after reading jubjub2m6's post, something popped in my head. i have wanted to build a V8 1st gen (79-85) RX-7 for a while now, but i have never had the money. well, guess what? i might be getting the money

now, i know a small block chevy V8 will fit, but what about a PONTIAC 389 V8? i know where there is a freshly rebuilt 389 with 13:1 pistons sitting that i might be able to get cheap. it was going to go in a open wheel dirt track car, but after the rebuild he found out it has a bad head. he had/has many more engines, so he didnt bother replacing the heads. according to him, stock heads will go right on with no problems.

now, if i can find a fairly cheap 1st gen RX-7 with a blown engine, i might just be able to make it work. that would be one heck of a sleeper, dont ya think? the only exterior mods would be a cowl induction scoop, and wider rear tires. if there is any fairly minor body rust, then it would stay. i could have some fun with that

so, now to my question. is a pontiac small block bigger than a chevy small block? if so, anyone know by how much?

thanks.

[This message has been edited by fiero_nightmare (edited 09-30-2002).]

Pontiac V-8's are big blocks. 326,350,389,400,428, & 455. The 301 is basically a re-decked pontiac block. It's more of a "medium" block than a small block. They are all larger than a small block Chevy.

thanks oreif.
i knew caddy, and olds engines were bigger, but i wasnt sure about pontiac engines. i dont think that engine will fit into a RX7 then. i cant afford to get a chevy V8 because if i did one i would want to rebuild it, get GOOD pistons, a good cam and have the heads rebuild. that would cost waaaay too much. it would be cheaper to just buy a 2nd gen firebird and drop the 389 in that. but then it would probably be too slow. i want something in the low-mid 13 second 1/4 range. now i cant figure out what to do. i might just have to get a RX7 and install a junk yard 305 or 350 for now. it would be better than nothing, and it would be easy to mod the engine over the winters.

anyone know of any cars that a 389 will go into, yet are fairly light weight?

i was thinking cutlass, but i think they are too heavy, and it is very hard to find a good rear differantial out of the salvage yard. all i can find are 2:53's and such.

[This message has been edited by fiero_nightmare (edited 09-30-2002).]

To be absolutely correct, there are no big or small block Pontiac V8s, they are all the same size. They are so freakin big, however, that people refer to them as big blocks.

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interesting. it sucks, but is interesting

so then a 455 should be the same size as a 389? that would be perfect for a 2nd gen firebirds then. i know right now where i can geta 80 trans am for $2000 that has a blown engine. i am going to have to check on that...

Kinda off topic but i Love your Sig. with the fiero logo

quote Originally posted by tesmith66: To be absolutely correct, there are no big or small block Pontiac V8s, they are all the same size. They are so freakin big, however, that people refer to them as big blocks.

Buick's late69-70 model thin wall big block is both smaller and lighter than a chevy small block is. and in STAGE #1 tune the 455 is allso the highest HP of any GM motor under rated at 425 hp realy makes about 500hp box stock

they only made it a few years and it is NOT the early nail head 401 buick or swapable with early buick motors

find a GTO for the 389 but at 13-1 thats NOT a street motor

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Question wonder and be wierd

quote Originally posted by ray b: Buick's late69-70 model thin wall big block is both smaller and lighter than a chevy small block is. and in STAGE #1 tune the 455 is allso the highest HP of any GM motor under rated at 425 hp realy makes about 500hp box stock they only made it a few years and it is NOT the early nail head 401 buick or swapable with early buick motors find a GTO for the 389 but at 13-1 thats NOT a street motor

hmmmm. i just remembered something. every once in a while i drive by this house just outside the city, and in the back in a car that looks like it may be a GTO. it has the BIG grill openings, and the long rear side windows. i might have to check on that.

i know it is not really a street motor, but it could be driven on the street every once in a while. i would take it to the strip most of the time, and just drive it on the street to keep everything working right. i have the fiero and beretta for daily drivers

i am just looking for something i can take to the strip and not worry so much bout blowing up.

i am going to go drive by the house and see if the car is still there.

quote Originally posted by fiero_nightmare: interesting. it sucks, but is interesting so then a 455 should be the same size as a 389?

Yup. The 301 not withstanding, because it's a low deck block, all Pontiac V8's have the same external dimensions. This means a 326 and a 455 are direct swaps. There's a few differences you need to be aware of.

