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Discussion Starter · #21 ·
Bad news from the machine shop.
After pulling both heads and delivering to a man I trust, Smartest guy I know in a machine shop, and waiting to hear back I was disappointed to hear the heads are not in good shape at all.
He has an abandoned set of 455 heads, IE never picked up, for sale and wanted to know if I wanted to go that route. We talked about it and he said the intake ports are larger and would want to see my intake to check if they would fit. I have heard of getting 350 olds heads but have found no info on going big block heads on a 403. I already need exhaust manifolds/headers and that would mean exhaust also so my wallet is wearing thin. I just don't know enough about this, anyone got any ideas?
 

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Bad news from the machine shop.
After pulling both heads and delivering to a man I trust, Smartest guy I know in a machine shop, and waiting to hear back I was disappointed to hear the heads are not in good shape at all.
He has an abandoned set of 455 heads, IE never picked up, for sale and wanted to know if I wanted to go that route. We talked about it and he said the intake ports are larger and would want to see my intake to check if they would fit. I have heard of getting 350 olds heads but have found no info on going big block heads on a 403. I already need exhaust manifolds/headers and that would mean exhaust also so my wallet is wearing thin. I just don't know enough about this, anyone got any ideas?
I'll preface this by saying I'm no Olds guru, but have a passing familiarity with them.
Your biggest issue with the 455 heads is how big the combustion chamber is, what piston you can get if rebuilding the bottom end, and the resulting compression ratio.

do you know what casting letter the 455 heads are?
Olds Big Block use letters, and not numbers like the small block, for ID purposes.

If the heads are mid-70's smoggers, combustion chamber will be large, maybe making it hard for you to get much of a compression ratio.
 

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Discussion Starter · #23 ·
I'm not trying to make a hot rod any more then it was when new. My plan is to put heads on the car and get it running again. It ran well before just had a cylinder that was low on compression. we found old head gasket making one cylinder low and the heads have loose and or pitted seats and bad valves, guides. that along with broken bolts make repairs greater then the relative value. My friend has these heads at his shop and was offering them for much less then repairing mine His comparison of the heads and research as to the differences showed the intake runner opening size to be the biggest issue.I am sure he looked at the combustion chambers and the valve sizes in his comparison. I want to know if this is possible. I have a Pontiac friend but he knows nothing about Oldsmobile engines. The very few Olds people I have seen are big block fans and know little about the 403.
As far as casting numbers I have not seen the heads, just got the call about the condition of my heads today. Its going to be Dog to the vet in the am and drive to the machine shop to talk and look at the heads...also I need to take him the intake for comparison.
 

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I don't think ericnova was suggesting that you'll just have less compression, he's saying (and I agree) you might have not enough to really make the engine effectively work. You might have a 6mpg slug that makes 80 hp, or worse, just doesn't really run and will require extensive modifications to the ignition and carb just to maybe work. That's apocalyptic, but you'll be creating a ton of work for yourself and have an engine that is just not a viable powerplant.

Get us casting codes off the old heads and the 455 heads. If you're replacing smogger 403 heads with older 455 heads, you might have a chance.
 

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Bad news from the machine shop.
After pulling both heads and delivering to a man I trust, Smartest guy I know in a machine shop, and waiting to hear back I was disappointed to hear the heads are not in good shape at all.
He has an abandoned set of 455 heads, IE never picked up, for sale and wanted to know if I wanted to go that route. We talked about it and he said the intake ports are larger and would want to see my intake to check if they would fit. I have heard of getting 350 olds heads but have found no info on going big block heads on a 403. I already need exhaust manifolds/headers and that would mean exhaust also so my wallet is wearing thin. I just don't know enough about this, anyone got any ideas?
The firsts question is, WHICH "455 heads"? Most are fine, but the more common "J" castings from 1973-76 are smogger heads with crappy ports. Be aware that big block Olds heads are a great choice for most 403 builds. They have larger ports and usually larger valves than the small block heads used on the 403, and Olds used them from the factory on the 400 big block. A 403 small block flows just as much air as a 400 big block, so why restrict it with the factory small port heads?

There are two downsides to using the BBO heads, however. First, as noted above, all BBO heads came with chambers in the 82-84 cc range. This will drop the already anemic compression on the 403 unless you go to flattop pistons. Second, the larger ports on the BBO heads require port matching on the intake. There are only a few small block Olds intakes that have enough meat to allow this port matching - the Performer RPM 350 is one, the long-out-of-production Edelbrock OL4B is another. If the 403 is going into a Trans Am with a shaker scoop, neither of these options will allow you to retain the scoop without significant modifications.
 

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@joe, Will is not looking to build a hot rod he is just looking to get a good running car.

