Pontiac 400 build - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Hotrodding Basics
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 03-08-2012, 08:17 AM
Registered User
 
Last photo:
Join Date: Mar 2012
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Pontiac 400 build

Hi, I have a 1978 trans am in restoration, it has the Pontiac 400 in it with a turbo 350 transmission, I would like to build the motor, but would like some advice as to the best way. Some questions I have are, should i bore it out and put a 461 stroker kit in? Is this motor able to be twin turboed, and if so how does the block hold up? What kind of cost/power ratio am I looking at? What transmissions are best at which power levels, and what would you recommend for a rear gear ratio? If there is anything you would like to add that may be helpful, such as links to where I might find the products you are recommending, or anything to do with the car would be much appreciated.

Thanks for your time!

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 03-08-2012, 09:09 AM
68NovaSS's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Working with chromed bolts
Last journal entry: New to me T-Bucket
Last photo:
Join Date: Sep 2002
Location: Nine Mile Falls/Suncrest, WA
Posts: 5,284
Wiki Edits: 9

Thanks: 113
Thanked 139 Times in 130 Posts
For answers to your questions you need to tell us what you want, not have us tell you what we want. What are your goals, budget, intended uses, street, street strip or strip only? Twin turbos on the street....pretty aggressive thinking and high dollar. I've not gone turbo before, but would estimate $10 to $15k for the motor to make it right. I've got more than that in a prostreet 8-71 roots blown 383, doing my own assembly, not including the drive train or chassis.
__________________
Boost adds dignity to what would otherwise be a vulgar brawl...

Midnight Sun Street Rod Association
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 03-08-2012, 12:06 PM
WDCreech's Avatar
Grumpy Old Goat Herder
 
Last photo:
Join Date: Apr 2006
Location: Anchorage, Alaska
Age: 71
Posts: 1,331
Wiki Edits: 0

Thanks: 3
Thanked 35 Times in 33 Posts
As 68Nova said, we need more info. The first thing that you need to do is check the casting number of the block. You'll find the location of that number in the picture that I posted. Any number other than #500557 would be okay to build to a performance engine. The #500557 block was cast with thinner main saddles and won't stand much hopping up. I think 400 HP would be pushing it.

Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 03-08-2012, 06:03 PM
Registered User
 
Join Date: Nov 2011
Location: Virginia
Posts: 705
Wiki Edits: 0

Thanks: 0
Thanked 75 Times in 75 Posts
To add to what Bill has said, the "other" '78 block is the"988" (last three digits). That block IS as up to the task as any of the 400s. It will have a "XX" code on the front.

If you have the 557 and want to upgrade, find a 400 with the "good" numbers. These are more desirable than a 428 or 455 block due to the excessive main journal diameter in the "big" ones. A stronger engine can be built from the 400, regardless of what displacement you're after. The earlier 400s ('67-mid-'75) are still plentiful. Of course, a "screamin' deal" on a 428 or 455 wouldn't be ALL bad... But any more than a couple hundred, they're better left to the collectors. Good cranks are cheap.

As for the higher level stuff you speak of, yes, it's all "out there". The Pontiac enjoys a strong aftermarket and is a very effective power plant.

Decide what you want it "to do", and how much you're willing to spend. We can certainly help you.

Jim
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 03-08-2012, 07:00 PM
Registered User
 
Last photo:
Join Date: Mar 2012
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Well, I am a beginner, I am going to Lincoln tech here shortly for my associates degree. What I want is enough power so be intimidating on the street, what kind of horse/torque can i look for out of this block? Is 500 asking alot, assuming the casting code isn't 500557? The turbos can wait, because, looking at my budget.. the car is a sitting project that i throw some money into a couple parts or a kit when i am able to. Just looking for ideas. I pretty much want a car that can bark, and has enough bite to back it up if you know what i am saying. I will be getting the casting code within a day or two. but for now assuming it isnt a 500557 code, and doing it the cheap way with just cam, pistons, and stuff, with no boring or getting to high in compression. I was told flat top pistons would be best but that is about it.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 03-08-2012, 07:16 PM
Registered User
 
