# Another 400 build



## Dave2261 (Sep 28, 2021)

I have started restoring my 1969 GTO convertible that i did a partial restoration back in the 80’s. I rebuilt the 400 with a balanced forged rotating assembly, .030 over flat top pistons with valve reliefs, a very mild cam upgrade, stock #62 heads and Qjet manifold. The short block has maybe 5-6000 miles on it so I am not changing it in this build. I am looking at Butlers 340cfm Edelbrock,72cc, hyd roller top end package. Butler recommended one of their cams 282/288,230/236,.510/.521,114LS due to I am only using it for street. The kit comes with a low rise Northwind 4150 manifold port matched to the heads. They recommended a 850cfm mechanical secondary carb due to I and installing a Tremec TKX 5spd with 3:55 rear gears. The 72cc heads project a 10.3:1 compression ratio that should be ok with 93 octane gas, correct me if I am wrong please. I was planning on using 1.5 rockers and a set of Dougs long tube headers. I am planning on reusing my HEI distributor w/ vacuum advance.
I have been on this forum reading a lot and have gathered a ton of good information from you guys but I would like your input/suggestions before I pull the trigger on this purchase/build.


----------



## PontiacJim (Dec 29, 2012)

Butler knows what they are doing and build engines all the time. I don't think they will steer you wrong.

10.3 compression should be OK with the aluminum heads. The 114 LSA should also help keep cranking compression down, so that looks good.

What I would question is the 340CFM ported heads. In my opinion, for a 400CI that will be too much and the bottom end may be a little "soft" until port velocity gets moving. You may be OK with the TKO 5-speed and 3.55 gears as it will wind the engine up fast and get you out of the lower RPM's. However, 340CFM and that cam means a high RPM engine to take full advantage of it.

I don't think you will like the 3.55's with the TKO as it may be too "stiff" and your engine will be way down on the RPM scale as you are cruising at 70-75 MPH. Those heads/cam may be "balky" and not run too good at too low of an RPM and that is the purpose of the TKO overdrive.

So I would gear the rear end based on cruising speeds of 70-75 MPH and an RPM 2,200-2,400. Tire height will also factor into this. I am running a 9" with 3.89 gears and a tall 29" tire. This should put me where I see my engine RPM turning comfortable - not lugging, not revving too high. I got the .64 overdrive. Use one of the online calculators to figure MPH/RPM's/Tire Size.

On the heads, I honestly think 260-280CFM's would be plenty - even with a stroked 400CI. You would have better throttle response due to better port velocity. The engine will still pull hard, maybe even better due in part to a wider useable RPM range.

Have not used a Northwind intake, but I believe it is a single plane. In my opinion, a single plane intake is fine for racing and it also would match the bigger CFM flowing heads as BOTH would be intended for mid-to-high RPM's - not what I want for a street car, but doable and fun if you like hammering on the car. I would rather see a dual plane intake like the RPM performer and the 280CFM heads.

Not a fan of the double pumper, but we have members who like/use them. You will most likely have to do some tuning of the 850 to dial it in. I like a vacuum secondary carb as it is more forgiving and provides the carb CFMs when needed as RPM's increase. Better still, I am a 2 x 4 guy and nothing looks better than dual quads - on any engine. So the carb can work.

Again, my opinion, and I am not an expert nor build Pontiac engines for a living. So take my suggestions with a grain of salt.


----------



## Dave2261 (Sep 28, 2021)

Thanks Jim for your response. I have been trying to rely on Butler because they have a great reputation. I believe they are going through a Covid-19 situation because you cannot get anyone on the phone. However as you have pointed out some of their recommendations are more suited for a high rpm motor ie; racing etc. I had some reservations on the single plane manifold just for the same reason you stated. The 340 cfm heads was a little surprise but after what you said and a little homework I think understand what you are saying about port velocity. I used the Tremec calculator for the TKX, rear gears and tire size to choose because that combination put my cruise speed at 2200 rpm. As you said this combination is going to be lacking in the low rpm range. I need to start looking to see what aluminum heads are available in that cfm range. I have never been a big fan of the dbl pumpers but that was their recommendation because I was running a manual transmission.
How do those duel quads run? Do they require a lot of setup or maintenance? Would they possibly help with the port velocity issue?


