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Discussion Starter #1
Greetings All,

Just purchased a numbers matching '67 GTO...

I'd like some feedback on balancing keeping the car a true example of an original, but possibly upgrading to Disc Brakes, freshening up the motor (maybe a bit more cam), and maybe swapping in a different rear gear....

What crosses that line between helping or hurting value vs. improving performance?

Regards,
Paul
 

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You can do all the above, just KEEP the original stuff so IF you sell it you can change it back.......be careful messing around inside a motor with an older rebuild!!!!!! I might skip the cam job if I were you. IMHO Eric:cheers
 

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Discussion Starter #3
Eric,

Thanks for the feedback...tracks my thinking exactly.

As to the motor...I've built a couple of 400's, nothing radical. My thoughts for this one is to pull the motor so I can clean/detail the engine compartment, and rebuild the motor from the bottom up. Probably upgrade to a bit larger hyd. lifter cam...

Not sure what the downside is...

Paul
 

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What crosses that line between helping or hurting value vs. improving performance?
Hi Paul, I can say unequivocally, without any doubt whatsoever, that the answer to your question is.... "it depends".

If you're talking about a super rare combination that's one of a handful ever built, then anything that strays from original is going to hurt resale value. If it's one of the "mass" combinations that were made in high numbers, a few judiciously chosen enhancements might also increase resale value. Better brakes and suspension make the car safer and more fun to drive, and if you really are going to drive it then either you'll have to run avgas/racing fuel, or you'll need to build that motor so that compression is compatible with the fuel you can get. If "go fast" is your thing then depending on how much you want to spend, you can fairly easily turn that 400 into a 550+ horsepower torque monster using readily available parts and services, still using the original numbers-matching block. (For the 3rd year in a row, the car that has won the title as the fastest street car in the state of Arizona is a 1974 Pontiac Trans Am. It runs low 8-second quarter miles and is likely to be in the 7's next year. In race tune he's in the vicinity of 1000 HP - and it's a Pontiac.)

The first question you have to answer though, is what matters to you most? Do you care most about preserving resale value (i.e. making the car valuable to someone else) or do you care most about enjoying it? (i.e. making the car valuable to yourself.) If it's the first, then generally you'll want to keep things original. Otherwise, build whatever you want and make no apologies.

For example, I myself have a numbers-matching 69 GTO hardtop, TH400 automatic, YS code 400 that I've had since college. I'm within 4-6 months of having it done at my present pace, if things go well. I needed to replace a quarter panel and also repair some other rust, so I had the car media blasted. The car was originally Palladium Silver with black interior, black vinyl top. When I got the metal work done and was ready to move on to surfacing/blocking, I had a decision to make. Do I keep the vinyl top and original color (even though I don't like vinyl tops and wasn't wild about the color) or do I nuke the top and paint the car whatever color I like? I quite literally agonized over this decision for a couple of weeks, even though I'd already upgraded the brakes, the rear axle, and especially the engine.

It was the "who am I doing this for?" question that finally got me going. (HINT: the vinyl top is a distant memory and this car is going to be mile-deep-need-a-safety-belt-do-I-don't-fall-in black.)

You'll get a bazillion opinions, but the only one that matters is yours. It's your car and you're the one spending the money on it. Do it however suits you.

Bear
 

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Bear, I do like a silver car, and am not too fond of vinyl tops......MILE DEEP BLACK is what I am going with on my 67. It was originally red with a black vinyl top and black interior.....I lost the top, am doing a red interior, and a black paint, looks like a black hole don't fall in paint job!:cheers Eric
 

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do they make that mile deep paint in a Bahama Blue Metallic???.....lol, love black cars and that red interior will pop Eric.
 

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How many miles on the car? If low original miles, I'd just reseal the engine and pretty much leave it alone. As for other upgrades, bolt-on improvements are reversable and won't hurt value. As stated above, it's really up to you. You could pull the original #'s engine, mothball it, and build a 400 or 455 or whatever to your liking that runs strong on today's fuel. That won't hurt the value, either. My first car was a Platinum Silver '66 GTO....I love that color on these cars, and you don't see it often. Black's great too, though!!! Good luck.
 

