what 400 engines will fit?
 

I'm in the begining of another project .... to convert my 67 temptest convertible into a GTO. To start, I want to loose the straight 6 and put in a 400. I'm not really looking to keep it original, rather have some fun and build how I want it. But I need help in figuring out what engines will fit this. Are there certain years, and codes I should be looking out for? Are 400's available in short and long blocks? Why would I want a short vs long block?

all pontiac V8 engines will fit from about 1964 to 1980. get a 400 if you want, but you will need the frame motors to replace the 6 cyl frame mounts. I would like your 6 cyl engine mounts, both the frame and motor mounts.

That's good to know that most 400's will fit. I'll be pulling the 6 cyl out in the next week or 2 and will get a better look at the frame mounts. I'll get back to you on them.

Are their variations on the 400, such as short and long blocks I should look out for? or are they basically the same. I'm not real familiar with Pontiac's, mostly chevy small blocks. The reason I'm thinking about a 400 is I believe it's the most common, want to keep it Pontiac and wasn't looking for a struggle to find something. If you have any other suggestions I'd like to hear... thanks much.

One other issue to be aware of is the fuel line running from the tank, on the 66 Tempest I switched from OHC-6 to a 400, the line went up the passenger side on the OHC-6 not the drivers side as with a V-8. I'm not sure, but wouldn't be suprised if a 67 Tempest had the same fuel line location.Not a real big deal. If you want to run a fuel line up along the drivers side you probably will have to lift the body to get it through the frame.

Short block means just the bottom end of the motor. Long block would be the bottom end with atleast the heads included. Any 400 will fit, but I would try to find one from 67 to somewhere in the mid 70' s. I put a 78 400 in a 66, and had to drill and tap one side for motor mounts, and had to fabricate an adaptor for the other side because there was no bosses to drill and tap. Sorry, I don' t know what year they started leaving these bosses off, but it was in the late 70' s. Hope this helps.

The Tempest with OHC had the fuel line on the passenger side becasue the fuel pump is located on that side with the OHC.

Is that a single or 4 barrel OHC you have there?

George

It's a single barrel OHC 6cyl. Really cool set up if I wanted to make it into a Sprint Tempest. but I prefer the 400 (ish) size engine.

BTW.... thanks for all the great feedback so far. I know I'll have more questions through this project.

personally I would stay 74 down because it's more of a drop in deal shouldn't get cought up in having to drill and tap bosses .

thats exactly what i was going to say. i remeber years back i built a 1976 400 for my 66 GTO and it didnt have the right bolts holes for the motor mounts i needed. it was a real pain in the butt to take it to the machine shop and have them drilled and tapped.

good luck on your GTO conversion. sounds like we think alike whne it comes to our cars. i cloned my 66 lemans and did what i wanted to mine. I built it for ME not the next owner (if there is one)

If going why not go BIG---455? You noted is a clone and your not looking to keep it original but rather have a fun driver. I just rebuilt my 389 now 406 and tell the truth wished I'd grabbed a 455 and built up from that.