Just need a lil insight

[ugly_od_eb]

My holley is finally dialed in... i had to buy the lil plastic cams for the accel pump... ended up using the tallest one (brown) and works perfectly no stumble when i punch it from idle... anyway i put a fibre glass tear drop scoop from summit using stainless allen screws (looks bitchin) and hood pins to shit can my hood latch (hated it stickin through the grill) i got a new 14" holley air cleaner with a 2" air cleaner spacer (to clear the linkage and fuel line (and to go up into the scoop when i drill holes in the back). Now for the things that annoy me... i got so much on tap for supply (as in air/fuel/exhaust) that i dont think the stock 302 can keep up the demand, so it breaks up at 4500rpms (valves floating maybe?) so my next Heavy mod is a set of 68' 53cc 302 heads with chevy 202 intake 160 exhaust that i got stockpiled, a luntai bracket master II cam/lifters 512 lift 290/290 duro, and im undesided on which roller rockers to use, a set of motorcraft shorty headers, and tall valve covers (also undesided).... so watcha think?

EDIT: Forgot to add timing gear (the noisy one lol)

 

[DirtDonk]

You may have said in previous posts, but what model carb are you running?
What size and orientation of exhaust system?
Engine new? Rebuilt? Old worn out original?

Does it just run out of steam at 4500 or does it act like the valves are floating? If old, maybe your cam is worn out. Or compression is down a bit.
If so, then those other mods you're talking about should do the trick.

Oh, and what ignition? Could you have a rev-limiter set too low?
Just a thought.

Paul

 

[broncnaz]

Could be weak valve springs, to much timing, Bad wires or dist cap or your secondaries are too lean or opening to soon or not opening at all. Do you have headers? Personally I think your choice of cam is way to big and will cause more issues. I'd look at something in the 270 range and below. The 290 range is good for light cars. If it was a roller cam then 290 might be ok. heads should be ok and I'd run something other than shorty headers most shorties are not much better than stock manifolds SBF engines need more help on the exhuast side than the intake which is usually why most SBF cams have dual pattern duration they just need more on the exhaust side of the house.

 

[ugly_od_eb]

Engine spudders and surges at 4500 in 2nd ragged out so... yeah
im runnin TA 670 with a weiand steath intake, the engine as far as i know is bone stock, stock igntion besides a msd coil, as for the shortie headers i got them for free and in great shape "not installed by the way"(the stock manifolds are cracked anyway) and my exhaust is custom made, 2.5" tubes about 2 foot after the manifolds then 2.75" all the way back with super 40 dual chamber flowmasters, as for the size of the cam its perfect because the heads will keep up with the demand and will be port matched, anyway its a mud bog truck and will be in the 5-6500rpm range most of the time, im not sure which igntion to go with but it might be the offroad MSD box with billet distributer and 2step rev limiter, I also plan on going with 39.5x13.50 Iroks with a gear change from 4.56 to 5.13 ;D

 

[broncnaz]

And the rest of the story. That kinda helps enlighten us.
Might look at your plugs after your run I have a feeling your secondaries are to lean. even a stock cam and springs should run up to 6000 rpm easy. I cant say much about your future setup but it should work ok But I would port those heads big valves mean little when you have small ports like the stock heads do.