[C-lane]

Hello, New to the pontiac game...WAS a Ford guy. Anyways here is my issue. I purchased a 65 tempest. It came with a 65 389 wa code heads have a 91 code on top of center exhaust ports chambers looked closed probably original from motor. The crank needs turned. I purchased a good 75 400 it came with new water pump and all kinda new parts. What sold me other than new parts gaskets etc was the 6x8 heads milled to 94 cc's and ported and polished. What I'm wanting to do is put the 400 crank(since its not needing turned) in the 389 put new bearings in (not sure of size) and put the 6x heads on the 389. Then install a cam. My question is will the 6x heads be good on 389, what cam should I use, are they the same cranks, what size crank bearings and what heads came off the 389 and what are they worth. I look to get rid of all the stuff I ain't using but want to get the best out of what I got. Also are the stock intakes the same. Thank you in advance

[azbirds]

The cranks are the same dimensions. If you are boring the block and putting new pistons in the 6X8 heads will work. IIRC the 389 heads had different valve angles and the 389 pistons have valve reliefs for those heads.

[C-lane]

What if I just change the piston and not bore it out? I hate the compression ratio on the 75 400

[C-lane]

What would a real pontiac enthusiasts do in my situation of course without breaking the bank

[ponyakr]

Originally Posted by C-lane

Hello, New to the pontiac game...WAS a Ford guy. Anyways here is my issue. I purchased a 65 tempest. It came with a 65 389 wa code heads have a 91 code on top of center exhaust ports chambers looked closed probably original from motor. The crank needs turned. I purchased a good 75 400 it came with new water pump and all kinda new parts. What sold me other than new parts gaskets etc was the 6x8 heads milled to 94 cc's and ported and polished. What I'm wanting to do is put the 400 crank(since its not needing turned) in the 389 put new bearings in (not sure of size) and put the 6x heads on the 389. Then install a cam. My question is will the 6x heads be good on 389, what cam should I use, are they the same cranks, what size crank bearings and what heads came off the 389 and what are they worth. I look to get rid of all the stuff I ain't using but want to get the best out of what I got. Also are the stock intakes the same. Thank you in advance

I'm no expert, like many here are. But I'll take a stab at some of these questions.

A factory '65 4-barrel intake would have been for an AFB carb. The 400 intake would be for a Q-jet.

I think the crank will fit, but the entire rotating assembly would need to be re-balanced.

The 6X heads have valves that are at a different angle than the valves in the 389 heads. Because of that, the piston valve reliefs are in a slightly different location. But, unless you go with a big cam, the valve relief location probably won't matter. I remember somebody here posting that they had used a decent size cam in this situation, without any problems. Don't remember who, or the exact engine/cam specs. Maybe whoever that was will see this & give us the details again.

With 94cc heads, a 389 won't have much compression. Therefore, from a performance standpoint, a small Voodoo cam, such as a 262 will probably be about what you need.

http://www.lunatipower.com/Product.aspx?id=1775

But, if that cam would cause valve to piston clearance problems, there are lots of low lift cams, that will work. Of course, the 1st that comes to mind is the 068 clone, such as a Melling SPC-7.

I assume that you want to use the pistons that are currently in the 389. Need to see what they are. Some 389's have been rebuilt with standard bore 400 8-eyebrow pistons, which have valve reliefs in the 389 & 400 locations.

Or, if you're gonna bore & go with new pistons, you can go with std bore forged, SP L2262F pistons, with the 6X heads. Some don't wanna bore their 389 block that big. It's your call.

No market for used bearings. You'll need bearings for whatever size the crank you use is. If it's standard & doesn't need turning, then you need standard size bearings. Have no idea if the crank is std or if it has been turned down some, in a previous build. With all the work done to the heads, it stands to reason that the shortblock was probably rebuilt at some point. You need to find out exactly what you have, in both engines.

I have no idea of the worth of the 389 heads or intake.

If the 400 is "good", as you say, why do you not wanna run it, instead of the 389 ?

[C-lane]

Originally Posted by ponyakr

I'm no expert, like many here are. But I'll take a stab at some of these questions.

