[Maxthe222]

Hey gang,

Let me start off by saying yes, I know that I won't get very far with the stock 6x4's, I understand the limitations, and that getting D-Port Edlebrock or KRE aluminium heads would be more effective. Well, with the cost to ship those over to Australia at the moment, how long it'd take for me to get them, and how I would like to retain the relatively stock look, I'd like to hold onto the 6x4's for now.

So they're bare metal, cleaned up heads right now, and I'm starting from the ground up. It's a factory bore 1979 400 PWH block. Likely just going to 0.030 for now. Looking at possibly flat top 0.030 KB or Sealed Power piston heads. Considering keeping the original Armasteel rods, and definitely keeping the original 17059263 Rochester Quadrajet. Keeping factory intake as well, will look into porting options for it.

In terms of components for the heads, such as valves, lifters, springs etc, what are some good combinations to consider? I've read that you can port the heads out from 93cc to something like 87cc, does anyone have feedback on what the limitations there are? I think I can expect that my best case scenario will end up something like 9.5:1 in terms of compression.

Is there also some sort of resource out there I can use if I need to prod the head guy in the right direction for porting? Like porting specs or measurements? They'd likely have next to no experience with Pontiac heads down here.

[tempest1964]

Jim Hand wrote an excellent book on porting those very heads. And he got excellent performance with them. Amazon (among others) sells the book. Here is a link:
https://www.amazon.com/How-Build-Per.../dp/1884089674

[Maxthe222]

Originally Posted by tempest1964

Jim Hand wrote an excellent book on porting those very heads. And he got excellent performance with them. Amazon (among others) sells the book. Here is a link:
https://www.amazon.com/How-Build-Per.../dp/1884089674

Ahhh, I saw the Rocky Rotella one and bought that one about just rebuilding Pontiac V8's, I didn't get a hold of the "Max Performance" one. You could say.... it had my name all over it

[Jay S]

It mainly depends on what your goals are, the cam’s attributes, and the efforts put into the porting. Here is some of the porting results I have done on 6X heads on the intakes at different levels.
Stock…208 @.5” lift
Bowl porting…[email protected]” lift
Bowl and Ceiling porting…[email protected]”
Porting,Jim Hand [email protected]”
2.11” valve, RA4 ports, tall ceiling, short side work, [email protected]”
2.125” valves, RA4 ports, short side work, tall ceiling [email protected]”
2.125” valves, RA 4 ports, short side radius turned sooner, ceiling matched to short side, [email protected]”

[Stan Weiss]

I know it is a big country and you maybe to far away. But I would talk with Tony at Knight Engines.

Stan

[Maxthe222]

Originally Posted by Stan Weiss

I know it is a big country and you maybe to far away. But I would talk with Tony at Knight Engines.

Stan

Not that far away in the grand scheme of things, I've heard of this bloke before. He's experienced with Pontiac heads? Are you here in Aus?

[Skip Fix]

I think Jim Hand added 1.77 exhaust and the E/I ratio was almost high enough to need a single pattern cam.I found the same when I added those and bowl and port matched the 6X-4s on the 400 in the 81 TA. I used 5.09 "regular" D port length valves for a better IH on valve springs.

[Stan Weiss]

Originally Posted by Maxthe222

Not that far away in the grand scheme of things, I've heard of this bloke before. He's experienced with Pontiac heads? Are you here in Aus?

No I am in the USA. I don't know if Tony has built a Pontiac. The reason I brought up his name is I post on another forum where Tony also posts. I have seen the variety of different engines he has built and the knowledge that he has shared.

Stan

[ta man]

A great valve spring for stock installed height and length valves is a Crower 68404 spring.
What et or horsepower are you looking for?

[TA63]

Originally Posted by ta man

A great valve spring for stock installed height and length valves is a Crower 68404 spring.
What et or horsepower are you looking for?

How much lift at stock installed height can that spring handle? I want to use the crower 60240 cam with some 1.65 rockers

[ta man]

Originally Posted by TA63

How much lift at stock installed height can that spring handle? I want to use the crower 60240 cam with some 1.65 rockers

Crower 60240 .422/.446 lift
Crower 60919 .470/.470 lift

I was using the Crower 60919 with 1.65 HS with no issues.

Crower recommends the 68404 spring with those cams.

[Cliff R]

Need a bit more info.

It appears that you are just going to have the 400 bock bored and new pistons?