----------



## PontiacJim (Dec 29, 2012)

Dave2261 said:


> Thanks Jim for your response. I have been trying to rely on Butler because they have a great reputation. I believe they are going through a Covid-19 situation because you cannot get anyone on the phone. However as you have pointed out some of their recommendations are more suited for a high rpm motor ie; racing etc. I had some reservations on the single plane manifold just for the same reason you stated. The 340 cfm heads was a little surprise but after what you said and a little homework I think understand what you are saying about port velocity. I used the Tremec calculator for the TKX, rear gears and tire size to choose because that combination put my cruise speed at 2200 rpm. As you said this combination is going to be lacking in the low rpm range. I need to start looking to see what aluminum heads are available in that cfm range. I have never been a big fan of the dbl pumpers but that was their recommendation because I was running a manual transmission.
> How do those duel quads run? Do they require a lot of setup or maintenance? Would they possibly help with the port velocity issue?


2,200 RPM's at cruise speeds is good. My taller tires called for the 3.89 gearing to put me about the same range.

Dual quads are more of a visual. Not any more difficult to set-up/use than any other set-up. You would need a 2 x 4 aluminum intake, carbs, linkage, air cleaners. Gas mileage may suck, especially if you open them up a lot. LOL Just not for everyone, but they look bad-ass. The single 4-Bbl of course is the easiest/neatest way to go.









Ram air dual quads?


Ok have all the pieces together to get the duals on the Tempest. Thanks to a few members added another 1/2" spacer to clear the waterneck. Picked up a GTO hood as i will need the scoop for clearance to keep it under hood. Appears that someone got it stuck at some time and used the can...




www.gtoforum.com













Dual quad jetting questions


I have a stroked 400, now 467ci with moderately ported 6X heads. I am running two 600cfm edelbrocks on top of an edelbrock P65 dual plane intake manifold. Break in is complete and it is running fairly well, but I'm sure it is not running to it's full potential. I have the adjustment kits for...




www.gtoforum.com





The cast iron factory Q-jet intake is hard to beat, along with a good Q-jet. The RPM Performer is a good aluminum intake. 

Speedmaster seems to have a good aluminum RA IV head that flows 280 CFM out of the box. Couple guys at PY have them and they seem to be good heads. They are made in Australia, NOT China.









Pontiac 400 455 215cc 72cc Ram Air IV Hydraulic Flat Assembled Cylinder Heads


SpecsBrand:SpeedmasterPart Number:PCE281.2168Part Type:Cylinder HeadsCylinder Head Style:AssembledCylinder Head Material:AluminumCylinder Head Finish:NaturalCombustion Chamber Volume (cc):72 ccCNC-Machined Combustion Chamber:YesIntake Runner Volume (cc):215 ccExhaust Runner Volume (cc):175...




www.speedmaster79.com










PY Online Forums - Bringing the Pontiac Hobby Together - View Single Post - First Look @@ High Performance Injuns SpeedMaster Heads


PY Online Forums - The online meeting place for Pontiac Enthusiasts all over the world.



forums.maxperformanceinc.com










speedmaster alum head rocker arm stud part number - PY Online Forums - Bringing the Pontiac Hobby Together


speedmaster alum head rocker arm stud part number Pontiac - Street



forums.maxperformanceinc.com





"Made it to Norwalk with the out of the box SM heads car has a bog from the carb I’m using but has gone [email protected] see what tomorrow brings. The engine is a 1970 455 + .060 good rods and pistons stock crank with the SM heads cam is a comp hydraulic roller .520/.540 236/242 113 LSA. I did use solid rollers I had on shelf. Intake is a SM Black Friday single plain I made match heads. Personally I would consider this engine a street engine at 10.7 and the little cam. Carb was the weak link this weekend I used a 800 spreadbore holley I had on shelf."

