400 engine build/Arkansas Machine shop who has Torque plate

[hester6787]

I need some advise on rebuilding a 400 for a 67 Firebird. The engine is a 76 400 with 6X heads. I am looking to build it for street and strip use and for around 400 to 450 hp and Ibf of torque to the wheels. I have read How to build Max-performance Pontiac V-8s and I have got a pretty good idea of the parts I want to use and I'm looking for any suggestions.
These are my ideas:
I want to ask my Machine shop to bore the engine .03 over, Port and Polish the heads with intake runners matched, and get 9:1 to 9.5:1 cr by zero decking the block and milling the heads to the necessary amount.
I have a Edelbrock performer RPM intake.
-Edelbrock 650 carb.
-stock 6x heads
-good stock rods
-good stock crank
-th400 trany
Looking to buy:
-KB Silverlite Pistons
-Lunati Voodoo cam P#LUN-60903 kit (includes lifters, valve springs, retainers, locks and stem seals)
-Molly Rings
-Clevite 77 Main, Rod, and Cam bearings
-Melling Oil pump
-ARP Bolt set

If anyone sees any problems I'm going to run into with this setup, my goals, or machine work please let me know or any suggestions would be great!!
Oh, and does anyone know a shop in Arkansas that has a Pontiac 400 torque plate?
Thanks

[critter]

First, do not buy that Edelbrock carburetor. Even Vic Edelbrock doesn't run them on his cars. I hate them. Either get a properly built Qjet or a Holley. You'll be happier.

I'm curious on what let you to Lunati on the cam choice? They're not terribly well known for Pontiac stuff. What are the specs on that cam.

You mention 6x heads. Are they 6x-8 or 6x-4 heads? I'm thinking you might want to look at raising the compression some.

I do not know of anyone in Arkansas with a Pontiac torque plate but there has been some talk within the club of buying one and sharing it with anyone who's doing an engine build, so long as they are dues paying members. We never did get around to doing that. Anyone still interested in that idea?

Welcome to the forums!

[hester6787]

Critter, thanks for the reply.
The problem is I already have the Edelbrock Carb, it came on the engine when I bought the car.
When I get the money saved up I'll change it. I have a Qjet, but it needs rebuilt. How much would that run me?

I was planning on buying a Comp cam k-kit, but after talking to some guys they said that the lifters that come in the kit are junk and I would be better of with the Lunati cam and its about the same price so I was going to go with it.
The cam specs are:
Cam Style: HYDRAULIC FLAT TAPPET
For engines with Compression Ratio: 9:1 to 9.5:1
RPM Operating Range: 1600-5800
Intake Duration @ .050 in. Lift: 227
Exhaust Duration @ .050 in. Lift: 233
Advertised Duration: 268(Intake) & 276(Exhaust)
Valve lift with 1.5:1 Rocker Arm Ratio: .489(Intake) & .504(Exhaust)
Lobe Separation Angle: 110

The heads are 6x-8s, I think, they came off a 75 Bonneville 400, so I think they are 101 CC heads? not sure though. I would go check the numbers for sure, but they are at my parents house right now.

And yes, I'm planning to Raise the compression by zero decking the block and milling the Heads.

That sounds like a great idea to me, sharing a Torque plate!!! I'm looking to do this build by the end of this month though, so if you don't mine me asking, who do you get to do your bore work?
Also, how do I become a member of this club?

Thank you for the help, any other suggestions or oppinions on my build would be greatly appreciated!!

[Pontova]

First, I really like the Lunati cam specs you posted in a 400 with 9.5-1 compression. One thing, with unported heads I wouldn't expect much more than 390-420 HP at the crank not the wheels. Secondly, the 1976 block you posted needs to be researched to verify it isn't the weaker blocks not strong enough for high HP builds. Third, Depending on vehicle weight with the Lunati cam you listed you'll need between a 2500-3000 converter or a manual tranny for optimum performance. Forth, NEVER use hyperutectic pistons in a Pontiac, go forged or cast only. Finally, the Edelbrock carb you listed would never make big power so it would have to be a "starter" carb. Welcome to the site!!! JD

[hester6787]

Pontova, thank you for the information. I am planning to have the heads ported, polished and the intake runners matched. I'm not sure how much Hp that will add, but hopefully I'll be close to 400 hp and 430 Ibf of torque to the wheels? The block isn't the stronger block, but I'm not planning to go over 450 Hp. Will it not handle 450 Hp? About the pistons, I've heard different things about hyperutectic pistons, but you are the second person who has told me not to use them. What pistons do you like the best for a 400? I initially wanted to just use Sealed Power Cast Pistons, are those ok? And about the Carb, it came on the engine when I bought it and there is nothing wrong with it so I just I'm just going to live with it until I can save the money for a bigger one. Unless someone on here would like to buy it? When I do get the money what kind and size of carb. would you recommend?
Thank you for your help!!!

