77 400 Pontiac rebuild
 

Hello All,

I'm new to the forum and want to say hello.

I own a 1977 Grand Prix LJ. I looked for this car for over 20 years. Finally I found the one I was wanting!! It had all the options I was looking for. So happy to have found her. Anyway I am in the process of making it truly mine. I will be taking out the engine soon for a rebuild, and painting the car. I have a plan in mind for the way I want it to perform.

I know for a fact that the Pontiac 400 is a different animal. My frame of reference has always been Chevy engines. I would appreciate any advice for this rebuild. I want to get this right the first time, if you know what I mean. Does anyone know the best headers to fit this engine with D port 72 cc aluminum heads? Also just good solid advice on parts that work and perform well together? I have a Edelbrock performer RPM intake and 800 cfm carb installed now.

Appreciate any info..........

Thanks Gregg

Welcome to the PY forum !

If you have a casting number 500557 or 568557 block, I would not spend that much money on it. Those "557" blocks have thin, weak main webs, which have failed in numerous engines.

Since you plan on alum heads, you obviously want more power. So, I recommend putting larger chamber alum heads, on either a 455 or a 400 block stroker shortblock.

Here's an example.

http://lenwilliamsautomachine.com/455_Short_Block.html

If you go with a 400 block stroker, I'd go with a FORGED crank upgrade, which will cost $300-$400 extra.

A 400 block storker, with 87cc Edlelbrock D-ports, would make a nice streetable pump gas GP engine.

https://butlerperformance.com/i-2445...tegory:1287735

KRE has 85cc D-ports, but do not have the exhaust crossover hole. They are a little cheaper than the Butler/E-heads.

http://www.krepower.com/Pontiac%20Al...er%20Heads.htm

I wouldn't go overboard with the cam.

The Summit 2802 is a decent & cheap 455 cam.

https://www.summitracing.com/parts/s...RoCJdgQAvD_BwE

Here's a few more.

Crane 283951

https://www.summitracing.com/parts/c...IaAusEEALw_wcB

Crower 60243.

https://www.crower.com/camshafts/pon...m-284-hdp.html

Voodoo 268.

http://www.lunatipower.com/Product.aspx?id=1776&gid=287

Howards 410051-14.

https://www.summitracing.com/parts/h...w/make/pontiac

Well, you'll get lots of different opinions on cam choice, depending on what cubic inch you choose, how much power you want, and your budget.

But, I think we can all agree that you need to have it built by somebody who knows & has experience building Pontiac engines. Some Chevy guys can really mess up a Pontiac build.

Good luck with your build !

Welcome! I remember when my schoolmate and next door neighbor got a one year old '77 GP after we graduated high school. Pretty car, pale metallic green with white vinyl top and interior.
He raised the hood and there sat a Buick engine! That blew my mind..lol, so if that's the original engine, count yourself lucky to have gotten one of the last Poncho V8s.
https://www.nytimes.com/1977/03/15/a...sinful-to.html

Thanks guys....... Yes I do have the original Pontiac 400 in mine. I have read a lot about all the screw ups by GM back in that era.... I would have been upset to find a different engine than was supposed to be in the car as well. I have been researching the paint color for my block....... around 1976 / 19 77 years it seems GM abandoned the "Pontiac Blue" color and painted blocks in what they call Corporate GM Blue........

http://forums.maxperformanceinc.com/...1&d=1520366998

Picture of my Pontiac

Nice Grandprix :3gears:

I'm looking to have a good solid 450 HP or so when I'm done with this rebuild. I want it to run on 89 octane....... I'm not looking for it to be an everyday driver...... just want to be able to drive it to car shows and around town every once in a while. I have an engine builder to help me but as I mentioned before, I know you all probably know some things that work well and not so well........

I just got back from tooling around the country side and drove through town........ this car renews my soul every time I take it out..... Nothing IMHO duplicates the feel of it!!

But, I think we can all agree that you need to have it built by somebody who knows & has experience building Pontiac engines. Some Chevy guys can really mess up a Pontiac build.

Good luck with your build ![/QUOTE]


For Sure...................

For Sure...................[/QUOTE]

Where are you located , I'm sure all member's here have their local Pontiac Guru.

Wow, that is a super nice '77..

77? Good choice. I owned 3, all SJ's. Great cars. You'll love it.

