[#1WideTrak]

I just got word back that my 428 block ('69 YH 2-bolt main) took a 30 overbore to clean up. I have had this block and miscellaneous parts for too many years, but I am finally ready for a build up. I have #12 Ram Air III heads that are supposed to be untouched minus a possible milling. I have a '66 421 crank, too.

I have decided I want to go with a roller cam setup, and I was beginning to sway towards a set of aluminum heads (Edelbrock or Kauffman). I started having grand thoughts of higher compression with aluminum heads and their out of the box flow capability.

On the other hand, I am one cheap person, and I hate for stuff to sit around with no purpose. I am really thinking to make use of the Ram Air III heads, but stick with a roller cam.

I know the 428 + 72 CC chambers (max CC, if they're untouched) is going to yield high compression, so dished pistons are required. Years ago someone told me to stay away from dished pistons saying going away from a flat top will cost me "quench." Just recently someone said, "No, dished pistons will begin to give you a semi-hemi chamber."

I've just got to decide what route to take for the heads. I was curious if a set of dished 428 + 030 pistons have a great enough price that the money spent over flat top pistons would be better spent on going with aluminum heads.

My goal is to have a solid (maybe low) 13 second ET and 100-105 mph trap speed '72 Grand Prix using a 200R and stock rear gears (3.08 or 3.23) that still has tame street manners. It weighs 4200 lbs with me in it.

I prefer to run Ram Air (repro) manifolds over headers. I think that alone detours me from the Edelbrock heads. ?

I figure up to 105 mph trap with 4200 lbs will require about 380 hp. 100 mph will need about 330 hp. I am so far out of the loop on Pontiac Power, I am not sure what I can get with a tame combo that will idle similar to stock. I know the roller setup should give me more power while staying tame over most standard cams.

In haste, I bought a set of Harland Sharp 1.65 rockers many years ago, and chickened out installing them when I read I might have to open the holes for clearance. They were to be strictly bolt-ons without pulling heads. I'd like to put them to use if they are feasible with the right roller cam.

Even though the GP is just a weekend toy, I want to run no more than 93 octane pump gas. I may drive it up to the T/A Nats or Norwalk in the future.

I've thought about Eagle rods, but really don't know much about them. I always liked the idea of a 428 over a 455 for more rev capability with the shorter stroke.

Any advice is appreciated.
Brent

[Z Code 400]

Brent,

Welcome to the PY Forum!!!!

Your heads must be cc'd as there is a lot of variation in the combustion chamber volumes on stock Pontiac heads. I have seen many chambers that are advertised in charts as having a 72cc chamber, but in reality have more than 76 cc's of total volume.

On a 428 with a 72cc chamber, .021" deck clearance, a .041" gasket and assuming a 6.7cc piston dish, your 428 would have a whopping 10.62:1 static compression ratio (SCR) which is too high for most available pump fuels.

I am very conservative with compression ratios on street engines. Many feel you can safely run an iron headed Pontiac with 10.00:1 SCR on 92 octane pump gas and some do, but here in California where we have 104° summer temperatures, I prefer to stay under 9.50:1 SCR.

The common 6X-4 head, milled slightly to yield a 90cc chamber and zero-decking the block would yield 9.40:1 SCR.

What other machine work has been done to the block??? What rods are you using??? What type of transmission and rear axle ratios are you planning on using???...Robert

[cutrone]

#1 WIDE,
I'm using KRE alum "D" ports, with my 428.
comp 288 HR
perf. RPM
850 DP
Ross dished pistons ( about 10:1 comp),Eagle rod, 4" stock crank.

All I can say is.. listen to some of the advise from guys on this board & you will have an awsome running G.P.

[66bonne]

Brent - Sounds like you have a lot to think about !!
Edelbrock heads are out if you want to run long branches. If you want to go with an aftermarket head be sure that you can get the right headers for your car beforehand.
If you get the "right" roller cam you will probably not need the 1.65 rockers but if you do go with them you would need the push rod holes elongated.
If you are looking for a nice hydraulic roller cam with good street manners but will perform at the strip - talk to P-dude, Ken Keefer http://www.angelfire.com/fl4/pontiacdude428/
I have one of his custom grind rollers in my Catalina and love it. Your goal for time and MPH is very doable tho you may need a tad more horsepower.
Good luck and keep us posted.

[#1WideTrak]

Originally Posted by Z Code 400

Your heads must be cc'd as there is a lot of variation in the combustion chamber volumes on stock Pontiac heads. I have seen many chambers that are advertised in charts as having a 72cc chamber, but in reality have more than 76 cc's of total volume.