[critter]

That cam should work pretty well. I was only curious to see if it was a symmetrical cam which it is not. That additional duration on the exhaust will help.

I don't know how mechanically inclined you are but building a Qjet isn't that hard to do. Using Cliff Ruggle's book makes it easier. That carb will be fine to start with but it will seriously limit you. A 750 cfm Qjet should take all you give it but there are 800 cfm units. That's explained in his book. Any Holley 750 would be another good choice. Folks have trouble with Demon's quality control, but I have an 850 Speed Demon that has been a flawless performer for me.

There's nothing wrong with cast pistons except for the weight. Stock rods and stock cast style pistons with good ARP rod bolts will be fine if you're not out torture testing it at the track every weekend. Those KB's have a reputation for losing ring lands in Poncho motors. Some say it's due to folks using the incorrect ring gap. I for one don't care to be the gunea pig to test the theory.

The block strength is still a matter of some question. Again, it depends on how badly you intend to abuse the car. I'd say don't worry too much if you intend to be a casual racer, making 3-6 trips to the track per year. However, if I was racing every weekend I'd think about it more.

[hester6787]

Critter thank you for the reply. I'm going to College for mechanical engineering, so I hope I could figure out how to rebuild a Qjet, I don't know though, I've never rebuilt a carb before. I'll buy Cliff Ruggle's book and see what I can do.

I have some good news, I found another good 400 block and its a stronger 1973 block, the best part about it is its free. I tore it apart today and everything looks good. It has 4x heads on it and a Qjet carb with it, would you happen to know what size of carb it would be or is there no way of telling with out running the numbers? I don't know much about them. The block has date Code F293 and casting number 481988 and it has X5 on the front.

I'm still going to use my other 6x heads on my build though.

As far as the pistons, you and others have me convinced to not go with the KB pistons, I think I will just get some Sealed Power cast pistons and ARP bolts.
Thank you for your help!!
Any other suggestions or opinions on this build would be greatly appreciated.

[77TA]

I thought Marty had a plate... Id sure be interested in chipping in to buy one for club use to if that's on the table.
That cam is very close to a copy of the comp extreme energy cams and will work great with the lower compression engine.
Welcome to the board !!!

The edelbrock carb is pretty much a carter copy I think. If it works it is fine, if it doesn't they are hard to get right from what I read...

[Sam I Am]

Spend the money and get some TRW or other good brand of forged pistons. You get what you pay for, and the bottom end is not the place to try to save money.

The easy way to tell if it's an 800 casting, there is a small bump in the primary bores. If that carb is original to the 1973 engine, chances are that it is a 750 casting.
I've read that all the later model Qjets were 800 castings, but they limited throttle plate angle to limit flow, sometimes as low as 500 CFM. These "limited" Qjets will be jetted down for the original application on the smaller smogger engines of the day.
A Qjet is pretty easy to put back together, they just have some things you need to watch out for, like leaky fuel bowl plugs. Should all be covered in the Cliff book.

[critter]

Part of what you should understand is that Pontiac motors are torque motors. Most of us don't spin them all that high but if you intend to do some serious racing the lighter the rotating assembly the better off you are. I'm not sure what Johnny is running in his GTOs but I know he says he spins them on up there. If I intended to see the north side of 6000 rpm I'd be investing in a solid bottom end, just like Sam said.

That said, some have had years and a lot of passes on stock cranks, 2 bolt main caps, cast rods with good bolts and heavy slugs. They make the torque and if you don't twist them too tight they'll hold.

Have you ever priced out any of the stroker assemblies from the big Pontiac builders for your 400 block?

[hester6787]

77TA, Sam I Am, and Critter, thank you for the info.

77TA, I would also be interested in chipping in for a Torque plate. Or if someone has one I would gladly pay to use it.