Just another head choice to look at. Some prefer to get them bare and them add our valves/springs/retainers, etc.. Black Friday seems to be the time to get your best deal on them.


----------



## Baaad65 (Aug 29, 2019)

Did you check out Kaufman Racing they have three chamber choices and three porting options, out of the box d port heads flow 260 with the 72cc heads going for 1247.00 each fully dressed. Porting to 290 is 250.00 ea. I agree with PJ it sounds like Butler is selling you a race motor with topside parts like that, unless you're going to spend a lot of time in the 3000-7000rpm range. I'm running that same cam (14inches of vacuum) on my Butler motor with mildly ported iron heads, 92cc chambers so about 9.4 compression, edelbrock Performer rpm, 1.65 rockers, Quick fuel 850, 2.5" ram air exhaust manifolds and it's pushing 500hp plenty to get me in trouble, but it is a 461.


----------



## Baaad65 (Aug 29, 2019)

And FWIW I'm running an M23Z trans with a 2:98 first gear, 28" tires, 3:42 twelve bolt and I spin about 2400rpms @ 60 mph..I don't plan to go on any cross country trips but it's plenty fun on the short trips 👍


----------



## Dave2261 (Sep 28, 2021)

Have an update I would like to run by you guys. Looking at going with Edelbrock Performer RPM CNC 72cc heads and Edelbrock Performer RPM intake. Butler will port match the heads to the intake. The heads flow 259 cfm intake and 186 cfm exhaust at .500 lift. Are these flow numbers good or should I have them ported to get closer to the suggested 290 cfm? I will be running a Qjet four barrel carb, any suggestions on how or who to use to build/ tune the carb would be appreciated. I will be using a pair of Doug’s long tube headers with 17/8” primary tubes and 3.5” collector to 2.5” pipe. I have had two suggestions on what cam to use. Compcams suggested a 224/230,.502/.510, 110 lsa and Butler suggested 230/236,.510/.521, 114lsa. Both come out with almost identical valve overlap by the formula that I found online. I am a little confused on that. I was always under the impression that the lower lsa was directly correlated to larger valve overlap resulting in the rough idle and lower vacuum readings. Both of the companies said that those cams would work for my street use and need for vacuum. As always thank you for your input.


----------



## Baaad65 (Aug 29, 2019)

I have the Butler cam you listed in my 461 with 1.65 rockers and have 13-14 inches of vacuum and also have the Performer RPM with a 1/2" phenolic spacer, iron heads ported to 230-240, 9:36 compression, 2.5 ram air exhaust manifolds and an 850 QFT carb...was dynoed at 472 hp/526 tq before I swapped out the intake, carb and rockers so I would think I'm close to 500 hp and runs great and reliable for the last three years, jus saying.


----------



## PontiacJim (Dec 29, 2012)

Dave2261 said:


> Have an update I would like to run by you guys. Looking at going with Edelbrock Performer RPM CNC 72cc heads and Edelbrock Performer RPM intake. Butler will port match the heads to the intake. The heads flow 259 cfm intake and 186 cfm exhaust at .500 lift. Are these flow numbers good or should I have them ported to get closer to the suggested 290 cfm? I will be running a Qjet four barrel carb, any suggestions on how or who to use to build/ tune the carb would be appreciated. I will be using a pair of Doug’s long tube headers with 17/8” primary tubes and 3.5” collector to 2.5” pipe. I have had two suggestions on what cam to use. Compcams suggested a 224/230,.502/.510, 110 lsa and Butler suggested 230/236,.510/.521, 114lsa. Both come out with almost identical valve overlap by the formula that I found online. I am a little confused on that. I was always under the impression that the lower lsa was directly correlated to larger valve overlap resulting in the rough idle and lower vacuum readings. Both of the companies said that those cams would work for my street use and need for vacuum. As always thank you for your input.


259 CFM is good. If you had a stroker engine, then you might go more CFM's, but then you would want a larger cam to match, bigger carb, etc..

