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Trying to put a Pontiac GTO 400 engine in my Chevrolet truck.
oldfixerupper
Member Posts: 1
I've been planning this truck for years and have nearly finished. After contemplating for so long about what engine I wanted in my truck I run across this Pontiac GTO 326 engine, it's basically the same as a 400, plus it's been bored out to a 400. I bought it with the hopes it would be going in my truck with so many agreeing it would be a good idea but now I'm not so sure. CAN I PUT A PONTIAC GTO ENGINE IN A CHEVROLET TRUCK? I want to go with this but now that I'm starting on the swap people have started telling me that it wont work. I'm confused, will it or wont it? Help!
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FWIW, GM used to put Pontiac engines in their trucks. The 1957 GMC used a Pontiac 347, and I wouldn't be surprised if the 1958 used the 370.1. I'd imagine there are other examples. The 347, 370.1, 326, 400 et al, and even 455 can be traced back to the old Pontiac "medium block" (Pontiac never did the big-block/small-block thing like Chevy, Mopar, Olds, or Buick) 287 from 1955.
So, if nothing else, if you got some schematics and diagrams of the old GMC trucks that used Pontiac engines, you might be able to see how they fit in versus a Chevy engine.
Also that 326 was not bored out to 400. I don't know who told you that, but it's not possible. Boring out a 326 to .30 over only gives you a 331cid, and .60 over is about the limit for most engines.
You can build a 326 to be very robust, but boring it out is the least of the process to get decent HP.
This is why, if you want a healthy engine, use a Chevy crate---just buy as much power as you can afford or want.
Or if you buy a used engine, hear it run and take compression and oil pressure readings, or just forget it.
While it can be done, you would be far better off to take mr shiftirght's suggestion.
We've put a 455 in a 70 chev pickup, but it was a lot of work and to be honest, I wouldn't do it again.
That was never a "GTO " engine. The 326's came in Le Mans and lesser models.
It wouldn't be worth the trouble and headaches that would be involved.
Yeah, that's what I thought. I know there was a wussed-down version of the GTO in later years, but at least it was still a 400 V-8. I think it was a low-suds 2-bbl version designed to run on low-octane fuel. Basically, the credit engine that they offered on the Catalina?
I do always get fascinated by these engine swaps mother nature never intended, though. But, they should only be done if you have money to spare, and don't care about taking a loss.
I never understood why that would have made such a thing or why anyone would have bought one. It's either a GTO or it's not.
Pontiacs bolt right in just like a weak kneed chevy small block. Differance is tha TORQUE for any stock pontiac is far beyond any chevy mouse motor.
NO, a 326 can not be bored to a 400.
I have detailed build photos showing a 400 hp 413 ft/torque 350 pontiac motor in a 79 GMC that is used to pull a 2 car car trailer. Bolted right in with NO fab work necessary.
After '70 or so, didn't Pontiac mainly look towards the 400 and 455 for their performance engines? I think one reason Chevy put out high-performance 350's was because the 454 was so heavy, so a high-output lightweight smallblock had a lot of uses. But Pontiac didn't do the biglock/smallblock thing. Instead, they had more of a "medium block" design that served all their displacements, so a Pontiac 350 probably wasn't any lighter than a 400 or 455. So, say, if you wanted a 350 hp engine, it was just simpler to get that 350 hp out of a 400 or 455, than a 350.
Yeah, a Chevy 350 is a 4.00 bore and 3.48 stroke, while the Pontiac 350 was a 3.88 bore and 3.75 stroke. So the Chevy was more of a revver, but I guess the Pontiac was better for torque?
The Chevy 327 had the same bore but an even shorter stroke, so would it have been a better engine to hop up than the 350?
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.
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".
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?
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.
To:num1pontiacman
You said you have pictures and info to do a stock parts bolt-in?
Care to share?
To:num1pontiacman
You said you have pictures and info to do a stock parts bolt-in?
Care to share?
All 3 are needed. I can't post photos here, fire off a message to me at [Email removed] and I will try and point you in the right direction.
I just recently bought a 69 Pontiac 428 big block and I am wanting to put it in a 79 short bed Chevy truck and I am in need of some assistance on what type of headers I should use for clearance from the frame
This is a duplicate posting. In the duplicate I suggested that you get a header mock-up kit:
http://www.stainlessheaders.com/customheaders