Welcome my Friend!
We both live near Terre Haute IN.
I help him as much as I can and told him he would get good info here.

" I'm looking to have a good solid 450 HP or so when I'm done with this rebuild. I want it to run on 89 octane..."



The "557" blocks are said (by some) to be good to 400hp. Some have lived beyond this. Some have failed below it. It's a gamble and YOUR choice. I'd save it, for possible future resale, and build using a 455 block or a non-557 400 block.

You can make 450hp with a 400 cube engine. But, it's so much easier with 455 or more cubes. Plus you can do it at a lower rpm & have more low end torque.

Your call.

"...We both live near Terre Haute IN..."

Looks like ya'll are not too far from Paul Sandoval.

http://www.sandovalperformance.com/contact

Less than 4 hours from Paul Knippen. He posts here as Paul K , I believe it is.

https://www.facebook.com/PaulKnippensMuscleMotors/

Some have mentioned this guy, in East Troy, WI.

https://www.bizapedia.com/wi/schican...mance-llc.html

It's a little over 5 hours to KRE.

http://www.krepower.com/

Just under 6 hours from Butler.

http://www.jbp-pontiac.com/

About 6 hours from DCI.

http://www.dcimotorsports.com/servic...ngine-builder/

Hey, looks like ya'll are surrounded by Pontiac engine builders. But the cheapest decent Pontiac crate engines I'm aware of are built by Len Williams. He's in OK.

http://lenwilliamsautomachine.com/Home.html

Thank you all for information,

A couple of questions............ Do I for sure have a 557 block that is suspect to failure? Is there an easy way to figure out if I have a 557? What exactly fails on a 557 block? I would think any block is susceptible to failure. :confused: I would really like to keep original block in my car if possible.

As I mentioned earlier I have no plans to race this car...... just a burnout here and there and a highway dive now and again. Are the failures of 557 series due to stress issues?

again thanks for your information,

Gregg

"...Is there an easy way to figure out if I have a 557?..."

The casting number is on a pad below the rear of the passenger side head, as seen in the 3rd pic below.

"...What exactly fails on a 557 block?..."

The thin main webs crack at one of the main cap dowel pins holes, as you can see in the first 2 pics below. I've read that Pontiac tried some hollow dowel pins(4th pic), in place of the solid pins, so that the pins would absorb some of the stress and possibly reduce the possibility of cracking the web.


Has worked for some---broke for others. Many have bragged about how much power they made with a 557 block & how long they lasted. How lucky are you ? :confused:

IMO,450 real HP with a 400 wont be a very nice driver especially trying to run 89 gas.Tom

I love Grand Prix's... but low comp. 400 + buckets of cash = 450 HP
 

[QUOTE=1977GPX;5855526]I'm looking to have a good solid 450 HP or so when I'm done with this rebuild. I want it to run on 89 octane.......

"I would really like to keep original block in my car if possible".

considering the 2 statements above are a stretch of what is possible and a definite money pit.....

I recommend pulling the 557 engine and preserving it for the future.
Buy the engine of your dreams (450 HP) , drop it in and do some burnouts.
You will also need to replace the 8.5 BOP rear end after you bust the case open with 450 HP.
Then the Turbo 400 tranny will get smoked 'cause it is in the middle of your latest upgrades.

You need a detailed plan of how to get to your end goal...and a pile of money to execute the plan!!!

This site can help you with the plan.

The 557 block is not how to get there.

Dave

Dave,

I should have mentioned this but forgot. I have already replaced rear-end with a posi-truetrack I had a reputable guy put it in for me last summer. He assured me it would take the HP that I was wanting, and would stand behind it if anything happened.

I also had the TH 400 taken out and rebuilt and reinforced to handle the 400 plus HP as well. Again this was done by a reputable local guy, that also said he would stand behind it as well. I trust both of these guys.

This 557 cast block thing is giving me concern. I really appreciate your advice. Going to talk to my builder and show him all this information. I’m still not sure if I have this block yet.,... but it’s sounding like I probably do.

If the block is the matching numbers block to the car, it will be the 500557 block

The 481988 basically were cast to the end of the year 1974, I have one that came in a 75 Transam, has a date code of Ixx4 , but stamped 75.

Their were some 481988 blocks for W72 Transam untill 1978.

Doing a search on the forum wil lget you all the info you need,