Last photo:
Join Date: Mar 2012
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
hoping to get like 350 horse and like 400 torque to the back wheels if possible, for now. also with this power, if i wanted to up the gear ratio from 2.73, what should I switch too? How much would this effect rear wheel power?
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 03-08-2012, 07:59 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by Phoenix7828
Hi, I have a 1978 trans am in restoration, it has the Pontiac 400 in it with a turbo 350 transmission, I would like to build the motor, but would like some advice as to the best way. Some questions I have are, should i bore it out and put a 461 stroker kit in? Is this motor able to be twin turboed, and if so how does the block hold up? What kind of cost/power ratio am I looking at? What transmissions are best at which power levels, and what would you recommend for a rear gear ratio? If there is anything you would like to add that may be helpful, such as links to where I might find the products you are recommending, or anything to do with the car would be much appreciated.

Thanks for your time!
Knowledge is power.

I'd suggest sticking w/an NA build at first, then later on add the turbos, etc. if you still feel the need.

Before going too far, check the block numbers to be sure of what the displacement really is, and to see if the block is the stronger 400 or not. But regardless of the casting number of the block you have, if it's a 400 it will handle 350 to 400 HP w/a stock 3.75" stroke as long as there's no nitrous or boost involved and the RPM is kept reasonable (</= 6000 RPM).

Keeping the revs down isn't an issue when building a Pontiac engine when using a streetable hydraulic valve train and factory D-port heads, and the cast rods- if inspected, given ARP hardware, and resized- will suffice, although forged rods are a plus if they can be afforded. Stock crank is fine, too.

You have the good 8.5" 10-bolt "coporate" rear end in your F-body. Every stock T/A I've seen has had a posi from the factory. The 8.5" corporate rear end uses a 2-series differential carrier for 2.41 and 2.56 gears and a 3-series differential for 2.73 and lower (higher numerically) ratios. This means if you have a 2.41 or 2.56:1 rear gear ratio that you'll need a different carrier to use a performance ratio.

The ratio code is stamped into the axle tube but can be hard to read and the gears could have been changed during the life of the car. Instead of relying on the code, use one of the procedures shown HERE, or just pull the rear inspection cover to count the teeth or look for the ratio stamped into the ring gear. This gives you an opportunity to see the gear condition and change the fluid.
NOTE: The gear lube stinks to high heaven, put down sand or speedy dry, lots of newspapers and a big pan to catch it and do not get it on you unless you want to stink for a few days.

Don't go overboard w/the rear gear ratio. I'd not use anything steeper than a 3.73, and personally I like less gear- like 3.36-3.55-ish because through the years I just grew tired of buzzing down the highway at elevated RPM. If you use an OD automatic, this advice goes out the door- you can run a LOT of rear gear if you have a 0.7:1 OD.

Same thing w/the torque converter- no need to over do it. The Pontiac makes good torque from low in the power band and too much stall speed could pass much of that torque by if the converter isn't matched to the powerband. You do want a strong converter, though.

This barely scratches the surface but along w/the other advice, this will give you a starting point.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 03-09-2012, 08:12 AM
Registered User
 
Join Date: Nov 2011
Location: Virginia
Posts: 705
Wiki Edits: 0

Thanks: 0
Thanked 75 Times in 75 Posts
500 HP is a slam-dunk. A 400 with a good "solid" cam, lightly ported heads and good induction/exhaust will get there on 93 octane.

WADR, reusing the cast rods is a recipe for disaster. The cost of resizing the ("junk when new") cast rods, with good bolts, is within $50 or of a set of 5140 forgings. For every "stock rod success", there are 100 Pontiacs in scraps heaps with cast rods hanging out of the pan.

Agreed, at 400 HP, the 557 block will suffice. Not much "room for growth" though.

The Pontiac's biggest advantage is making "big" power at lower revs than other engine families. Until you pass about 700 HP, they nearly ALWAYS make more torque than HP. Very good in a heavier car, too. The 461 (400 block, 4.25" stroke) will "mimic" 455 for power output and be physically stronger.

