OK, I'm trying to figure out what brand of parts to put in the 455 block. My first question is the crank. I see ones list as 4.21" and 4.25" What does that mean?

Also any suggestions on pistons and rods? I picked up a performance rebuild book and it talked about Keith Black pistons. Anyone using them? If they are, who's running what? Dome, Dish, or Flat top?

Now about rods. Molly or H-beam. If I read things right, the difference would be how much horsepower they can handle. I'm hoping to get over 500hp with the block.

Last thing, roller rockers. Are the scorpion roller rockers any good?

Just a little back round on what I have already.

Block 74 455
#96 heads
edelbrock torker II intake
edelbrock 750cfm carb
was planning on going .030 on the pistons.

Any help would be greatl appreciated.

i believe the 4.21" and 4.25" is the stroke. what compression are you looking for? the domed pistons would give the highest compression depending on the heads you are using. are you using pump gas or racing gas?

Scoobie, did Keith Black write that book, by any chance?

There are about 80 other questions you have to answer first.

Do you want opinions, or facts?

I'll give you one opinion: Build it for 9.2:1 compression so it will run on pump gas.

Ok ... I lied. Two opinions: You don't want HP. You want torque. Unless you are going to run in an unlimited class of racing, torque is what will accelerate your car. A 500 HP motor that gets all its power above 6,000 RPM will be all but useless on the street.

If you want to have a whole bunch of money left over for a good point job, there's a very reasonable way to build a 455 that will still burn all the tread off your tires every time you touch the gas. You've already got the heads, but most of the other parts you are reading about, or already have, are not the best for the combination you could and should build.

The 455 build up was written extensively a couple years ago.

My Favorite 455 Combo

Thr combination discussed there sounds similar to setups Jim Hand describes in his book.

I have '96' heads already and a 400 block. I want to remain a stock appearance down to the 400 block markings and intake. What do you think of the 462 Eagle stroker kit?

I talked it over with a local machinist who said he would get the Eagle unbalanced crank and attend to balancing in his shop because they only did so-so on that. He had a high dollar balancer in house. That and a twenty foot wall of Snap on cabinet stuffed with tools.

Everything had a place and everything was in place. His shop was absolutely clean and tidy. He builds some of the faster Buick GN V6 engines around.

I'm a ways off from needing an engine, but if folks feel like keeping this thread alive, I'm interested in filling out a parts wish list.

I have been doing some serious thinking over the last couple weeks. Have a 70 455 with 15 heads and really want to put it in my 69 convertible but I think I will be better off to leave the numbers match drive train intact... maybe search for a roller coupe and put the 455 in it. Either that or sell the 455... I don't know. From what I understand even a mild 455 will require extensive mods and I don't want to ruin an original car. Also got a catalog from PAW... seem to have good prices and come pretty good recommended from my buddy. What do you guys think of PAW rebuild kits?

I think you can put together a far better engine kit by choosing your own parts and buying them a'la carte from Summit. The cost won't vary that much, but the opinions might!

The #15 heads leave a lot of that 455 on the table.

Roger that on Summit, Q. I'll take your advice.

What exactly do you mean by "they leave a lot of that 455 on the table?" Not good heads? Or need to have them ported and enlarge the valves? They are 87cc, right? Also have some 5C heads I could use... if they are worth it.

Larger valves.

The #15 heads have small valves. And, they actually make better 400 heads, since they have chambers that are the right size for a pump-gas 400. Large valves and screw-in studs, though more costly than milling a set of 5C heads, will help keep the factory valve train geometry. The 5C would benefit from larger exhaust valves, too, though it's not as critical on a 400.

So in that case, I could run the #15's with large valves and screw in studs on a 74/75 YH 400 block I have out of a Bonneville, and remove the 5C heads from the 400 and with some work, put them on the 455? I had thought of that actually but didn't know if it was feasible. Maybe in the long run I would be better off selling the 455 and keeping the 400 for my bird (won't have to modify the car for the torque monster).

What you describe is probably what I would consider doing.

Both sets of heads will take about the same effort to make them "equal" for the motors they will go on.

