Reconditioned 452 heads. What upgrades should I consider?

[Zymurgy]

Goldie I suspect has burnt valves. I am going to confirm this tomorrow. I have never performed any internal work on the engine, except change the timing belt and cam 10 years ago.

I am not looking for anything which will change her drivability. She has a 383, factory 4 barrel, cast exhaust manifold. No plans to change any of those components. Single exhaust but a dual exhaust is planned.

Here is my base plan, which was suggested to me by a very reputable mechanic years ago. 452 heads and hard exhaust seats these are the only comments he made at the time.

This is a new to me so I would appreciate any input and what might give me the most bang for the buck.

 

[CBODY67]

Are there NO good machine shops near you? The reason a valve "burns" is that that particular exhaust guide is worn and lets the valve wobble as it seats, sometimes not seating squarely when it closes, which ends up causing a hot spot on the edge of the exhaust valve. With time, it can cause a small flat area on the edge of the valve, which compromises sealing capabilities. From my experiences, it is usually #5 or #7 on our 383s, fwiw.

Any machine shop should be able to do the bronze-helicoil guides. Then re-touch the valve seats and possibly de-burr the ports. That, plus a good machine-cut surface should be all that's needed. Adding hard seats is good to do, too.

In earlier times, I might have opted for the factory double-springs, or springs w/dampeners, but in reality, you don't need them if all you do is normal driving below possibly 4000rpm, mostly. Your choice there. IF the engine already has them, part of the normal valve job is checking the pressure and adding some thin shims as needed, to get things back up to spec.

Many people perceive they need the 1.81" exhaust valves, but just how much more power will they provide at 5000spm than the 1.74" exhaust valves? The might be "the biggest possible", but is that little bit of additional flow really worth the price on a street motor?

Of course, a good set of gaskets and valve seals completes everything.

IF you order the Indy heads, DO talk to a sales rep and inquire about if the heads are ready to use, "out of the box", rather than needing to be disassembled and cleaned, first. Just to make sure in case there might be any issues with their shop not cleaning things well before they are boxed for sale. Plus inquire about warranty coverage and procedures, just in case.

Enjoy!
CBODY67

 

[Zymurgy]

Are there NO good machine shops near you? The reason a valve "burns" is that that particular exhaust guide is worn and lets the valve wobble as it seats, sometimes not seating squarely when it closes, which ends up causing a hot spot on the edge of the exhaust valve. With time, it can cause a small flat area on the edge of the valve, which compromises sealing capabilities. From my experiences, it is usually #5 or #7 on our 383s, fwiw.

Any machine shop should be able to do the bronze-helicoil guides. Then re-touch the valve seats and possibly de-burr the ports. That, plus a good machine-cut surface should be all that's needed. Adding hard seats is good to do, too.

In earlier times, I might have opted for the factory double-springs, or springs w/dampeners, but in reality, you don't need them if all you do is normal driving below possibly 4000rpm, mostly. Your choice there. IF the engine already has them, part of the normal valve job is checking the pressure and adding some thin shims as needed, to get things back up to spec.

Many people perceive they need the 1.81" exhaust valves, but just how much more power will they provide at 5000spm than the 1.74" exhaust valves? The might be "the biggest possible", but is that little bit of additional flow really worth the price on a street motor?

Of course, a good set of gaskets and valve seals completes everything.

IF you order the Indy heads, DO talk to a sales rep and inquire about if the heads are ready to use, "out of the box", rather than needing to be disassembled and cleaned, first. Just to make sure in case there might be any issues with their shop not cleaning things well before they are boxed for sale. Plus inquire about warranty coverage and procedures, just in case.

Enjoy!
CBODY67

Thanks I really appreciate your input. We have been losing our good machine shops around me. I was referred to the Indy heads for warranty and reliability, and he recommended the 452 heads.

I will look into your recommendation of reconditioning my existing set up. I have a buddy who should be able to refer someone, but he has had some issues recently. I am also hoping I don't lose out on my whole summer driving season. It was acceptable driving last fall or I would have worked on this over the winter.

 

[FURYGT]

A 1966 383 including 383-4bbl cars had 516 heads, which had 1.60 exhaust valves. Weren’t the 516 and 915 heads closed chamber vs 906, 452 & later heads open chamber and therefore they use different pistons? It’s been a longtime since I thought about the head differences.

