84firebird

hey, I contacted mallory recently about some high rpm issues arising again now that i want to race, before i bumped up the fuel and got a few hundred more rpm out of her, but it still died off around 5000 rpm, now to clarify it'll rev higher than 5000 in gear, but it takes forever once it gets to 4500.

i contacted mallory to make sure my ignition was up to snuff, i have an 85 series distributor with the most aggressive timing curve, all in by like 1800 er somethin like that, msd super cond wires, ...

now when i contacted mallory the tech guy said that he wasnt surprised, said 'As you know the coil that comes with it 0-5500 rpm add a little cylinder press, I'm not surprised. You could add a box like a hyfire 6.'

now I spent $150 on the distributor and coil... and sitll dont even know what the coil voltage is... but, has anyone used these hyfire boxes before? think it'll help?, think i need a new distributor or a better coil?

it's something, in neutral it'll fly right up past 6 as it should, but load it and, it isnt pleased... lookin for input, the more fuel i dump in the worse the bottom is too, like i'm flooding it hence the @1800rpm timing all in , any questions plz ask

it's a 1972 355. weiand high rise, holley 750 2.5 high flow power valve, currently 74 jets in front and metered in the rear at i believe 70, i put all the way up to 80 in the primaries and gained a few hundred rpm up top, but i lost on the bottom end, so my 1/4 mile was worse than the 74s, the secondary spring is the lightest one the air cleaner is huge and new, the ignition is accel header plugs, msd super cond, mallory dist 854801C. 0-5500 coil, the engine is 72 vette heads 2.02/1.6 valves, roller tip rockers, 9.3-1 claculated compression, including gaskets and deck etc. the cam is a lunati 230* 230*, 480"/480" cut on a 109* center the backend is 2600-2800 stall, (i always stall in that viscinity) th350, 3.23 rear gears, i have 4.10s but i'm afraid i'll top out if i cant rev above 4500-5000, tires are 27.5" tall 255 tread

i've been screwin with this for awhile, and the last time i thought i had it with jetting larger but that only helped to a degree, i went to the track and it fell on it's *$@...

any thoughts i'll give a shot
thanks guys
Josh

markinkc69z

Coil voltage really isn't important. Inductive ignitions only produce the voltage required to jump the gap at any point in time. If you want to test the output of your ignition and see if more energy would help then open up your plug gap another .010" and see if you lose more rpm capability. If you do lose more rpm then either their module sucks and doesn't have proper dwell control or the coil can't charge enough at higher rpm due to its contruction. (or both) A CD box like a Hyfire6 will hit the coil with several hundred volts instead of 14 from your alternator/battery. More in=more out. The box will bypass the module and give you extended rpm capability. Changing over to a CD only coil with the Hyfire will further improve its capabilities.

How much voltage do you have at the HEI when its running? Is it hooked up with 10 gauge wire? (or the stock 84 Bird wiring)

Did you change valvesprings when you installed the cam?

Did you buy an ignition because you had this problem?

What is the total timing set to and does your balancer year match the pointer?

Can you make the engine ping?

Are you still running the car off the weak factory intank fuel pump?

1racerdude

It could be a valve spring issue also.

84firebird

first the answers

I'll check that voltage at the hei, it's the stock wiring, hadnt really thought of that

valvesprings were changed, but i'm afraid that they may not be what i ordered, as i did get em off ebay

didnt buy anything because of this problem, just looking for help to see what i need to buy, cuz yea i dk

balancer year didnt match, but i painted a fine line at the 0 mark on my timing pointers and zeroed it while i had the heads off for the build. i run 12*+24* in the curve but i am waiting for timing tape to make sure it only advances to 36*, i only have the 12* on the timing tab and the curve's numbers, no actual hard data

i've never pinged the motor, but i have had the timing set to where any more timing and she wont turn over

i've actually got a mechanical fuel pump because it was a v6 and yea it had mechanical,

thanks for the input on the coil and hyfire, it's starting to mae sense to me, I'll give that .010" extra gap a shot and see what happens, and then i need a new module and/or coil? what kind of module/coil should i go with, something aftermarket out of summit catalogue maybe? or am i getting ahead of things

anyway yea, i'll give the plugs a shot and check that voltage and repost
THANKS

84firebird

how likely would valve springs be? like it'll rev that high in neutral, i kinda figured if the valves were floating it wouldnt?

1racerdude

It revs so quick at free RPM's ya won't notice it. Now if ya held it there(not advised) ya probably could.

markinkc69z

The rate of rpm gain is totally different in neutral and there is no load so it doesn't really make a good test.