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Discussion Starter #8
Bear, Geeteeoh,

Thanks for the feedback....

Ultimately, the budget will dictate. I'm in no hurry right now...We're just going to drive and enjoy the car for awhile, and then make the improvements over time that make sense.

How do the YS code motors (10.75 cr) deal with today's pump gas?

Regards,
Paul
 

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+3 for silver. 10.7:1 is too high for pump gas, need to get it to 9.5 or lower to avoid detonation on todays gas, if you will be driving it a lot you will have to have reliable source for high octane in the 106 range, if you want to keep block get new set of heads with a larger chamber to tailor the CR, and save your matching ones, again this is a bolt on to make the car streetable and as long as you save the originals it won't effect value. Another option would be get your pistons dished to bring it in line, all depends on how original you want it to appear from the outside.
 

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How do the YS code motors (10.75 cr) deal with today's pump gas?
Honest answer? They don't. Not if they're really 10.75:1. "Safe" I consider to be 9.3:1 or less with iron heads, around 10.2:1 with aluminum. Aluminum runs cooler and "pulls" more heat out of the chamber, which is good for controlling "nasty D" but bad for making power. All things being equal, you "need" more compression with aluminum to make the same power as the iron head at a lower compression.

Also consider this: again all things being equal, the difference between 9.3:1 and 10.0:1 on a 461 is only worth about 8-10 HP on a motor that's already making 450-500 HP anyway, so it really doesn't seem worth it to push the limit on a street motor. On a max-effort race motor where every tiny bit of power makes a difference, maybe --- but then a race motor will probably be running on high octane racing fuel anyway so it really becomes a non-issue.

Also keep in mind that factory compression ratios were like factory HP numbers --- usually fantasy. A stock 400 with 71cc chambers, a head gasket that's .040 compressed with a 4.120 bore, 6 cc's worth of volume in the piston valve reliefs, and .020 worth of deck height (what Pontiacs "usually" are, untouched), is really only making 10.095:1 compression --- a long way from 10.75:1. That 10.75:1 factory number does not take into account the additional volume in those valve reliefs, nor does it include the tiny bit of volume around the perimeter of the piston from the piston top down to the top of the first compression ring. I'm not sure why the factory did it that way, my guess is that in 1969 when we had "good" leaded fuel freely available, there was no reason to care about a "measly" .05-.08 of compression, and higher numbers looked good in the marketing brochures. 10.095 is still too high for even 93 octane though. With a very aggressive cam (very late intake closing event) you MIGHT be able to squeak by with a perfect tune for air/fuel, and a VERY good cooling system --- but considering the miniscule power gain for all those headaches and risk, why bother?

If the pistons are good and there's enough "meat" left in the tops to be able to cut a dish to increase the volume from 6 cc's to 15 cc's, then you'll be at 9.269:1 with a whole lot more safety (some places you can't even get 93 octane any more). Doing that will also cost you quench volume (less combustion efficiency due to decreased turbulence), but it's definitely one low cost alternative. If the pistons are good enough to be able to get that volume with a D-shaped dish (or if you buy forged aftermarket replacements that are already D-dished), then you don't have to give up the quench area.

Another would be to go with thicker head gaskets. Cometic makes them in all sorts of compressed thicknesses and they're expensive, but they're also reusable. Starting with that same 400 and changing nothing else except running a set of .075" compressed Cometics puts you at 9.383:1. That option costs you in terms of quench area too, but if you're looking for the absolute cheapest way to make the engine live on 93 and you understand the trade-off's you're making, it's not a bad alternative.

It's been said before, but never rely on factory numbers/measurements. Always measure all 8 chamber volumes in your heads, and your deck heights, yourself. They do vary from the published numbers, often by enough to make a big difference.