One of the things I didn't consider, though, is altitude. You're way up there and probably need to run more compression than us guys down here on the beach. You might want to think about how much driving you're going to do away from home. If it's not too much, then keep the #15 heads on the 455 (after you put in larger valves) and adjust your jetting to accomodate the thinner air.

Thank you, Q.

Q lives by a beach...

I am 16" deep in snow and he talks about a beach.

Thanks Q....

Anytime, Tom, Anytime!



Of course, it comes at a price!

How about eternal dedication and friendship?

Can't buy much but piece of mind.

Without reading any posts, I would build the motor at 9.1 to 9.4 to 1. A gear of 3.23 to 3.36 would be excellent with the torque of a 455.

I do not recomment installing a 455 that is built close to stock HP/torque for reasons of body flex and damage to suspension components.

If you build a 455 to run on pump gas without head mods (porting) you should be around 300 HP. Stay close to that. That 455 will produce so much torque that, over time may pay a toll on body.

If you drive the car normally (yea, right!) You can live with the 455 in a 67-9 Bird forever.

Stick with stamped steel rockers, save your $$

Rods? Stock resized with ARP bolts.

So ... without reading any posts ... that's the best you can do? And, when it comes to 455's in a first gen, you recommend the "Build it Down" approach?

Not the best..I could elaborate, but yes, I would build it down based on some of the Camaro and Firebird bodies I have seen with engines estimated in the 500 ft.lb. torque range.

I do like your idea on your build, but a first gen can only handle with traction, suspension and frame mods. A full frame car, absolutely no problem.

My 67 has stress cracks in the sail area and gaps in doors which the door protrudes 1/8" from the quarter panel. That damage from a 428 that ran high 11's..I did weld in connectors, but too late.

You will not see any issues with occasional fun, but my car was at the track 4-6 runs a month for 6 months over 3 years. Now I have to figure out how to rectify.

I know I am likely being overly cautious and his car would probably not see the abuse and fun I had with mine, I have an anal issue with unneeded problems that could be rectified with proper setup.

I could recommend alot of items along with your motor build Q, but then again, who actually follows through with personal experience and advice?

The more I think about it, the more I am scared to ruin my car by putting the 455 in it. It's matching numbers, etc. 350 2bbl convertible, 2.56 open rear and has led a very nice life and has never been mistreated (at least in the area of overpowered engines). It's rust free and crack free. Also my Grandpa bought it new. I think I will leave it alone... Especially now that I see the price of that coupe here in Colorado Springs on Ebay. I wanted the original block and th350 set aside so I wouldn't ruin them but now I think maybe I need a coupe project for this 455 or 400 I have. Actually I have a guy in Denver who wants the 400 so maybe better sell to finance parts for the convertible. Hell, it's fast enough as it is. I almost killed myself in it lots of times when I was around 18 going 140 with the top down... stuff like that.

Thanks guys for all the help and if anyone knows of a roller coupe in Colorado...

Tom, you are absolutely right. If I recall, the impetus for that thread wasn't whether it was a good idea to put a 455 into a Firebird, but how to build the motor inexpensively with factory parts.

Every time someone wanted (or wants) to build upo a 455, we (the community) usually advise building it down, AND adding the subframe connectors and better body bushings. Maybe not blatantly, but we're pretty good about being consitent.

One of the other caveats that I usually preach is using sensible tire sizes in the rear. Tires are a lot easier to replace - and less expensive - than axles or differential units. In addition, the body twisting should be less if you're not hooking up all that torque.

But in your case (with the number of trips to the track) you probably would now recommend a back-half job to anyone contemplating that much strip time, right?

My 67 had 10" slicks or DOT drags, 12 bolt rear 3.55 gear. The DOT drags are 200 traction, the Radial T/A's (drivers) are 300.

I had to run 12 and up because at 11.99 sec ET and lower, I needed to insatll a cage which was not an option.

Realistically, balck halved cars usually run narrowed rears and tubbed aluminum and 4 links. Most of the guys in the mid 9's and below are set up like this..

Q, you could realistically install your motor in any First Gen...with the additional expense of proper and safe suspension mods..I would hate to see a car get "played to death" otherwise.

