396 Chevy combo......
 

guys, ineed a quick history lesson. what is the difference between the 3 different hp combos on the 396? i see the 375 seems to be hit the worst, why? is it that much better?

thanks to all,

wade owens #3913
66 chevelle
under construction stocker

The 325 and 350 HP engines have oval port heads with smaller intake ports and valves, less compression, and cam (hydraulic instead of solid, too).

The 375 is getting hit for two reasons. It has a lot of potential, and that potential is being exploited, by a lot of people.

It has the same heads, cam, intake, and carburetor as a 427-425, with 30 less cubic inches to feed. So it rev's higher and makes more HP per cubic inch, common when you have engines restricted by various rules.

The 396-375 is also very common, a lot of people run them, in everything, Chevelles, Novas, and Camaros, to name a few. They fit well in A, B, and C, in both the Camaro and the Nova.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

thanks alan, i appreciate you taking time to comment.

wade o

Stocker Fan,
The way the 375 HP guys are flying I wouldn't be surprised if they don't get some added HP at mid season. There have already been several runs much quicker than the 1.15 trigger point. In my opinion, Any of those combos you ask about can be made workable. It's only a matter of how fast you want to go & how much do you want to spend.

Adger Smith

So is there any advantage or disadvantage over the 396 versus the 402.



Thanks, Alan Warman L/SA 4103

I don't know that there is really a lot of difference, I'd say Keith Lynch is as qualified to answer that as anyone, since last time I talked to him, he was running a 402-375, and Schroeder was running a 396-375, Keith is tuning both. They're both REAL fast, and can run A or B.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

I think the 402 might get a slightly smaller chamber & seems there is something about the ex valve.can't remember it all. might have just been with the 401 head You can check the blueprint specs to see.

Adger Smith

402 gets a bigger dome and the exhaust valve is a 1.88
396 is the 1.84 valve

Just checked the NHRA specs (1969 396 vs 1970 402) & it looks like the 401 alum. head gets a tighter chamber in both the 402 & the 396 @ 103.3 On the other hand the iron 396 is @ 104.9 vs the 402 iron @ 106.9.
Dome on the 396 is 40.05 @ .361 ht Vs the 402 with 39.53 @ .344 ht. That was probably done to equalize the difference in bore vol.(CC).
The 396 ex is 1.845, in alum & 1.725 in iron vs the 402 @ 1.885 in iron and alum.
It also looks like the 402 gets to use a better manifold than the original pancake version. I'm not real familar with the manifols esp. the 3967474, but it seems like the 402 & 396 would be at least equal in that area.
You need to check the NHRA Classification guide for the HP. There are some differences between bodies & stick vs auto in the 402 vs 396.
good luck hope this helped
DISCLAIMER: all numbers are form NHRA Tech Specs. I'm not responsible for type-o's or numbers that are transposed. I am responsible for my opinions.


Adger Smith

I haven't looked at ALL of the 396 and 402 engines, but supposedly any engine that can run the "163" intake is allowed to run the new "359" intake. Most of the big HP (375HP 396, 425HP 427 etc.) big block cars are running the 359 intake now, at least the ones I've seen.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

wow, i knew you guys would come through! thanks to all who commented on my question, i appreciate all the effort. my project has lost a little steam, i was disappointed when it all didnt come together as quickly as i thought it should. but, since the 2nd week of jan, the engine is 90% done, the trans is almost completed, chassis and suspension are completed and the body shell is painted. maybe i'll be ready for the last indy open or doorslammers. still alot to go....

thanks again, guys..

wade owens
66 chevelle l/sa

Alan,, We picked up a very nice virgin "163" intake a few weeks back at a swap meet for a future 375/396 combo. I'm not familiar with the "359" intake. Could you tell us a little more about it?
Thanks for any info,,,,,,,,,,,, Danny Durham

Danny, the "359" intake is the new GM replacement for the "163" intake, available at your local GM dealer. Well worth taking a look at.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

Danny,
The intake in question is a refined intake. The one I have examined had some very needed improvement over the 163 intake. You will first notice the fuel channels below the carb run across the plenum florr instead of down the ports. I would assume it helps with raw fuel (separated fuel) and helps it re mix with air. There are a couple of others thing , but it helps to measure & compare one to the other. A good piece & priced right!

Adger Smith

Also, the plenum wall is cut some. If you have a 69 or earlier car, you cannot run a cut plenum 163, but you can run the 359 with the shallow plenum cut. Compare the two side by side and you'll see and measure other differences.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

Thanks a lot fellas,, I appreciate the info. I'll let my buddy who is collecting the pieces for his son's 69 Camaro know about this. It makes sense to check out both intakes and go from there.
Alan and Adger,,, you guys are great! Danny Durham

The 396/375 hp cars that are flying and that are more than likely going to get hit with hp are us guys that run the aluminum heads. sometimes better is going to get you. like right know due to the hit we got at the begining of the year took from 375/390 hp to 375/395hp took my 69 camaro from 3485 to 3525 lbs min weight if we get bumped to 400 horse at 8.5 x 400 +170 ( aloted weight for the driver) = 3570lbs almost 100lbs. thats a tenth or they say............ but it is the best combo to run because its so fun.........

Jeremy Waibel
K&N B/SA 69 camaro
2231

The other real advantage to the 401 aluminum head is you don't spend tons of time and money hunting virgin closed chamber cast iron heads. GM stopped producing the 291 cast iron head about 5 years ago, and the others decades before that. Some of them (the 291 heads) are still around for a decent price. But if you go hunting the others, you can pay $1K for what amounts to worn out junk, and as much as $3K+ for good stuff, and that's BEFORE you do a valve job and mill them. We may build a 396 over the winter, depending on how NHRA treats the combination this year. If some of the guys keep hammering it, and NHRA hits it hard, we'll just stick with the 427.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

We did a little researching in the pits at Seattle this weekend and had a nice conversation with Cal and Mary Ann Method who had her Nova in "A" trim for the divisional. They had a "359" intake on the car and the GMPP aluminum heads. The feeling there was that another hit might negate the advantage of the aluminum heads and they might go back to the cast iron heads. Of course many racers have built up inventories of parts over time and can change back and forth as the need arrives. I guess for racers starting out with this combo it makes sense to go out of the GMPP catalog, at least to get the new car up and going.
My 2 cents.................... Danny Durham