[fredo4000]

Hello,
I have a 79 400 4sp out now out of a ta. Stock 3:23 rear. The block has about 120k on it. The trans has a newer duel friction clutch. I am planning on using the stock q-jet, manifold(modified?) and distributor. I like everything to be stock except internals.

What are my limits with the 6x-4 heads which Im going to use? The heads will probley recieve just a clean up and valve guide replacement and new valves. I have a set of Hooker Super Comp Headers, street version. What are my limits as far as cam selection if I decide on doing a 30 over and use a 455 eagle crank, improved rods and pistons?

I'm looking for alittle noticable idle, and 1/4 mile times in the low 13's. I don't want to waste money on a miss match combo of parts. Max rpm in the 5000 range.?
Ive seen big cube kits out there, but given that im going to use the stock carb modified for the cam and engine and the manifold, not sure of the approach and hoping I'm not missing something here........Thanks for looking ...Mike

[Mr. P-Body]

Mike,

The combo you speak of is quite common. The carb is an 800 CFM unit, so with a little tweakage, it's just fine. Talk to Cliff Ruggles about that one.

The 6X heads have excellent potential. ALWAYS "upgrade" to the 1.77" exhaust valve. Some judicious port work will get you easily to the 500 HP level. Your stock intake can have a bit of work done, as well, making the whole package "come together".

Depends on your budget, but we've been using more and more of the Comp XE solid roller grinds. There are a couple of VERY effective flat-tappet solids, as well. For a hydraulic, flat-tappet, I wouild recommend XE274H for this build.

You will read and hear the late lock is no good. In truth, it's NOT as strong as some of the earlier castings, but to the 500 HP level, it will be fine.

I also advise buying a complete rotating kit rather than trying to "piece" one together. Eagle's offering is as "sorted out" as any out there. Good stuff!

Jim

[77TA406]

Also, using the 6x-4 heads on a 400 will require milling the heads a lot and zero decking the block in order to get the compression to a decent level. Most people don't recommend using pop up pistons. When I built my 400, I elected to go with a early casting, 72cc iron head and a TRW 2262 pistons with a 12cc total dish to put the compression where I wanted it. Low 13's will probably reguire some chassis mods to get it to hook good enough. I'm really happy with the way my mild 400 runs. Speeds are right around 104 mph, but my best et is a 13.70 due to poor traction. Jmho
Chris

[fredo4000]

Thanks for the replies. It helps to pinpoint the fact its all in the type of headwork done. After looking around at some kits I thought maybe using the 468 eagle kit with the Ibeams for the bottom end, the xe274h comp kit, comp 1.5 rollertip rockers, felpro gasket kit, mod the quad, and intake manifold to match the headwork. The problem is to what degree of modification to the heads is required given that parts list? 3angle valve job, new valve guides, new ss valves 2.11/1.77 and how much porting and smoothing of the intake and exhaust runners are nessary. How do you know if you send them out to be reworked your not being ripped off? I couldnt tell a good job from bad job. I hear all these flow rates talked about, but it all seems kinda greek to me..Is using a 468 kit gonna jump my compression just my increased cids? Do I need to mill the heads any further? looking for 9.5 to 1 comp.....?

[440GP69]

a 468 with 6x4 heads is an awesome combo, my 463 is ending up at just under 9.5:1 with 96cc heads, you should remember when you put a 4.25 stroke crank in a late block like yours will add a lot stress, 468 is a better way to go but i would recomend an earlier block for a 500hp build, 375-400hp would be getting iffy IMHO, the heads will need porting to hit 500hp for sure and Jim at CVMS aka Mr P-body is one of the best at putting together one of these setups, I highly suggest talking with him before you decide on anything because he can point you in the direction you want to go and he can build one of the best engines out there, JM2C

[Mr. P-Body]

The Eagle "kit" consists of high quality H-beam rods, light weight forged pistons, plasma-moly rings and Clevite bearings (we sub in Federal Mogul mains, as they're 3/4 groove instead of "full groove"). While some of this MAY sound like "Greek", it means the stuff is among the highest quality. The crankshaft is cast steel, rather than forged steel. At the power level you desire, this is not an issue. The cast crankshafts are known to withstand 700 HP all year, and 800 in some applications. At the 500 HP level, they'll be fine.

Thanks for the vote of confidence from 440GP69. However... We DO believe the later blocks are fine until the 600 HP line is "crossed". The larger displacement DOES raise the compression significantly. The 6X heads are quite well suited to this application. Only a "clean-up" cut is required to get to around the 9.2-9.5 range. No reason to "press the edge" of compressoin for a pleasure-mobile. If it were a "class racer", that would be a different story. By keeping it under 9.5:1, you can usually count on fuel to NOT upset the "mix".

We (CVMS) tend to emphaisize more the final power output and drivability, rather than flow numbers and other indicators of "potential". Flow numbers are no guarentee of power, but just another indicator. We also believe too much is made of "cnc" porting, as a marketing tool, and also, no guarentee of performance. We use good old fashioned "work" to get heads where they need to be. Since every application is different, it's unreasonable to think a "one size fits all" approach is better. A professional head porter doesn't need a machine to maintain consistency. Typically, we spend about 10 hours on the porting bench for a real strong 461 application (500-plus HP).

Jim

www.centralvirginiamachine.com

[PunchT37]

Also, if that`s a PWH code block, or origional `79 w-72 4 speed block, then it`s NOT the "557" block or weak block. Check the casting in the rear and look for "XX" in the valley center and "400X" on the side.

