Topic: 1978 Trans Am - 400/W72 rebuild question.

[Daniel78ta]

Hey guys...
I have a 1978 trans am with the W72 400 in it. Currently has 67k original miles.  I'm saving up to have it re-painted if a few years but, I want to rebuild the motor and transmission first.

Below are some things I would like to do to add a little power to the motor when it's rebuilt.  I'm not looking to built a powerhouse but, something with a little more noticeable power!
Will the following give me a noticeable power increase?

1) Complete motor rebuild / bearings, rings etc
2) Port and polish the heads / head rebuild
3) Port the intake to match the heads
4) have the valves ground
5) possibly deck the heads
6) slightly bigger cam than the stock W72 cam
7) Ram Air Restoration headers
true duals all the way back
9) rebuild the Quad 800 CFM carb.
10) have everything repainted to look like new.

Will these things together give me that noticeable power increase I'm looking for?  I will not be racing it or anything.. Just looking for maybe a 50 to 60 HP bump with more torque that's super reliable.  The stock W72 has 220hp.  Think that would bump me up to near 280?

Thanks guys
Dan s
Cedar falls, Iowa
W72 / WS6

[72blackbird]

Hi Dan,
The mods you listed will put you in the 260-280 hp range with tuning, but with 67k mi. you could do the bolt-ons, heads and cam and still make around 275 hp without rebuilding the shortblock (provided your oil pressure and compression is good). You can rebuild your shortblock with cast pistons and rods, but once you've seen what detonation can do to cast pistons you'll use forged pistons from that point forward. Cast rods will also be fine, but forged 5140 replacement rods cost $250/set, ready to run with ARP rod bolts- cheap insurance for an occasional lead foot or a missed shift. Upgrade your stock 2-piece spin-welded valves to 1-piece forged stainless valves along with forged pistons and rods and your 400 will be near-bulletproof.

In addition to these upgraded parts I would have the rotating assembly balanced and the block zero decked- these procedures not only ensure good bearing life, but also reduce detonation and help your engine build power.

Geno

[Daniel78ta]

hey Geno.
Thank you for the advise!  I will look into them forged pistons and rods. If going that route I might as well have the blocked punched 30 over!  When you stated - having the "rotating assembly balanced" - I'm guessing you ment on having the crank balanced! Since I'm not building for racing or super high RPMs is I really necessary?  But, extending the bearing life is a plus!

I really appreciate your input... My end game plan after the motor rebuild is to have the car professionally tore down and repainted with all new decals. It's a tall and expensive order but, hopefully I can reach that goal.....someday!

Thanks again.
Dan s.
Cedar falls, ia
W72 / WS6

[72blackbird]

hi Dan,
I see Sealed Power forged pistons for around $350/set on Ebay, summit and Jegs all the time. Pontiac parts vendors like KRE, Butler, CVMS, and Ken's Speed and Machine all sell the 5140 rods for around $250/set, so you should be able to find them as well. I recommend using a Best Gasket graphite rear main seal too- I've used them in my builds for over 6 years now (no customer reported problems to date).

A balanced assembly benefits a street engine by allowing the engine to operate and rev smoother- it also puts less wear on the bearings, so even though you may not be building a 500 hp 400 or revving it to 6500 rpm it will definitely help your engine live longer. I have all of my builds balanced- cutting corners like omitting balancing is a quick way to get a bearing oil film failure and a rod knock. It's definitely better to spend a little more money and have the engine last much longer.

Typically the first overbore most Detroit V-8 engines get is to .030", to get rid of the taper at the top of the bore (where the most cylinder bore wear occurs). Sometimes .020" over pistons are also available, depending on the manufacturer. Your machinist will tell you what you need.

Geno

[Daniel78ta]

Thank you Geno...
Your advise has been very helpful. 
Now for the not so fun part which is saving us the rest of the $$$$ to get it done!!

thank you again
dan
cedar falls, ia
W72 / WS6

[Daniel78ta]

Hey Geno...
one last question for now... From what we discussed on my rebuild - would you have a suggestion on what cam i should use? 

Im looking for one thats more efficient with a tad more throaty sound than my Stock W72 cam in my 400.
I dont want it to be super choppy.  Maybe just a little more beefy - Semi Smooth idle but, sounds like it has a little more balls than stock. 

