# Intake upgrade for 64 389?



## southerz64 (Apr 3, 2018)

I am having my engine rebuilt as I'm writing this.... It currently boasts an "old School" EP-4B Edelbrock manifold for the intake manifold. The engine builder would like me to upgrade the intake to an Edelbrock RPM Performer. He say It will increase performance. While researching a purchase, I ran into various comments and issues. My problem is Edelbrock does not currently make a manifold for 61-64 389 engines (that I know of).. What is the difference between the 1964 engine block then say a 65-67 389, where this particular intake will not fit? Am I stuck using this old manifold because of my 1964 block? Or is it a head issue.
Also, if I'm able to use the RPM manifold, will clearance be an issue under the hood?


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## PontiacJim (Dec 29, 2012)

The bolt pattern of the head/intake, along with the water passages changed in 1965, so all '65 and up will interchange. 1961-'64 are the same.  Now if you have later '65-'66 389CI heads installed on your engine, then you could go with the Edelbrock, but EP4B ("E" stands for "early") is for the '61-'64 engines with the P4B would be for the 1965 and up engines. 

So no go on the Edelbrock Performer intake. Best bet of course is the 3 x 2 intake/carbs. The P4B is said to be just a little better than stock, but weighs less, so still a good manifold for a 5,000 RPM engine. It also takes a square bore style carb (vs a spreadbore like the Q-jet) so you can use the factory Carter AFB type or go with a Holley. If you have the stock carb, I recall it is rated at 575 CFM's. Model 3647-S for the manual trans & #3648-S for the automatic. For reference, the stock Carter AFB had a Primary bore size measuring 1.438" (approx 1 7/16") and the Secondary bore size measuring 1.688" (approx 1 11/16") and is the same from 1964-1966 except for the model numbers.

I would add an open 1/2" spacer under the carb which should give a little more performance. 

Points to consider: install a set of aftermarket forged connecting rods to replace the originals - inexpensive insurance and really not much more than rebuilding stock rods and adding ARP rod bolts. Factory oil pump pressure specification is 30-40 PSI above 2,600 RPM's. Use the better/later 60 PSI oil pump. Some rebuild "kits" still use the 40 PSI pump and some of the big Pontiacs only had the 40 PSI pump as they were not intended to be used for high performance applications like the GTO. The '66 factory specs were upped to 45-50 PSI above 2,600 RPM's. I don't have the specs for '65, but the oil pump pressure was most likely upped beginning in '65. 

Your engine builder should know his Pontiac's. Pontiac's are not chevies and all too often many machine shops tend to know how to build a chevy or ford and then apply that to the Pontiac - and you may have a dog of an engine on your hands if the correct & matching parts are not considered.


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## WheelHorseman (Oct 15, 2017)

southerz64, I'm excited for you; you're going to have a lot of fun with that fresh engine! I too just went through a bit of a struggle trying to decide on cylinder heads and carburation. It's smart to get advice from knowledgeable members like PontiacJim who have been there, done that. I'd like to add that I have been a bit shocked by the prices of a complete, ready to go tri-power, although luckily I think the pre-65 tri-powers may be more reasonably priced. Back in the early 1980's when you could still find them in junkyards, I remember seeing some early tri-powers on the big cars ('58 through '63) still in the yard, or on a shelf in the shed, but never the later years- those were pulled off and sold when they came in. PontiacJim would know which intakes took the "small base" Rochester two barrels and which ones took the larger base carbs, maybe that cut off is '65, which wouldn't bolt up to your heads anyways. I contemplated "rolling my own" '65 or '66 tri-power, but the end carbs are expensive and very hard to find, at least on E-Bay. The manifold, linkage, air cleaners, valley pan, goose neck, and fuel lines add up pretty quick, too, but Wright's Tripower reproduces a lot of good looking parts. I'm not sure what your budget is, but many of the "restored" or "refurbished" tri-powers list for well into the $1K - 4K range, (at least that's what the "Buy it Now!" prices are.) You may find that brand new, square bore "4150" four barrel Holleys are quite a bit cheaper and should be plentiful used, as many muscle car guys are now moving to various EFI refits. (Not to overload you, but maybe just take a peek at the FAST EFI or Holley Sniper, for example- both fit on square bore mani's like yours.) Read the forums on cylinder heads and compression ratio- I've been told that out that my '67 670 heads were not going to work well with today's pump gas, but perhaps your '64 heads will work well with the right pistons? And I'll bet you've probably already read about upgrading those pressed in rocker arm studs but it's the first thing I read about the '64 motor way back when.