I think I've read that before. Is that the reason it's been said most Pontiacs have about half a number of compression less than advertised?

On a 428 with a 72cc chamber, .021" deck clearance, a .041" gasket and assuming a 6.7cc piston dish, your 428 would have a whopping 10.62:1 static compression ratio (SCR) which is too high for most available pump fuels.

Is that 6.7CC dish about all that is feasible, or did you just use that example from past experience?

I am very conservative with compression ratios on street engines. Many feel you can safely run an iron headed Pontiac with 10.00:1 SCR on 92 octane pump gas and some do, but here in California where we have 104° summer temperatures, I prefer to stay under 9.50:1 SCR.

Memphis gets toasty (and humid) in the summer, and we're right at sea level here. (Doesn't octane requirement decrease with higher elevation?)

What other machine work has been done to the block??? What rods are you using??? What type of transmission and rear axle ratios are you planning on using???...Robert

It's had the basic cleanup and overbore done. And it is supposed to have cam new cam bearings pressed in. A friend picked it up and took it to his preferred shop that has done a lot of Mopars and Pontiacs. I need to get with my friend to give him some money, as the block was completed about two weeks ago. It looked so bad with rust, my primary reason to send it off was to see if it was still usable - before deciding how to handle the buildup. This friend had built many engines, and he will keep the block at his house, and I'll go over there in my spare time, and he help me build it.

I have pictured using H-beam rods, Eagle, but I am open to suggestions. If I can make this work with the RAIII heads, I'll gladly use the money saved on the heads elsewhere in the motor.

Originally Posted by cutrone

#1 WIDE,
I'm using KRE alum "D" ports, with my 428.
comp 288 HR
perf. RPM
850 DP
Ross dished pistons ( about 10:1 comp),Eagle rod, 4" stock crank.

All I can say is.. listen to some of the advise from guys on this board & you will have an awsome running G.P.

Hey Bernie!!! With the overdrive I want to do, maybe I can make a trek and park my GP next to yours someday. Your GP is still my favorite of all I have ever seen. Your spanking a LS1 Bird at Norwalk is still something I need print and frame someday. Hehehe. Have you seen the recent calendar thread on the GP list? I'd like to submit a pic of your car for the calendar if that's okay with you.

Originally Posted by 66bonne

Brent - Sounds like you have a lot to think about !!
Edelbrock heads are out if you want to run long branches. If you want to go with an aftermarket head be sure that you can get the right headers for your car beforehand.
If you get the "right" roller cam you will probably not need the 1.65 rockers but if you do go with them you would need the push rod holes elongated.
If you are looking for a nice hydraulic roller cam with good street manners but will perform at the strip - talk to P-dude, Ken Keefer http://www.angelfire.com/fl4/pontiacdude428/
I have one of his custom grind rollers in my Catalina and love it. Your goal for time and MPH is very doable tho you may need a tad more horsepower.
Good luck and keep us posted.

As long as elongating the holes doesn't create any possible problem, I don't mind doing that. If ultimately it's best to sell my 1.65s and get a set of 1.50s is best, I might do that. Your numbers under your pic is pretty wild. I don't care to cut better than a 2.0 60' time, so your combo seems about like what I want. Thanks for the lead on P-dude.

I was told some KRE heads had porosity(?) issues, but I'd assume that's been resolved. the D-port look would be my preference over the E-heads. The header/manifold options is my second reason to use them if I go aluminum.

I appreciate the replies!

[Z Code 400]

Brent,

The 6.7cc figure was based on an average 4 valve relief piston. How much you can safely dish a piston is dependant on the piston used...Robert

P.S. IIRC, a 3.00" cup .080" deep in a piston yields about 10cc's of volume...

[cutrone]

Brent,
Welcome to PY, I have not been on the GP list in a while. Those awsome pictures you took are yours to do as you wish.
Will you be going to Norwalk this year ? If you do we have to get together.

Bernie

[Will]

Nothing at all wrong with running a properly dished piston, people do it all the time. Pontiac even used a dished piston in the 428s so that they could use the same heads as on the 400 engines and not end uop with a higher compression ratio.

Means you have to order custom pistons, but that should be no big deal. I have a set of custom dished Ross pistons for my 428 with 74cc #061 heads.

The custom pistons will allow you to use the #12 heads you have so the extra cost for them should be offset by not having to buy new heads.

That said, the KRE aluminum heads would be an excellent choice for your engine if you want to go that route and should make your performance goals easier to reach. They will accept the RA D-port manifolds, no problem.

