Rebuilding 62-series heads - Pontiac GTO Forum
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post #1 of 12 (permalink) Old 04-18-2018, 07:05 PM Thread Starter
 
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Rebuilding 62-series heads

Hey everyone, I am about to have someone do some work on the heads on my '69 GTO. I am puffing an unhealthy amount of blue smoke on startup and am hopeful that it is an exhaust valve seal issue.
The guy doing the work is going to change all of the valve stem oil seals to start, and he has just sent me a message suggesting that an upgrade to 'positive spring-loaded Viton seals' would be a good first step.

Now, my friend is not a 'Pontiac' guy, but he has rebuilt several Pontiac 400's and a 428 or two, and I trust him. I am aware, however, that there is an incredible wealth of knowledge in this forum, and I am hopeful that someone here has something to say on the subject, whether that be 'go for it Joe, that's an excellent idea; several of us have done the same' OR 'dude, you really need to find a Pontiac guy because there is no option for those seals on your 62-series heads.'

So, please, fire away!

Thanks for taking the time.

Joe

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post #2 of 12 (permalink) Old 04-18-2018, 09:27 PM
 
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have the guides been replaced? What lift cam are you planning on running? there gets to be a point of valve lift where there will be contact with the stock retainer. On one pair of my 197's, I had them built with the viton seals on the exhaust, those particular heads will never see more than .424 gross valve lift, as that is what the cam is ground for & rules specify the engine can not exceed that amount. Another engine, our 447 has heavily ported 7K3's, a small roller cam, with it's valve lift, a little over .560 with 1.65 rockers, there is no way viton seals could be run.
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post #3 of 12 (permalink) Old 04-18-2018, 09:40 PM Thread Starter
 
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Originally Posted by Pinion head View Post
have the guides been replaced? What lift cam are you planning on running? there gets to be a point of valve lift where there will be contact with the stock retainer. On one pair of my 197's, I had them built with the viton seals on the exhaust, those particular heads will never see more than .424 gross valve lift, as that is what the cam is ground for & rules specify the engine can not exceed that amount. Another engine, our 447 has heavily ported 7K3's, a small roller cam, with it's valve lift, a little over .560 with 1.65 rockers, there is no way viton seals could be run.


I just got the car in November, 2016 and spent all of last summer enjoying the hell out of it.
Iím afraid that I donít know anything at all about the internals (yet)
I am guessing that itís still running the stock cam.
The previous owner installed an Edelbrock Torker intake and carb, a pair of nice Tin Indian valve covers and a Tin Indian air cleaner, but as far as I know thatís it.
It runs really well on 91 octane fuel which also leads be to believe sheís still pretty stock.
My guy is going to do a compression and leak down test, examine the heads and go from there.
I will pass on the information that youíve provided - thanks again Pinion head

Joe


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post #4 of 12 (permalink) Old 04-19-2018, 07:52 PM
 
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PH: " Another engine, our 447 has heavily ported 7K3's, a small roller cam, with it's valve lift, a little over .560 with 1.65 rockers, there is no way viton seals could be run."

PJ: Are you sure? Ported and reworked the bowls on my 7K3 heads and had my machinist install Viton seals. Maybe they won't work with the stock 7K3 valves, but I went with the taller RA IV valves. My machinist said my heads with the springs he set up should be good for about .600" lift. I will be running a solid Crower cam with .501" using 1.5 rockers or .551" with 1.65. Maybe I am missing something, but this is what the machinist did to my heads.

Disassemble,Clean, Magnaflux Heads.................$40
Surface Heads............................................. ........$100
16 Bronze Valve Guides.......................................$52
Bore & Install Valve Guides..................................$200
8 Ferrea RAIV Stainless Steel Intake Valves..........$88
8 Ferrea RAIV Stainless Steel Exhaust Valves........$88
16 Valve Springs........................................... ........$92
16 Valve Spring Retainers.....................................$48
3 Angle Valve Job,Set Valve Spring,Install Valves..$300
and Install Viton Valve Seals.
7/16" ARP Big Block Rocker Studs..........................$118
Heater Hose Nipple/Passenger Side......................$25
Freeze Plugs (6)............................................... .....$16
OWNER Supplied 7K3 Heads........................................$0
OWNER Port/Polish/Open Valve Throats and ........$0
Chamber Work
TOTAL less heads & any head work.........................$1,167
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post #5 of 12 (permalink) Old 04-19-2018, 10:07 PM
 