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## southerz64 (Apr 3, 2018)

First off, I want to thank you guys for the plethora of knowledge. I am relaying the information you have supplied to my builder. When given the motor over to him, he was under the impression I had 670 heads installed.. (hence his suggestion of a different manifold). But after going over the numbers more closely myself today, I realized the heads were indeed 1964 GTO #9770716 heads, which explains the EP4B manifold. I had always wondered if they had been changed sometime in the motors life, which I guess is still possible but period correct non the less. Engine dude said: The motor was bored .40 upon dismantling with some minor modifications done to the heads, due to some rust in one of the cylinders from a shot head gasket at one point, he is boring to the next size up (.60) this should put it close to 400ci. The carburetor that was currently on the motor was a Holley #4776-2 (a 600cfm double pumper.) He suggests a QFT (Quick Fuel Technology) 750CFM. He also suggests solid lifters w/ flat tappet cam, to replace the hydraulic lifters currently installed. He is also upgrading the oil system as well, said that was the down fall of most Pontiac motors..? The motor ran like a raped ape... (14 years ago lol) so any improvement of the current HP will be a bonus. I am trying to shy away from putting a 3X2 carburetor in the car. I've seen others in my club that have removed them and were glad they did for performance and drivability reasons.

I have been building my Goat from the ground up for the last 10 years.. I know every nut and bolt of the car.. Unfortunately, when it comes to engine stuff, I'm as dumb as a box of rocks.... Thank you for adding some rocks to my box.lol:wink3:


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## Pinion head (Jan 3, 2015)

Not sure what oilng mods your builder is planning. High volume oil pumps are a NO NO for near stock Pontiac V8's, will suck the stock pan dry. Have examined the results several times after local idiot shops have ordered and assembled a 400 Pontiac, I seem to be the guy with all the good crankshafts (not sure about that). With this builders suggestion of the Performer RPM with what he thought were 670 heads, I'd be vary wary of his Pontiac expertise. 

The Performer RPM intake has been out over 20 years and many early versions worked well, but when mounted on well ported Dport as well as well ported round port 455 HO heads. The RPM also been combined with many stock to moderately ported Edlebrock & KRE Dport head 434-474 builds. On stock flow small valve heads, and stock flow Dport big valve heads on a 389, will be hard pressed to gain anything other than weight savings over cast iron. Last, over last few casting runs, lots of fun and expense to get the later produced RPM intake flanges to mate up properly, been there twice


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## southerz64 (Apr 3, 2018)

I just off the phone with the builder and I guess I was mistaken.. He was aware that the heads were 716.. He wasn't aware, that no one hadn't made a current upgraded manifold that would fit that block (by now). We are sticking with the EP4B Edelbrock and adding a 1/2 spacer like Jim suggested. I also brought up the oil situation. He also stated that high volume is NOT what you want for the same reasons you pointed out. But high pressure is a must on the GTO 389. He mentioned because of the valve size on these particular heads, dished pistons were needed to run pump gas.. I am looking into getting Dougs DPort headers #D564 . Has anyone had any fitment issues using them on a 4spd sedan? Builder is also drilling and tapping the heads for studs for the lifters and the outer bolt for the headers. Thanks again for the info!


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## PontiacJim (Dec 29, 2012)

southerz64 said:


> I just off the phone with the builder and I guess I was mistaken.. He was aware that the heads were 716.. He wasn't aware, that no one hadn't made a current upgraded manifold that would fit that block (by now). We are sticking with the EP4B Edelbrock and adding a 1/2 spacer like Jim suggested. I also brought up the oil situation. He also stated that high volume is NOT what you want for the same reasons you pointed out. But high pressure is a must on the GTO 389. He mentioned because of the valve size on these particular heads, dished pistons were needed to run pump gas.. I am looking into getting Dougs DPort headers #D564 . Has anyone had any fitment issues using them on a 4spd sedan? Builder is also drilling and tapping the heads for studs for the lifters and the outer bolt for the headers. Thanks again for the info!



My resources state that the 1964 GTO 389 is the last of the "thick wall" castings and can be bored .090" over safely and was a favorite for racers because of this - and it could be taken out further if you sonic test it. It has the provisions for the later starter that bolts to the block and accepts the later bellhousings/transmissions (1965 & up type). The block has no chamfers in the block for the valves while '65 and up do.

If you go .060", you can use the 1967 & up 400CI pistons which I am sure your builder is aware of. However, the valve angle is different on the 389 versus the 400, 22 degrees/389 heads & 14 degrees/400 & later heads. The scallops in the pistons are located differently on the 389 vs the 400 pistons. Pistons like the Keith Black offers the FHR pistons which has both valve pockets. If you go with a dished piston to lower compression, this will likely provide the needed clearance as well. So valve-to-piston clearance will need to be checked depending on your cam's lift/duration. 9-to-1 compression thereabouts is a good compression to shoot for with iron heads and pump gas. The HP loss from 10.5 ish compression can easily be made up in the build.