I'd skip right past the Speed Pro forgings, WAY too heavy, pins are really heavy, stock ring packs, and most I've seen end up WAY too far down in the holes at TDC when you mock them up. To optimize things for compression you need to start out with a piston that's close to the top of the block at TDC so you aren't cutting a lot off the block to deck/square it. Plus pistons/pins are reciprocating weight and thick ring packs are "drag" in the engine. Upgrades in that area pay off in vehicle accelleration and ET/MPH at the track or in a good street race.

6X-4 heads just aren't the best choice for a 400 build if you plan on running optimum compression for pump gas. You have to cut them pretty hard, and zero deck with a two valve relief piston to get much over 9 to 1 compression. Compression is your friend with these things if you are looking to make good power (torque) with a 400 build as it allows for larger cams with less negatives at idle and in the "normal" driving range.

I've done a good many 400's here, and helped a LOT of customers with them. They will run right with the big CID 455 and "stroker" builds but you aren't going to get there easily with 9 to 1 compression.

For a 400 build to 1hp/CID you don't need a lot of head flow. Well prepared 6X heads will flow PLENTY of air for that deal without heavy porting, but once again the have big combustion chambers so not much squeeze. I typically look for 62's, 46's (1969) or other heads with smaller combustion chambers for 400 builds. You can EASILY manage 10 to 10.5 to 1 compression with factory iron heads if you keep the squish tight and choose the right camshaft.

I would NOT use the factory cast iron rods, they are press pin and there are just too many far superior options out there these days plus most are full-floating. They don't make any more power than a cast iron rod but for sure you'll sleep better at night knowing you have a much stronger forged rod in there when you spin it up pretty hard........

[Maxthe222]

Originally Posted by Cliff R

Need a bit more info.

It appears that you are just going to have the 400 bock bored and new pistons?

I'd skip right past the Speed Pro forgings, WAY too heavy, pins are really heavy, stock ring packs, and most I've seen end up WAY too far down in the holes at TDC when you mock them up. To optimize things for compression you need to start out with a piston that's close to the top of the block at TDC so you aren't cutting a lot off the block to deck/square it. Plus pistons/pins are reciprocating weight and thick ring packs are "drag" in the engine. Upgrades in that area pay off in vehicle accelleration and ET/MPH at the track or in a good street race.

6X-4 heads just aren't the best choice for a 400 build if you plan on running optimum compression for pump gas. You have to cut them pretty hard, and zero deck with a two valve relief piston to get much over 9 to 1 compression. Compression is your friend with these things if you are looking to make good power (torque) with a 400 build as it allows for larger cams with less negatives at idle and in the "normal" driving range.

I've done a good many 400's here, and helped a LOT of customers with them. They will run right with the big CID 455 and "stroker" builds but you aren't going to get there easily with 9 to 1 compression.

For a 400 build to 1hp/CID you don't need a lot of head flow. Well prepared 6X heads will flow PLENTY of air for that deal without heavy porting, but once again the have big combustion chambers so not much squeeze. I typically look for 62's, 46's (1969) or other heads with smaller combustion chambers for 400 builds. You can EASILY manage 10 to 10.5 to 1 compression with factory iron heads if you keep the squish tight and choose the right camshaft.

I would NOT use the factory cast iron rods, they are press pin and there are just too many far superior options out there these days plus most are full-floating. They don't make any more power than a cast iron rod but for sure you'll sleep better at night knowing you have a much stronger forged rod in there when you spin it up pretty hard........

1. That's basically it, was just going to slightly bore out the block and replace the pistons. I wasn't confident about retaining the original Armasteel rods, so hearing that from the professionals was all I needed to hear to back off using them. What other details should I also provide?

2. Do you have any rods you suggest? I'll take care to ensure I avoid the Speed Pro ones. It was more just a matter of convivence since they were available from a local source.

3. I understand 6x4's aren't the most optimal choice, but the possibility of finding a set of #62 or #46 heads down here is basically non-existent. I'm currently in the market for a set of #96 heads for a 1971 Formula 400/4-speed I have as well, but I'd like to finish of my Fire Am first. The cost to ship a set of heads down here as well is exorbitant at the moment due to the poor exchange rate and shipping costs. If I was prepared to go to that stage in cost, I'd of just bought aluminium aftermarket heads. I'd also like to retain a relatively original engine bay as well.

[Maxthe222]

Originally Posted by ta man

What et or horsepower are you looking for?

I'd like 400 from a 400

[Cliff R]

400CID, .030" over, stock untouched #16 heads, Crower 60916 cam, high ratio rockers, 419hp/453tq.

400 CID, .030" over, stock untouched #16 heads, Crower 60243 cam, high ratio rockers, 424/465hp.

Same basic engine set-up with out of the box KRE heads, Crower 60916 cam, 440hp/464tq.