My Stock W72 Cam:
Advertised Int/Exh:   274/298
Int/Ext Duration @.050:   192/210
Gross Lift Int:  .395
Gross Lift Exh:  .401

Lots of cams to choose from.. You have a lot of experience in this area so, i was hoping maybe you have a suggestion!  Manufacturer & Size? 

thank you Geno..
dan s
cedar falls ia
W72 / WS6

[Chuckles]

I actually like the Edelbrock Torker-Plus cam and matched intake.

http://edelbrock.com/automotive_new/mc/camshafts/locator.php?part_number=5057&submit=go

[72blackbird]

Hi Dan,
There are a few cams I would recommend for a 8-8.5:1 400. The Crower 60240, Summit 2800, and Crower 60916 all would work well- these are all 112 LSA cams that produce good vacuum for power brakes. Of these three, the 60916 will sound just a little more rough than the rest, but not as lopey as a 110 LSA Comp cam XE262H. The 60916 also has the most lift of the three (.455/.470), so you will get a bit more cylinder filling and more mid range with a performance exhaust.

You will also have to switch over to an adjustable valvetrain with poly locks and straight rocker studs since you will have more cam lift than stock, but this should be done in any performance rebuild- if you don't the bottleneck studs and non-adjustable rocker nuts will cause binding and bent pushrods. Full roller rockers aren't necessary, but I would upgrade to roller tip rockers as well.

Geno

[Daniel78ta]

Thank you 72Blackbird and Chuckles. 
I will take a look into these cams you have listed..
your advise is appreciated.

dan

[Daniel78ta]

Hey Geno,

What do you think of the Crower 60918 cam?  Ever used that one?
Link to it:

http://www.crower.com/index.php/camshafts/pontiac-287-455-v8-torque-beast-hydraulic-278h.html#

You had previously recommended the Crower 60916.  I found a video on YouTube - it's a 68 GTO with that crower 60916, sounds fantastic!  A guy could clear off his driveway with that cam - no broom necessary..      For my TA I'm looking for just a little less lope..

From the research I have done - it looks like the Crower 60918 is a little step down from the 60916. Do you think the 60918 would be a good choice?  Better than my stock cam but, not as much lope as the 60916.

I like what I read about the 60918.. Just wondering if that would fit a moderate build a little better. 

Dan

[72blackbird]

Hi Dan,
The Crower 60918 does have a bit longer overall duration than a 60916, but the power range moves down a little- idle is also similar to the 60916, a healthy lope like the 60916 but a little smoother. If you think the 60916 is a bit too lopey, you'll think the same about the 60918. You would also have to mill your 6x-4's to get 9.2-9.4:1 SCR, a requirement to get power out of either one of these cams.

The Crower 60240 is the mildest sounding of the three cams I recommended to you- it doesn't sound stock, but has a small hint of what it can give. Once you're off idle it sounds nice- power range is from 1300-4200 rpm, a great daily driver cam with excellent low end and mid range power. The 60240 also works well on 8-8.5:1 SCR 350's and 400's.

Geno

[Daniel78ta]

Hey Geno..
That 60240 just might be the ticket.. It's very tempting to go with a monster of a cam but, I think in the long run I might regret it.  Something with a little more lump and more performance than the stock W72 will be great!

After some research and talking with you I think this is what will be done to my W72 400:

1) Complete motor rebuild / bearings, rings, oil pump etc
2) bore .030 over
3) forged pistons and forged rods
4) zero deck the block
5) balance the crank
6) Port and polish the heads
7) head rebuild, new springs & rockers
8 ) Port the intake to match the heads
9) new stainless 1 piece valves
10) crower 60240 cam
11) Ram Air Restoration headers
12) Ram Air UESYS-1 x-over exhaust 2.5"
13) rebuild and sup up the Quad 800 CFM carb
14) have everything repainted to look like new.
15) turbo 350 transmission rebuild

(speed pro federal mogul has a .030 rebuild kit with the forged pistons that looks good)

Also, my father owns his own auto repair shop. I have faith he will be able to get that motor tuned and running razor sharp!

At the moment this is the game plan for my 400. What do you think Geno? Am I missing anything important? In your opinion would that be a nice strong mild build that won't need lots of attention to keep up and running smooth!  What kind of HP and Torque do you think will be generated? 