The Edelbrock carb I have is on a 400 that I think has spun a bearing, I haven't taken it apart yet, but anyways, the carb has ran fine for the 6 years I've had it on the engine.
When I get this 73 400 engine build done and put the carb on, if it runs good I'll probably just keep it until I can afford a bigger one. But if it doesn't I've got a Qjet that I'm going to try to rebuild.
thanks

Sam I Am, I'll look into the TRW pistons. Are the TRW pistons aluminum? Do you know the cheapest place to get them from and about what a good price to pay would be? I agree that I shouldn't try to skimp out on the bottom end but the thing is I have a friend that has some new Sealed Power Cast pistons he wants to sell to me for $240, and that price has been hard for me to beat. But I will for sure look into the TRW's.
I got the numbers off the carb and I'm going to try to look up what size it is.
Thanks for the help!!

Critter, I was planning to set my rev limit to around 5500 RPM's, just to be safe since I'm going to be running stock rods with ARP bolts and a stock crank. Although, if I do get the TRW pistons, will that allow me to run at a higher RPM, or am I already pushing my luck at 5500? I guess what I'm trying to say is, I'm wondering how much benefit am I going to get for paying the extra money for the TRW pistons? If I could get some TRW's for around $350 I guess I would just go with them since the money is not much different.

I have priced the stroker assemblies and I have been drooling over them the whole time I've been researching this build, but from what I've seen, they are a little out of my price range right now. I've just got one semester left of College after this one and if I can find a job I plan to order one soon after!! I'm getting a little worried about finding a job though the way the economy is right now, but we'll see. The 468 stroker kits from Bulter Performance look awesome, I think they are about $1700 just for the rotating assembly though. I thought about a one of the stroker kits from eagle, but they are a little high for me too and I'm not sure what all goes into getting a stock 400 block to accept a stroker crank.

Thanks for the help guys!!
Please let me know any other suggestions you have!!

[lmd]

I need some advise on rebuilding a 400 for a 67 Firebird. The engine is a 76 400 with 6X heads. I am looking to build it for street and strip use and for around 400 to 450 hp and Ibf of torque to the wheels.

Before you spend any money on that block, you may want to first secure a way to mount it into the chassis. The 2 bolt bosses were probably deleted from the mold that block came from. The now defunct Indian Adventures use to sell conversion motor mounts, I don't know where you can get them now, I made my own when I needed them.

-good stock rods

Before buying the rod bolts, you may want to ask your machine shop if they will even install the bolts and recondition the rods, most shops do not want to mess with them considering the cost of an import H-beam rod these days.

-KB Silverlite Pistons

Ring gaps are critical due to the way the piston expands, common to pop the tops off of them regardless of brand engine they are installed. Nothing wrong with the cast pistons, I shifted a couple motors with them at 5800 for years.

Oh, and does anyone know a shop in Arkansas that has a Pontiac 400 torque plate?

Not critical.

[hester6787]

IMD thanks for the info.

I have found another block, its a 73 block and I'm hoping the mounts that came with it or the mounts I have in the car now for the 76 block will work. I'm not sure and I haven't got to check it yet.

I haven't checked with my machine shop yet about the rods, but I will for sure do so soon.

About the Pistons, I think I have decided to go with either some cast ones or some TRW Forged ones, I've heard too many bad things about the KB's.

So, about the torque plate, if I have my engine honed without one, what are the negative outcomes?

Thanks for the reply!!!

[critter]

Downside? Well, perhaps it's not quite as "round" as it should be but with that said, I'm on 11 years with my block that was done without the torque plate. No ill effects that I can see for a street/strip car.

[hester6787]

I see, well that makes me feel a lot better, because I can't find anyone who has a Torque plate for a 400. I was just under the impression from some other guys that honing with a torque plate is a must.
Thanks for the info, that will save me a lot of money not using one!!

[hester6787]

Now since I'm going to use the 1973 block for my build, I have some questions.

Will I have any trouble with moving the parts off my other 1976 engine? For example, say instead of spending the time to clean up the oil pan and the water pump housing that came on the 73 block, will the already clean parts off my 1976 block swap over?

