Timing for 1971 M code 351C

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Author Topic: Timing for 1971 M code 351C  (Read 1234 times)

Offline BAC

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Timing for 1971 M code 351C
« on: February 14, 2019, 08:51:55 PM »
Hi, can someone point me in the right direction as far as initial and total timing for a '71 M code 351C with C6 auto?  Motor is stock as far as I know apart from a Comp cams 265DEH.

While I'm at it, is that an OK cam for a mild M code 351C or is there something better I should consider?  Planning on fitting long tube headers as well as 3.50:1 rear gears and 2500rpm stall.
Cheers,
Brian

Offline GLENN 70

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Re: Timing for 1971 M code 351C
« Reply #1 on: February 14, 2019, 10:21:42 PM »
With vac line blocked set Total timing at 34 deg @ 2500 rpm approx on 98 fuel . . Then check at idle to see what it's at ,10 deg would be nice ,buy who know how the dizzy has been set up .  Test drive and see if it pings under load ,then report back .  You can set the timing on a road test by advancing it till it pings under load ,then backing it back a bit till it stops pinging ,then check with a timing light and see were its at . What's the dizzy ? Points or electronic ? .  Set total timing 1st at 34 not setting the initial 1st . Report back please .

Offline BAC

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Re: Timing for 1971 M code 351C
« Reply #2 on: February 15, 2019, 12:07:30 AM »
Thanks Glenn, sounds pretty much the same deal as for a Windsor - just wasn't sure if a closed chamber Clevo would be different so thought I'd better ask.

Ignition is Pertronix as fas as I know but will check and report back after I have a crack at setting the timing tomorrow.
Cheers,
Brian

Offline 66 Stang

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Re: Timing for 1971 M code 351C
« Reply #3 on: February 15, 2019, 01:00:47 AM »
Bac, I have 351 M code with FMX, mine pings at anything more than 30 degrees total, and 16 degrees base, it improves a little with some octane booster.

Just remember the 351 M code was a high compression motor, from factory.

Offline BAC

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Re: Timing for 1971 M code 351C
« Reply #4 on: February 15, 2019, 09:21:51 AM »
I have 351 M code with FMX, mine pings at anything more than 30 degrees total, and 16 degrees base, it improves a little with some octane booster.

Is yours a '70 or '71 M code? 

I seem to remember reading they dropped the compression slightly for '71.  I think the '71 M code might be around 10.7:1 and the '70 more like 11.
« Last Edit: February 15, 2019, 09:23:48 AM by BAC »
Cheers,
Brian

Offline GLENN 70

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Re: Timing for 1971 M code 351C
« Reply #5 on: February 15, 2019, 09:52:22 AM »
BAC 10 and 34 should be ok on 98 but if it pings drop it back to 32 and if no good back to 30 Total ,but you need 10 deg at idle min .    66 stang  your  16 at idle might be a bit high unless you have a huge cam where 16 is needed . Your timing might be coming in to early ,it's a strang thing to set up these days . A friend of mine with a 408 Stroker has had plenty of timing problems and pinging . We tried many times to get it right with a timing light but no good . We ended up doing it by ear and road testing and ended up with 11 deg and 31 total at best then checking by timing light . He now has a msd unit that he can change the timing advance rate by his lap top and now it's as good as it can take . 1971 - 351/4v was 10.7 with stock cam .
« Last Edit: February 15, 2019, 09:53:53 AM by GLENN 70 »

Offline barnett468

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Re: Timing for 1971 M code 351C
« Reply #6 on: February 15, 2019, 10:49:46 AM »
Thanks Glenn, sounds pretty much the same deal as for a Windsor - just wasn't sure if a closed chamber Clevo would be different so thought I'd better ask.


ummm...wait a minute, exactly what do you mean by "closed chamber clevo"?

are they the orig 351 closed chamber heads or the 302 clevo heads?

are the pistons domed, flat, or dished?

what is your gear ratio now?

what temp does it run at?


that cam is decent for an all around (non high perf) cam.