Same engine with the 60243 cam 450hp.

Kind of interesting but the same engine with the larger Crower 60919 cam didn't make any more power but idled rough and less vacuum at idle speed.

I helped a local customer here with his 68 FB. 400 CID, steel rods, aftermarket forged 2 valve relief flat top pistons, decked/squared, tight squish, 62 heads from KRE (ported), Crower 60243 cam, Rhoads lifters, high ratio rockers, stock iron intake, stock (rebuilt/recalibrated here) 1968 Q-jet, stock points distributor, TH350 built here, one of my custom torque converters, 3.73 gears. On DOT's thru the mufflers high 11's over 116mph.

I've seen quite a few bigger CID builds, some with aluminum heads, aftermarket RPM and T-II intakes, 850cfm carbs, MSB billet distributors and such that don't run any quicker than that engine does using iron heads and lots of stock components.

So don't sell the 400's short, they are capable of great power and performance in one of these vehicles..........

[25stevem]

The basic carved in stone rule of thumb is ( and especially ) in reference to motors of 400 cid or less ( and with less then 9 .4 to 1 compression) is that the minimum port area and in turn the port velocity that the factory 14 degree ( D port. ) heads have is well sorted out for great power up to 4500 rpm on these size motors.

Now in the above where talking about a port volume of 155 CCs at best.

Then here’s what happens many times.

You slap on a aftermarket head with a minimum of 14% more port volume ( 180 CCs) to a out of the box max of 28 % more CCs and now at a minimum to get back the same level of throttle response you had with the stock iron heads you need to rev the motor up that minimum 14% more, and or stuff in 14% more rear gear to make up for the reduction in the AVERAGE amount of torque the motor use to make.

One big part of the limited performance gain that build like the last one that Cliff posted about is this , in the rpm range where the motor is now down on torque numbers the motor is also reving up slower.

This has a big impact on accelerating the mass of the car number 1, and number 2 getting the motor up into its new higher rpm range power band fast.

It’s the average numbers that are produced in a motors intended power band that matter the most!

In terms of street strip performance the amount of time that a motor spends between 5000 and 5500 rpm is very small when you have the cars rear gears of in a ratio range that can be lived with on the street.

You still need a wide power band of near 3000 rpm from off idle.
Stuffing in a bigger cam with heads of a port volume that only comes into there own at 4000 rpm and then do so with only a 2000 rpm wide power band is a commonly seen pit fall that folks make!

Oh yes, the motor sounds really fast and impressive now, but only offers up a 2 to 3 mile a hour increase in 1/4 mile times once the car got the rear gears changed out to start to make good use of that new and narrower power band that was expensively built into the motor!

[Maxthe222]

Originally Posted by Cliff R

So don't sell the 400's short, they are capable of great power and performance in one of these vehicles..........

I don't doubt them at all, that's why i'm definitely looking forward to getting mine on the road as soon as possible

[Cliff R]

"One big part of the limited performance gain that build like the last one that Cliff posted about is this , in the rpm range where the motor is now down on torque numbers the motor is also reving up slower.

This has a big impact on accelerating the mass of the car number 1, and number 2 getting the motor up into its new higher rpm range power band fast.

It’s the average numbers that are produced in a motors intended power band that matter the most!

In terms of street strip performance the amount of time that a motor spends between 5000 and 5500 rpm is very small when you have the cars rear gears of in a ratio range that can be lived with on the street.

You still need a wide power band of near 3000 rpm from off idle.
Stuffing in a bigger cam with heads of a port volume that only comes into there own at 4000 rpm and then do so with only a 2000 rpm wide power band is a commonly seen pit fall that folks make"

Correct. We saw next to NOTHING going from a 228/235/112 cam to a 231/240/113 cam in terms of improvements in average power. It also didn't help that the RAIV cam has over 80 degrees of overlap so bleeding of a lot of cylinder pressure at lower RPM's. Even with that said take the exact same build and increase the compression ratio a FULL point or so and everything changes. The added compression trumps the losses from the larger cam, vacuum at idle improves, throttle response, power at low RPM's etc. It will run equally as well as the smaller cam/less compression engine everyplace and have some added upper mid-range and top end charge.

I've never much liked the RAIV cam in a 400 build with around 10 to 1 compression and "D" port heads. Those engines are "lazy". I get more complaints from that combo here to the shop than any other. Take the same engine, port the heads to 240-250cfm, increase the compression ratio into the 11 to 1 range and you'll be hanging on for dear life on your first test drive!........FWIW......