A factory '65 4-barrel intake would have been for an AFB carb. The 400 intake would be for a Q-jet.

I think the crank will fit, but the entire rotating assembly would need to be re-balanced.

The 6X heads have valves that are at a different angle than the valves in the 389 heads. Because of that, the piston valve reliefs are in a slightly different location. But, unless you go with a big cam, the valve relief location probably won't matter.

With 94cc heads, a 389 won't have much compression. Therefore, from a performance standpoint, a small Voodoo cam, such as a 262 will probably be about what you need.

http://www.lunatipower.com/Product.aspx?id=1775

But, if that cam would cause valve to piston clearance problems, there are lots of low lift cams, that will work. Of course, the 1st that comes to mind is the 068 clone, such as a Melling SPC-7.

Well seems like every answer just leaves more questions haha. So than in you opinion would it just be easier and cheaper to have the 389 crank resurfaced and put a mild cam in and the 6x heads on or to just deal with the low compression 400 (bottom end complete) and put 6x heads on it with high energy cam? Then sell the 389 as is. Trying to figure out which direction to go.

[ponyakr]

"...just deal with the low compression 400..."

The 389 will have less compression than the 400, if you put the 6X heads on it.

"...with high energy cam?..."

IF the 400 shortblock is good, & ready to run, as is, I'd put the 6X heads on it & go with the Voodoo 262 cam I linked.

But, if you don't know that the shortblock is ready to run, I'd probably go with a 2800 Summit cam & lifters, to save a few bucks.

If the shortblock is tired, the Voodoo cam might not be a good idea. Any idea what cam is in the 400 now ?

[schultcd]

It sounds like you think the 400 is low compression because of its bottom end components. You need to understand that it is low compression due to the 6X heads. If you put them on the 389 it will be even lower compression because of its slightly lower displacement. Your heads are milled to about the same chamber volume of 6X-4 heads so you get a slight increase there. If you want higher compression I would suggest finding some ‘67-‘70 large valve heads for your 400. The problem with these is they don’t have hardened seats. Like you said, more answers brings more questions.

[77 TRASHCAN]

MGood info here, decision making will be interesting...

Be careful here when speaking the words "High Energy" those cams are OK, only if they are NOT the XE versions! Beware!

Pontiac changed their heads, intakes starting in 1965. 64 and earlier intakes will not fit 65 and newer heads. 65 and newer intake fit all real Pontiac engines (not 301 or 265's) till the last 400 was made in late 70's!

It sounds like you may need to disassemble everything you've got for the best decision...

If it was mine, I'd pick the cheapest route to getting an engine running (keep the 389 parts together and keep the 400 parts all together) reliably, then do a proper build on the other engine (not everyone thinks like me...) grinding the 389 crank would not be anything crazy expensive. But, I'd want to completely take it down, clean oil passages, replace freeze plugs before I reinstalled it...

Don't discount a low compression 400, with the right cam and tuning they are not that bad!

[Sirrotica]

Don't forget the 75 400 has a bevel around the outside edge of the crown of the piston to further lower the compression, I still would probably go with the 400 than the 389, the compression with the 6X heads on either block will probably be very similar considering the 389 doesn't have the bevel on the crown of the piston.

The 6X heads will breathe better than the 91 heads all around, and as has been said don't discount how well they can run with stock compression. 400 rods are also marginally stronger than 389 rods, probably not going to make a difference in this application though.

I would not put any money into the 389 just to sell it, get the date casting codes and post the parts with block code and casting dates and ask whatever basic comparable 390 ford parts would bring from a full size galaxie, or best offer. You might want to post the block codes and find out what body the engine came out of to find out what it's worth. If it's a GTO engine it might bring more money. The first question you're going to get is block code and casting date from most people on here. 65 389s have thin castings and many times will only go .030 over.

Just checked the 91 cylinder head code and it shows 1966 389 2 bbl 8.6 to 1 compression. That may be what year the 389 if the block matches the heads. Most likely came in a 2bbl Catalina/Ventura. Also a thin wall block many times too, .030 overbore if you don't sonic check it, sometimes they are thicker, no rhyme nor reason to wall thickness.