[fredo4000]

Thanks For All the replies.
I have the block broke down and it has the x x in the lifter valley. And is stamped PWH. The block and trans match the vin#. So to me it looks like the W72 block and not a transplant or service replacement.
So maybe a Butler or Eagle 461 kit w/cast crank and comps xe274h kit and limited head work and a stock manifold workover would not be a mismatch? Im gonna guess adjustment on the apv on the quadajet, check plug color and jump jets if need be? Reguarding the head work and adding 1.77 valves, it seems the shops I talk to say I would be better of buying new heads rather then spend the 1100-1500 to set the 6x-4 heads up ? And if so would just cleaning up the heads now with the 2.11 and 1.66 kill the cam? Would the comp XE268H kit be a better choice then? My guess would be Id be in the 375hp range....?

[HaloMedic]

Please correct me if im wrong, im still on the learning curve when it come to building pontiac engines,
with a 1979 block, the thinner cylinder wall, will any mod past 400 hp last, and then the heat, any mod on this year engine, will you need to change to a lower vol.water pump or to one that is more efficient, and a better radiator, didnt want to hijack the thread.

[vtxman]

Originally Posted by fredo4000

Thanks For All the replies.
I have the block broke down and it has the x x in the lifter valley. And is stamped PWH. The block and trans match the vin#. So to me it looks like the W72 block and not a transplant or service replacement.
So maybe a Butler or Eagle 461 kit w/cast crank and comps xe274h kit and limited head work and a stock manifold workover would not be a mismatch? Im gonna guess adjustment on the apv on the quadajet, check plug color and jump jets if need be? Reguarding the head work and adding 1.77 valves, it seems the shops I talk to say I would be better of buying new heads rather then spend the 1100-1500 to set the 6x-4 heads up ? And if so would just cleaning up the heads now with the 2.11 and 1.66 kill the cam? Would the comp XE268H kit be a better choice then? My guess would be Id be in the 375hp range....?

It is my understanding that this XX block is as good and strong as any Pontiac block and would be a great candidate for a 461 Stroker kit. I have the same block and I going with the Butler kit.

As far as the heads are concerned, I think there are two choices. Send them to Dave at SD performance or buy aluminum Edelbrocks. For a little more than $1000 Dave will port and build the heads with all new components as well as convert to 1.77 valves. This is the route I am choosing with my 6X heads. I want my engine to look stock, and therefore the aluminum Edelbrocks will have to wait for another build. You local machine shop will probably be upwards of $500 and what do you get? Maybe guides and a valve job.

Here is a link to Dave's site for a list of what you get with his package. An incredible value.

http://www.sdperformance.com/listPro...p?categoryID=5

[440GP69]

yep sd-perf is great to deal with they are doing my 260cnc ported 6x heads, but don't overlook Jim at CVMS he is also the "MAN" don't be shy give him a call, the xx or w-72 block is plenty strong for a stroker build!

[fredo4000]

Thanks again for the info,
That was my thought on the heads. I really like the stocker look. And if they can be mproved to work at a good level with the 461 stroker kit and the XE274H kit that could be nice. I too am one the learning curve. I had picked up Jim Hand's book on pontiac building, very good read.
Also talked to comp cam support on that 274h kit. The tech said there would be no issue with the build, said 284 was alittle to much and said that the 268 kit was alittle short on rpm. Also said I could use stock rockers and pushrods, not that I am but thought that seemed alittle bit of a stretch.
Maybe this 274 is not that radical. Not sure how it is really gonna turn out with that cam as you can't just shop them llike you would a LCD tv or something. And as I understand it again, its the degree of headwork that would dictate how well the engine will respond, as wellas carb and intake work..

[440GP69]

not too many will tell you what cam to use but i would recomend a crower ram air 4 cam 231 in 240 ex .516 lift with 1.65 rockers 113lsa and i feel is a better cam for a 9.5:1 460+cid stroker i think the 274 cam is ok in a 400 but use what ever you want, Jim Hand has had a lot of success with the ra4 cam as have i and many many others!

[vtxman]

I agree with 440GP69.

The Crower #60919 is a proven cam in that application, and is what I will be using in my stroker build. I currently have the Summit 2802 in my .060over 455 (469 cubes) and I couldn't be happier with it. 2500 rpms and up, it is unbelievable. The 60919 should be a step up from the 2802 cam.

Another cam I like is the Crower 60310 Solid lift. I haven't tried it yet, but I have read great reviews on it.

These are some of my favorites. Hope that helps.

[fredo4000]

Update; dropped off the block and heads. Chose the eagle 461, 6x-4 with Ferrea 1.77 with some porting added. Went with the crower 60919. Stock intake and hooker headers. Gonna get a quad upgrade kit for the motor specs from Cliff Ruggles. Will the stock fuel pump, proline distibuter replacement be good enough? Trying to cover all my bases before dynotime in the next month. I'll video the engine pulls and post. Please keep in mind its my first real build and trying to get it right the first time.
Thanks the responses. Mike

[Transam Stripper]

If that block was mine I would get another to rebuild. That PWH is a rare block. I wish I had my PWH for my car. It gone before I ever got the car. The PWH is really rare. As far as I know all PWH blocks had a XX. For the people trying to restamp a block for '79 T/A it would have to be a XX block to start with. I'm happy to see I'm not the only one hopping up a rare '79 T/A. I love my 428 and wouldn't put it back stock if I had the original motor.