It is possible to make the ol' Injun rev, too, though. If you have good bottom-end parts and "enough" cylinder head, a 400 can rev with anything. It takes a LOT more cylinder head to get the bigger displacements to rev, but if the budget s "there", it too, can be done.

There are many myths and superstitions surrounding the Pontiac (as with most engines this "old"). Jim Hand's book "How to Build Max-performance Pontiac V8s" published by SA Designs, can shed a lot of "light" on the truth. It's the most current study of the Pontiac and street performance. It is NOT a "how to build a race motor" book.

Jim
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 03-09-2012, 04:07 PM
Registered User
 
Last photo:
Join Date: Mar 2012
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
So, I am in love with the idea of 700 horse. Lets say I my budget is 4-5000, what can we do with that? keeping in mind I only have a stock turbo-350, so that will also need to hold up the power. And for futures sake, could you explain the ol injun rev for me?

Last edited by Phoenix7828; 03-09-2012 at 04:13 PM.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 03-09-2012, 05:04 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Besides the fact that 700 hp is useless on the street, 700 HP is asking a lot from a stock block. At 700 HP NA, there won't be much that isn't aftermarket. Turning a Pontiac into a BBC doesn't work for me, my loyalties are trumped by the practical concerns, including the cost. Ain't saying don't do it, ain't saying can't be done. I AM saying if you do the 700 HP deal, you're gonna need deep pockets, and you'll still be bumping into BBCs that will lean on you real hard.

Butler has done some outstanding work w/turbos on the Pontiac engine. If I was looking for big numbers from a Pontiac, personally that's where I'd be looking to get those numbers from- turbocharging. Getting 700 hp NA makes the engine much more high strung, too high strung for a DD IMO. If this is a W/E toy or full race deal, that's a different thing.


The engine above makes >900 hp on pump gas, and guess what? It does it at <6000 rpm. Click on the image for the entire article.

I'll leave the high rpm advice to those who do it. Personally I prefer to take advantage of the strong suit of a Pontiac- really good torque made at a relatively low rpm- and that doesn't require revving past 6000 max, and in the case of a 55, that engine can run effortless 12's in your F-body w/3.08 rear gears shifting at 5000 rpm, and can do it on 89 octane gas.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 03-09-2012, 09:10 PM
Registered User
 
Last photo:
Join Date: Mar 2012
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Okay, yea this is a street toy, I am going to be living in the race capitol of the world so I may drag it once or twice, but how much is too much power for the street? When on the street I want it to be intimidating, enough power to out run them little tuners, but not too much.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 03-09-2012, 09:29 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Trends


The engine above (click on the image for the article) is a 535 cid all-alloy Pontiac that uses a big bore/long stroke (4.35" x 4.5") along w/a relatively mild cam (248/254 duration @ 0.050" lift). This NA build makes 650 HP @ 5400 rpm/690 ft/lb @ 4400 rpm.

Another build- this one using a stock 455 block and crank- made 618 HP @ 6100 rpm/594 ft/lb torque @ 4500 rpm using a flat tappet cam w/260/268 duration @ 0.050" lift. This engine was built for the Engine Masters Challenge, so is not what one would ordinarily build for an engine that was to last. For example I'd be very concerned about losing the lobes at the kind of spring pressure they used not to mention the lifter bores, but there are crutches for this. This engine should have a solid roller cam. But again- if it was me and I wanted a durable engine, I'd be looking at the aftermarket blocks for big numbers.

The main point in mentioning these engines is to point out a trend, and that is: It does not take a lot of rpm to make good power from a Pontiac engine. All the engines I've mentioned here used Edelbrock aluminum heads. You cannot expect these numbers from D-port heads, or ANY as-cast Pontiac head for that matter. So regardless of what else you may do, plan on a set of aftermarket heads if you want to make any serious power.

BTW, the builder of the alloy engine, Ken Crocie (who also has been building Pontiac engines for about 40 years), used to be w/H-O Racing Specialties (Craig Hendrickson and Kern Osterstock. This was a Pontiac parts business and is where I used to get some of my parts from before some of the Pontiac vendors that are around today were in business. Crocie took over the business some time ago, renaming it H-O Enterprises I believe, but AFAIK its not currently in business.

