396 BB Question=Need advice

[alsriv2]

Hello everyone.

I have an interesting dilema and need some advice regarding a camshaft.

Let me give you some background first.

I have a '69 C10 longbed that came from the factory with a 396. The previous owners have done some work to the engine that was not done well. When I bought the truck the engine was in pieces in boxes in the bed. (unfinished project)
Here is what I have:

'69 C10 396 Longbed
3.73 posi rear
Hughes performance TH400 with 2500 stall converter
Original 396 engine block
'71 402 heads (better flow) (Changed by P.O.)
Hooker headers/2.5" exhaust/x pipe dumping out in front of the rear wheels

I selected a performance machine shop in my area that has a fantastic reputation, the engine has been completely overhauled and they have done outstanding work. I am very pleased with their work.
Work done:
Forged crank - balanced
Line bored block
Probe forged pistons - 10.1 compression/rods line bored and balanced
Cyl bored .060 over
Heads completely overhauled with new stainless valves
New springs and valve guides
1.7 ratio roller rockers
Rotating assembly completely balanced

I left the cam selection to them as I do not know much about cams and there are too many choices for me to pick thru. I had thought a good hyd flat tappet cam is what I wanted, but decided to upgrade to a roller cam due to the possible issues with modern oils.

Here is what they installed:
New Lunati Hyd roller cam (Part Number: 50249LUN)

Cam specs:
(From manufacturer) Hydraulic, rough idle. Good cam for bracket racing in 454 cubic inch motors. Needs 3500 RPM stall converter, headers, 10:1 compression ratio or better and 4.10 gearing. Works well with nitrous!

Advertised Duration (Int/Exh): 290/300
Duration @ .050 (Int/Exh): 232/242
Gross Valve Lift (Int/Exh): .578/.595
LSA/ICL: 112/110
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 3600-6600

Here is my question. In the pre-build discussions with the machine shop, I described that I wanted a strong and reliable build with great low to midrange power and that the truck would be used on weekends and occasionally taken on the highway for vacation. This truck would never be raced or see a track.

I am concerned the cam they selected is too radical for what I want to use the truck for and I have the opportunity to have them change the cam before it goes to break in and dyno. After it goes thru the dyno process, the replacement costs come out of my pocket.

Any thoughts or suggetions would be very much appreciated.

Take care.

Al
'69 Chevy C10 396
'69 GMC 2500 Custom Camper

[WAAF]

THEY'LL pick a cam with overlap because of 10.to 1 and iron heads and 87 swill pump gas/
you might be better served with 9.to 1 pistons and an mild rv type cam..
are those probe pistons 10 t 1 with your cc heads? have the engine or heads been milled, upping the compression?
might want to ask the machine shop why they picked that cam
us giving you info only works with the info you give..
if the compression is more like 11 to 1 because of the overbore and any milling , it change the machine shops reasoning over what we might say...

[WAAF]

and is this a 60 over 396 REAL 396
or a 60 over 402

[alsriv2]

Good questions presented.

This is a real '69 396 that has been bored .060 over. The block is the original from the truck. The PO installed the '71 402 heads "for better flow".

The Probe pistons installed now actually produces right about 9.87:1 compression with the machining/truing work that has been done. They have told me I will be happy with the cam installed, but I am concerned based on what Lunati published describing this cam.
But, I hired these professionals so maybe I should trust them.

This is my first ever performance BB build.

By the way, WAAF is a great station. I used to live up in York and listened frequently!

Take care.

Al

[WAAF]

Originally Posted by alsriv2

Good questions presented.

This is a real '69 396 that has been bored .060 over. The block is the original from the truck. The PO installed the '71 402 heads "for better flow".

The Probe pistons installed now actually produces right about 9.87:1 compression with the machining/truing work that has been done. They have told me I will be happy with the cam installed, but I am concerned based on what Lunati published describing this cam.
But, I hired these professionals so maybe I should trust them.