Cam choice is like opinions, you'll get 100 "best cam choices" from 100 people. Just use common sense, and go for it.

Go with the 114LSA. The 110LSA typically builds more cylinder pressure at lower RPM's - which you don't want if you already feel you will have 10.3 with the iron heads. You will also have a broader power curve.

More overlap equals rough idle and lowered vacuum. However, one cam with a lot of overlap in a smaller cube engine may not sound or be as radical in a larger cube engine. So it just depends.

I got 57 degrees overlap from the 110LSA and 55 degrees from the 114LSA. Bring in the 114LSA cam to 112LSA and I get 59 degrees of overlap. Get down to 110LSA and the overlap is 63 degrees.

BUT, the important part here is the Intake Closing Point. The majority of street cams check in with an intake closing at 0.006-inch tappet lift (advertised duration) at between 62 and 72 degrees ABDC. A smaller number (like 62 degrees) will raise the dynamic compression (cylinder pressure) while a larger number (later closing) will decrease it.

This will give you an effective compression ratio, or dynamic compression. You can have 10.3 static compression and have the intake valve closing early, or closing late, which will give you your dynamic/effective compression.



Wallace Racing - Effective Compression Ratio Calculator



Here is another calculator you can play with. The generally accepted conservative estimate is 8.0 to perhaps 8.5:1 dynamic compression ratio for 91 octane pump gas. I would aim for the lower side of 8.0 for iron heads and 8.5 for aluminum heads. This is no guarantee that you won't have detonation as many other variables come into play like engine temps, timing, inlet air temps, quench/squish area, etc.. 






Effective Compression Ratio Calculator | UEM Pistons







uempistons.com





Make sure you get the correct head bolts with the Edelbrock heads. Believe you need the RA IV head bolts. Standard heads will have a couple bolts too short and when you torque them down, you will rip them out of the block and then you are in big trouble.

Generic Overlap numbers to consider:

Valve Overlap in Degrees - Best Ranges. Smaller cubes should lean towards the left of center, Big cubes should lean towards right of center.
Towing - 10-40
Street Car - 30-60
Hot Street - 50-75
Street/Strip - 70-90
Race - 85-100
Pro Race - 95-115

Included a general rule of thumb for selecting duration numbers and the factory Pontiac cams and their overlap numbers.


----------



## Fast Frankies GTO (Nov 22, 2021)

Dave2261 said:


> Have an update I would like to run by you guys. Looking at going with Edelbrock Performer RPM CNC 72cc heads and Edelbrock Performer RPM intake. Butler will port match the heads to the intake. The heads flow 259 cfm intake and 186 cfm exhaust at .500 lift. Are these flow numbers good or should I have them ported to get closer to the suggested 290 cfm? I will be running a Qjet four barrel carb, any suggestions on how or who to use to build/ tune the carb would be appreciated. I will be using a pair of Doug’s long tube headers with 17/8” primary tubes and 3.5” collector to 2.5” pipe. I have had two suggestions on what cam to use. Compcams suggested a 224/230,.502/.510, 110 lsa and Butler suggested 230/236,.510/.521, 114lsa. Both come out with almost identical valve overlap by the formula that I found online. I am a little confused on that. I was always under the impression that the lower lsa was directly correlated to larger valve overlap resulting in the rough idle and lower vacuum readings. Both of the companies said that those cams would work for my street use and need for vacuum. As always thank you for your input.


Im going through a similar build as you. Happy to compare thoughts. I have the 400 HO engine. I am thinking of having my #16 heads cnc ported to 230 cfm and use a crower 60243 cam.
I want to keep the stock intake manifold to keep everything looking original. The cylinders will be .30 over so technically a 406 ci.

Also want to keep my quadrajet. Lots of talk about using a different intake and uickfuel carb. Im not bringing this to the track but i think it will make about 425 hp.

I have heard that an electric fuel pump may be needed at the higher rpms to keep the quadrajet full of gas.


----------