I'd think that a tractable 500-550 HP would be about the limit and even there the torque is what will tax the available traction. Another plus to a turbo is that the power comes on in such a way that you can (mostly) control it. But a NA 500-550 HP engine should give you a lot of fun and street cred to boot.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 03-10-2012, 11:43 AM
Registered User
 
Join Date: Nov 2011
Location: Virginia
Posts: 705
Wiki Edits: 0

Thanks: 0
Thanked 75 Times in 75 Posts
I was not suggesting to build a 700 HP engine. I was indicating the accepted power limits for practical applications using the stock block. 600 HP on "pump gas" is quite common with 461s and larger. The 505 is VERY capable without stretching any "limits". Traction seems to be limiting factor of how quick they "go".

Yes, the Butlers have more experience than most with turboed Pontiacs. Their '63 Tempest ProMod is currently the quickest Pontiac in history (6.26 @ 227, IRC) and is a turbo-charged (BIG turbo) iron block (IA-II), E-headed alcohol MONSTER!! Ken Keefer (aka "Pontiac Dude", Brooksville, FL) is another with lots of experience with power adders and Pontiacs.

Moving to Indy? Cool track. Friendly town. We try to go every year, but health and money sometimes stops us. '09 was my last trip. I hope to make it this year.

Jim
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 03-11-2012, 09:36 PM
Registered User
 
Last photo:
Join Date: Mar 2012
Posts: 8
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I am assuming I will need headers. Any suggestions on exhaust? I have also been looking at buying a functional hood scoop, the one that opens when the kick down cable pulls back. And I have the turbo-350 tranny, will that do or should I invest in the t-400

The picture below is what my motor as it sits
Attached Thumbnails
Click image for larger version

Name:	trans am.jpg
Views:	275
Size:	95.1 KB
ID:	63913  
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 03-11-2012, 10:58 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by Phoenix7828
I am assuming I will need headers. Any suggestions on exhaust? I have also been looking at buying a functional hood scoop, the one that opens when the kick down cable pulls back. And I have the turbo-350 tranny, will that do or should I invest in the t-400

The picture below is what my motor as it sits
Walker turbo-style mufflers get good reviews. I used 40 series Flowmasters that were 3" from the collector to the dumps that exited just before the rear axle- this can cause a drone inside the cabin though, and if there are any holes in the floorboards there can be CO leaking into the cabin- something that's potentially lethal.

I used sound deadener scavenged from the junkyard to insulate my '81 Camaro floor, but this can get heavy if it's the tar-type of insulation. There are insulation mats that are lighter like Dynamat and others, but this starts to get expensive so it all depends on your budget and needs. It is better in some cases to give up the potential for the most HP for a system you can live with.

I like to use a cross over between the two sides aft of the collectors and before the mufflers. This changes the frequency of the exhaust to a more pleasant tone- at least to most. I'd say for a performance 400 engine a 2-1/2" system would be the minimum, and if this is going to be a 450-plus engine, 3" would be the minimum I'd use.

Either the TH350 or 400 can be built to hold the power. The TH400 "wastes" more power and weighs more, but is cheaper in most cases to build strong enough for most streetable engines. I used a TH400, I added a better sprag, a short tailshaft and a shift kit along w/a rebuild kit (seals, gaskets, bushings, frictions and steels) and it was fine behind my 455.
Reply With Quote Quick reply to this message
The Following User Says Thank You to cobalt327 For This Useful Post:
UnderestimatedF150 (02-01-2014)

Recent Hotrodding Basics posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pontiac 400 Build dobie6982 Hotrodding Basics 8 02-18-2012 12:22 PM
Pontiac 428 build NAUBandit Engine 4 06-22-2010 09:16 PM
Pontiac 400 build up. handymann3 Engine 9 02-02-2010 07:05 AM
Pontiac 400 build up UngerMarkus Engine 1 04-05-2009 06:53 PM
pontiac 455 build help jarrettandroski Engine 3 05-07-2008 01:34 AM


All times are GMT -6. The time now is 05:26 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.