.
« Last Edit: February 15, 2019, 11:18:17 AM by barnett468 »

Offline BAC

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Re: Timing for 1971 M code 351C
« Reply #7 on: February 15, 2019, 11:19:58 AM »
ummm...wait a minute, exactly what do you mean by "closed chamber clevo"?
Closed vs open chamber heads - maybe I should have said quench chamber?

are they the orig 351 heads or the 302 clevo heads?
Original 351 heads with the '4' cast in the corners

are the pistons domed, flat, or dished?
AFAIK they are stock so flat?

what is your gear ratio now?
3.00:1

what temp does it run at?
Around 190-195F but I haven't done the blanking plate/Windsor thermostat conversion yet

that cam is decent for an all around (non high perf) cam.
:thumb:
« Last Edit: February 15, 2019, 12:48:13 PM by BAC »
Cheers,
Brian

Offline BAC

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Re: Timing for 1971 M code 351C
« Reply #8 on: February 15, 2019, 12:53:55 PM »
Set total timing 1st at 34 not setting the initial 1st . Report back please.

Timing seems pretty much spot on with 34 total around 3000rpm and 12 at idle. 
Cheers,
Brian

Offline barnett468

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Re: Timing for 1971 M code 351C
« Reply #9 on: February 15, 2019, 01:34:52 PM »
ok, it will have less potential to ping if you install the 3.50 gears or get it to run a little cooler.

obviously, it can ping if it is too lean as well.

You have around 10.3 compression if it is standard bore.

.

« Last Edit: February 15, 2019, 04:13:11 PM by barnett468 »

Offline GLENN 70

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Re: Timing for 1971 M code 351C
« Reply #10 on: February 15, 2019, 06:14:11 PM »
Well 12 and 34 is spot on as long as it doesn't ping at that . 3.00 gears are lazy 😂. So are 4 v heads ,too big on a low revving 351 .

Offline BAC

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Re: Timing for 1971 M code 351C
« Reply #11 on: February 15, 2019, 06:50:32 PM »
Well 12 and 34 is spot on as long as it doesn't ping at that .
No pinging that I've detected.  Just going through everything and wanted to make sure the timing was set right.

3.00 gears are lazy 😂.
That's why the 3.50 ones are going on  :evilone:

So are 4 v heads ,too big on a low revving 351 .
Everybody says that, but having owned Mustangs with a 331 stroker, 351W and a 428 big block I don't reckon the 351C 4V suffers in comparison.  Certainly gives the impression it likes to rev more than any of those so see how we go with the shorter gears and a higher stall.
Cheers,
Brian

Offline barnett468

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Re: Timing for 1971 M code 351C
« Reply #12 on: February 16, 2019, 10:42:17 AM »
So are 4 v heads ,too big on a low revving 351 .

nope, but tuning them to the optimum level helps over the lame smog era settings. yes, a 2v head will provide a little better low end power, but it's not a huge difference. the problem with the people that say 4v heads are too big is that they either read that on the internet, or they way over cammed their engine and/or never tuned it properly after they installed the cam or put in a big cam with the lame 2.80 or 3.00 gears etc. it's nothing that you haven't come across a bazillion times by now with al the cars you looked at.

i still miss that green, turbo, big block camaro.



« Last Edit: February 16, 2019, 10:45:54 AM by barnett468 »

Offline barnett468

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Re: Timing for 1971 M code 351C
« Reply #13 on: February 16, 2019, 10:47:44 AM »
That's why the 3.50 ones are going on  :evilone:

it's gonna feel like it gained 75 hp with those gears and headers, and the high stall will simply help cause it to roast the bejesus out of the tires.

Offline GLENN 70

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Re: Timing for 1971 M code 351C
« Reply #14 on: February 16, 2019, 11:40:05 AM »
Barney banana I still mis the green supercharged big block Camaro 😂 . BAC 3.5 gears only with I min of 26 tall tyres thank you . A hi stall converter is what it needs .

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Re: Timing for 1971 M code 351C
« Reply #15 on: February 17, 2019, 05:35:22 PM »
Hi Brian, If you are looking to replace your thermostat a DAYCO DT66A is a CLEVLAND correct 82 deg C unit. I have been told that the tooling has been sold to Bob Mayer Racing ??? If you can't locate one you can drill 1/8" hole in 3/4"welch plug and tap into restrictor plate and use Windsor thermostat. This stops hot water circulating from heads back to pump and block and not going to radiator ( when thermostat opens all flow is through radiator). Also need to drill two 3/32" holes in skirt of thermostat.

Online pgold

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Re: Timing for 1971 M code 351C
« Reply #16 on: February 17, 2019, 06:46:11 PM »
Hi Brian, Correction the two holes in thermostat need to be 5/32" or 4.5 mm. See post started May 4 2013  Electric Fan Size. for  more info and photos.

Offline BAC

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Re: Timing for 1971 M code 351C
« Reply #17 on: February 17, 2019, 09:15:41 PM »
Hi Brian, Correction the two holes in thermostat need to be 5/32" or 4.5 mm. See post started May 4 2013  Electric Fan Size. for  more info and photos.