I think the best course of action is to have a machine shop redo your heads.

 

[413]

What year is the engine? What heads are on it now. I wouldn’t go from closed chamber heads to the open chamber 452’s.

find a machine shop to repair your heads. You don’t want bigger valves in a stock driver 383 car. And I would keep the 1.60 exhaust valves, hood throttle response and bottom end torque for driveability. Bigger valves hurt bottom end and only show you a gain at higher RPM and foot down on the throttle. Nothing for cruising down the freeway 60-70mph.

and what are the symptoms and what diagnosis have you done to say you have burnt valves?

cold and hot compression test
vacuum gauge

 

[Zymurgy]

What year is the engine? What heads are on it now. I wouldn’t go from closed chamber heads to the open chamber 452’s.

find a machine shop to repair your heads. You don’t want bigger valves in a stock driver 383 car. And I would keep the 1.60 exhaust valves, hood throttle response and bottom end torque for driveability. Bigger valves hurt bottom end and only show you a gain at higher RPM and foot down on the throttle. Nothing for cruising down the freeway 60-70mph.

and what are the symptoms and what diagnosis have you done to say you have burnt valves?

cold and hot compression test
vacuum gauge

Thanks.
It is a 1966 it is all the stock set up and original heads. Symptoms it has had a slight miss for years,no change with 2 new set of ignition wires. Now it is missing really bad. My vacuum gauge readings are fine. I am going to do the compression tests tomorrow and go from there.

 

[413]

Is the vacuum gauge steady or fluctuating? How much vacuum does it have.

many things can cause a miss. So keep it simple at first. Valve job is not simple. Is the choke set up properly, or does it blow black smoke and load up the plugs. That can cause a miss.

Does it have a vacuum leak, causing a lean miss? Carb idle circuit plugged? Do you have factory AC or power brakes? PCV problem? Remove all vacuum lines and plug the connectors on the engine and see of the miss is gone.

so much to check and do before condemning the valves.

I have spares and like to swap in another part to see if it fixes it. Carb, distributor, ignition box, etc.

 

[Zymurgy]

Is the vacuum gauge steady or fluctuating? How much vacuum does it have.

many things can cause a miss. So keep it simple at first. Valve job is not simple. Is the choke set up properly, or does it blow black smoke and load up the plugs. That can cause a miss.

Does it have a vacuum leak, causing a lean miss? Carb idle circuit plugged? Do you have factory AC or power brakes? PCV problem? Remove all vacuum lines and plug the connectors on the engine and see of the miss is gone.

so much to check and do before condemning the valves.

I have spares and like to swap in another part to see if it fixes it. Carb, distributor, ignition box, etc.

Thanks I need to check all these things again. It would be nice to find a simpler less expensive solution. My friend who is helping me is an ex-mopar mechanic and is very knowledgeable. I am getting together my check list for tomorrow thanks!

 

[CBODY67]

When our '66 Newport 383 2bbl got a burnt valve, it still drove reasonably well, but was down on power going up hills and such. Had a rough idle too, as it was dropping one cyl. I could two-foot it and not be quite as noticeable.

A quick check for a burnt valve is to take a red shop towel, then with the engine idling, go to the back and loosely drape the towel over the end of the exhaust pipe. If everything is normal, the shop towel will "blow in the breeze", but if there is a burnt valve, that breeze will be interrupted by a negative pressure pulse which will momentarily suck the towel into the tail pipe. It happens very quickly and you have to watch closely for it, but it happens.

That old "shade tree trick" will verify the burnt valve. Then you can remove a spark plug wire to see when two cyls are not hitting. That identifies the particular weak cyl. An analog way of doing a "cylinder balance test", which can be done before draping the shop towel, too. KEY thing, be insulated from the car body when pulling and reinstalling the plug boots, or turn the engine off between times.

The option to do just the one head is fine, but the other guides and such will be worn, too, just not causing problems.

The larger-chamber 452s, which also came with induction hardened valve seats, can lower the compression ratio a bit so gasoline can be easier to find. On my '67 Newport 383 4bbl, the 906s resulted in a trace rattle at WOT, rather than worse.

It might well be that unless Indy puts hard seats in those 452s, any factory induction hardening would probably be removed when the larger seats were ground for the 1.81" exhaust valves. Just an observation.