Bear
 

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Fxnjetz, let me share with you my personal experiences with my '67 GTO. I purchased my '67 YS GTO convertible (th400 trans/3.36 rear gear) in 1983 with 125,000 miles on the clock. Motor had never been opened...just a timing chain replacement in the '60's or '70s. Car ran like a scarded cat, and burned serious rubber on the 1-2 shift in "drive". In about 1985, Califronia's fuels started to degrade, and the car now started to ping like mad on light load and WOT. I purchased a set of open chamber heads (Ram air 3 #12's) and this helped a little, but I still had the problem. In 1988, I overhauled the motor at 173,000. Went .030 over with an 067 cam. Car still pinged. I was taking the car on vacations, (Yellowstone, Grand Canyon, etc), and I had a special gate valve to bleed off vacuum advance on long light load pulls, and I also used Edelbrocks water injection. Small help, still pinged. I tried 104+ octane boost. Pinged and fouled the plugs with yellow and red fuzzy stuff. In 1991, I gave up on running high compression in this engine. I installed an 068 cam and some big chamber heads, but didn't do my homework. They were HUGE chamber heads....114cc. I ran these heads for years, enjoying poor fuel economy, lackluster performance, and regular grade fuel without detonation. Two years ago I got tired of my GTO running like a Chevy and I installed a set of 87cc iron heads on it. What a difference. The car felt like it shed 2000 pounds of weight. Recently, I removed the 3.36 rear gear and installed a 2.56 posi unit that was a gift. I drive this car a LOT, and long hours at highway speeds are the norm. I now have a car that runs really strong, and gets 19-plus mpg, so I drive it a lot more often. If you want to drive your car a lot, change the heads. If you want to drive it once a month or so, you'll need to run race fuel. The 1967 YS400 in our GTO's is a Prime Detonator. You have three things against you: High compression, a closed chamber head that requires a ton of spark advance to make it work (and the ONLY closed chamber head Pontiac made in 1967), and a camshaft grind that builds a ton of cylinder pressure. Your stock YS 400 has an 067 grind cam in it, making it even more prone to detonation than if it had an 068 (HO) or 041 (ram air) cam. You could change out the cam and bleed off some cylinder pressure, but that would be a band-aid on the compression problem and bite you at WOT on the top end. Sorry for the long ramble, but I've been driving my '67 YS GTO close to 30 years now, and the only thing that worked for me was to drop the CR to 9:1.
 

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Discussion Starter #13
Bear/Geeteeoh/et. al,

After being out if the game for 30 years.... It appears I may have found a new home.

Thank you all for your time, and sharing what is obviously a lifetime of experience, as well as a passion for the cars, and the technology. Thank You.

This is my 3rd and probably last 67 GTO, and we intend to drive it, enjoy it, improve it, make some noise/smoke (the good kind) with it, and just hang out with gearheads again.

Looking forward to it.

Regards,
Paul
 

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Thanks instg8tr, will do...

Geeteeoh....The plan for the moment is to hunker down for Winter, and break out the Goat come Spring. (It's still in transit from Cali as we speak). We'll most likely drive it as is next season, just to get an opportunity to shake it down and get to know the car.

By next Fall, We'll have had lots of time to do the homework, make a coherent plan for Improvements. I plan on doing quite a bit of driving with it, so not interested in band-aids. Probably looking at phasing the work over 2-3 seasons...(at least the major mechanicals).....the rest I know will be an ongoing battle between my OCD and my budget.

When all is said and done, I want the car to be a prime example of the breed, but with enough new hardware/technology to make it fun and practical to drive. Neck snapping, tire scalding, quickness, on modern pump gas will also be a prime motivation....

...now where did you find those small CC heads for your Goat??

Regards,
Paul
 

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here you go Paul, anything after 65 will fit your car you want the larger valve sizes with around 87cc-90cc chamber, bear can tell you more exactly for that magic 9 - 9.5:1 CR, nice thing about our engines is that all the heads will interchange on all the blocks 326-455.

Pontiac V8 Casting Numbers
 

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Instg8tr,

Great resource thx.

Given the wide variety of choices at least in terms of heads, and assuming the goal is to get to something greater than 72cc's, Are there good/better/best head configurations in terms of porting/flow characteristics?

I realize that there may be infinite choices once you start altering bore/piston/block configuration, just curious if there is at least a baseline consensus when it comes to optimum heads.

Regards,
Paul
 

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no problem Paul, just passing on what i have learned over the last few months after getting back into it after 20 yrs. sounds like a good plan, if the engine is relatively fresh you should be able to do the tweaks from the top end and not have it laid up in the garage for more than a week, all of the engines have flat top pistons stock so the heads will determine the CR and gasket thickness (titan copper ICS) can be used judiciously to tweak it further if need be.

