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Whats the difference?? Q code/4v.

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Anderslober View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Anderslober Quote  Post ReplyReply Direct Link To This Post Topic: Whats the difference?? Q code/4v.
    Posted: 30-September-2022 at 3:52AM
Ok guys….before I run out and get a new (stock) cam…….please see below pictures.
72 Q-code engine.
The 72 Ford manual has different numbers…..and doesnt use the term ‘Q-code’.
The other numbers are ‘official’ engine numbers from Pantera forum. 
I need to know IF a Melling SYB29 will fit stock springs and pushrods………

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Anderslober Quote  Post ReplyReply Direct Link To This Post Posted: 30-September-2022 at 3:52AM
Pantera Q-code numbers👇

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 30-September-2022 at 11:38AM
Q-code refers to the 5th character of the car's VIN number, this character changed for various model year 4V engines. in 1970 and the 1st 1/2 of 1971 the 4V engine was an M code, then from 1971 1/2 through 1974 the 4V engine was a Q code. the biggest difference between the 2 was the M code came with closed chamber (high compression) heads and the Q code came with open chamber (low compression) heads.

check this out


me personally i'd put a Comp Cams 268H in it. it closes the intake at 60* ABDC improving the DCR, near stock lift and perfectly compatible with stock accessories and rear gear

https://www.compcams.com/high-energy-218-218-hydraulic-flat-cam-for-ford-351c-351m-400m.html
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Anderslober View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Anderslober Quote  Post ReplyReply Direct Link To This Post Posted: 30-September-2022 at 12:57PM
Nice cam shaft the 268h. Isnt 494 lift to much for stock spring/pushrod setup?
I mostly trust the numbers from the 72 Ford manual.
Why is there a differnce? Qcode Pantera and 4v Ford manual numbers…..that is my real question…….
Shouldntbthe numbers be the same?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 30-September-2022 at 4:31PM
the screenshot of the manual shows Theoretical Valve Lift to be .427"  intake  / .453" exhaust,

is that a 1970 or 1971 manual? Q code will not appear in a manual, it's a specific model year designation for the 351C-4V engine that Ford used in the VIN (vehicle identification number). look at you VIN and see if the 5th character isn't 'Q' ? 1970 - 1971 1/2 M codes, and 1971 1/2 - 1972 Q codes are all 351C-4V engines but there are some differences such as the camshafts

the valve lift for 1972 should be .481" / .490", the difference between that and .494" is on the order of minuscule. the thickness of a sheet of paper. the stock springs are safe to run the '505' cam which has .505" lift and safety clearance for valve spring coil bind so yes the Comp 268H is good to work with the stock springs and pushrods

IDK if i've posted this chart George put together, it has a ton of info comparing the various 351C-4V engines. FWIW all the hydraulic lifter engines use the same 8.4x" length pushrods, the solid lifter Boss engine used a slightly longer 8.5x" pushrod but that is because of the different lifter, different valves, and mechanical lash


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Anderslober View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Anderslober Quote  Post ReplyReply Direct Link To This Post Posted: 30-September-2022 at 7:21PM
The manual is 1972 Ford shop manual. My car is a Q-code car. 351c-4v/4spd.
This is exactly my question………why the difference? I cant find any of those ‘481/490’ numbers anywhere. I of course have the numbers in the official 1972 Ford shop manual to go by. Where do you find the other numbers? And what correlates 481/490 to 1972 351c-4v engine? I need to see the official Ford numbers…….where?
I have uploaded my marti-report to the forum multiple times.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 72FordGTS Quote  Post ReplyReply Direct Link To This Post Posted: 01-October-2022 at 1:38AM
Originally posted by Anderslober Anderslober wrote:

The manual is 1972 Ford shop manual. My car is a Q-code car. 351c-4v/4spd.
This is exactly my question………why the difference? I cant find any of those ‘481/490’ numbers anywhere. I of course have the numbers in the official 1972 Ford shop manual to go by. Where do you find the other numbers? And what correlates 481/490 to 1972 351c-4v engine? I need to see the official Ford numbers…….where?
I have uploaded my marti-report to the forum multiple times.


