1967 428 - Pontiac GTO Forum
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post #1 of 6 (permalink) Old 02-03-2019, 09:34 AM Thread Starter
 
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1967 428

I recently stumbled onto a virgin 428 block with crank. I have been thinking about building a motor for my 68 GTO to replace the numbers matching number motor and put it on the shelf. I'm not too hung up on what block I put in my goat and originally thought would build a 400. My question is: should I put this block out for someone wanting to restore a 67 with a 428 and if so; what is a fair price? I'm not sure if anyone is interested in a 428 block. Give me your thoughts. Thanks
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post #2 of 6 (permalink) Old 02-03-2019, 11:48 AM
 
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428's & 455's use to be in high demand. But, since the cheap 400 block stroker assemblies came along, the 428 & 455 blocks are not worth as much. And since the 428 didn't come in an A-body or F-body, there are not many guys restoring 428 cars.

Guessing that a good 428 or 455 block might not be worth more than maybe $600, unless it was some rare 455 HP number.

I assume that a 481988 400 block is one of the most common desirable blocks nowadays, for stroker builds.

I suppose pinion head would know more about the current block values than anybody here.

Last edited by bigD; 02-04-2019 at 11:29 PM.
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post #3 of 6 (permalink) Old 02-03-2019, 09:03 PM
 
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Originally Posted by dcoydad View Post
I recently stumbled onto a virgin 428 block with crank. I have been thinking about building a motor for my 68 GTO to replace the numbers matching number motor and put it on the shelf. I'm not too hung up on what block I put in my goat and originally thought would build a 400. My question is: should I put this block out for someone wanting to restore a 67 with a 428 and if so; what is a fair price? I'm not sure if anyone is interested in a 428 block. Give me your thoughts. Thanks
I would use the 428 in your '68. The 428 was installed in the GTO as a swap for the 400 by dealers. Royal Pontiac in Royal Oak, Michigan, was one such dealer that installed three of the 428's which had the "Bobcat" treatment. Talked to a guy at a local car show who was from Long Island, NY, where street racing was big time and many dealerships offered upgrades through Motion Performance and other dealerships. He purchased 2 new 1968 GTO's. He purchased his GTO with a 428 & 4-speed. He purchased a GTO convertible for his wife. He still has the 428 engine and it was in a hot-rod he built. I looked at it and it was a 1968 428.

Here is one such 428 GTO installation - https://www.mecum.com/lots/CH0911-11...-royal-bobcat/ There was also a magazine article on a new '68 GTO with the swap.

That said, the 428 was a popular swap in many GTO's for more power or because you blew up the 389/400. The 428 is unique in that it has the 4.0" stroke. It will put out more HP/TQ than a 400CI and easily rev higher than the 455CI.

Built correctly, it may actually bring up the value of your car along with pickling the original engine.
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post #4 of 6 (permalink) Old 02-04-2019, 11:46 AM Thread Starter
 
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Great responses. Thanks especially to pontiacjim. I am curious about the build specs required used for the 425hp. May price some options and go from there. Will still consider posting in classified for sale section or selling outside of forum. Probably more engine than I need...
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post #5 of 6 (permalink) Old 02-04-2019, 06:39 PM
 
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Great responses. Thanks especially to pontiacjim. I am curious about the build specs required used for the 425hp. May price some options and go from there. Will still consider posting in classified for sale section or selling outside of forum. Probably more engine than I need...
Never enough engine nor more than your need.

The 425HP engine would have most likely been a blueprinted engine, ala Super Stock. To run the engine on the street & pump gas, you are already going to de-tune it a bit. Next is the cam selection which determines the nature of the engine. You want to build a Pontiac for Torque over Horsepower which is what the factory aimed for anyway. So cam selection can also tame down the engine & still give you plenty of pull.

Cubic inches rule and its why many go with a stroker kit for the 400CI (as well as the best bang for your buck pricing). The stroker kits also have the advantage of a smaller main journal size which can reduce bearing heat on higher RPM engines - which seems to be the folklore as to why 455's spin bearings. You also get a smaller rod journal for the same reason, plus it allows for a longer Chevy rod that compensates for the longer crank stroke so the crank-to-rod ratio is improved.

My opinion on the the larger 3.25" main journal is really not a problem when you pay attention to the build. The 455's cranks are cross drilled to better supply oil to the rods, not sure of the 428. Most 455's had the lower 40PSI oil pumps in the B-body cars and I am not sure if they got the baffled oil pans which came out in 1971, so it is my opinion that this is where many 455's that got hammered on lost their bearings. Case in point is the early 1977 200 horsepower TA 6.6 400CI engine built through October 1976. "Customers complained of lifter noise and severe loss of oil pressure under 'wide open throttle' acceleration and/or severe uphill grades. The early engines were produced with a 40PSI oil pump and unbaffled oil pan." A Pontiac Technical Service Bulletin was issued in January 1977 correcting the problem. The fix was a new 60 PSI oil pump and baffled pan, both covered under warranty. The internal pan baffle helped to reduce oil starvation during acceleration, braking, & cornering. So if Pontiac was having oiling issues under hard acceleration with a meager 200HP 400CI, how do you think a more powerful and torquey 455 did? So is the bad rap because of the larger main bearing journals as folklore would suggest, or was it an oiling system issue? Drive like grandma and there will probably never be any trouble, but those who ran the 455 hard, well..........


So a good oiling system, 60PSI oil pump, baffled pan, and the use of 3/4 grooved main bearings will go a long way in any performance build using the larger 3.25" main journals.

So nothing really trick to building a dependable 428. Uses the same #16 heads or other choices having 2.11" intake valves and screw-in rocker arm studs. Head cc's and dished pistons can be juggled to get a pump gas friendly compression ratio of 9.0-9.2 UNLESS you live at a high altitude and will want more compression to compensate.

Should you decide to sell the engine/crank, a 4-bolt main would pull in more money. I would bring it to a machine shop and have the crank checked & magnafluxed, and have the block cleaned up (if needed) and magnafluxed for cracks. Use a local shop so your efforts can be verified along with the receipts from the local machine shop. Then I would throw it for sale for $1000 if it checks out and then see where it goes from there. I have seen complete 428's in my area go for $1400 to $2400, when they rarely pop up.
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post #6 of 6 (permalink) Old 02-05-2019, 05:15 PM
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Originally Posted by bigD View Post
428's & 455's use to be in high demand. But, since the cheap 400 block stroker assemblies came along, the 428 & 455 blocks are not worth as much. And since the 428 didn't come in an A-body or F-body, there are not many guys restoring 428 cars.

Guessing that a good 428 or 455 block might not be worth more than maybe $600, unless it was some rare 455 HP number.

I assume that a 481988 400 block is one of the most common desirable blocks nowadays, for stroker builds.

I suppose pinion head would know more about the current block values than anybody here.
I agree with this. A stroked 400 block gives you the added inches with a stronger bottom end and better oiling. Back in the day, the 421, 428, and 455 were the holy grail. To some, they still are. Depends on what you are after. Many see the 428 as the perfect compromise between the high revving 400 and the torque monster 455. It has tons of power AND torque. For a '67 car, I would be inclined to build the 428 because it was a period modification done back in the day. Again, depends on what you're after. Years ago, my '65 GTO had a 428 in it when I bought it. After I blew it up, I built up a period correct 389 and never looked back. My 389 actually runs harder than the old 428 did (higher performance build vs stock build). If you want to sell the block and crank, $600 or so would be a real-world price.
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