racin66coupe

alright, a question that i will make related to mustangs a little while later on in this thread.

so i have a oval track race car. 85 monte carlo. the engine is a 350 with world S/R heads, stock cast intake/exhaust, and a isky SL1 cam specs:
Valve Lift (.390 .410) Valve Lash hot (.000 .000) ADV Duration (268 272) .050 Duration (228 232) LC 108

and the carb is a holley 4412 2 barrel
( all the stuff ive listed is all thats allowed in the rules for my division)

the bottom end of the engine is completely stock. and its backed by a 2 speed powerglide (not allowed to run manuals)

OK, now for what im confused about. i should be turning around 6200RPM at the end of the track, but im only turning 54-5500 and i really seem to be down on power from what i should be making..

i have a couple ideas from other racers. the plug wires we got we had to cut ourselves and were not sure if we got the best of connections so i am going to get some other plug wires. i did replace the rotor/ coil/ cap in the dizzy. and it is locked down at around 38* advanced. i also was running autolite 25's but i think i am going to switch to NGK's racing plug.

now for the carb question, could i be down on power from a dirty carb and it not being tuned right? and why im not spinning an extra 700 RPM?
the jets that are in it currently are 68's and i cant seem to figure out how to get the powervalve out?

can anyone shoot me in a direction to start at as far as jetting and powervalve goes? how hard is it to rebuild the darn thing and is it definatly worth it?


oh, this is related to mustangs because carbs are used on mustangs and this info can be used on mustangs too

67mustang302

Well, first it's a 2bbl limited race car. It's gonna be down on power, especially on the top end since the rules tend to make them asthmatic above 4,500rpm.

If the carb is dirty then yes, that can throw the tune off which can cost power. Sometimes it can cost a lot of power. you could try getting a 2bbl race carb if they're allowed, they tend to perform FAR better than the stock POS's.

As far as tuning, you'd need to check the plugs and see where it's at. If it's rich, lean it out....if it's lean, fatten it up.

racin66coupe

ok, i got the powervalve out, and thers 3 numbers on it. a 3, 4, 5 and a 7. wth??

and i know its going to be down on some power. but compared to some cars with stock engines im barely keepin up with them..... and no its not in the corners LOL
i should be turning atleast 700 more RPM/s

67mustang302

Or they're cheating. Or they're running a much better carburetor. Or your tune is way the hell off. Or a combination.

racin66coupe

yes, maybe; kinda doubt it, and its a good possibility

racin66coupe

as said " if you aint cheatin you aint winnin"
we all cheat a little bit... just depends how much the track likes you

67mustang302

Or how much MORE they like someone else.

Pull plugs, cut off the whole threaded portion so you can see all the way down to the bottom of the insulator where it joins the plug body, and post pics from at least 3 different directions that show all the way around the plug.

racin66coupe

if i can figure that out i will at somepoint this week, but im going to rebuild the carb and put some bigger jets in first. i got advice to put 72's in. and im sure it needs rebuilt

kalli

i count 4 numbers .... :-)

that stamping annoyed me already as I don't get why they would fill the top with numbers either. Anyway, all holley powervalves are x.5 (like 6.5, 7.5, 8.5)
So I'd guess the number next to the '5' anticlockwise would be your x.
At least that's how I understand it.

Anyone else another idea let us know

my77stang

a) how stiff are your valve springs? spinning up even a baby cam too high with weak springs will float valves and limit your top end.

b) can you advance/retard the cam via the lower timing chain gear? if the rules allow it and you retard it the motor will run better at higher rpms.

c) don't bother with NGK's, pretty much everybody in the world will tell you good ol' autolite coppers are the way to go.