383 stock bottom end with xe275hl cam

[Polara880]

Hi! I' putting together a 383 for my 65 polara. The stock bottom end was good so I left it alone. Here's what I have for the build

- stock 65 bottom end with stock piston
- e street heads with 74cc chamber
- 1.5 ratio roller rocker
- performer 383 intake
- edelerock 750
- comp cam xe275hl

Now just wondering if Im goin to run into valve clearance issues with this cam. Valve lift is .525

Any info would be greatly appreciated

Tyler.

 

[FURYGT]

For someone to answer your question, unless they are familiar with e street heads they are going to need to know more about the heads. Open or closed chamber i.e., pre-'68 style 516's or '68 & later 906, 346 etc. style heads.

 

[Polara880]

Here is the info on the heads. Im running 75cc chambers

 

[Davea Lux]

Usually anything over .5 lift there could be valve clearance issues, it will depend on what gaskets you run on the heads and whether or not you are running any advance on the cam timing. I am going to assume you have done the prep work on the lower end. Plasti-gauged the rod and mains and checked for copper showing on the bearings. Engine should also have a new roller timing chain with this cam. Roller cams are a necessity for race engines, but are usually not a good choice for street engines if the engine did not come with this type of cam and yours did not. Many roller cams,(comp Cams) do not have good durability for street use.

The other issue is that a high performance cam puts a lot of stress on a seasoned engine. If you are going to go the high performance route, you will be better served having this engine align bored, balanced and rebuilt BEFORE trying this type of upgrade. You do not want to be picking pieces of your stock, matching engine off the street. You will also need a high performance exhaust to take full advantage of these upgrades.

Dave

 

[Polara880]

I think I might just switch cams to a xe274h. Here are the specs for it.

 

[Polara880]

I will be running the double timing chain and yes i did the proper check on the bottom end. I think the xe274h cam will work better for my set up

 

[Davea Lux]

I think I might just switch cams to a xe274h. Here are the specs for it. View attachment 180431

That is a better choice. Note that this cam will need a stall convertor and transmission valve body modifications and probably not produce enough vacuum to run a power brake booster. Ok with a vacuum booster pump and 2500 stall convertor. Fairly crappy mileage for a street machine. Might want to consider the 383 magnum cam as an alternative.

Dave

 

[Polara880]

That is a better choice. Note that this cam will need a stall convertor and transmission valve body modifications and probably not produce enough vacuum to run a power brake booster. Ok with a vacuum booster and 2500 stall convertor. Fairly crappy mileage for a street machine.

Dave

Sorry forgot to mention I'll be running Schumacher shorty header, 727 trans w/ transgo shift kit, 2500 rpm stall and have 4:10 gears out back.

 

[Davea Lux]

Sorry forgot to mention I'll be running Schumacher shorty header, 727 trans w/ transgo shift kit, 2500 rpm stall and have 4:10 gears out back.

All good choices, might also need a shift governor mod as you will be will be outside normal shift pattern.

Dave

 

[LocuMob]

I think I might just switch cams to a xe274h. Here are the specs for it. View attachment 180431

Steve Dulcich recommended this cam for my 66, setup very closely to yours but with Stealth heads.

 

[FURYGT]

Might be worthwhile to talk to Dwayne Porter at Porter Racing in Vermont. He is an expert at working on MOPAR heads, high performance and racing engines. His contact info can be found at:

Porterracing

He has done a lot of work for folks racing in the SuperCar Racing series that I race in.

 

[moper]

I would be very careful with regard to the piston to valve. E streets have larger intake valves, that camshaft has a fairly early and quick intake valve opening event, and the pistons have no reliefs. The closest the intake valve gets doesn't come at max lift, but rather during or just after the overlap event at the end of the exhaust stroke when the piston is moving away from TDC. You should put a layer of clay in line with the valves on the piston and carefully rotate the engine with checking springs in the heads to check piston to valve clearance.

 

[CBODY67]

With stock pistons, it would be good to aim for the max lift used on the HP/Magnum cams, as a general rule. I don't know that the cylinder head choice, per se, would affect piston/valve clearance, but the valve diameter in the heads being larger might.

If the short block is on the engine stand, you might check the main and rod bearings and see how much wear is on them. "Wear" is fine, but "gouges" aren't. Plastigage for clearance. Don't need to check them all, just a few, I believe, will give you an idea. If you happen to check the thrust bearing, you'll need to make sure that's retorqued correctly when done.

Sometimes, you can shorten the lift and extend the duration a little to compensate for any suspected power loss from the less valve lift. At least that's my theory.

Comp Cams are fine, but look at some of the Lunati grinds, too. The VooDoo ones, plus they also have a "factory performance" one for Chryslers.

Enjoy!
CBODY67

 

[Bighead440]

I bet with that duration the XE275HL cam will clear. The .525" lift basically means nothing as far as V/P contact is concerned. A zero deck 383 with a .509" PurpleShaft hydraulic will have contact, almost guaranteed, I have seen customers do it TWICE on '69 model engines. Those MoPar cams have over 244* duration @.050" lift, which puts you in trouble quicker than the 231* intake duration of the XE275HL, or the 230* of the XE274H. Degree the cam to 106 intake centerline and verify the clearance just to be sure.