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Jim, just passing on what we determined. 7K3's when I picked them up in a trade, had considerable port work and SI intake & exhausts installed (in '68-70 length). Ended up pulling the ex valves and installing a set of Manley race flow exhausts, both intakes & exhaust valves are aprox .15" shorter than RAIV valves. Many have found the tuliped RAIV valves to actually flow a less than std profile valves and are not using them even in RAIV engine builds. For my use they would also have slightly more mass with the longer valve.
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post #6 of 12 (permalink) Old 04-20-2018, 06:55 PM
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Correctly setting up a non-factory valve train is not a trivial exercise by any means. Everything snowballs, and all the parts: cam lifters, valve springs, valves, valve installed height, seals, guides, rockers, pushrods have to be carefully selected to work together, and almost always involves some machining on the heads to do things like cutting the spring seats to get the correct spring installed height (or using shims), and machining the tops of the valve guides for seal clearance/retention. Everything that moves has to be measured and fit properly. It's time consuming, exacting work and can get expensive in a hurry.


For your "oil smoke" problem, the first thing to check should be the valve stem/valve guide clearance. If that's out of tolerance, then anything else you do to try to solve the problem will just be wasted money.

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post #7 of 12 (permalink) Old 04-20-2018, 07:43 PM Thread Starter
 
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Correctly setting up a non-factory valve train is not a trivial exercise by any means. Everything snowballs, and all the parts: cam lifters, valve springs, valves, valve installed height, seals, guides, rockers, pushrods have to be carefully selected to work together, and almost always involves some machining on the heads to do things like cutting the spring seats to get the correct spring installed height (or using shims), and machining the tops of the valve guides for seal clearance/retention. Everything that moves has to be measured and fit properly. It's time consuming, exacting work and can get expensive in a hurry.





For your "oil smoke" problem, the first thing to check should be the valve stem/valve guide clearance. If that's out of tolerance, then anything else you do to try to solve the problem will just be wasted money.



Bear


Thank you Bear. That is exactly the type of information I am looking for.
Without sounding too needy can you direct me to a reliable source for these, and other related specs and tolerances?

Much appreciated

Joe


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post #8 of 12 (permalink) Old 04-20-2018, 08:09 PM
 
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Originally Posted by Pinion head View Post
Jim, just passing on what we determined. 7K3's when I picked them up in a trade, had considerable port work and SI intake & exhausts installed (in '68-70 length). Ended up pulling the ex valves and installing a set of Manley race flow exhausts, both intakes & exhaust valves are aprox .15" shorter than RAIV valves. Many have found the tuliped RAIV valves to actually flow a less than std profile valves and are not using them even in RAIV engine builds. For my use they would also have slightly more mass with the longer valve.
OK, knew you were building more based on super stock specs for your car to enter it in the stock drags. They also have valve retainers that can gain a little more height, but you have to make sure no interference with the rocker arm hitting them.

Not sure what the "all out" lift limit would actually be on an iron Pontiac head, either D-Port or O-Port. Have a listing of some older cams from the 1980's. Flat tappet cams: The highest lift in a hydraulic cam is a Comp Cams with 1.65 rockers - Int/.569" Ex/.585". The highest lift in a solid cam is a Crane cam with 1.65 rockers - Int/.649" Ex/.668"

With regards to roller cams, Lunati seems to be the highest using 1.65 rockers - Intake/.742" and Exhaust/.735". Several other grinds by Nunzi, Competition Cams, Isky, and Norris all in the .700" range as well. The Isky cam with 1.65 rockers on a 108 centerline, Int/.726" Ex/.728" shows an rpm range of 4800-8800 RPM's, BUT, my guess is that these cams may have been aimed at the RA V heads/engine.