The "716" heads are very good heads. I assume "drilling and tapping the heads for studs" are the rocker arm studs. You have options. ARP # 290-7201 rocker arm studs are made specifically for doing this. This is NOT the same a a Big Block rocker arm stud often used to replace the factory Pontiac screw-in studs found on later HP heads - it has a different threaded base: Here is a comment on these studs and their installation on the '64 head:

"Use ARP 290-7201 rocker studs but be prepared, they cost about $100 for 16 studs whereas BB Chevy rocker studs cost about $20 a set.
--The ARP studs are not BB Chevy rocker studs but are studs designed by ARP specifically for Pontiac heads with pressed in studs. That is because the holes left in the heads after removing the pressed in studs are too large to tap for 7/16"-14 BB Chevy style rocker studs and a 7/16"-14 heli-coli must be used. You can eliminate the heli coil step by tapping the head for 1/2"-13 threads and using ARP 290-7201 studs.
--If you decide to use BB Chevy style rocker studs, don't use heli-coils, use E-Z Loc thread inserts.
--I have used the ARP 290-7201 studs on 1963-1964 GTO/421 HO Pontiac heads where you must mill the stud boss 3/8" and then tap the stud hole for 1/2"-13 threads. The 1966 and earlier heads do not have a stud boss that is milled for guide plates, instead the push rod guides are an integral part of the heads. Be advised, ARP studs have 7/16"-20 Class 3 rolled threads which are not designed for BB Chevy 7/16"-20 prevailing torque locking nuts. You should use full roller rocker arms and poly-locks with ARP studs.
--The stock Pontiac rocker arm slots fit the shank of ARP 290-7201 7/16"-20 x 1/2"-13 screw-in rocker studs, stock 3/8"-24 x 7/16"-14 Pontiac bottle-neck screw-in rocker studs or GM BB Chevy 7/16"-20 x 7/16"-14 screw-in rocker studs. No problem there, but read and heed the last two sentences in the previous paragraph.
--The threads on the ARP studs are 1" long, requiring either a deepening of the hole or shortening of the stud. Be sure to use Liquid teflon to seal them if you break into the port."

My Pontiac engine building source book (1974) also states that the push rod holes in the head are too big and to add push rod guide plates. (other sources say you don't need them) The ones I found recommended on the internet are Competition Cams adjustable small block chevy guide plates. The forum thread I found states,"Guideplates to be used are Comp or Isky "adjustable" units, "listed" for small block Chevy. When guideplates are used, the "slots" for the pushrods must be opened to 1/2" diameter hole. Here is a listing for a set of guide plates: Comp Cams 4835-8: Adjustable Pushrod Guide Plates SBC 265-400 | JEGS 

You can also buy these single if your machinist wanted to try one to see how it works: Comp Cams 4835-1: Adjustable Pushrod Guide Plates SBC 265-400 | JEGS

You don't really need anything more than stamped rocker arms for most cams. Comp Cams makes a good 1.5 piece. I used them on my 400CI build. They have the long slots for higher lift cams so no binding and grooved rocker arm balls. The 1.52 rollers seem to be a good piece, but a little more money. Am using a set on my present build just to try them.

You will also want to get a set of poly locks for the rocker arm studs (especially if you go solid cam) that will work with your valve covers. There are short & long poly locks. If any problems, you can get thicker valve cover gaskets and even a spacer so you can use your 389 covers.

The same book says that the TRW 1961-'62 HI-Po Chevy 283CI intake valve can be used in the "716" head. It is tuliped & swirl polished, 1.94" in diameter, and slightly longer 4.915" vs 4.870" and is cheaper than the Pontiac valve. Probably unavailable, but this was written in 1974!

A three angle valve job will add performance to the heads. Pontiac uses a 30 degree intake seat and 45 degree exhaust seat. HO-Pontiac performance engine build guide states the three angles on the intake seat as 15-30-45 and exhaust as 30-45-60.

Check pushrod length with any work done to the head.

Solid cams are fine, but keep in mind that they have that old school "ticking" sound that only a true hot rodder likes and others get annoyed by. They require periodic adjustments if you don't mind this. I went with a solid cam on my build and a noisy gear drive, just because. LOL 

Make sure you replace the oil pump shaft with a hardened aftermarket shaft. The "ears" on the factory piece can break off - just had one of our members experience this and had to pull the engine and replace parts. They are cheap insurance. I just got mine from Nightmare Performance as recommended by member BearGFR. A little pricey, but an excellent piece with top quality. Has a collar on it to keep it securely in place which is why I purchased it. Have used the more inexpensive shaft on several engines with no problems ever, so they certainly work well. Nightmare's product was just an extra I chose to try in my build: Standard sleeved & hardened oil pump driveshaft

I purchased Doug's headers for my 455CI build. Have yet to get to the point of even assembling the engine. But, they look very good. Mine are the ceramic coated ones, but the plain should work and be cheaper in price. A good quality header paint should work. I have read that these fit the best with the least amount of hassles, so I am giving it a try. The '68 has the pivot style cross-over clutch shaft and it is recommended to use the 1965 piece which is a straight tube, so I picked that up as well. Down side seems to be clearances for the oil filter when it comes to a change and oil gets all over the headers. It is also recommended to use a mini-starter for added clearances in that area as well and you can position the solenoid away from the heat of the header tubes. Went with a RobbMc mini-starter with my build. RobbMc Performance Products - Pontiac Starter


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