steNcho

Hi guys, I just swapped my old 286h hydraulic flat tappet cam for a Comp Cams XR280 solid roller. My neighbor is a drag racing champ here and he helped me with the swap.

Engine specs:

Block: 355 sbc 4 bolt mains.
Cam: XR280 solid roller - 242 248 duration at 050 lift, .570 .576 lift, 110lsa
Heads: World Products Sportsmen 2 - 64cc chambers
Intake: Edelbrock Victor Jr.
Carb: AED 750 mechanical secondaries
Pistons: TRW forged flat tops

I haven't gotten around to tuning the car yet. Drove it around my neighborhood and it seems to have more power. I just wanted some opinions on timing and carb jetting and valve lash.

The cam card says lash should be .018 intake and .020 exhaust. We adjusted the valves cold and set them at .022 intake and .024 exhaust. I'm probably gonna re-do them this weekend but does this seem okay?

The base timing is 23 with 15 degrees mechanical advance so 38 degrees total timing all in as soon as possible with my MSD Pro-Billet dizzy. Does this look right?

Carb jets are still the same as before the swap. Primaries are 69 and secondaries are 71 or 72 IIRC. This seems way small to me. What do ya'll think?

Btw I live in Curacao. It's an island in the caribbean so 90 degree weather all year. Thanks!

five7kid

iTrader: (14)

The valve lash would be okay for cam break-in. After that, I'd readjust them to the cam card spec.

Sounds like too much total timing. 36 total mechanical (no vacuum) should be all that it needs. Only way to know for sure is by dyno or time slips.

Do you have both primary and secondary power valve? If primary PV only, your secondaries are jetted too lean. If no power valves, it sounds a bit lean, but a wideband O2 sensor is the best way to know that.

305sbc

iTrader: (3)

To run that much initial, you're going to need to wire up an ignition kill for starting it when it's hot. Otherwise, you'll kill starters.
Slow cranking when hot is the first symptom.

steNcho

Thanks for the advice. The carb has only a primary power valve. I'm goin to re-adjust the valve lash this weekend and go over the other little things. The weekend after that it's racing time again . Going to change the timing to 36 and see how she reacts. I have a powermaster ministarter that I'm sure can handle the hot starts. She always starts right up and that used to be with locked out timing on my old dizzy. Thanks a lot for the help I'll post back as soon as I make some changes.

steNcho

Allright, set the valve lash to cam car spec today. Btw initial timing is set at 20 degrees with 18 degrees mech advance in by 3000 RPM. Also raised the jetting. They were 69 in the front and 70 in the back. We put in 71 front and 75 rear. Took the car out for a spin and checked plugs. Still burning a bit white so I left the fronts and put 78 in the back. Didn't drive the car yet with this jetting but I'll probably drive it tomorrow and see how she does. Thanks for all the help everyone!