Take care,
CBODY67

 

[gyknot]

If you do decide it needs a valve job, have the stock heads rebuilt. All stock with hardened seats. The seats are almost a standard upgrade anymore when having heads done.
With the stock 383, you don't need any upgrades. Using your original heads keeps your compression right where it should be.

 

[MEV]

I had heardened valveseat 452's i couldnt give away from my 66 440. It is really hard to match the performance and value of the 440 source aluminum stealth heads. Just paint them blue and no one would know the difference except your back muscles.

 

[commando1]

452 heads and hard exhaust seats these are the only comments he made at the time.

Had he not said it, Mike, it's exactly what I would have said.
Best of all the BB heads, even better than the over rated 902's.
They flowed as good as the 440 Source as tested by a magazine.
Just be aware they use a GM shortie plug. Most people don't know that, put in the Champions, and it runs like crap because they ain't seated.
Best of all, they're seasoned. A ton of people have said the 440S needed further work after receiving their's.
BTW, they're nicknamed Motor Home heads and they have extra water passages.

 

[MEV]

Also remember aluminum allows for higher compression ratios on pump gas. Although if your motor is stock, you will not have an issue. If you are going to step it up in the future the heads would already be good to go. I think the stealth heads had any issues worked out long ago. I ran mine stock out of the box initially with excellent success, then later sent them off for full cnc porting at modern cylinder head.

 

[FURYGT]

Had he not said it, Mike, it's exactly what I would have said.
Best of all the BB heads, even better than the over rated 902's.
They flowed as good as the 440 Source as tested by a magazine.
Just be aware they use a GM shortie plug. Most people don't know that, put in the Champions, and it runs like crap because they ain't seated.
Best of all, they're seasoned. A ton of people have said the 440S needed further work after receiving their's.
BTW, they're nicknamed Motor Home heads and they have extra water passages.

452's are not a good option, nor are the 440 source heads as they are open chamber heads and he has closed chamber heads. Open chamber big block heads started in 1968 with the 906 heads.

 

[Zymurgy]

Well it was a very easy diagnosis. I do have burnt valves. I think I am going to stay with my original heads and have them reconditioned. My friend has a great source for the machine shop and his guy fortunately is still working there.

He is about 2 months out, now I have to make my decision to have it done now or wait until this fall. I am going to give it some thought. It ran pretty nice this morning in the cool temperatures. It wasn't crazy about the hot weather we had here last week.

 

[MEV]

Agreed, changing to open chamber heads, aluminum or not, will lead to lower compression and performance. If you can have hardened seats added to the closed chamber stock heads, you should be good. I suspect that you will rapidly run into diminishing cost returns for any additional "performance" options you select for reconditioning your stock heads.

 

[commando1]

452's are not a good option, nor are the 440 source heads as they are open chamber heads and he has closed chamber heads. Open chamber big block heads started in 1968 with the 906 heads.

You are correct. I forgot about the lower compression.
Unless he wanted to put in domed pistons which I'm sure he doesn't.

 

[65CopCar]

You are not that far from BES Racing Engines (I figure 2 hours). No one better than Tony. Have them go through your heads.

 

[D Cluley]

I had a burnt valve problem with my '65 years ago and replaced the original closed chamber heads with a set of 452s because I got a really good deal on them.

I am not knowledgeable enough to argue with any of the numbers that have been posted here. I very well may have less power than before, but based on the way I drive, I am satisfied with the performance of the car.

The lower compression does have one nice feature, I am using 89 octane gas where it needed 93 before.

 

[Ripinator]

Well it was a very easy diagnosis. I do have burnt valves. I think I am going to stay with my original heads and have them reconditioned. My friend has a great source for the machine shop and his guy fortunately is still working there.

He is about 2 months out, now I have to make my decision to have it done now or wait until this fall. I am going to give it some thought. It ran pretty nice this morning in the cool temperatures. It wasn't crazy about the hot weather we had here last week.

Mike: I think you have made the right decision. When I had my '66 440 (with 516 heads) rebuilt, I went with no modifications to the heads in the associated valve job. Throttle response is fantastic, and I'm very happy. Since I was into a full engine rebuild, I did go with a mild dual pattern Comp cam with new springs and lifters. However, you probably don't wanna go that far, and you shouldn't need to.