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Trying to put a Pontiac GTO 400 engine in my Chevrolet truck.

23 messages,  Last post on Jan 30, 2013 at 8:26 PM

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What is this discussion about? Chevrolet C/K 10 Series, Performance Mods, Truck

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#14 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [Mr_Shiftright] by num1pontiacman

Apr 13, 2011 (10:25 am)

Replying to: Mr_Shiftright (Apr 09, 2011 11:22 am)
"The original poster was asking about putting in an old 326 motor (??) of dubious origin and specs, so that's where our advice was directed toward possibly a Chevy crate engine."
 
I didn't address the "GTO 326" mainly because it just doesn't exist. Pontiac never put a 326 into a GTO.
No 326 can't be bored to a 400, that is a laughable statement.
 
Early Pontiac blocks, (326-428) 69 and back, can easily bolt into a GM truck, 60-87, but the 70 and newer blocks (350-455) have a center boss that the motor mount can bolt to that makes it even easier to bolt in.
 
"He didn't mention access to other Pontiac engines at the time. The Pontiac 350 is not an engine most people want"
 
Most people do not know the true potential of any Pontiac engine. However, most people cop out (when making the sacrilegious swap of a Chevy into a Pontiac firebird, GTO etc) and take the small block route because of limited money and make the compromise of going with an inferior motor. I know that isn't the point of the OP but it goes along with what is being discussed.
Loads of Pontiac 350's were offered with big valve heads and a minor notching of the block needs to be done to use them IF the block isn't factory notched already, many were.
The biggest problem in building a Pontiac is people use "Chevy" thinking when addressing Pontiac's and frankly, they are as different as day and night. A Pontiac 350 can easily make 350-360 HP in stock configuration.
 
The answer to the original poster is this, yes you can use a 326 in a GM truck. It along with a BOP trans will bolt right up and go. A 350 Pontiac is a better choice because of torque potential. The 400 would be overkill unless you are pulling heavy loads or you are building a performance truck.

#15 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [num1pontiacman] by Mr_Shiftright HOST

Apr 13, 2011 (9:18 pm)

Replying to: num1pontiacman (Apr 13, 2011 10:25 am)
A 326 has a cast crank and pistons, doesn't it? Another not so great feature.

#16 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [Mr_Shiftright] by num1pontiacman

Apr 14, 2011 (6:36 am)

Replying to: Mr_Shiftright (Apr 13, 2011 9:18 pm)
Yes, a 326 does have cast pistons and crank. I had one in a 67 tempest that had 338,753 miles on it when it was pulled. Ran good, didn't smoke and had good compression and a .006" lip. If maintained well those high nickel blocks wore very well.
The application dictates the parts necessary for the build in any build. Cast pistons and crank are perfectly fine in the right application.
58 GMC trucks came with a Pontiac 370 engine from the factory. I have one on an engine stand with over 700,000 verifiable miles on it. It will clean up at .020".

#17 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [num1pontiacman] by Mr_Shiftright HOST

Apr 14, 2011 (7:59 am)

Replying to: num1pontiacman (Apr 14, 2011 6:36 am)
I agree, cast crank and pistons are fine for everyday use but woe to the man who attempts to add significant power to an engine built that way. It's not going to end well.

#18 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [Mr_Shiftright] by andre1969

Apr 14, 2011 (8:03 am)

Replying to: Mr_Shiftright (Apr 14, 2011 7:59 am)
I agree, cast crank and pistons are fine for everyday use but woe to the man who attempts to add significant power to an engine built that way. It's not going to end well.
 
I think Mopar switched from forged to cast crankshafts sometime in the mid-1970's, and I've heard a lot of people groaned about it. Would that have given them a higher failure rate in everyday use as well, or just cause problems when you try to hop them up?
 
If you have an engine that uses a cast crank and pistons, could you just put swap in a forged crank and pistons? Presuming, of course, that an older version of the engine with the exact same bore and stroke used forged at one time?

#19 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [Mr_Shiftright] by omarman

Apr 14, 2011 (10:18 am)

Replying to: Mr_Shiftright (Apr 14, 2011 7:59 am)
I don't remember Pontiac cast cranks and pistons from that era being trouble prone for street/strip use. Nodular cast iron or Armasteel (PMI - not steel despite the name) was used for most Pontiac V8 crankshafts except early super duty (racing) engines. Depends on your definition of "significant power" though.
 
For example, and maybe a true Pontiac guru out there can take a better whack at this, I looked up factory GTO Ram Air engines:
The original Ram Air 400/360hp ('67?) used cast crank and pistons.
Ram Air II 400/366hp = cast crank and pistons
Ram Air III 400/366hp = cast crank and pistons
Ram Air IV 400/370hp = cast crank and forged pistons
Ram Air V *crate engine* factory HP rating? = forged crank and forged pistons
 
Super Duty engines prior to the '73-'74 455SD used forged steel cranks. But other than the Ram Air V crate engine, was there any factory GTO Ram Air engine with forged crank+pistons? I'm thinking that if you are driving a Pontiac street machine and have problems with damaged cranks or "holed" pistons, there may be other issues causing that -- detonation, excessive wear or poor assembly?
 
If the OP was considering a Pontiac 326 swap into a GM truck for the street then forged crank and pistons sound like overkill to me. Just depends on how heavy duty the truck's purpose will be.

#20 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [num1pontiacman] by tjb1ham

Jul 07, 2011 (1:10 pm)

Replying to: num1pontiacman (Apr 14, 2011 6:36 am)
I am looking to put a Pontiac 400 into my '72 GMC Pickup (already have both).
 
To:num1pontiacman
You said you have pictures and info to do a stock parts bolt-in?
Care to share?

#21 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [num1pontiacman] by tjb1ham

Jul 07, 2011 (1:13 pm)

Replying to: num1pontiacman (Apr 09, 2011 10:52 am)
I am looking to put a Pontiac 400 into my '72 GMC Pickup (already have both).
  
To:num1pontiacman
You said you have pictures and info to do a stock parts bolt-in?
Care to share?

#22 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [num1pontiacman] by ssbelair64

Jan 30, 2013 (5:46 pm)

Replying to: num1pontiacman (Apr 09, 2011 10:52 am)
Hey im working on putting a pontiac 71 400 into my 65 chevy pickup. You mentioned that you used componants for a direct bolt in. Which motor mounts did you use?

#23 of 23 Re: Trying to put a Pontiac GTO 400 engine in my Chevrolet truck. [ssbelair64] by num1pontiacman

Jan 30, 2013 (8:26 pm)

Replying to: ssbelair64 (Jan 30, 2013 5:46 pm)
It is a combination of motor mount perches, motor mounts and the motor mount bracket that bolts to the block.
All 3 are needed. I can't post photos here, fire off a message to me at chris_r29hotmail.com and I will try and point you in the right direction.

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