You're right. Knowing what I know now, I would definitely take the time and expense to upgrade to subframe connectors and better body bushings, brakes and rear spring bushings if I would have gone through with putting either my 455 or 428 into my convertible.

When I first got the car, I had no idea that the unibody design was developed during GM's limitation on engine size, and that the torque of the 400 was the design criteria.

20/20 hindsight: I'm glad I kept the 455 in the GTO and the 428 on the stand.

The damage would not be readily apparent, but over time, stress cracks in paint at sail panels, distortion of the upper sail and roofline and door misalignment.

I am not a second Gen expert, but were TA's 70-71 (Higher HP/torque 360/370 455 HO) utilizing full frame or subframes?

Those cars (70-71) are 4-600# heavier but still interested in that frame issue.

unibody .. same as the 69's unfortunately.. the Firebird never had a full frame
Dave

No convertibles, though, and I'd stay away from the T-top cars. I haven't heard of any issues with 2nd gen cars.

My '69 convertible has been subjected to twisting forces because of the suspension, but from cornering forces as well as acceleration. I used mine for autocross events (with the usual suspension mods) and a lot of playtime on my favourite winding road. After a hard left under substantial throttle, I would have to stop and pop the left rear fender right over the wheel well back out. Subframe connectors and a 4 point roll cage are in the works for the next stage.

OK after reading all the post I have some more information. My bird is going to be a driver only in the sometime. On some nights and weekends. I have a work truck so I don't need to drive my bird to work and on nice nights I have a jeep cj. Actualy I have to many vehicles. Motorcycle, jeep cj, jeep grand cheeroke, and work truck. So you see the bird is to cruise around and show off a little. I don't plan on taking it to the drag strip either. There will be however the occasion line locks and burn outs. So I'm not concerned about getting stress cracks. I have poly bushings in front and rear.

So I am looking to try and get a lot of horsepower out of the engine. I'd like to get 500 hp but will settle for above 400.

The book I have is called "how to build Max-Performance Pontiac v8's". Written by Jim Hand

Did anyone pick up Car Crafts issue for January 2006? They have an article in there about Aluminum D port heads. They did a dyno testing using 7K3 heads ( because they couldn't find a pair of #96 haha which I have) and the new D port aluminum.

With the short block stock and running a crane cam, 7k3 heads, edelbrock performer rpm intake and a demon 830 cfm carb, the engine posted 494 TQ @ 3,500 and 390 HP @ 4,700 rpm.

Switching out to the D-port aluminum heads it tested 539 TQ @ 3,600 rpm and 427 HP @ 4,500 rpm.

So if Car craft can get that with a stock short block on pump gas @ a 9.2:1 compression. I'm hoping to get a little more than that by doing some work on the block with new pistons.

There's no horsepower in the block. It's in the heads.

If all you want to do is raise compression, switch to 72cc heads and shell out for racing gas.

So should I just run with what i have now and just bore the block out to .030 and run a set of dome pistons?????

YOU
DON'T
NEED
DOMED
PISTONS.

Flat tops with a small chamber vs domed pistons in a big chamber = around 20 less hp for the domes. Notice that increased airflow improved the torque as well as the horsepower.

The power in the short block can be from reduced friction, better ring seal, zero deck to improve squish, etc., but that should be done in a good engine rebuild anyway, and as Q says, the main gains are in the heads with better airflow and combustion efficiency. If you go with aluminum heads, raise the compression ratio about 1/2 point to compensate for the heat lost to the heads.

Even though I have not read the article, I would assume that the Aluminum D ports are the new KRE heads, and are not Edelbrock. They will have a full point higher compression than the 7K3 heads, which is where a good bit of those torque and horsepower gains come from.

Did the article happen to compare the flow bench data from the Aluminum heads to the 7K3's? I'd be very interested to know what it might have been.

Who the heck uses dome top pistons in a Pontiac motor? Who produces them? I think they are special order through Ross or Wiseco..but only in racing (serious) applications not street.

