Author Topic: 1970 RAM AIR 400  (Read 2538 times)

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Offline noslow_ta

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1970 RAM AIR 400
« on: February 13, 2010, 07:17:00 PM »
I have a 75 trans am the engine has spun a bearing .I have found a good deal on a 70 ram air 400 engine that is complete and seems to be a good engine. I was wondering if this was the best year of the 400.

Offline Rick

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Re: 1970 RAM AIR 400
« Reply #1 on: February 13, 2010, 07:36:20 PM »
Welcome to 78TA! :) :)

The 1970 RA 400 is a good engine, but if you are planning to use in on the street you have to be aware that the stock Static Compression Ration (SCR) is a little high for the 93 octane (max) pump gas readily available today.  If you are planning to use it on the strip or you have access to higher octane (like aviation) gasoline then you will fine.  The 93 octane stuff they sell today can't be squeezed higher than about 9.3:1 or so without fear of detonation or "pinging", which will destroy rod bearings and do bad things to your pistons.  HOWEVER, it's also quite easy to drop the high SCR by having the pistons relieved a few CCs by a competent machine shop.

Alternatively, you can bolt the stock heads from your 75 engine onto the 70 short block if you don't have much money -- that will give you about a SCR of about 8:1, which will run with about anything you can buy for gasoline.  If you use the 75 heads, your SCR will be a tad higher (~ 0.4:1) than stock because the 75/76 engines used "chamfered" pistons to accomodate the then-new unleaded gasoline.  The 70 400s used true "flat top" pistons that did not have that chamfer.

I don't know how familiar you are with Pontiacs, but swapping heads is easily done and you'll have all the parts you need to do that if you wish.  Feel free to ask any questions that come up, and somebody here will be happy to help! ;)

Offline noslow_ta

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Re: 1970 RAM AIR 400
« Reply #2 on: February 14, 2010, 01:34:16 AM »
 :)Thanks for the advice I was wanting to put the 70 400 in and take my stock engine and build it to be a good street running car. What is the best way to build a 400? A lot of people that have not been a around Pontiac don't know. THANKS FOR YOUR INPUT

Offline Rick

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Re: 1970 RAM AIR 400
« Reply #3 on: February 14, 2010, 06:19:13 PM »
Take a bit and look through this section of the forum, and you'll see several combinations that have been discussed.  We have several people here who've done it, including the guy who built the world-record holder "Dirty Bird" that you've probably seen in HPP and Pontiac Enthusiast (that would be Mr. P-body).

But there are a few common areas of agreement on 400 builds:

For street use, you don't want to go higher than 9.3:1 or so for use with pump gas.  Higher SCRs can make power ONLY if you use the appropriate octane rated fuel, and they don't sell that at Starvin' Mavin's or Circle S.

Stock cast connecting rods, while reliable from the factory, are a major liability in these engines (even for the street) anymore.  With the low price of forged rods you are taking a large risk by reconditioning a set of 30-year old cast rods for your new engine.  Using forged rods is cheap insurance.

Stock cast cranks (nodular or Armasteel) are perfectly acceptable for any reasonable Pontiac V8 build.

Pontiac engines are notoriously easy to overcam, and it's far better to be UNDERcammed a bit rather than OVERcammed.  Many a guy has been disappointed after he stuffed a too-large cam into his street Pontiac V8.

Stock cast intakes are better than aftermarket intake manifolds (with the exception of the Edlebrock Performer II, which gives the same performance but is lighter) for a streetable Pontiac V8.

D-port heads respond very well to the kinds of porting suggestions contained in Jim Hand's book on Performance Pontiac V8s.

If you want to make power, the stock cast iron "log" manifolds are deficient.  You'll do better with a set of good tube headers, but unless you are trying to wring the absolute last iota of power out of the engine (most street engines don't) you'll be happier with a set of RARE cast iron headers that are replicas of the 1970 RAIII D-port exhaust manifolds.

I could go on and on, but as I say there are many 400 buildups that have been discussed, so you'd do better to find those and read them for yourself. ;)

Offline y88rick

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Re: 1970 RAM AIR 400
« Reply #4 on: February 14, 2010, 07:01:09 PM »
mr p-body is a very very knowledgable guy as Rick said if you have a serious question definately go to him with it. he wont sideways your answer and will help you figure out whats right for you.
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Offline rad400

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Re: 1970 RAM AIR 400
« Reply #5 on: February 15, 2010, 08:19:15 AM »
So the big questions is it a Ram air III or RA IV? IIIs will be #12s or #13s, and I think IVs or 64 can't remember, old age haha.
Conrad
79 Trans am 400 t400 3500 stall #12 heads holley 750 vac carb. Torker II intake 3:73:1 gears 12 bolt rear.

