Just signed up so hey everyone , 1st mustang but been around them , just got it this weekend and it was being built I assume for the track here is whats in it 306 c.i. , Edelbrock heads , 1.6 int. rockers , 1.7 exh. rockers , e303 cam , Edelbrock Victor JR manifold , Holley 670 street avenger , MSD 6AL ign. , Headman headers , H-Pipe , Flowmasters , subframe con. welded , Tremec T-5 , Centerforce clutch , 3.73 gear , and Weld Draglites with new street tires , oh and its an 87 coupe with a 89 gt lower all rebuilt , Idles mean and runs pretty good but not 100% , still needs some tuning , question is do I have too much carb and the wrong manifold for daily street use even with all the other work done or do i need to tone it down some maybe a 600 carb and rpm manifold or will that be a waste to the other parts , sorry so long .
new guy here - too much carb ?
- Thread starter mikemann0
- Start date
-
Sponsors (?)
bdazzgt
I had to jerk off the cable to get it to stop.
too much manifold for the street, the Victor JR rpm range is 3500-8000 RPM. IMO kinda high for a daily driver i had a performer and it was great for my 84. I think the carb is ok but too much manifold
Stever89
5 Year Member
I've got a similar setup, even the Victor jr, except I've got an Edelbrock 1406 (600 CFM) and I sometimes wonder if even that's too much. I've readjusted fuel pressure and it's better, but with 2.73 gears in 5th at highway speed, it's loading up. I'm hoping to remedy that with a 3.55. Out of the gate she's awesome though, no problems.
The victor Jr isn't helping. They're good manifolds but a street car benefits greatly (with a 302/306) by using a good dual plane. I did this swap years ago (from a Torker 289 to a victor Jr to an RPM). Going to the RPM was a world of difference in terms of MPG, driveability, responsiveness, and cold starting. I would venture to guess that teh RPM was making probably 30-50 more lb-ft at 2000 RPM than the Jr did. And I ran an 830 carb. Mild 5.0 with an Erson hyd. roller camshaft, long tubes, flat tops and ported iron 1975 351w truck heads. Nothing special-but would surprise a lot of people.
Theres a lot of things to look at if you're loading up and/or idling poorly at lower speeds. A lot of timing advance can affect it. Too little timing. VACUUM LEAKS. Dist rotor out of phase. And a ton of other things.
I'm one of those people who believes that there is no such thing as too big of a carb. I even ran a 1050 Dominator (9375, IIRC) on that same exact engine for a good while because at that time the 830 was on the race car for a while when it was running gas (before changing to methanol). The 1050 performed well but on a 4150 manifold won't clear the stock hood when screwed to an adapter. I had a 4" cowl which came on the car.
With enough tuning, a 670 will be fine. You'll just have to experiment with stuff. Check timing first. They don't like a lot of timing. Seems like about 25° is about all they'll take at low speeds (initial + vacuum advance). Or if it's too little, they'll be real lazy, idle poorly, load up, that kind of thing. Vacuum leaks will cause stuff like that too. I haven't done this on a carb'd car but on injected cars, I made an adapter out a piece of PVC pipe, with a cap on the end with a male quick connect fitting that would usually go into an air tool (it has a 1/4 NPT thread, drill & tap the cap, screw it in), which clamps to the throttle body. I'll then pressurize the engine to no more than 10-15 psi (measure off of a vacuum/boost gauge) and then use soapy water to check for leaks in the most likely places. Throttle shafts, hoses, fittings, trees, "tee's", etc. Fix those leaks and it'll run a LOT better. On a V8 if you check for vacuum leaks that way, you need a lot of volume so make sure the compressor is up to the challenge. A little compressor won't do it-but they work for a 4 cyl engine. Just be careful. Too much psi can bust stuff. Found that out on a 2.3 once. Pegged the 30 psi gauge and before I knew it hoses were breaking-among other things.
Theres a lot of things to look at if you're loading up and/or idling poorly at lower speeds. A lot of timing advance can affect it. Too little timing. VACUUM LEAKS. Dist rotor out of phase. And a ton of other things.
I'm one of those people who believes that there is no such thing as too big of a carb. I even ran a 1050 Dominator (9375, IIRC) on that same exact engine for a good while because at that time the 830 was on the race car for a while when it was running gas (before changing to methanol). The 1050 performed well but on a 4150 manifold won't clear the stock hood when screwed to an adapter. I had a 4" cowl which came on the car.
With enough tuning, a 670 will be fine. You'll just have to experiment with stuff. Check timing first. They don't like a lot of timing. Seems like about 25° is about all they'll take at low speeds (initial + vacuum advance). Or if it's too little, they'll be real lazy, idle poorly, load up, that kind of thing. Vacuum leaks will cause stuff like that too. I haven't done this on a carb'd car but on injected cars, I made an adapter out a piece of PVC pipe, with a cap on the end with a male quick connect fitting that would usually go into an air tool (it has a 1/4 NPT thread, drill & tap the cap, screw it in), which clamps to the throttle body. I'll then pressurize the engine to no more than 10-15 psi (measure off of a vacuum/boost gauge) and then use soapy water to check for leaks in the most likely places. Throttle shafts, hoses, fittings, trees, "tee's", etc. Fix those leaks and it'll run a LOT better. On a V8 if you check for vacuum leaks that way, you need a lot of volume so make sure the compressor is up to the challenge. A little compressor won't do it-but they work for a 4 cyl engine. Just be careful. Too much psi can bust stuff. Found that out on a 2.3 once. Pegged the 30 psi gauge and before I knew it hoses were breaking-among other things.
Stever89
5 Year Member
I've ran a Jr on the street many times on a 302. They can be good if the rest of your engine is built to run a lot of top end. My street intake of choice is the Wieand Stealth...IMO it can't be beat for a street intake. My 347 dynoed with one, and everyone at the shop said it would be the bottle neck...then they were all shocked at the numbers it put down.
As for the carb...it's a tad too much but it can work just fine. You may give up a bit of throttle response compared to a 600 and maybe a little bottom end.
As for the carb...it's a tad too much but it can work just fine. You may give up a bit of throttle response compared to a 600 and maybe a little bottom end.
Ok , Did the rpm mani. swap sat. kept the 670 street avenger but used a 1 " spacer so the air cleaner dont hit the dizzy , Went without any issues - couldnt believe it , runs a 100 % better as far as street manners go , now on to headlight replacements next then paint , thanks for the info everyone .
Stever89
5 Year Member