This is my first ever performance BB build.

By the way, WAAF is a great station. I used to live up in York and listened frequently!

Take care.

Al

you can always run it by the cam maker hint hint..

[alsriv2]

Didn't know I could do that...will give that a try.

Thanks!

Al

[webfoot]

That cam would be a dog on the street, 60210 or 60211 seem a lot closer to what you are looking for.

http://www.lunatipower.com/Product.aspx?id=2155&gid=289

[alsriv2]

Originally Posted by webfoot

That cam would be a dog on the street, 60210 or 60211 seem a lot closer to what you are looking for.

http://www.lunatipower.com/Product.aspx?id=2155&gid=289

I had originally picked the 60202 cam, but decided against a flat tappet cam and go with a roller. The 60210 and the 60211 looks to be more along the lines of what I wanted (based on Lunati's description).

Thanks for the information.

Al

[nomrlz]

like mentioned. they bigger cam could be to help with the higher compression. it may be a bit big for your set-up i would think

[tubbedII]

Originally Posted by alsriv2

I left the cam selection to them as I do not know much about cams and there are too many choices for me to pick thru.

IMO, since you're paying these guys for their expertise, I'd run the cam they selected before swapping it. I would just make sure they knew I was concerned about it being too radical and ask what my options were if I wasn't pleased.

[HEI451]

One giasnt engine problem that makes for all sorts of issues when not done correctly, is quench distance. This is the distance between the flat deck area of any piston, to the flat deck of the cylinder head adjacent to it, at TDC.

Get this distance wrong, and no amoount of other engine voodoo will make it work. A lot of general engine builders don't have a clue as to how to do this right.

Older engines usually had steel shim head gaskets of between .020 and .024 thickness. Then, the piston deck was down in the bore at TDC of between .020 and .025. Adjustment of piston deck down in the borte vs head gasket thickness allowed some small adjustment to get the quench distance between .039 and .045.

When quench set correctly, mixture is helkd in the inactive areas of the bore/piston top, and not allowed go escape, keeping those areas both cool, and mixture charged, to stop detonation and pinging.

Along comes pack type head gaskets, with thicknesses of .040 to .055, and he whole works goes to heck real quick.

To get the quench distance right these days, we usually select a head gasket thickness of .040 to .045, pack type gasket, and "zero deck" the block, piston flat areas flat equal with the head gasket deck on the block.

This method is what all the Chevy ZZ engines use, and it allows about 3/4ths of a compression point more compression over having the quench wrong. This is how they can use as much as 10.25:1 on their small blocks, and 10.00:1 on their big blocks with iron heads, and "puke" gas.

Ask your engine builder if he is aware of "zero deck" and "quench distance". If he doesn't know the above info, find another engine builder that does.

[ItsRandy]

Originally Posted by alsriv2

I have an interesting dilema and need some advice regarding a camshaft.

Let me give you some background first.

I have a '69 C10 longbed that came from the factory with a 396. The previous owners have done some work to the engine that was not done well. When I bought the truck the engine was in pieces in boxes in the bed. (unfinished project)
Here is what I have:

'69 C10 396 Longbed
3.73 posi rear
Hughes performance TH400 with 2500 stall converter
Original 396 engine block
'71 402 heads (better flow) (Changed by P.O.)
Hooker headers/2.5" exhaust/x pipe dumping out in front of the rear wheels

I selected a performance machine shop in my area that has a fantastic reputation, the engine has been completely overhauled and they have done outstanding work. I am very pleased with their work.
Work done:
Forged crank - balanced
Line bored block
Probe forged pistons - 10.1 compression/rods line bored and balanced
Cyl bored .060 over
Heads completely overhauled with new stainless valves
New springs and valve guides
1.7 ratio roller rockers
Rotating assembly completely balanced

I left the cam selection to them as I do not know much about cams and there are too many choices for me to pick thru. I had thought a good hyd flat tappet cam is what I wanted, but decided to upgrade to a roller cam due to the possible issues with modern oils.

