906 big block valve ?

[dodge71demon]

Is it possible to use oversized 2.11 intake valves in a 906 head without hitting the flat top pistons on a untouched 383 HP motor? Real MILD upgrade on the hydraulic cam and .035 shaved off the heads- stock rockers and pushrods. This is what the machinist want's to use instead of reworking the guides and I have concerns -- comp cam # 21-223-4 = 477/480 lift

 

[oldkimmer]

............I'd b more concerned about hitting the cylinder wall.......depends on how much lift the new cam has............kim..........

 

[69 Cuda 440]

Is it possible to use oversized 2.11 intake valves in a 906 head without hitting the flat top pistons on a untouched 383 HP motor? Real MILD upgrade on the hydraulic cam and .035 shaved off the heads- stock rockers and pushrods. This is what the machinist want's to use instead of reworking the guides and I have concerns

The 2.11" Intake Valves will be fine on the 383, and will not touch the Cylinder Wall.

Heads are milled .035", but what is the Combustion Chamber CC volume.

Double check to make sure that they have 'not' been milled before.

#2843906 Cylinder Heads typically left the factory with the Chambers at 88.5 CC's.

So if they have been milled {.035"}, the CC level should be
around 80 CC's.

Now the 'Million Dollar Quuestion' .......... What is the lift of the Camshaft ?

 

[dodge71demon]

OK the cam is Comp number 21-223-4 = 477/480

 

[69 Cuda 440]

OK the cam is Comp number 21-223-4 = 477/480

Comp Cams XE268H 'Extreme Energy'

Hydraulic
Single-Bolt Cam Timing Gear
Lift .................... .477"/.480"
Duration ............. 268*/280*
Duration @ .050".. 224*/230*
Lobe Seperation ... 110*
Centerline ........... 106*
Overlap ............... 54*

A Great Street Camshaft, with a slightly rough-idle.

With the Cylinder Heads milled {.035"} you will still enough clearance between the Piston and Intake Valve {2.11"}.

 

[moper]

Yo ushould be fine - but you should check piston to valve clearance carefully when assembling it. The point of max lift is not the closest point the valve and piston reach, so simply opening the valve with the piston at TDC won't cut it. You have to clay the top of the piston, connect the chain, and turn it over. Then measure the clay.

 

[bOb shingler]

why not a 2.14" intake valve?

 

[69 Cuda 440]

Is it possible to use oversized 2.11 intake valves in a 906 head without hitting the flat top pistons on a untouched 383 HP motor? Real MILD upgrade on the hydraulic cam and .035 shaved off the heads- stock rockers and pushrods. This is what the machinist want's to use instead of reworking the guides and I have concerns -- comp cam # 21-223-4 = 477/480 lift

Where are the Flat-Top Pistons sitting 'depth wise' in the Cylinder.

 

[needsaresto]

I cant see why the upgrade? The cam is small and there won't be much benefit performance wise.

 

[EL5DEMON340]

My 383 was at zero with the stock pistons, cam was a lunati with 474 / 495 lift .220 at .050. 915 heads that had maybe .010 off. .039 felpro gasket. I used clay and don't quite remember the numbers but it was very safe

 

[69 Cuda 440]

My 383 was at zero with the stock pistons, cam was a lunati with 474 / 495 lift .220 at .050. 915 heads that had maybe .010 off. .039 felpro gasket. I used clay and don't quite remember the numbers but it was very safe

Good Information

We still don't have the all the Specs from the 'Original Poster'.
* Piston Depth
* Cylinder Head Combustion Chamber CC's

On a recent 383 Build, we had;

* 'Zero Deck' w/Flat Top Pistons
* Cylinder Head Combustion Chamber @ 84.0 CC's {Head Milled .017"}
* Fel-Pro #1009 Head Gasket {.039" Thickness}
* Camshaft .509" Lift / 292* Duration {248* Duration @ .050" Lift}

> Clearance was .079" Intake and .088" Exhaust

That's about as close as you'd like to go.