To answer your question, there is no difference between a 351C-4V, 351-CJ or 351 "Q-Code" in 1972 - it's all the same engine.  Technically the Q-code or CJ is the 1972 version of the 351C-4V.  Ford never used the "Q-code" name, this is just a name enthusiasts applied based on the VIN.  There were only a four 4V versions of the 351C and they were as follows:

  • 1970-1971 - 351C-4V (VIN code M) used in 1970-71 Torino and Mustang
  • 1971 Boss 351 (VIN code R) used in 1971 Mustang BOSS 351 only
  • Late 1971-1974 351C-4V "CJ" (VIN code Q) - used in late 1971-73 Mustang and 1972-1974 Torino
  • 1972 351 HO (VIN code R) used in 1972 Mustang only

I have the same 1972 shop manual with the same specs listed.  I believe that it is an error in the book as it lists the cam specs for the earlier 351C-4V (M-Code) used in 1970-71 (see George's chart).  I know you want to trust the factory literature, but George Pence is the penultimate authority on 351C engines, so his stuff is as good or better than the factory info. 

Rockatansky is our expert here, and his knowledge isn't far of George's.  IMO, I'd follow Rock's recommendation of a 268H cam or Elgin E-953-P cam.  Or I'd do George's custom grind for the CJ engine.  It seems like you are over thinking this....

Vince

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Post Options Post Options   Thanks (0) Thanks(0)   Quote texanrebel Quote  Post ReplyReply Direct Link To This Post Posted: 01-October-2022 at 4:12AM
I worship at the alter of Rock & Vince Wink 
Just kidding, I trust the info from George Pence via this forum...this is my #1 source
1972 Montego GT
1977 Mercury Monarch
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Anderslober Quote  Post ReplyReply Direct Link To This Post Posted: 01-October-2022 at 4:27AM
Yes, yes….totally! The advice and knowledge here on the forum is astounding. I was just wondering WHERE the numbers came from, because I couldnt find them. I could only find the numbers in the 72 manual……and then I got ‘confused’ with all the other numbers that were comin’ in, and they couldnt be found in the manual.
I am gonna go all out on the 268h cam…..and hope it works in my stock setup. I am not a ‘performance-dude’…Just good stock/OE performance for me.
Just one thing, cam MUST be USA made!…….no China/etc/etc for me. I have been unlucky a couple of times…
Yes…’over-thinking’….hehe…but, if the 72 manual is in ‘error’…then good that I over-thought!🤠👍🍹


Edited by Anderslober - 01-October-2022 at 4:32AM
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 01-October-2022 at 5:55AM
i thought maybe the manual had a misprint also, it happens. i think the camshaft lift info is carried over from the 1970-71.5 model year M code engine. i just checked my copy of the 1972 Engine manual and yup it's the same as yours, shows 1970-71.5 cam lift numbers. 1st time i think i've heard of finding a misprint in the factory manuals, you have to know you're doing your homework when you find a mistake in reference material!

i believe George's chart to be correct?

i ran the 268H in my 1st Cleveland powered Gran Torino in the early 1980's. that engine began life as a 2V mated to an FMX auto transmission with 2.73 rear gears. the 268H was a great match to such a 'low performance' combo. then i picked up another 268H a few ago and ran it for a while in another 2V headed engine, i still have it around here somewhere and will run it again if i ever get off my Censored
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 72FordGTS Quote  Post ReplyReply Direct Link To This Post Posted: 01-October-2022 at 6:09AM
FWIW, I checked my old Peterson's Repair manuals which lists all the cam specs for cars from the 70s. It shows the 1972-73 351-4V (CJ) engines with .480/.488 lift and the 1974 as .480/.490 lift.  It shows the 1971 351-4V as .427/.453. 

So, it seems Ford didn't update the manual correctly.  I'd be curious if the 1973 edition was corrected.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Anderslober Quote  Post ReplyReply Direct Link To This Post Posted: 05-October-2022 at 2:42AM
Has anyone checked the cam numbers in the 73 manual?
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