Here is what they installed:
New Lunati Hyd roller cam (Part Number: 50249LUN)

Cam specs:
(From manufacturer) Hydraulic, rough idle. Good cam for bracket racing in 454 cubic inch motors. Needs 3500 RPM stall converter, headers, 10:1 compression ratio or better and 4.10 gearing. Works well with nitrous!

Advertised Duration (Int/Exh): 290/300
Duration @ .050 (Int/Exh): 232/242
Gross Valve Lift (Int/Exh): .578/.595
LSA/ICL: 112/110
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 3600-6600

Here is my question. In the pre-build discussions with the machine shop, I described that I wanted a strong and reliable build with great low to midrange power and that the truck would be used on weekends and occasionally taken on the highway for vacation. This truck would never be raced or see a track.

Sounds too big to me. How did the machine shop figure 3600-6600 RPM was "Great low to midrange power"? That is when the cam is installed in a 454, not a .030 or even .060 over 396. Like I said...sounds too big to me.

[HEI451]

That particular cam IS too big, of which, I thought all of us were in agreement with. Just another reason to have someone that actually knows engines do the work on this one.

[prostreetC-10]

Originally Posted by alsriv2

Hello everyone.

Hello!

[mud.man.rj]

A 396 head is not a good breathing head like a 454 head. The 396 punched ,030 from Factory is a 402, that is why the block is 396 and the heads 402, so really a 402 your working with that is punched out another .030 to make it .060 over. No big deal but still to much cam, it would work in a lighter car with a bigger stall, but even then would have to push it a bit to make it work and not as enjoyable to drive. You having a truck, heavy, makes it even worse. I have built a lot of engines for trucks, 2wd and 4wd and also a lot of cars, you won't be happy for sure, drop down in size so you only have to do it once.

[alsriv2]

Thanks everyone.
I appreciate all the advice and knowledge presented here. I will be meeting with them this afternoon and iron out everything. The engine is mostly assembled and is in the paint process now. Going with a "burnt orange metallic" like the recent GM paint color. Hope to have it in the breakin/dyno process at the beginning of the year.
This build has been an adventure and I am looking forward to getting my truck on the road.

Take care,

Al

[WAAF]

roller cams don't need a break in

[SSC's76]

True on the break in but rings still need seated. Cam is big for a 396/402 I would not run it if it were me for some thing i'd take on a family vacation even in a bigger 454-502. Let us know what the machine shop says when you confront them. Im sure they do good work and have a reason for this cam choice but i cant think of what that may be

[alsriv2]

Its been a long time since I updated my status here, but after all this time, the truck is finally drivable. Long story, many moves across country and truck was always in a different location than where I was.
Have some good friends now that have helped me. Many things have been discovered about the engine and truck, so I am still working thru a bunch of unknowns.
1. The rear end is a 3.07 - not the 3.73 the PO claimed it was.
2. Hughes performance TH400, but unknown converter installed...PO says it is a 2500, but that remains to be proven.
3. The holley DP is a monster that is really a racing carb. No choke or typical linkages and the choke body area has been machined off. But the truck does run well with it, however I am fighting a fuel issue. Sputtering and cutting off like it is running out of gas, but has a constant 9.5lbs of fuel pressure measured at the carb input. Carb was professionally rebuilt by Baker Outlaw Fuels in PA, so everything should be ok. Tank is venting, sending unit is new, all 2 fuel filters are new, 3/8 fuel line.
4. Have no idea what the "all in" timing should be, but the engine timing is currently set what it was ran at DYNO, but would be nice to know the correct setting.

Looking forward to getting this thing dialed in with assistance from my friends here.

