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Author
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Topic: Need help fine tuning new set-up
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iamonewithjustin
Gearhead Posts: 185
From:
Registered: Nov 2004
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posted 01-13-2006 02:44 PM
 
I just swapped in a T5 for a C6. T5 has the 3.35 1st ratio. Changed from 2.79 open to 3.89 trac-loc. I also ditched my junkyard holly 600vac for a new street avenger 670.Now that I have a tach I can actually tell what my car is doing at various RPM.
By the feel of it I had previously thought that I was reving it to the end of the power band but come to find out power falls off heavily as I cross 3000RPM. That problem was solved easily. (After investigation I discovered I was only getting between 4 and 5 volts to the coil. I rewired it with a good 12v source.) Now you can feel a HUGE kick as it really takes off at around 3000.
The problem is: With those gears I feel it should do alot better below 3000. Even in first it dosn't pull very hard below 3000. I know 3000 is where the power should come on for this motor but there shouldn't be such a difference between 2000 and 3000 RPM. Power should come on smoothly not kick in all at once. Where should I start when trying to help out that bottom end. Motor is stock 2V. Timing is 35* by 3000. My distributor is using one of the lightest springs (silver) and the middle one (blue).
The carb is straight out of the box. I am not sure what jets are in it. It has the orange accelerator pump cam. It has an adjustable vacuum secondary. It is set directly in the middle of the soonest vs latest it could come in. Do you guys think it would help to bring the secondaries in earlier? Any suggestions would be appreciated. -Justin ------------------
73 mach 1
351C 2v (20k on rebuild)
Holly street avenger 670 on top an E-brock dual plane.
MSD coil amd distributor (no box)
Ford racing T5, 3.89 trac-loc
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V8 Thumper
Gearhead Posts: 4777
From: Phoenix, Arizona
Registered: Dec 2001
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posted 01-14-2006 09:56 AM
I'm no Cleveland expert, but even the 2v ports are very big and may not make stump-pulling torque low down in the rpm range. It almost sounds like your cam timing is late... have you done a cam swap on this motor? If so, did you degree it in? ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" 12.58/110 on street tires, more to come;) All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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iamonewithjustin
Gearhead Posts: 185
From:
Registered: Nov 2004
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posted 01-14-2006 08:23 PM
Never gone that deep into the motor. It was rebuilt 2 years before I got the car.I played with it some more today. I tried using the lighter spring in the vac secondaries. It made the problem very exagerated so I changed it back. I have a better feel for the problem now though. It pulls to about 1500, then you can feel it get slightly soggy. As you cross 2700 it really goes though.
As I said it has a 3.35 1st and 3.89 rear. If I floor it at like 1 mph it will chirp the tires, accelerate, then as you hit 3000 it rips them free all of a sudden.
Opening the 2ndaries earlier exagerated the problem. The engine must be getting to much air (not enough fuel). I would like to try increasing the jet size next.
What do you guys think?
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bbjay351
Gearhead Posts: 308
From: Festus, Mo Us
Registered: May 2004
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posted 01-15-2006 10:38 AM
I can tell you that clevelands love a big carb. What kind of power are you looking to get? Is it a daily driver or just a play toy? I have a 950 on mine with 2V heads that have been ported and polished, locked out the dist. It has an msd 6al box, and accel coil. 600" solid flat tappit cam, and weiand xcelerator intake. The tranny is a C-4 with a 4500 converter, and 4:56 gears in the back. It loves a lot of cam, and a big gear. I can drive it pretty decently on the street and go cruise it without any worries. I love those motors, tons of options, just depends on what you want.
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V8 Thumper
Gearhead Posts: 4777
From: Phoenix, Arizona
Registered: Dec 2001
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posted 01-15-2006 12:41 PM
You'd need to hook up a vac gauge and record the data through various driving conditons, but the power valve and accelerator pump circuits may need some fine tuning. Bringing the secondiaries in sooner and their resulting bog makes perfect sense, especially with those big ports. ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" 12.58/110 on street tires, more to come;) All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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iamonewithjustin
Gearhead Posts: 185
From:
Registered: Nov 2004
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posted 01-16-2006 03:42 PM
It's my every other daily driver. It has the stock cam and since it's a '73. I think that there is alot of timing retard built into that cam too. I was considering a cam and timing set as my next project. Something like a comp cams 268H. Do you think that will help it alot? Or will it be more of a minor gain?
How will that compare to the addition of long tube headers? I know they will help the bottom end alot too.
I can't really afford either but I have a bad habbit of spending money I dont have. I just can't decide where to spend it.[This message has been edited by iamonewithjustin (edited 01-17-2006).]
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ericcasas
Journeyman Posts: 99
From: Austin, TX
Registered: May 2005
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posted 01-17-2006 03:34 PM
I'm w/ V8 Thumper. Start w/ the basics first. If you have a vacuum leak somewhere, it will kill your bottom end. Vacuum is gone after 3000 RPM and that's where you seem to start running right. Sounds like a vacuum leak to me. I don't see anything else that could make a 'dramatic' difference without effecting top end as well.-E
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iamonewithjustin
Gearhead Posts: 185
From:
Registered: Nov 2004
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posted 01-17-2006 07:57 PM
The only vacuum lines I have hooked up go to the distributor advance and to the right side valve cover. The left valve cover has a tube 6 in long but not connected to anything. The cap on the right side is very loose and it obviously dosn't seal. Is that considered a source of vacuum leak? Intake and carb gaskets are fresh and I am confident that there is no leak there. I will measure the vacuum and let you guys know what I get.
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ericcasas
Journeyman Posts: 99
From: Austin, TX
Registered: May 2005
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posted 01-18-2006 04:55 PM
Yeah dude, that loose fitting might be it. Also look for nipples hanging off the carb. sometimes they are way in the back. Also, double check your PCV valve to make sure it seals up correctly. Let us know what you read vacuum wise at idle. It should have a really rough idle barely wanting to stay running if you have a strong leak.------------------
http://ericcasas.mustangsandmore.ws
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lonewolf
Gearhead Posts: 419
From: Colorado; M&M #3117
Registered: Jul 2003
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posted 01-18-2006 06:19 PM
I agree with the vacuum leak and I would check around the seam between the intake and the heads, especially if you used the valley pan as the intake gasket.A couple of other questions:
- What intake are you running?
- How are the primaries jetted? On the carb front, I am assuming you set the idle, float levels and all of that or are you running factory settings? Another thought I just had....are the unused vacuum ports blocked off on the carb? ------------------
Lonewolf
1968 Coupe in Pieces
99 1/2 F250 [This message has been edited by lonewolf (edited 01-18-2006).]
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