Here is an interesting H-O cam, the HC-01/068HL. Cam Centerline - Int/109 Ex/ 119, Overlap - 49 degrees, Duration - Int/272 Ex/282, Lift with 1.65 rockers - Int/.511" Ex/.561", and it notes idles at 800 RPM's and has 14" of vacuum. It would appear that the way the cam centerline has been split, it has a Lobe Separation Angle (LSA) of 114 degrees, but a rather small overlap of 49 degrees which is why it has good idle/vacuum characteristics and yet nice street duration numbers and a high lift with the 1.65 rockers. 1.5 rockers give the lift as Int/.465" Ex/.492" which are still some nice street numbers.
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post #9 of 12 (permalink) Old 04-21-2018, 08:46 AM
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Thank you Bear. That is exactly the type of information I am looking for.
Without sounding too needy can you direct me to a reliable source for these, and other related specs and tolerances?
The whole thing is a process. You start with making some choices: which cam are you going to use, and with rocker arm ratio are you going to use? Everything follows from those two choices. The relative "aggressiveness" of the cam lobes combined with the amount of lift determines how much spring pressure it needs in order to keep the lifters riding on the cam at all times. To get the full picture you also have to choose a maximum operating RPM for the engine and make sure you never exceed that. The higher the RPM, the stronger the tendency is for the cam lobes to 'throw' the lifters off of the cam, and the more spring pressure is required to not allow that to ever happen. Your cam vendor must supply all this information - detailed cam specs and the spring pressures (both closed and fully open) needed to control it. They should also want the details on which lifters you plan to use. Heavier lifters = more inertia = more spring pressure needed.

Once you know the spring pressures you need at both open and closed states, the next step is to determine valve lift using the combination of cam lobe lift and rocker ratio (and valve train type --- solid lifters always require some amount of "gap" - valve lash setting - that has the effect of reducing total lift at the valve and thus spring travel). You need to know valve lift in order to get springs that 1) have to proper open and closed pressures and 2) are capable of providing the required valve travel without either going into coil bind or being "too far" away from coil bind. Usually there will be more than one set of springs that will 'work', so you have to choose based on other qualities such as quality, cost, and required spring installed height. Spring installed height is the distance between the bottom of the valve spring retainer and the surface the bottom of the spring sits on (the spring seat). It's determined by the combination of valve length, spring retainers, and locks. If the distance is too great, the springs won't produce enough pressure to keep everything under control. If the distance is too close, spring pressures will be too high (which tends to wear out parts quicker) and you also run the risk of driving the springs into coil bind (where the spring 'stacks up' solid) and/or having the bottom of the retainers hitting the tops of the valve guides -- both of which tends to break parts and destroy engines.

There are special cutters for removing material from the head's spring seat surface if the measured installed height is too close, and there are shims you can put under the springs if they need to be 'shortened' (however shims are only available in a few standard thicknesses so sometimes in order to get your installed heights 'perfect' you have to do both - cut the spring seats by a small amount so that a shim will 'bring it back' to the correct height).

Once you have all the installed heights correct, you have to check to make sure that the retainers don't contact the valve guides or stem seals at full lift. There are special cutters to trim the tops of the valve guides too, if needed.

Once you have all of this correct --- the right springs installed at the right height to provide the right spring pressure and with just enough travel with respect to coil bind and parts interference --- you're still not done.

Now you have to fit rockers and pushrods. You have to choose a pushrod length that does two things: makes the best possible contact patch on the valve stems throughout the full range of valve lift and also ensures that the rockers have adequate clearance between them and all the other parts - i.e. the spring retainers and the purshrods themselves - throughout the full range of motion. Some builds with solid lifters benefit from using pushrods that restrict the oil flow to the top of the engine also, if that control isn't being provided by some other means, so that's a consideration too.

Plus -- if you're running 1.65:1 rockers then you have to make sure the pushrods don't rub anywhere in the heads. It's common to have to use a grinder to widen the pushrod passages in the heads if they came from an engine that originally ran 1.5:1 rockers.

Yeah, there's a lot too it. You can't just grab any old cam and throw it into an engine and expect to get the best results. "Everything" has to be matched and fitted to work with "everything else". Sure, you can put a big old lumpy cam into any engine and make it "sound hot" as long as all you ever do is let it sit and idle to impress your friends at the local burger joint, but if you want to actually be able to drive the car, make power, and have it not self-destruct then there's a lot more work to do.

Bear

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post #10 of 12 (permalink) Old 04-21-2018, 10:41 AM
 
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Great info for my build. I will need to figure all this in on the 389.
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