[doubleClutch]

I recently purchased a Magnum 280H Hydraulic Flat Tappet Camshaft. I have 1.65 roller rockers, and a 2000 stall. Here are the specs:
Operating Range: 2000-6000 RPM
Duration Advertised: 280° Intake / 280° Exhaust
Duration @ .050'' Lift: 230° Intake / 230° Exhaust
Valve Lift w/1.5 Rockers: .480'' Intake / .480'' Exhaust
Lobe Separation Angle: 110°
I used the Cloyes timing chain set from the jegs kit. The engine fired up perfectly before we installed the cam. After the install it is getting spark, but not firing. We replaced all top end gaskets, tightened all bolts, and there were no leaks. I was trying to figure out if the lift was too high with the 1.65 rockers. What should the timing be set at? It is for a street setup with headers, 750 carb, and an e-cutout. It is a 77 400 y4 engine.

[formula kid]

See that you have the rotor in the correct position aimed at # 1 tower in the dist cap while at top dead center. The timining is ajusted by turning the dist right or left. Remember Pontiac's run counter clock wise. Hope this is of help.

[2manyT/A'S]

Valves too tight?

As stated above,double check distributor position/timing.

[crider]

Also when you get #1 up to top dead center make sure you are on the compression stroke. It's very easy to get the timing 180 out when doing a cam swap.

[Dens71TA]

How did you align the dots on the cam gears when you installed the cam? Dots on top the engine is firing on #1 and dots closest together its firing on #6.

[BILTIT]

Usually a timing problem. I just changed cams and thought i had the timing dead on, after some coughs and sputters i realized i was one tooth out.

[doubleClutch]

The first time we installed the cam both #1 and the bottom gear had the dot at north or 0 degrees. We took the engine back apart, and put the 2nd gear 180 degrees off #1. It seemed like it was still like 1 tooth off though. It doesn't seem like we can get it perfect. Wouldn't the car still start, and run roughly if it was slightly off?

[johnsma22]

Just an aside, when you installed the 1.65 ratio rockers did you have the pushrod holes in the head elongated to accommodate the higher ratio? If not, the pushrods will rub on the heads. Also, did you tighten the rockers to the factory spec of 20 ft/lbs of torque? You can't do that if you went with anything other than the stock parts. 20 ft/lbs will now keep all the valves slightly open and not allow it to fire.

[BILTIT]

Getting fuel?

[GTOWAGON]

did you remember to install the fuel pump excentric

[doubleClutch]

Sorry for all the noob questions, this is my first Pontiac (I have done as much searching as I could. I have been at this stump for couple weeks now, and we tore the top end down to get the timing perfect 3-4 times and the car still wont start). I have searched on the the 1.65 rockers a bunch of times, and seen different opinions. I might just switch back to 1.52 rockers because the only reason I bought a roller rocker set to solve the push in stud backing off problem. Also, can I get shorter push rods?

I drove the car with the 1.65 rockers and the old milder cam with no problems for about a week. Is it the cam lift/rocker lift combination that is too high? Would you be able to hear the rods rubbing the heads, or would the push rods just fail after a certain amount of time. How hard is it to have the pushrod holes in the head elongated. I am guessing it requires machining. I am also doing the labor alongside mechanic familiar with older Pontiacs, but used to newer cars. We didn't adjust the rockers yet either. We just tightened them, so the rockers wouldn't move. He said we could do that once the car started one time.

[BILTIT]

How did you adjust the rockers? You need to adjust them properly first. If using factory rocker studs then the aftermarket rockers will not work. To put in the aftermarket rockers you will need the proper studs and polylok nuts. There is a procedure to properly adjust rockers, a search should find it. Did you check to see if you have fuel?

http://forums.maxperformanceinc.com/...ker+adjustment

http://www.2quicknovas.com/happyvalves.html