What to do to 351c 4v heads?

[barnett468]

What are your rear gears?

I'm guessing the stock gear 3:23???

ok, then if you want faster acceleration and don't drive long distances at 70 mph, i would install numerically higher gears in your specific case. the best ratio for you just needs to be determined. then of course a different cam etc, but again, just a cam alone won't change much. if you install a smaller cam, it will have more low end power and less rpm but it won't make it accelerate much faster.

here is an rpm vs mph gear ratio calculator you can play with.

http://www.wallaceracing.com/gear-speed.php

 

[72HCODE]

something overlooked if these are open chamber V4 heads throw them in the garbage and get closed chamber heads.

 

[Jeff73Mach1]

something overlooked if these are open chamber V4 heads throw them in the garbage and get closed chamber heads.

If this is your point of view, can I at least ask that you throw them in MY garbage?  OC heads get a bad rep, but with pop ups, they work great and there is less intake valve shrouding-just because you don't like them is no reason to think they are garbage.

 

[Hemikiller]

something overlooked if these are open chamber V4 heads throw them in the garbage and get closed chamber heads.

If this is your point of view, can I at least ask that you throw them in MY garbage?  OC heads get a bad rep, but with pop ups, they work great and there is less intake valve shrouding-just because you don't like them is no reason to think they are garbage.

Agreed, nothing wrong with them, just require the correct pistons.

 

[scgamecock]

Is there a way to tell which heads I have with the engine in the car??  As long as the numbers match like the PO said then it should be a 72 351cj.

Also, Did the heads not have the correct pistons stock???

 

[Don C]

The purpose of the open chambers was to reduce compression in an effort to meet the new emissions requirements. For '72 the pistons were still flat top.

'72 4V heads had the large ports and valves with an open chamber. The chamber size is approximately 75.4 cc, compared to approximately 62.8 cc for closed chamber heads.

Thinking about stroking your engine? CJ (Q code) heads with flat top pistons should give suitable static and dynamic (with proper camshaft) compression ratios for pump gas.

 

[scgamecock]

I am running AFD SP4V Heads and they are very comparable to the CHI 3v heads.  I love them and they make monster power.  

https://www.afdheads.com/collections/cleveland-heads/products/afd-sp4v-3v-bare-alloy-cleveland-cylinder-heads?variant=34022411022

Looks like these are almost $1700 per head.

No that's a set of 2.

Thinking about stroking your engine? 

No not stroking it.  I am trying not to go overboard on the motor.  Yall are getting close to convincing me to just use the iron heads.  I am just wondering if I would still be better off getting the AFD heads if they are $1700 per set like Kevin says.

 

[Don C]

Make sure that's not for a bare set, that you will have to add valves and valve springs to, and have the valves lapped.

 

[scgamecock]

looks like an assembled set but i will check.  i am surprised at the price when all the others are over a $1k a piece.  

https://www.afdheads.com/collections/cleveland-heads/products/afd-sp4v-3v-bare-alloy-cleveland-cylinder-heads?variant=34022411022

 

[tony-muscle]

Does any one knows of where we can find dyno runs from similarly built engines with different heads, such as 4V OC and CC, 2V, AFDs, CHIs, Elderbrock?

I can find flow bench data but it will be interesting to see full dyno data.

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[jpaz]

I just looked at that link, and those heads are 1,695.00 bare and the complete sets are 2,700 ish? Maybe I read it wrong, not really sure what ones you were looking at. Plus it says the 3v version is sold out. Just saying

 

[barnett468]

Also, Did the heads not have the correct pistons stock???

All engines had the correct heads and pistons for the mfg's intended use, but the stock parts are obviously not always the best choice for a performance build. There were 2 types of combustion chamber design used on the cleveland heads and the heads on some of the other mfg's engines. One is referred to as a "closed chamber", which in general is considered by most people to be best for reducing the potential for engine knock/pinging etc when the proper pistons and proper squish/quench clearance is used, although there are some that feel the other design on a cleveland, which is referred to as an "open chamber", can provide the same potential to reduce engine knock/pinging. The design of a cleveland open chamber is significantly different than the open chamber design on any other mfg's head and is also referred to as a "poly angle" design.

 

[Don C]

Does any one knows of where we can find dyno runs from similarly built engines with different heads, such as 4V OC and CC, 2V, AFDs, CHIs, Elderbrock?

I can find flow bench data but it will be interesting to see full dyno data.

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Dan Jones ran some dynos in the old 351C forum:

http://351c.net/board/index.php?/forum/152-351c-dyno-parts-testing-project/

There are some other dyno runs here:

http://www.the351cforum.com/viewforum.php?f=4

 

[turtle5353]

I just looked at that link, and those heads are 1,695.00 bare and the complete sets are 2,700 ish? Maybe I read it wrong, not really sure what ones you were looking at. Plus it says the 3v version is sold out. Just saying

I bought the same set and they are $1695 for a pair bare. Add in whatever you want for valve train on top of that. For decent stuff you would have around another $1,000-1,500 depending what brand valves and springs you choose. I love them. Work great.

 

[scgamecock]

Its driving me nutts not knowing what is in the motor. I know it has a mild cam due to the lope but outside of that I have no idea who built the motor and what was used. The plan right now is to get the car road worthy, do the body work and then pull the motor next fall. If I can wait that long!!!!!

 

[Don C]

Lope doesn't necessarily mean the camshaft, it could also be a burned valve or valve recession. Have you run a compression test on all cylinders?

 

[scgamecock]

Lope doesn't necessarily mean the camshaft, it could also be a burned valve or valve recession. Have you run a compression test on all cylinders?

Way to burst my bubble Don!!! lollerz

No have not ran a compression check.  What should the cylinder pressure be?  You just put a guage with a spark plug adapter on it and disable the ignition and spin the motor over right???

 

[tony-muscle]

Its driving me nutts not knowing what is in the motor. I know it has a mild cam due to the lope but outside of that I have no idea who built the motor and what was used. The plan right now is to get the car road worthy, do the body work and then pull the motor next fall. If I can wait that long!!!!!

That drove me crazy as well.
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[Don C]

I just happen to have a spreadsheet that should help you that is attached to this thread:

https://www.7173mustangs.com/thread-compression-altitude-calculations?pid=115411#pid115411

As you will see, there are several variables that influence the compression readings.

Remove all of the spark plugs, and it's a good idea to at least remove or ground the high voltage lead from your coil, or the wire off the positive terminal (don't let it short out). If you have an aftermarket electronic ignition follow their instructions, some are sensitive to having high voltage bouncing around from a coil.

 

[73pony]

looks like an assembled set but i will check.  i am surprised at the price when all the others are over a $1k a piece.  

https://www.afdheads.com/collections/cleveland-heads/products/afd-sp4v-3v-bare-alloy-cleveland-cylinder-heads?variant=34022411022

That price is bare heads.