351C performance question - Please chime in

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wawazat
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Location: Beverly Hills, MI

Re: 351C performance question - Please chime in

#11

Post by wawazat » 09 Oct 2018, 19:29

My 351 C is pretty sluggish off the line. I'm running a 2.75 open final drive behind the three speed-stock from OEM 351W 2V stock motor-which I believe is the root cause in my case. Pulls hard when revs come up. The previous owner had the engine rebuilt. It came with 4V heads, an unknown cam, Edelbrock dual plane 4V intake and carb, and a Mallory distributor and MSD coil. The carb failed and was replaced with a FiTech system. The ignition was replaced with a used MSD 6AL and non-vacuum advance distributor (great price and I will set up the FiTech to control timing) with a new MSD coil. Borla 2.25" dual exhaust and Doug's headers as system on the car was janky, rusty and fell apart. One exhaust manifold was cracked. I installed new plugs last spring along with plug wires, new MSD cap and rotor. It idles well and pulls cleanly but cannot rev quickly while driving. I've been taking fuel out (playing with AFR and accel pump) which has helped.
I've got a 3.70 center and TKO-600 to go in this winter. I'm looking at clutches and lighter flywheels now. I think that those changes should help her a bit.
1969 Cougar convertible restomod

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bsbeck
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Re: 351C performance question - Please chime in

#12

Post by bsbeck » 10 Oct 2018, 07:28

I'm still chasing my "bog". I just finished replacing the power brake booster (which had a very bad vacuum leak). I also went ahead with a new master cylinder. I'll be bumping the timing up again today, since the vacuum leak is fixed and then I'll report back.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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bsbeck
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Re: 351C performance question - Please chime in

#13

Post by bsbeck » 10 Oct 2018, 07:33

Canted 393, I never did report back on tire size. Measuring across the back tire, it's like 26 1/2 inches. The back tires are 275/60s on a 15 inch rim. Fronts are 235/60 on 15 inch. These were in place when I got the car and they are very beefy. I've noticed they scrub in the back wheel wells when I go over a big bump.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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canted 393
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Location: New Hampton IA

Re: 351C performance question - Please chime in

#14

Post by canted 393 » 10 Oct 2018, 17:29

275/60 come out to 28 inch so if you go back to 14 inch tire you could pick up 200 rpms at 60 so it might help . That is unless you do a lot of 4 lane driving, keep bumping up your timing and see if that helps.

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bsbeck
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Re: 351C performance question - Please chime in

#15

Post by bsbeck » 10 Oct 2018, 20:30

Canted 393, New brake booster and master cylinder in place but still got a vacuum leak under the dash. I chased it down to a vacuum hose that I don't know what it is. I posted it on another topic here on the forum. Help me out if you can please.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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bsbeck
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Re: 351C performance question - Please chime in

#16

Post by bsbeck » Yesterday, 17:37

After new brake booster/master cylinder, fixing the vacuum leak under the dash, tuning the carb, adjust the timing and some fresh 93 octane and a bottle of 108 octane booster.....I'm smoking the tires now. She's running good. Thanks everyone for the advice.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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Cougars_R_Grr8
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Location: Pahrump, NV

Re: 351C performance question - Please chime in

#17

Post by Cougars_R_Grr8 » Today, 00:17

Glad to hear it. Now go out there and represent.
'68 Standard Cougar - 302 4v J Code 4 spd (1 of 536) *SOLD*
'73 F250 XLT Ranger - 390 *Also SOLD*
'63 F100 Stepside - *NEW PROJECT*
'14 Camaro SS vert
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