[PGSigns]

I would set the fuel pressure down to about 6. Get a good timing light and see what you have. If it was run on the dyno and they tuned it it should be close and you should have got a dyno sheet with the results of the dyno session and what the timing, jets and other info on it.
Jimmy

[geezer#99]

X2 on the fuel pressure. You only need 6 psi.
Here’s a link on setting your timing.

http://www.badasscars.com/index.cfm/...d=76/prd76.htm

Easy to check your stall. Hot break it in a parking lot somewhere. Squeeze the throttle up until it breaks loose. With a 3.07 gear it might not try to spin. Just jumping hard on the loud pedal will give you a flash stall. That number is usually 3-500 rpm higher than your static stall.

[alsriv2]

Thanks for the input guys. This was an old thread but still very relevant for me today. Drove truck ~16 miles last night and knew something was not right. Made it to destination and discovered the old edelbrock fuel pump had 0-1psi output.
I am converting it to an Holley electric this weekend with a 6-7psi output.

Also in the plans this weekend is to convert the front end from drums to disks and install a new power brake booster/master cylinder.

I will keep this up to date better and thank you for your ideas.

[68Gold/white]

Did you same engine parts that the machine shop built the engine with???

Everyone has an opinion concerning engine combo's. A bunch of things to consider. Quench is such an important issue, one that not a lot of folks have knowledge of or the hows and whys of the proper quench distance, post 11 is dead on about quench....

The cam IS big, but not too terribly big. Would be OK for a 454. Being a roller helps, less overlap...

Your combo of parts CAN be made to work, even with that carb. It just depends how willing you are to spend time dialing carb and dist. in....

3.07 gear will work with what you have also. It's going to shred tires easily enough as is...

[alsriv2]

Originally Posted by 68Gold/white

Did you same engine parts that the machine shop built the engine with???

Everyone has an opinion concerning engine combo's. A bunch of things to consider. Quench is such an important issue, one that not a lot of folks have knowledge of or the hows and whys of the proper quench distance, post 11 is dead on about quench....

The cam IS big, but not too terribly big. Would be OK for a 454. Being a roller helps, less overlap...

Your combo of parts CAN be made to work, even with that carb. It just depends how willing you are to spend time dialing carb and dist. in....

3.07 gear will work with what you have also. It's going to shred tires easily enough as is...

The engine shop is very knowledgeable with the proper setup regarding quench and all those things. I remember having many conversations with the owner of the shop and while I did not understand all he talked about, I was comfortable he knew what he was doing. They are well know back east for building high quality drag racing/street engines and I know they spent decent time with mine. The dyno video I have, even though it is a bit short, this engine appeared to do well.

[alsriv2]

Just dug out the dyno sheets.
34deg all in is what it was dyno'd at.
As for the engine, it sat in storage for 5.5 years after dyno, so there are some unknowns.

That 9.5 I reported earlier was after it had been running for 20 minutes or so at idle. After I made the journey to my friends house (16 +/- miles) I shut the engine down. When we went to restart it, it started hard, then died after driving 300 feet down the road. Took a look and the fuel pressure gauge was showing 0-1psi at the carb. Dead pump.

I like the fact the engine is running at 185 to 190 at all speeds, idle or 70mph.

I had a custom 3" exhaust bent for it, complete with hooker headers, an X pipe and flowmaster 44's. The exhaust empties out at a 45deg angle on the back side of the rear axle under the bed. No drone in the cab, sweet deep mellow sound.

As for the Dyno, I do know they used their own fuel supply system, bypassing the engine fuel pump. So that means my pump is an old, dry pump. I guess lucky it even worked after all this time. That being said, I am going to convert over to electric and get the fuel pressure down to where it belongs. The engine runs strong, but with it starving for fuel, performance has been a bit dismal.
Right now the truck is running Mickey Thompson tires on all 4 corners, but they are bias ply and need to be replaced due to age. Having a terrible time locating 13" wide 15" tires.
The fronts are 10" wide 15's so those are not an issue.
The truck was setup for racing but have no idea if it ever made it to the track, but it sure looks nice with its stance.