|04-03-2013 02:15 PM|
Get it tuned up/set up correctly and get a performance baseline (Some time slips) with sticky tires
before making any assumptions.
A out of the box distributor curve will not be right.
The basics are in my posts.
This is a good time of year for track testing. The ET slip never lies. Get some sticky tires.
You need to clairify exactly which Jegs heads you have.
|04-03-2013 11:38 AM|
|vinniekq2||read post # 6 and the others|
|04-03-2013 11:27 AM|
|nvyblue03||i am running 10.5:1 ratio....i have 1.6 rockers as well. f-bird...what kind of cam should i be running....also would it be worth the money to get my heads or ported or go with something different. i feel decent power down low but not much in the mid range.....i am going to check my timing this afternoon.. what would be accurate timing do yall think?thanks|
|04-03-2013 10:36 AM|
|techinspector1||Without knowing the piston crown configuration, nobody here can tell you anything. If the pistons you have in the motor now are flat-tops, the static compression ratio could be 10.5:1, if they're 30cc dished pistons, the static compression ratio could be 8.5:1. Until we know the skinny on the pistons, we're flying blind.|
|04-03-2013 10:18 AM|
|vinniekq2||agree with fb,nvyblue03 needs to participate here|
|04-03-2013 09:58 AM|
You are jumping the gun in assuming the heads are the cork in this combo.
(the 180cc heads would not have been my choice for this motor but they can be tweeked easily.)
The cam is lame.
|04-03-2013 09:11 AM|
In the end the only real solution is a large port head while keeping a careful eye on Dynamic Compression Ratio (DCR) while your there.
|04-03-2013 08:35 AM|
If this motor has a dished piston or a flat top piston and (72cc heads) and the Deck clearance was not dialed in
("0 deck") then the cr will be modest.
What piston? what installed TDC piston deck clearance?
If you want 500hp you can get it but you will have to change things.
The cam is not serious enough. The converter and gears are not serious enough if you are going drag racing.
But you need a performance baseline to verify your hunch on this cars performance.
(a day at the drags to get some time slips..."test and tune" on sticky tires)
I see a 110-112 MPH (1/4 mile) car here.
Assuming correct tune up/setup.
When ever dealing with a combo that is not performing to expectation:
Always start with doing a basic engine cranking compression test first to verify general engine health. FIRST
DId I mention EXHAUST SYSTEM and fuel system
|04-03-2013 08:20 AM|
Timing should be 24-26deg at idle 34-36deg @ max advance (a 10deg advance bushing)
Jetting 70 to 74 pri 80 to 84sec 4.5" power valve .031 shooters.
What is the 1/4 mile ET and MPH?
What is the car lacking? low rpm torque, top end power?, RPM????
What is your power goal.... ET/MPH goal from that combo?
Both the cam and the 180cc heads are small for big serious horsepower.
But it should be no slouch on the street.
Exhaust system is critical too. It has to flow to make power. Test with open exhaust and collector extensions.
The MPH from a 1/4 or 1/8 mile drag test tells the tale of how much HP it is making. (with known car weight w driver)
While I really like the Jegs/Profiler aluminum heads (If that is the head you have), I would not have used the 180cc head on this 406 motor.
(It can be improved a lot with porting)
|04-03-2013 08:19 AM|
would you post tune up specs and clearances please,and CR
|04-03-2013 07:58 AM|
|nvyblue03||71 chevelle.turbo 350.10 bolt w/3.73.....2800 convertor|
|04-03-2013 07:48 AM|
What's your initial timing?
You need lots of initial with that setup.
18-20 initial. 14 in the dizzy and another 10 from the vac advance all in by 3400.
Also. What car? What trans? Rearend? Convertor?
|04-03-2013 07:44 AM|
what are the tune up specs you are currently using?How many CFM do the jeg heads flow?
what makes you think its not performing correctly?
|04-03-2013 05:08 AM|
Help with Heads
i have a sbc 406 with eagle forged crank,eagle forged rod 5.7,kb pistons,xr288-10 cam..236 intake,242 exhaust,110 lobe @.05,edelbrock performer intake,holley 750 mech secondaries......i currently have the jegs aluminium heads 180cc intake,72cc combustion chamber, 2.02 intake,1.6 exhaust.......this motor is just not making anykind of power like i think it should.....should i change the heads and if so what should i get? i just think i need to be making more power. how does this setup look or what should i change to make power. any input will be appriciated.