326, 350, 400 use a 3.0" main bearing
389, 421, 428, 455 use a 3.25" main bearing
So you can only swap cranks with the same main bearing size (unless you do some machining)

Also, there are 2 different types of motor mounts used. 2 bolts and 3 bolts. Some blocks have 5 bolt holes so either type of mount will work. You can get adapters to put a 2 bolt motor mount block in a 3 bolt motor mount chassis. Careful shopping though, and you can get the right block to start with.

All heads interchange. This gives you lots of flexibility in flow and compression.

The 400 is better for hi-rpm because of the smaller main bearing journal.

The 455 is undersquare, and is not suited for hi-rpm, but is an incredible stump puller at anything below 5500 rpm. A recent magazine build up of various big blocks (Hot Rod?) did a comparison of the Buick 455, Pontiac 455, Olds 455, Chevy 454, Mopar 440, and Ford 460. The Pontiac didn't win the highest torque honors, but they also said, they don't know what the Pontiac's torque peak is - because below 3600rpm, the dyno couldn't hold the engine!! And by that point, the curve was already on the way down.

Even if you get it cheap and even if it will fit the application you will have a unique but seriously expensive to maintain bastard on your hands. Take a look at the parts availability and prices for any PMD engine. Just take the SBC price times three to start

If you want a drag car, why don't you buy my Cutlass?
http://www.autotrader.com/findacar/vdetail.jtmpl?car_id=110739987&dealer_id=&certified=n&max_price=5495&start_year=1984&end_year=1984&address=55779&search_type=used&make=OLDS&model =OLDCUS&min_price=5495&distance=75&advcd_on=n&advanced=n&color=&car_year=1984

I am VERY flexible on pricing.

quote Originally posted by thomas_l: Just take the SBC price times three to start

Um, no! Unless you've got a rare engine (RA IV, SD455, 455HO), the parts are only slightly more expensive than a SBC. SBC's are a dime a dozen, so yes, their parts are cheap. Pontiac parts are well in line with most manufacturer's prices. Besides, have you priced Hi-Po Olds or Buick parts lately?!?!? THAT's expensive!

I have a 350 cubic inch '96 LT1 out of a buick roadmaster for sale. 265 h.p. 330 torque should be plenty for an rx-7. Iron head, so after a while when more money is available and you want to go insane, you can switch to an aluminum head. Only 30,000 miles on it. Has the wiring harness and ecm.

Just a short trip down to Milwaukee for you to pick it up.

i looked at the car, and it is a lemans. the body and frame are rusted out, so it is just scrap.

fropuff- i REALLY wish i could buy it, but i wont have enough money for a few months. i would offer to trade you my 91 beretta GTZ and my 3800 fiero, but i dont think you would go for it

frontal lobe-. those engines are nice, but its not what i am looking for. i could probably buy edelbrocks H.O chevy 350 that has 320 HP for not much more than your engine, and i wouldnt have to worry about wiring

i have an idea as to what i might do. i have a 86 SE sitting in the back yard right now that has been hit in the front. i have another front end to weld on from the parts car. the 2.8 is shot, so that is perfect for another engine conversion. i am thinking TBI 4.9 caddy V8, and maybe a little nitrous. that would give me a nice drag car, and if the engine blows i could get another one cheap from the salvage yard. that would be easier, and cheaper than anything else i have thought of. i just wonder how many transmissions it would go through

[This message has been edited by fiero_nightmare (edited 10-01-2002).]

quote Originally posted by fiero_nightmare: i have an idea as to what i might do. i have a 86 SE sitting in the back yard right now that has been hit in the front. i have another front end to weld on from the parts car. the 2.8 is shot, so that is perfect for another engine conversion. i am thinking TBI 4.9 caddy V8, and maybe a little nitrous. that would give me a nice drag car, and if the engine blows i could get another one cheap from the salvage yard. that would be easier, and cheaper than anything else i have thought of. i just wonder how many transmissions it would go through

Have you checked out my thread in GFC? Might give you some ideas.

I have a Pontiac 350 in my '88 Chevy truck (it was available and I needed a motor to get it running) and it is a big heavy lump. It is just about as big as a BB Chevy, and weighs as much as one. Can't wait to get it out of the truck!

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