Offline jphillips3333

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Re: 1970 RAM AIR 400
« Reply #6 on: February 15, 2010, 08:21:13 AM »
IVs are 614?
John

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Offline Mr. P-Body

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Re: 1970 RAM AIR 400
« Reply #7 on: February 15, 2010, 09:56:34 AM »

   Conrad "read" my mind... Also, many outside the "Pontiac realm" believe certain head castings or block castings mean "Ram Air" when they may not.  Not ALL 400s equipped with 12s ("Ram Air III", 366 HP 400) are necessarily Ram Air engines, as the manual transmission GTOs and Firebirds with 350-horse 400s also had them. 13s were never on "Ram Air" engines, though there is the misconception out there they were.  13s were on 350-horse 400s with auto trans in GTO, Firebird and Grand Prix.  NOTE: If it IS a "Ram AIr III" engine, the exhaust manifolds will be the "HO" versions, large and "4 into 1".  The 350-horse engine got the "log" exhaust.

   Ram Air IV engines have "round" exhaust ports, as opposed to the standard "d-port".  Easily recognized. Yes, "614" is the casting for a '70. 722 is a '69.

   There's a two letter "code" stamped on the front of the block which will tell you whether or not it's really a Ram Air engine. WS and WW are the manual codes for GTO. Firebird guys can chime in with the Firebird-specific codes, but I know a '70 T/A had WS. The automatic trans cars had different codes, all beginning with "Y" or "X", but I can't recall off-hand. Wallaceracing.com has an excellent database with the correct codes for most years.

  Replace the rods!

Jim
« Last Edit: February 15, 2010, 09:58:20 AM by Mr. P-Body »

Offline rad400

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Re: 1970 RAM AIR 400
« Reply #8 on: February 15, 2010, 09:51:10 PM »
John, and Jim thanks for the IV head number. I forgot it was 614.
Conrad
79 Trans am 400 t400 3500 stall #12 heads holley 750 vac carb. Torker II intake 3:73:1 gears 12 bolt rear.

Offline noslow_ta

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Re: 1970 RAM AIR 400
« Reply #9 on: February 16, 2010, 05:41:36 AM »
Thanks after checking the casting numbers out, I found out that it is a 400 out of a 70 grand pix model j car with 400 turbo trans with 350hp. The car has been sitting for about 20 years. It was a old ladys sons car that died over seas. Ran good ween the car was parked. I took out the spark plugs and it turn freely buy hand . Im hoping every thing looks good on the botem end. I dont have alot of cash right now to do much to it but was thanking about just replacing the iol pump water pump rear mane seal head gaskit kit. Im just trying to get the old brid back on the road. Do you all think Ill be alright about doing that
thanks

Offline y88rick

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Re: 1970 RAM AIR 400
« Reply #10 on: February 16, 2010, 06:56:10 AM »
inspect EVERYTHING as you tear it down and if all checks out, why not?
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Offline Mr. P-Body

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Re: 1970 RAM AIR 400
« Reply #11 on: February 16, 2010, 09:05:25 AM »


   Compression will be an "issue". The '70 engines wre advertised as 10.5:1, and in reality were around the 10:1 mark. That engine should have 13s on it, right?  Steps should be taken to lower the ratio unless you're willing to "mix" race gas in with 93. It WILL detonate "as is". Retarding the timing might make the "sound" go away, but not the problem.

   All in all, though, a 350-horse 400 is an excellent "starting point". '70 is right up there as THE most desirable year.

Jim

Offline norwood

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Re: 1970 RAM AIR 400
« Reply #12 on: February 16, 2010, 07:10:03 PM »

   Conrad "read" my mind... Also, many outside the "Pontiac realm" believe certain head castings or block castings mean "Ram Air" when they may not.  Not ALL 400s equipped with 12s ("Ram Air III", 366 HP 400) are necessarily Ram Air engines, as the manual transmission GTOs and Firebirds with 350-horse 400s also had them. 13s were never on "Ram Air" engines, though there is the misconception out there they were.  13s were on 350-horse 400s with auto trans in GTO, Firebird and Grand Prix.  NOTE: If it IS a "Ram AIr III" engine, the exhaust manifolds will be the "HO" versions, large and "4 into 1".  The 350-horse engine got the "log" exhaust.

  


1970  Automatic Trans Ams  came with a YZ coded RA III motor, the manual cars got the WS.  The Auto version of the RA III in the Trans Am came with  12 or 13 heads, the manual came with 12 only.  The RA III in the Trans Am is also rated at 345 HP auto or manual.
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Offline noslow_ta

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Re: 1970 RAM AIR 400
« Reply #13 on: February 22, 2010, 11:53:06 PM »
The engine turned out to be a XH from a 70 grand prix J model . if i put my hei dustribiter from my 75 on it would it help the valve spark detanation.And do you all thank it will fit. The moter has some funny looking exhuast manifolds looks alot defrent from my 75 manifolds could it have HO heads. The frist and last exhaust ports are round the midell two are almost ablonged shape.
THanks

Offline 72blackbird

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Re: 1970 RAM AIR 400
« Reply #14 on: February 23, 2010, 02:29:28 AM »
What number heads are on the motor? I'm not really concerned about the exhaust manifolds on the 70 400 unless you plan to use them, but the stock exhaust manifolds from your 75 400 should bolt onto the earlier motor (unless they're round port heads).

Your HEI will work on the earlier 400, but won't solve your detonation problem with the higher compression in the 70 400- the only way to solve that is to run dished pistons and lower the compression. The 70 400 will definitely not be a drop-in-and drive solution, since it should also get forged rods and a refresh.

Geno