[CROS34]

Well, I have been out of the game for about 10 or 15 years but looking to get back into it with the purchase of a ’77 or ’78 TA. The ’77 has a 403 and the ’78 a 400. My final decision is going to be based on motor. I have a ’70 TA with a ram air III I rebuilt back to stock with no issues and have rebuilt a few other 400s in my time, all stock. Question is, I am looking to get about 400HP out of the motor and don’t know if either will make it. I am just starting my research, and reading that the 403 and later 400s each have their own issues when it comes to strength to support 400+HP. I am not apposed to starting from scratch with block, crank, heads, etc…. on an early 400 block, but I am not that knowledgeable in engine building to match all the parts and pieces, to achieve my end goal. Maybe a create engine but not sure of the quality of parts or workmanship. If someone can point me to threads that this has been discussed or in the right direction, I would appreciate it. Life has slowed down so now it's my turn......

['ol Pinion head]

If the '78 is a W72 400 car, should not be that hard to build to near 400 gross hp. Many a ported milled 6X-4 400 build out there.

Little closer to "optimized stock" check out the 400 W72 build Dennis Jenson put up a topic on a year ago. Keep in mind, no mild head porting was done on those 6x-4's, & the cam choice was kept fair close to stock to be able adhere to PSMCR rules.

https://forums.maxperformanceinc.com...72#post6303809

[nUcLeArEnVoY]

You trying to keep it stock appearing and conservative, I'm guessing? Because a W72 block is a late-run 400 casting that can support as much power as any early 70's block. A stroker kit, 6X-4 head porting, and cam alone should bring you to 400 HP and those aforementioned blocks can easily handle it. Way more, actually. If you have an early 400 or W72 400, you can hit 500+ HP and entertain the thought of e-heads to handle the higher compression, pending your budget.

It's the plain-jane 500557 blocks that they started producing in the mid 70's you need to steer clear of, what with their weaker main webbing in the saddle of the block to save weight. I wouldn't build a motor to past 350 HP on one of those.

[77 TRASHCAN]

Roger, thanks for that link. A great reference in building a near stock 400.

Paul Carter built a 400 a few years ago. Posted the build, here. Another great 400 build!!!

[CROS34]

Thanks for the information. I thought I read that the L78 and the W72 were the same block and were the only engines available in the '78 besides the 403. If true, no mater the 400 engine it should be a good block to start with?? I can get ahold of some #13 heads if the heads are not the 6X4. From the pictures of the car, it has the TA 6.6 badging and the chrome valve covers but they are easily added. The owner is not a car guy and doesn't know much about the car, besides keeping as he bought it years ago. I have requested a picture of the cowl tag, to check the RPO codes, but besides the valve covers, 6" oval snorkel and the TA 6.6, is there any other way to determine the engine type with the car being a days drive away?

[Trevor78]

To identify a '78 W72 other than the bolt-ons, the engine block is now 491988. The regular 400 block was 500557. The 1977 W72 used the same block as regular 400, 78 had the 2 400's, 79 only the W72 as a manual.

A well-known and fantastic W72 write-up from John Witzke.

http://pontiacformula.free.fr/schema/W72.pdf

[Quad]

Is there any other way to determine the engine type with the car being a days drive away?
If you can guide the seller to get codes for dates, & engine [e.g. for 1978 the W72 were WC & X7], heads [6x-4 vs 6x-8] , etc
Best bet would be if the seller can id the block series; e.g. XX481988.
http://www.wallaceracing.com/engine1.htm has heaps of info.
All 1978 400's were L-78; The W72 was "an option on the L-78 400"; hence L-78/ W72 designation.

[Trevor78]

only had to read one simple block code, all the rest are bolt-ons and can be added to anything, a 350P...

[CROS34]

Thanks everyone for the information. I guess the seller is not that interested in selling the car as I get resistance from them with each question. I don't mind driving 10 or 12 hours dragging a trailer but I want to know what I am going for before I start out. I'm sure I will back here again, with more questions, but for now I have some good information to start with. Thank you.

[Trevor78]

or because he knows the questions will catch him out.