I need 915 head advice

[LR1970]

Hi, I am putting together a mild street driven 440 and will use a set of 915 heads. The compression will be around 9.5, hp exhaust manifolds, Edelbrock RPM intake, 750 Edelbrock carb, Comp XE268 cam 224/230 dur 4.77/4.80 lift, 727 with 2000 stall, 3.23 rear gears in a 1964 Dodge Polara. Car will be a daily drive and driven a bit hard around the back roads.

I will put in hardened exhaust seats and 1.74 exhaust valves. Is it worth it to do 3/5 angle valve cut, gasket match the intake ports, basic cleanup/porting? Machine shop work is very expensive now and if this kind of head work will not benefit me unless at high rpms there is no point, I guess.

Thank you

Leigh.

 

[furious70]

How much extra will it cost you there?

 

[Cranky]

Hi, I am putting together a mild street driven 440 and will use a set of 915 heads. The compression will be around 9.5, hp exhaust manifolds, Edelbrock RPM intake, 750 Edelbrock carb, Comp XE268 cam 224/230 dur 4.77/4.80 lift, 727 with 2000 stall, 3.23 rear gears in a 1964 Dodge Polara. Car will be a daily drive and driven a bit hard around the back roads.

I will put in hardened exhaust seats and 1.74 exhaust valves. Is it worth it to do 3/5 angle valve cut, gasket match the intake ports, basic cleanup/porting? Machine shop work is very expensive now and if this kind of head work will not benefit me unless at high rpms there is no point, I guess.

Thank you

Leigh.

Best place to spend money on factory heads is the valve pockets!!! The factory pockets suck and then the multi angle valve seats will work better for you. Don't know if you have leaded gas there but if you do, don't bother installing hardened seats....

 

[Runcharger]

Pocket port and good valve job. I would add 2.14 and 1.81 valves. However it may be cheaper to just spring for a set of aluminum heads at that point.

 

[R413]

Why do large valves with that tiny camshaft and 3.23 gearing? It won't gain anything and may slow it down, or hurt throttle response and drivability.

 

[451Mopar]

Unless you need to use the original iron heads, I would just get some aluminum heads, Maybe the 440 Source Stealth? They have the straight stock like spark plug locations.
I don't know how manifolds fit with the Edelbrock angled plug RPM heads?
With the Iron heads, the bowl area above the valves is what needs enlarged more than port matching. You might need to do some chamber work and/or milling to equalize the chamber volumes.

 

[#41]

You can save bucks pocket porting / blending runners yourself with a carbide bit in a drill. It takes a day to do a set. I do it on every head that goes on a car for 40 years. There are a few vids on Youtube you can watch for tips.

 

[69Bee]

I had about the same cam, and when I put 2.14"/1.81" valves, it really woke up my 426W. Use the bigger valves with hardened exhaust seats, open up the valve pocket (should be a no brainer as that is what I do when I install larger valves, gasket match the intake manifold/head, and any valve job should be at least 3 angles. The normal machine used today uses carbide seat cutters which have 3 angles by default, usually 30/45/60. I don't think the additional 2 angles (15/75-80) would be beneficial for your desired performance level. I would also recommend new valve guides and surface the heads!

 

[451Mopar]

With porting the iron heads make sure to have good PPE. The dust gets everywhere, and the cuttings are sharp.
Wear a mask, gloves, eye protection. A face shield and shop apron also helps.
I don't think the castings have cracking issues, but best to check them before investing alot of time porting them.

 

[1 Wild R/T]

If there were HP heads for you application I might pass.. But the fact you said you'll be adding 1.74 exhaust valves points to them being std 915 heads with the 1.60 exhaust valves.... Those castings need to be opened up for the valves to do any good... First set I worked on i was shocked how much material needed to come out....

 

[R413]

I had about the same cam, and when I put 2.14"/1.81" valves, it really woke up my 426W. Use the bigger valves with hardened exhaust seats, open up the valve pocket

Maybe your original 426W heads had the valves sunk and multiple valve jobs done in the past. He is putting in hard seats and 1.74 valve so it will be all new and valves up high to work like they should.

 

[69Bee]

Maybe your original 426W heads had the valves sunk and multiple valve jobs done in the past. He is putting in hard seats and 1.74 valve so it will be all new and valves up high to work like they should.

I used 906 heads. And, ALL pre-'71 heads need hardened exhaust seats as they were not hardened....

 

[Dave6T4]

I have about the same set-up in my '64 Polara. My cam is the old Mopar Performance piece that came in 440 and 383 HP engines; 276/284 duration, .480 lift. I used the "452" heads with hardened valve seats, and blocked the heat riser ports. I have an Edelbrock 750 cfm. carb on an Edelbrock Performer intake, with one step leaner metering rods on one step softer (natural colour) springs, and one step richer secondary jets. Factory H.P. exhaust manifolds are used with 2 1/2" / 2 1/4" pipes, and Hemi mufflers.The 727 has a mild shift kit in it, and the 8 3/4" rear end has 3.23 gears with Suregrip. I also have a '67 Coronet R/T set up the same way.
I find this is a good combination for no-fuss cruising, and some performance driving. In my opinion, I don't think the extra expense of aluminum heads or extensive (expensive) head work would improve your driving experience. If racing your car a lot, you would see improved E.T.'s with cylinder head modifications, but in cruising, car shows, etc., I doubt if you could feel any difference. It comes down to your choice of primary driving use.

 

[khryslerkid]

If using cast iron manifolds instead of headers is it really necessary to go through any head modifications?

 

[LR1970]

Thanks for everyone responding. I have other heads I could use. I bought a bulk lot of parts from a retired guy.
Would one of these others be a better head for this engine and my intended driving? No leaded fuel here.

The heads I have are,

stock 915 that need reconditioning
stock 906 that need reconditioning
906 unported etc reconditioned with new hardened exhaust sets and 2.14/1.81 valves
stock 452 heads that need reconditioning
452 heads that look to mildly ported with 2.14/1.81 valves, will need to be inspected, maybe reconditioned

I was thinking to use the reconditioned 906 heads with the bigger valves (no money to spend there) but was concerned the larger valves would not suit this engine and the type of driving I intend doing.

 

[Dave6T4]

If you already have the heads, use your reconditioned "906" s. Know that using a "906" or "452" will drop your compression pretty well a full point over using "915" s. Like 9.0, compared to 10.0. I like the the "452" for this reason, so my cars run on unleaded 91 octane gasoline (petrol). LOL
With the bigger valves, you could possibly move up to a cam with a little more duration and lift.

 

[BSB67]

I personally would take a rebuildable set of 915 heads w/ 1.6 exhaust valve over a trunk full of ready to run 906 heads.

I replaced a good set of rebuilt 915 heads with a ported set of 915s (260 cfm) on an exhaust manifold car with a .455” lift cam and they put 40 hp in the motor. 2.08” intake valve size.

A 2.14 valve will help every motor. It’s not cam specific. The low lift numbers are what improve.

I get it. Budget matters. But a properly built 440 pump gas quench motor with ported 915s a small cam and exhaust manifolds can make 475 hp and run well into the mid 12s with 3.23s, stock converter and street tires.