Hi Paul, I have just done the Cleveland cooling mod over the weekend.  Used the pre-made bypass blocker plate available from WCCC and a good quality Windsor style 180F thermostat. As for the hole size in the skirt, I've seen everything from 3mm to 5mm recommended so I split the difference and went for 4mm.   Have to say it seems to have made bugger all difference so it looks like my Clevo thermostat was operating properly in the first place.  Have converted to a thermo fan setup using the unit out of a BF Falcon which is an excellent fit on a '71. 

One thing I have noticed since having the digital temp readout from the fan controller is the gauge on my car reads half way at about 78C, two thirds at 82C and almost full scale at 90C.  This seems to be too high IMHO: as I understand it the engine should be operating around 85C with a 180F thermostat which is a little over  two thirds on my gauge.

Need to figure out if this is normal for a '71 or if either my gauge or sender is on the fritz...
Cheers,
Brian

Offline GLENN 70

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Re: Timing for 1971 M code 351C
« Reply #18 on: February 17, 2019, 10:26:33 PM »
BAC ,you could sneak it up to 35 deg or 36 even and see how it goes . Every engine is different and who knows what changers it's had since 1971 . I would be looking into a small hi stall converter 2500 rpm will do .

Offline BAC

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Re: Timing for 1971 M code 351C
« Reply #19 on: February 17, 2019, 11:40:16 PM »
you could sneak it up to 35 deg or 36 even and see how it goes . Every engine is different and who knows what changers it's had since 1971 . I would be looking into a small hi stall converter 2500 rpm will do.

Have a 2500 rpm stall converter waiting to go in after I get the 3:50 gears done.  Would you recommend a trans cooler for the C6 with the higher stall or should it be OK without?  It's only a cruising car with the occasional hard launch in the traffic light grand prix.

Take your point about them all being different.  It runs at about 190F now which I didn't think was too high but the temp gauge in the car thinks that's worthy of 3/4 or more of full scale.
« Last Edit: February 17, 2019, 11:42:22 PM by BAC »
Cheers,
Brian

Offline barnett468

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Re: Timing for 1971 M code 351C
« Reply #20 on: February 18, 2019, 12:49:02 AM »
The only sender that will read accurately is a factory ford one from the 70"s.

Offline barnett468

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Re: Timing for 1971 M code 351C
« Reply #21 on: February 18, 2019, 12:51:42 AM »
You do not need a trans cooler in your particular case  however, a larger capacity aluminum trans pan with a drain bolt on it is a nice upgrade if someone currently makes one for it.
« Last Edit: February 19, 2019, 03:07:34 AM by barnett468 »

Offline 66 Stang

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Re: Timing for 1971 M code 351C
« Reply #22 on: February 18, 2019, 01:28:35 PM »
Is yours a '70 or '71 M code? 

I seem to remember reading they dropped the compression slightly for '71.  I think the '71 M code might be around 10.7:1 and the '70 more like 11.

Mine is 1970 351 M Code.

Offline 66 Stang

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Re: Timing for 1971 M code 351C
« Reply #23 on: February 18, 2019, 01:32:17 PM »
BAC 10 and 34 should be ok on 98 but if it pings drop it back to 32 and if no good back to 30 Total ,but you need 10 deg at idle min .    66 stang  your  16 at idle might be a bit high unless you have a huge cam where 16 is needed . Your timing might be coming in to early ,it's a strang thing to set up these days . A friend of mine with a 408 Stroker has had plenty of timing problems and pinging . We tried many times to get it right with a timing light but no good . We ended up doing it by ear and road testing and ended up with 11 deg and 31 total at best then checking by timing light . He now has a msd unit that he can change the timing advance rate by his lap top and now it's as good as it can take . 1971 - 351/4v was 10.7 with stock cam .

Unfortunately yes it has a big cam, trust me when I say I enjoy the comfort of a stock motor, a cranky motor is like a cranky wife, hard work, who needs it.

Offline BAC

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Re: Timing for 1971 M code 351C
« Reply #24 on: February 18, 2019, 01:58:20 PM »
Unfortunately yes it has a big cam, trust me when I say I enjoy the comfort of a stock motor, a cranky motor is like a cranky wife, hard work, who needs it.

Mine has slightly lower compression than yours being a '71 and only has a mild cam.  Seems to be quite happy with 34 deg total timing as Glenn recommended.
Cheers,
Brian

 

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