Thanks Geno..
Hope all is well.
Dan s

[72blackbird]

Hey Geno..
That 60240 just might be the ticket.. It's very tempting to go with a monster of a cam but, I think in the long run I might regret it.  Something with a little more lump and more performance than the stock W72 will be great!

After some research and talking with you I think this is what will be done to my W72 400:

1) Complete motor rebuild / bearings, rings, oil pump etc
2) bore .030 over
3) forged pistons and forged rods
4) zero deck the block
5) balance the crank
6) Port and polish the heads
7) head rebuild, new springs & rockers
8 ) Port the intake to match the heads
9) new stainless 1 piece valves
10) crower 60240 cam
11) Ram Air Restoration headers
12) Ram Air UESYS-1 x-over exhaust 2.5"
13) rebuild and sup up the Quad 800 CFM carb
14) have everything repainted to look like new.
15) turbo 350 transmission rebuild

(speed pro federal mogul has a .030 rebuild kit with the forged pistons that looks good)

Also, my father owns his own auto repair shop. I have faith he will be able to get that motor tuned and running razor sharp!

At the moment this is the game plan for my 400. What do you think Geno? Am I missing anything important? In your opinion would that be a nice strong mild build that won't need lots of attention to keep up and running smooth!  What kind of HP and Torque do you think will be generated? 

Thanks Geno..
Hope all is well.
Dan s

Hi Dan,
Your parts list sounds good- here are a few things you can add to it:
-double roller timing chain
-PRW roller tip rockers, 1.52 ratio (includes polylocks)
-Best gasket graphite rear main seal
-Crower 68404 valve springs
-new retainers/ keepers

The advice I can give to you on porting Pontiac heads is to follow the porting techniques already established by well known Pontiac experts like Jim Hand, Rocky Rotella, and Craig Hendrickson (H-O Racing). I learned how to port heads using H-O Racing's Blueprinting and Assembly Manual back in the 80's- it only had simple diagrams, but I was still able to port my heads and the results were very good. The Pontiac books available now written by Jim Hand and Rocky Rotella have detailed pics and should give your head porter an excellent reference guide. DO NOT port Pontiac heads like Chevy heads- doing so will ruin them. Pontiac heads also do not need extensive porting or polishing to make them flow better- a rougher port surface will actually help keep the air/flow mix turbulent and help keep flow velocity up. Cleaning the bowls up under the valves, improving the port shape, and a good port match along with an upgrade to 1.77 exhausts will be more than enough to improve flow by 15-20%.

I built a similar 389/400 (389 bored .060 over) with ported no. 11's for a customer with a 65 GTO- we also used forged Sealed Power flattops, 5140 I-beams, a Crower 60240, and the heads were also upgraded to 2.11/1.77's and screw-in studs. SCR was set to 8.5:1 so 89-91 octane was more than adequate. The 389/400 also used a 670 cfm Holley Street avenger on a port-matched Performer intake, RARE manifolds, 2 1/2" dual exhaust w/ an x-pipe. The owner did upgrade the trans to a Bowtie Overdrives TH-700R-4, but even without that the car had great throttle response and excellent acceleration from off-idle to around 4500 rpm. The owner of this GTO drives his Goat at least 2-4 days a week, to work through LA traffic, so it delivers good vacuum and has excellent street manners. I see no reason your 6x-4's wouldn't do just as well on a 400 as long as the build and port work is solid. I estimated power at around 325-340 hp.

Geno

[Daniel78ta]

Hi Geno..
thank you for the tips and advice..!  I will make sure whoever Ports my heads gets a copy of Rockys Book along with a print out of the tips you posted.. I would not want my heads ruined!!  Im going to order up Rocky Rotellas book - "How to re-build Pontiac V8s" & his "How to Build Max-Performance Pont V8's"..   Looks like Jim Hands Book sells anywhere from $90 on up to $800 for a new/unused one!  Wow!!

Im going to start collecting parts for my re-build after the holidays.. A part here and a part there..  But, i might zip you a quick e-mail from time to time just to get your opinion on the parts / manufacturer before ordering..

I really appreciate your advice Geno..!
have a great thanksgiving!
dan s,
cedar falls, iowa

[Daniel78ta]

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