
Bore:​	4.040"	Stroke:​	3.480"
Displacement:​	356ci	Compression:​	9.25:1
Heads:​	Dart Sportsman II	Intake:​	Edelbrock Victor Jr.
Carburetor:​	Holley 750 dbl. pmp.	Exhaust:​	1 3/4" Headers
Max Torque:​	385 ft*lbs @ 3900 RPM	Max Power:​	402 HP @ 6100 RPM
Manifold Vacuum:​	9" Hg @ 800 RPM & 11.5" Hg @ 1000 RPM w/ no load.

 

[johnwoods]

COMP Cams XR282HR Dyno Results

Dyno results for XR282HR Chevy 350 Small Block Hydraulic Roller Camshaft

www.compcams.com

Duration @ 0.006":​	282° / 288°	Duration @ 0.050":​	230° / 236°
Max Lift w/ 1.5RR:​	.510" / .520"	Lobe Separation:​	110°
Lobe ID#'s:​	3315 / 3316	Intake Centerline:​	106°
Engine Type:​	Chevrolet 350 Small Block
Bore:​	4.040"	Stroke:​	3.480"
Displacement:​	356ci	Compression:​	9.25:1
Heads:​	Dart Sportsman II	Intake:​	Edelbrock Victor Jr.
Carburetor:​	Holley 750 dbl. pmp.	Exhaust:​	1 3/4" Headers
Max Torque:​	385 ft*lbs @ 3900 RPM	Max Power:​	402 HP @ 6100 RPM
Manifold Vacuum:​	9" Hg @ 800 RPM & 11.5" Hg @ 1000 RPM w/ no load.

View attachment 135697

One helluva cam. From my experience, COMP is a great company to deal with if you can give them the necessary specs of your rig that will enable them to recommend the "right" cam. The 282 roller is stout and with the 110 degree LSA, might even run power brakes without a vacuum canister.

 

[JKCamino]

COMP Cams XR282HR Dyno Results

Dyno results for XR282HR Chevy 350 Small Block Hydraulic Roller Camshaft

www.compcams.com

Duration @ 0.006":​	282° / 288°	Duration @ 0.050":​	230° / 236°
Max Lift w/ 1.5RR:​	.510" / .520"	Lobe Separation:​	110°
Lobe ID#'s:​	3315 / 3316	Intake Centerline:​	106°
Engine Type:​	Chevrolet 350 Small Block
Bore:​	4.040"	Stroke:​	3.480"
Displacement:​	356ci	Compression:​	9.25:1
Heads:​	Dart Sportsman II	Intake:​	Edelbrock Victor Jr.
Carburetor:​	Holley 750 dbl. pmp.	Exhaust:​	1 3/4" Headers
Max Torque:​	385 ft*lbs @ 3900 RPM	Max Power:​	402 HP @ 6100 RPM
Manifold Vacuum:​	9" Hg @ 800 RPM & 11.5" Hg @ 1000 RPM w/ no load.

View attachment 135697

?

 

[Old Bear]

Josh, Matteo lists that cam in his specs in the first post in this thread.

 

[gilby]

Wow, sound like ya got a good one, yea, you can take that one bolt out and re-seal it with no problems as long everything's torqued down . as far the oil pressure, that's great, rule of thumb is 10lbs for every 1,000 rpms.. let's see some pictures of it, would love to see it..

 

[cyberray]

?

Josh, Matteo lists that cam in his specs in the first post in this thread.

you may also note that the graph and specs are for a 356ci, not a 383. I wouldn't be surprised if he was actually pumping out quite a bit more power than that.

 

[El_Bambino]

Great info thanks. I'm glad to hear about the oil pressure being good.

Turns out I was leaking coolant from all of my water threaded inlets/outlets/plugs on the manifold and pump. The ARP sealer I used for whatever reason didn't work.

The engine seems to keep a steady 210-220 idle temp, is that too hot? I'm running a 180 thermostat I believe, big aluminum radiator too.

The cam hits hard, sounds amazing, the car really moves. I would guess it's mid 400hp/tq, but what do I know.
I've been in cars with more power, but not this old. It's a bit terrifying. Breaks tractions real easy. I still need to tune it so I'm sure there is more there. I'm not very good at tuning though so I may take it to a pro for that once the motor breaks in completely

Unfortunately at idle I don't have good brakes. Installed a vacuum canister which helps a little. As long as the RPMs are up I have brakes.

I'll upload some pics soon. I tried to make it as stock looking as possible. And video sound does not do the cam justice.

 

[cyberray]

your vacuum idle is low for a couple of reasons, but the primary reason is because of the cam. it's only spec'd for 9" at idle. you've also got a RPM manifold on there which is a high-rpm, hi-lift-cam design. this explains your brake issue at low rpm.

"Edelbrock Performer RPM intake manifolds have a high-rise, dual-plane design. They produce incredible top-end horsepower, while retaining good throttle response. Performer RPMs have larger plenums and runners to match the free-flowing exhaust, high-lift cams, and other modifications of a high-output engine. They're intended for high performance street or competition engines that run from 1,500 to 6,500 rpm. "

I'm sure one of our members will be able to give you some guidance on how to resolve that issue.

 

[roccodart446]

210 to 220 is ok, but hot and you have very little wiggle room.

If you have a big radiator and a 180 stat, what fans are you running? And what water pump?

 

[El_Bambino]

210 to 220 is ok, but hot and you have very little wiggle room.

If you have a big radiator and a 180 stat, what fans are you running? And what water pump?

i’m running a standard 5 blade fan with a clutch With a stock cast AC Delco waterpump.
What do you think?

 

[johnwoods]

i’m running a standard 5 blade fan with a clutch With a stock cast AC Delco waterpump.
What do you think?

1968-1972 Chevelle Cold Case Aluminum Radiator & Fan Kit, AT, Dual 12 Inch Fans & Shroud: GMA42AK
or
1968-1972 Chevelle Cold Case Aluminum Radiator & Fan Kit, MT, Dual 12 Inch Fans & Shroud: GMA42K

 

[roccodart446]

i’m running a standard 5 blade fan with a clutch With a stock cast AC Delco waterpump.
What do you think?

I think you need twin electric fans.

Stock fans work on stock engines IF they are used with a properly fitted shroud, even then they can fail. There is a reason modern vehicles use electric fans, they work and can be set to operate based on demand.

 

[El_Bambino]

Bummer. Then engine bay looks stock at a glance, I was hoping to keep it that way. Electric fans are...bleh. I'll like into it though, thanks!

 

[johnwoods]

Bummer. Then engine bay looks stock at a glance, I was hoping to keep it that way. Electric fans are...bleh. I'll like into it though, thanks!

Don't fret brother, with your factory shroud and top plate, few will notice the difference. But you will when you see the dramatically better cooling. Just keep in mind you may want to consider a sacrificial anode cap if you go aluminum.

 

[Old Bear]

I think Robert (hkdup87) has a clutch fan on the 540 CU (about 700+ HP) in his '69.
Let's see if we can call him up. @HKDUP87

Matteo, are your headers glowing red when engine warms up?
Best to check for glow at night.
If so, you might have a timing issue that is causing you to run hot.