As Q stated, basic motor parameters (Pontiac) HP is relative to chamber CC and size of piston reliefs (6.7 cc stock, 7-14 cc aftermarket). With all things equal, a 455 with 96 CC heads and 6.7 cc piston reliefs will be more HP than a 455 with 14 cc reliefs (volume). Cam and head flow are next in line in varations of increased HP..then intake/exhaust and carb. Kinda like working from block outward.

Assuming your heads (96) are at 96 CC's and .030 bore, zero deck, .039 gasket, you are at 9.5 to 1 with 6.7 cc pistons. You are fine with a "stock" rebuild. You should see 320-340 HP on the dyno. You go above 9.5 to 1 and do not know how to tune a carb or distributor, over time, detonation will get you. You could go up to 10.3 to 10.5 with aluminum heads. If you want more horsepower from a 455, you will have to decrease chamber volume to 72 cc heads (race gas) 80 cc heads (50/50 blend of 93 and 110) or 87 cc (blend of 20/80% 93 and 110) YOU WILL have to run a blend or be prone to detonation. If I remember correctly, you were on a tight budget, so your best bet is to buy a complete rebuild package from Summit or Jegs or have your engine builder make the choices. You start mixing and matching, you will spend 30% more and will be looking for trouble.


That is Chevy stuff. (Dome Pistons)

KRE D-port heads, 85 cc vs 96 cc on the 7K3 heads. I haven't checked their numbers but the article says 9.2:1 for the iron heads, and 9.8:1 for the aluminum, .6 difference, which would barely cover the heat loss into the aluminum. That makes the thermal efficiency very close for both engines.

The airflow data that was included averaged 10% more on the intake across the board and a little less for the exhaust. At .500" lift, the numbers were 7K3 - 211/162 cfm, KRE - 231/170 cfm. Valve sizes were 2.11/1.77 for the 7K3's, 2.11/1.66 for the KRE heads. At the "important" lift points (60% of max lift for the intake, 90% for the exhaust) the flow was about 10% more for both ports. The torque increase and the hp increase were also about 10%, no surprise considering that the engine is basically an air pump. Torque at 2500 rpm (starting point) was 450 for the iron heads, 465 for the aluminum heads, so no low end penalty for more airflow either.

The improvement isn't all due to the airflow, however. The timing needed for the best performance with the iron heads was 37 degrees, while the KRE heads with the revised chamber shape and better spark plug location only wanted 33 degrees. That points to a quicker burn and less "negative" work done as a result.

One other thing to keep things honest, they ended up using roller rockers (same ratio) on the KRE heads, which could account for up to 10 hp (but usually half that) depending on how bad the stock rockers were.

Cam was decent, with 230/236 @ .050" and .488"/.491" lift (Comp Cams actually), headers were a bit small at 1 5/8", no length mentioned.

So the whole point of the article was to showcase the performance gains in swapping out iron heads for KRE Aluminum when all else remained the same?

if you're dead serious on running domes, you may have to swap that poncho for a BBC 454 with oval ports for the street :p **********

Domed pistons have no place in Pontiac motor builds as Pontiac increased/decreased HP and compression by machined chambers of various sizes..unlike Chevy.

Essentially, yes. The point of the article was to test an alternative to the Edelbrock round-port aluminum heads. The D-port heads can be used with D-port headers and manifolds, so won't require a change to most cars' exhaust systems.

465 ft-lbs of torque at 2500RPM? Holy Crap. That would be Saweeeeet.

And 539 by 3600 rpm, not bad for a 455 on pump gas. Enough to rip the heart(beat) out of most pretenders!

How close to this performance can you get with '96' heads using 1.65 rockers, rhodes lifters and a carefully selected cam?

I'm not a fan of leak-down lifters because of the stress that they can put into the valvetrain, although I know that some like them. I prefer to get the rest of the combo right.

I don't know how good the 96 heads are (Tom or Q?), but if you have the same cubes, the same airflow, the same cam (not just the same specs) and the same compression, you should be in the ballpark for the iron head numbers. Getting a good engine builder to check and assemble the parts properly can make a difference of 20-30 hp as well.

It's less about the ratio of the rockers than it is about how the cam and rockers work together to open and close the valves. The heads need to be able to handle the lift that you are after, and the valvesprings need to be matched to the cam and rockers as well.