[Sirrotica]

FWIW, here's a 66 389 block posted in 2012 for sale.

Engine Blocks.---- 1966 YC code 389, bare block rough needs everything. $100.

# 91 heads probably are going to be very valuable being 2 bbl low compression heads....$50 OBO?????

Shipping is a killer for blocks and heads that aren't valuable, maybe offer local pickup only since they may not be worth a big dollar.

[C-lane]

Well I guess after all the extremely useful information you guys have provided. Thanks for that by the way. Information is priceless. Anyways I think I'm going to run the 400. I purchased from a friend and it only has about 60k on the engine. I'd prefer not to mess with the bottom end. The only thing it needs is one main cap tightened from where I checked bearing which was good. I am quite attached to the 6x heads since they are in great shape and ported. I plan on putting a cam probably one of the ones stated below. I wanted to put 1.65 rockers, better springs (it has new springs but no way of knowing size) and studs on them. But I also want to mill can have done for 200. Of course can't afford to do both rocker and mill so what do you guys think would give me the most gain? And if mill what would be a good cc? Will be using Rhoades lifter I that makes much of a difference. Thanks again for all of your help.
As for the 389 I'll keep together and sell eventually.

[steve25]

If the money was in the bank I would get the 389 armasteel Crank cut as it's a better Crank.

[OCMDGTO]

Pushrod holes might need to be opened up for 1.65 rockers. Nobody mentioned the 557 block, either, not sure what year that started. OP didn't really specify performance goals either. Cliff had a great thread on a HFT 400 build you might want to check out.

[C-lane]

Originally Posted by OCMDGTO

Pushrod holes might need to be opened up for 1.65 rockers. Nobody mentioned the 557 block, either, not sure what year that started. OP didn't really specify performance goals either. Cliff had a great thread on a HFT 400 build you might want to check out.

I opened the holes already just incase...i mean seems easy upgrade even if motors in car and running. Is the 557 block a poorly made 400? I kinda think my 400 had some numbers like that...have the rocky rotela book and there is a page talking smack about my 400 block haha. Though it stated for street applications it should be find around 400 hp. As for performance goals of course I want the max but unfortunately I don't have the funds. I was hoping to put 400-500 in motor. Cam and valve train mainly. I already have gaskets and everything else. So 200 on cam 200 on push rods and lifters...now my hiccup is if I should mill heads to get performance or if I should upgrade rockers and such. The rockers and springs on 6x heads look to be NOS basically. So which would yall rather have on this application (stock crank and pistons, unknown cam so far ported polished heads clean up mill on them to 94ccs hardened seats) 1.65 upgrade or milled heads?
I'd like a quick throttle response and some torque obviously lol.

[steve25]

Some info for you.
Stock D port non ram air (6X heads) springs and retainers only have room for .480" lift , and this is without whatever type of valve seal you choose to run.
The average stock installed height is 1.560".

[Sirrotica]

Just so you can look at the block and find out the last 3 numbers of the block will be 557 located behind the right cylinder head quite large numbers facing up. They can still be a decent block to 400 HP, sketchy at 500 HP.

A 75 block is right at the time the changeover to lighter blocks started so you could have either. I had a 75 T/A that had the older design block so they still used the better block in at least some applications in 75.

A quote about the newly lightened 350-400 blocks:

Emissions and Economy

New federal emission standards shook the industry during the 1975 model year. Pontiac utilized a single exhaust catalyst and a compression ratio of just 7.6:1 to ensure total compliance. High-ratio rear axle gearing was used to keep engine speed relatively low, which lessened emissions and improved fuel economy. Performance suffered and the 455 was emasculated to just 200 hp. A change that affected all 350 and 400 engines was the introduction of the “lighter” block castings in mid 1975. Pontiac knew that high-revving engines had become a distant memory, so in an attempt to shed overall vehicle weight, material was removed from low stress areas of the block. The blocks are reliable for normal duty applications, but should not be used in any high-performance effort.
Another significant change occurred in mid 1976. Pontiac eliminated the common harmonic balancer on most 350 and 400-ci engines backed by an automatic transmission. A crankshaft hub was used in its place and it served as an accessory drive and contained a top dead center (TDC) timing mark.