J heads were 80-82cc based on info shown below, most BB heads were 80cc, while his stock 403 heads are 83 cc.
It looks like the BB heads are smaller CC's, so it will help him slightly. My bigger question is are the heads drilled for 1/2" head bolts. I would not worry about intake port being a little smaller then head ports. In fact my guess the size will be very close depending on head and intake, the important part would be to make sure the intake seals up tight.

@will, I think you will be fine just need to look at intake port sizes to make sure you can get a intake gasket to seal tight.

Below is a link to head info shown below.

Rectangle Font Magenta Circle Pattern


Font Parallel Number Pattern Document

 

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Discussion Starter · #27 ·
Thanks guys. Im heading, pun intended to the shop toda with the intake it do some comparisons and try to figure out this mess.
I would love to be able to get it out and completely redone. Just can't right now. Truth is I will most likely have to sell her when she's. finished. We will have to see.
 

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Discussion Starter · #28 ·
The 455 heads are a G a head and have the numbers around the center valve cover bolt of409 100. They are also cast with a wheel symbol before CFD, and another casting says 246. I guess I never paid attention to the markings, I can see the screw in prints where they put the number plates in. My 403 heads are a 4A and have a date code of 279 with an indicator pointing to a single dot, there are two or three dots the indicator could have been pointed to. I am thinking that is a shift indication.

I almost think I need to start a second discussion for this next question and if I should please tell me. I talked to a Pontiac guy and he has a Pontiac 400 that needs heads, short block has been gone through. I am skeptical of the lower end giving the condition of the heads. Yet another way to go. I am not sure if the accessories and brackets will fit the different engine or not. The bell housing should be a BOP bolt pattern right?

Guys, I'm overwhelmed both with gratitude for your help but also with frustration for the decisions I have to make. I am sure this is never going to be a "numbers matching" car but do I want to change makes of engines? what would you do? and why
 

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Ok Ga heads are a good heads and are worth a few dollars, what's he asking? they will help your compression a little because they are 80 cc chamber VS the 403 (4A) heads 83cc.

I myself would go for the Ga heads if you can swing the price, Note I believe the machine shop will need to open the head bolt holes to 1/2", this is not a big deal.

These heads and steel shim (.015 thick) head gaskets should work nicely on you car. make sure you use stock steel shim gaskets, most head gaskets made by Felpro and others will be .040 thick this could cause quench issues, which could leads to spark knock

If you can wrap this up by just getting new old's heads you will be cheaper in long run, swapping the engine will add other minor issues that equal money, plus you say the pontiac 400 needs heads as well.

Quick thought of minor issues that will require more $$$ to install Pontiac 400.
1) Motor mounts
2) exhaust will need to be altered or replaced
3) Hoses and possibly radiator.
4) brackets and all accessories are different from Pontiac to Olds motor, does this 400 come with all brackets and pulleys

Font Temperature Circle Number Parallel
 

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Discussion Starter · #30 ·
I agree. That is my thinking at the moment. Came out to strip the intake so I can take it to machine shop Monday to see it it will work. When what to my surprise there is an elderbrock performer 350 olds aluminum intake. Cleared it off and looking at the mounting flanges it might have enough to cover the big block openings. We will see. He has a olds block we can mock up the heads to see if it will work.
He said he would drill the bolt holes for the bigger head bolts also. Somebody found a 135000 mile 403 for 995 plus shipping. Its a complete engine. Of unknown repute. Im starting the search for exhaust. We shall see what Monday brings.
 

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Ga heads are fine as noted, but most came with 2.000/1.625 valves. I'd go with the 2.070/1.625 valves used in the 442 motors if possible. You can machine the small valve heads for the large valves - the castings are the same. The ports are still a problem matching to the intake, as I discussed above.
 

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Discussion Starter · #32 ·
I spoke with Dick Miller on Friday. He is an Oldsmobile drag racer. Has a company with performance olds parts.
As we talked he asked what I have and what I want to do with said car. His conclusions were that the intake gasket will seal the two together but if I want pirt matching I would have to find something else perhaps big block intake and modify by shimming due to the differences in the block.
I ordered a 2711 performer intake because of corrosion damage to the coolant ports on the intake. Should be here Wednesday.
As far as valves. These heads are done and short of resizing the bolt holes it is good to go.
More news when there is some. Thanks for the invites and support
 

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Discussion Starter · #34 ·
Thats the impression I got. He is a wealth of knowledge.
I dropped the intake and gaskets to the machine shop. They were going to test fit next week.
Need to find exhaust manifolds now. From what I have read the 403 should work on 455 heads. The big difference was in the deck height of the block. Just need a set. Mine are cracked broken and studs snapped off.
 
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