I guess what I'm trying to say is are all the bolt hole patterns the same on the 73 and 75 engines, except for the motor mounts? Or am I going to have any issues with using internal parts off the 1976 engine. For example I plan to use the Crank from the 73 engine and the rods, from the 76 engine, any problems here?

Thanks

[critter]

No, so long as the crank and the rods can be matched up with machining. What I mean is that if the rods have been resized to the point the won't work with the cut on the crank.

That said, have you looked into the aftermarket rods that are available. I don't remember who but someone mentioned earlier in the thread about so many shops who won't mess with resizing stock rods with the aftermarket rods being available now. Depends on the price and the what the machine shop wants for resizing and reconditioning your stock rods.

I would try to stick with the accessories, brackets, etc. from the 73 block if I could. There were so many minor changes in stuff back then it might save you some headaches.

[hester6787]

Critter thanks for the reply!

I've talked to my machine shop a few times, but I haven't asked about everything I'm planning to do yet, because my plans keep changing. Right now, I'm just trying to figure out all my options and get all my parts together and see whats going to be the best parts to go with on the build. I still haven't had the time to get the 76 engine out of my car yet. The problem with the 1973 engine is the block is really good, but I was cleaning up the valley tray today and water has set on the top of it for too long and has rusted some really small holes through the top of it and I think the water pump housing may be no good also. I know the valley tray and the water pump housing off my 1976 block are good, so that is why I was wondering if I could swap them over to the 73 block. And about using the rods out of the 76 block, the reason I was wondering if they would work is because if I won't be able to use them in the 73 , then there would be no need for me to disassemble that engine when I get it out of my car, I would just go get some new ones.

But anyways, I'll look into some new rods just in case.

Also, the motor mounts in my firebird work fine with the 76 engine, do you think there will be some issues with making them work on the 73 engine?
Thanks for the help!!!

[critter]

I'm fairly certain the 73 block will have all 5 bolt holes to be able to mount the early and late motor mounts. Double check it but I think you're OK there. Guys, am I correct?

OK, gotta ask the all important question. You keep mentioning your machine shop. Do they know Pontiac motors? Keep in mind that they haven't built these suckers since 1978. There's a lot of guys with shops who think they can build anything but they Pontiac motor has some peculiarities all their own.

I know the valley pan and water pump cover should swap between the two. The only thing I'm saying is stuff like your pulley setup, power steering, alternator, etc. might be easier to fit if you transfer from the same year.

[hester6787]

Critter thanks again for the info.

The 73 engine has the 5 bolt holes, so hopefully that will work out ok and mount up with no problems

I plan to have my Machine work done at West Cylinder Heads in Arkadelphia. Somebody please let me know if this is a bad idea. The reason I chose them is because I had heard from lots of people that Brad West does great head work so I called him up and talked with him about what I'm planning to do and he seemed like a great guy. Initially, I had just planned to have him do the porting and polish work on my heads, but after talking to him for a while he seemed very helpful and willing work with me on getting the most horsepower for the money I'm wanting to spend. Yet, he was honest with me from the beginning and said he doesn't specialize in Pontiac engines, but I don't really personally know any other guys that do machine work and from all the other machine shops I've talked to, he seemed the most honest and helpful. Now, thats all I'm going by here, so if anyone knows someone who would be a better choice, please let me know. I just really like the idea of getting the head work and the block work done at the same place, that way there is no confusion on the compression ratio I'm wanting and all the other things that go with getting this engine built right.
That being said, I would still love to hear some suggestions on other machine shops if someone knows of a really good one thats not going to kill my wallet and that is within reasonable driving distance from Russellville.

I learned a lot from reading How to build max performance Pontiac V8's, but I really don't know just a whole lot about machine work on engines and so I'm very interested in knowing and understanding what exact peculiarities that the Pontiac motor has that are different from say an Chevy motor?

Sorry for all the little questions, I'm still learning.

Thats great news on the valley pan and water pump cover because I'm pretty sure the ones off my 73 block are junk.
But, yeah I'm pretty sure all the pulley setup is fine that I got off the 73 engine so I should have no problems there.

Thanks for all the great info, sorry if I sounds like I'm trying to get ahead of myself here on this build. But, I just don't want there to be some dumb little thing that I didn't consider that holds me up when I get all the parts back from the machine shop. I'm hoping to have all my ducks in a row so this engine will go back in the car smoothly, if that is ever possible. lol

Thanks again for the help!!!