I built the low compression 75 engine and used it in a dirt track car for 2 years, and then put it into a 65 GTO street car. Just a 068 cam and dual exhaust makes them run fine. Pontiacs are known for low end torque so you shouldn't have any problem there. Of course you can add to that by other upgrades, but it will still move your 65 body just fine.

[ponyakr]

6x-8 heads started out with aprox 101cc chambers. So, if they now have 94cc chambers they have already been milled a good bit. I think I've read that .060" is the SAFE amount that can be removed, tho I figure some have got by with a bit more.

"...unfortunately I don't have the funds. I was hoping to put 400-500 in motor. Cam and valve train mainly. I already have gaskets and everything else. So 200 on cam 200 on push rods and lifters..."

Since your budget is extremely low, I'd 1st find out what cam is in it now. You may not even need a new cam, or 1.65 rockers. Unless they're bent or something, your stock pushrods should be OK, for a small HFT cam.

If you do need a new cam, a Summit cam is the cheapest that I'm aware of.

https://www.summitracing.com/parts/sum-2800

https://www.summitracing.com/parts/sum-2801

Looks like Summit had a big price increase on their house brand lifters. Jegs still shows theirs for $49.99. They're made in the USA. I recently bought a set. The guy at Summit couldn't, or wouldn't, tell me what lifters would be in a box of Summit lifters. Wouldn't know 'til I opened the box. The pic shown in the Jegs lifter ad is not the lifter you'll get in a Jegs box.

https://www.jegs.com/i/JEGS/555/20702/10002/-1

At both Summit & Jegs, you need an order of over $99, in order to get free shipping.

If you need new springs, the CC 988-16 springs are what Summit recommends. They cost more than either the cam or the lifters. So, if your springs are adequate, that will save you some bucks.

https://www.summitracing.com/parts/cca-988-16

https://www.jegs.com/webapp/wcs/stor...rsistYmm=false

Here's pushrods, if you need 'em.

https://www.jegs.com/i/COMP-Cams/249/7851-16/10002/-1

https://www.summitracing.com/parts/mel-mpr-105

Lots of guys here like the 068 cam. The cheapest price I can find right now is the Melling SPC-7, for just under $100 + tax, from Auto Zone. This includes their current 20% off discount code.

https://www.autozone.com/internal-en...07135_705947_0

[C-lane]

Originally Posted by steve25

Some info for you.
Stock D port non ram air (6X heads) springs and retainers only have room for .480" lift , and this is without whatever type of valve seal you choose to run.
The average stock installed height is 1.560".

So stock springs would really be safe around .450? Would measuring installed height give me any clue as to if these are stock or not? Obviously don't have a spring load gauge so kinda in the dark. Studs look new too. the thread measured 3/8 diameter and the non threaded part of the stud is 7/16 so I guess they measure stud size by thread diameter? I just do get why someone would do a valve job and buy stock spec parts.

[C-lane]

Originally Posted by Sirrotica

Just so you can look at the block and find out the last 3 numbers of the block will be 557 located behind the right cylinder head quite large numbers facing up. They can still be a decent block to 400 HP, sketchy at 500 HP.

A 75 block is right at the time the changeover to lighter blocks started so you could have either. I had a 75 T/A that had the older design block so they still used the better block in at least some applications in 75.

A quote about the newly lightened 350-400 blocks:



I built the low compression 75 engine and used it in a dirt track car for 2 years, and then put it into a 65 GTO street car. Just a 068 cam and dual exhaust makes them run fine. Pontiacs are known for low end torque so you shouldn't have any problem there. Of course you can add to that by other upgrades, but it will still move your 65 body just fine.

Yeah I'm sure its a 557. I remember reading the book and running outside to see them numbers on my 400...will never forget that day hah. I guess its just the smog era stuff that got me shying away from the build when its obviously the better of the two choice I have. Made me feel better to know you put one in a gto. Wonder if I'm putting to much thought into it and should pick a direction and go.