Did manual disc front on mine w/2 reservoir master cyl., power steering, i feel these upgrades are for safety and comfort of driving and are necessary.

will probably do rear disc's when i find a good rear end since i will have to take the whole back off anyways

Not worried about keeping the motor stock so here is what i came up with did'nt go too crazy on the cam so i have room to go up if i am not happy with a bit over 400HP and around 500 lb torque, and she is mainly stock configuration under all the pretty stuff, besides it's "just a Tempest"....LOL





http://s1098.photobucket.com/albums/g372/instg8ter/1966 Tempest/
 

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I realize that there may be infinite choices once you start altering bore/piston/block configuration, just curious if there is at least a baseline consensus when it comes to optimum heads.
All open-chamber D-ports, at least the ones with the big valves and screw-in studs, are "about the same". Pre-unleaded fuel ones are going to tend to have smaller chambers that lead to detonation problems unless you do "something else" to manage compression, plus they lack the hardened exhaust seats for unleaded. (There are two opinions on that one, one says "it's always bad", the other says "it's ok unless you're heavily loading the engine all the time - like with pulling a trailer or something." - Pick your poison. I'm hoping the second group is right because that's the direction I went. :eek:)
A step up from those would be cast-iron round ports such as Ram Air IV, 455 HO, 455 SD, and others. Very expensive and hard to find now, and most also have small chambers and un-hardened seats as well (except for 455 SD).
Going up from there would be aftermarket aluminum. Both D-port (KRE and just out Edelbrock) and round port (Orginal Edelbrock, Tiger) are available. There are also some of what I'd call "exotic" because they aren't anything like any of those, can't use any of the factory intake manifolds, "really look different", etc. CV-1's are in that category, plus there are some efforts going on to reproduce the infamous Ram Air V's.

If you're thinking long term and you care about street performance and tire-shredding, then you'll probably eventually build a stroker. Nothing says "torque" like more displacement. Building a 461 out of a 400 is a very popular move. You've got the strength advantage that the 400 block has over the 455 (and 428, 421), the better oiling of the smaller mains, but with the torque making internal capacity and geometry. With the right cam and air flow (heads) 600 streetable horsepower is very attainable on 93 octane with a cast crank. Use a forged crank for more RPM ability and it can go higher. Getting there takes aftermarket aluminum heads that have been professionally ported by someone who knows what they're doing, enough cam to take advantage of that air flow, and a rotating assembly (and drivetrain) that can live at those power levels - and all that costs money - but it's not "uncharted territory" by any means.

Let me recommend someone to you. Jim Lehart at Central Virginia Machine Services. Jim's one of those rare guys who has enough real-world experience building motors of all kinds (not just Pontiacs) who also doesn't mind sharing information and recommendations. He helped me plan my 461, and spent lots of time with me, even before I ever spent a nickel with him. I did wind up buying most of my parts from him because it just seemed the right thing to do, but he never made that a condition of helping me. Great guy. I'd bet if you were to talk with him and share your goals and budget, he'd help you as well.

Bear
 

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Paul, I got my heads off of ebay. They are 1970 #15 heads from a 455 big car. They have 87cc chambers, which on a 400, gives me 9:1 compression. They are not the trick heads to get. I installed screw in studs, etc. to upgrade them. They have the small valves, too---which work very well with my tall rear end gears and automatic. A lot of the chamber volumes are not as posted on the charts, and need to be verified by cc'ng the heads. For instance, the '69-'70#13 heads are supposed to be 72cc, but are turning up to be about 80cc, which puts them "in the ballpark" for use. Doing the homework and research and hunting is a lot of the fun, and if you're not in a hurry, you'll be able to pay reasonable prices and get all the stuff you need. It sounds to me like you're doing the right thing with the car. One thing I think will surprise you, though....even stock, you will find that '67 is much more comfortable going down the road than newer cars. The rear wheel drive, long wheelbase, low height, and comfortable seating position are superior to today's front drive, high center of gravity, buzzy modern cars. The ONLY advantages of the new stuff is crash safety, sound deadening, and fuel economy. You just may find that not a lot of "improvements" are needed!!
 
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