Given your heavy car, fairly tall rear gearing and desire to run RA manifolds, I'd go with a somewhat conservative cam of around 224 @ .050" duration on a 112 or so lobe separation and about 8 more degrees exhaust duration. I'd also buy the large outlet manifolds from Ram Air Restoration Enterprises and install a dual 3" exhaust with crossover behind them.

And what's this business? -

Originally Posted by #1WideTrak

...I don't care to cut better than a 2.0 60' time...

Maybe it's just the way you said it, but that doesn't make any sense to me. I've cut a best of 1.66 60' time on street tires with a suspension setup for handing (stiff springs, big swaybars) in my Formula and averaged right around 1.8 - 1.9. 60' is the key to good ETs.

Good luck with your build, whichever route you go!

[#1WideTrak]

Originally Posted by Z Code 400

Brent,

The 6.7cc figure was based on an average 4 valve relief piston. How much you can safely dish a piston is dependant on the piston used...Robert

P.S. IIRC, a 3.00" cup .080" deep in a piston yields about 10cc's of volume...

Thanks!

Originally Posted by cutrone

Brent,
Welcome to PY, I have not been on the GP list in a while. Those awsome pictures you took are yours to do as you wish.
Will you be going to Norwalk this year ? If you do we have to get together.

Bernie

I won't make it up there this year. I'll CC you when I send a pic to Don.

Originally Posted by Will

Nothing at all wrong with running a properly dished piston, people do it all the time. Pontiac even used a dished piston in the 428s so that they could use the same heads as on the 400 engines and not end uop with a higher compression ratio.

Means you have to order custom pistons, but that should be no big deal. I have a set of custom dished Ross pistons for my 428 with 74cc #061 heads.

The custom pistons will allow you to use the #12 heads you have so the extra cost for them should be offset by not having to buy new heads.

That said, the KRE aluminum heads would be an excellent choice for your engine if you want to go that route and should make your performance goals easier to reach. They will accept the RA D-port manifolds, no problem.

Given your heavy car, fairly tall rear gearing and desire to run RA manifolds, I'd go with a somewhat conservative cam of around 224 @ .050" duration on a 112 or so lobe separation and about 8 more degrees exhaust duration. I'd also buy the large outlet manifolds from Ram Air Restoration Enterprises and install a dual 3" exhaust with crossover behind them.

And what's this business? -



Maybe it's just the way you said it, but that doesn't make any sense to me. I've cut a best of 1.66 60' time on street tires with a suspension setup for handing (stiff springs, big swaybars) in my Formula and averaged right around 1.8 - 1.9. 60' is the key to good ETs.

Good luck with your build, whichever route you go!

Thanks for the input Will! I think I will go with the RAIII heads then, if dished pistons aren't that big of a deal. When you call out that spec cam, are you still thinking in terms of a roller?

Regarding the 60' comment, I am used to seeing LS1 F-bodies cutting sub 2.0s and blowing up the rears. Granted, that's the M6 cars, but at the same time, with my T/As, I consider a 2.0 a fair 60' (especially when I had to work them down from 2.2+ on street tires), so that's all I would expect to squeeze out of the Land Yaht!

[Z Code 400]

The RA Manifolds and 3.00" exhaust, as mentioned by Will, is a very good idea indeed. That should let you have your cake and eat it too, so to speak.

I would also suggest asking some members here how the dished piston affects the selection of their assembled quench distance.

Will is also close to what I would recommend for a camshaft, although my approach might be a bit different. As most of you know, I prefer to keep overlap @ .050" at or near 0° on any street car for overall idle quality, vacuum and street manners. In consideration of the previously mentioned stock #12 heads, 3.08:1/3.23:1 axle ratios and 200-4R, I would use a hydraulic roller with around .536"/.536" lift - 227°/233° @ .050" on a 115.5° LSA for a broad powerband...Robert

P.S. The wider LSA will yield more octane tolerance and allow slightly higher SCR.

[smagnotti]

Many people forget that you have about 1.5 CCs of #1 and# 2 compression ring backland volume you need to add into your compression figures if you do not run a gapless ring to get your compression figure dead nuts on!

[mth]

Hello guys, I was reading the posts and hoped that you can tell me a few things. I just bought a 69 428 from another member and I was wanting to know a few things about this motor and you guys look to know alot about 428s. My block is a yh code 089746 and the #s at the back of the block are 9792968. It is a complete motor with #46 heads and the 4 bbl intake. I think i heard that they made 3 variations from 360-390 hp ca anyone tell me what this motor is and any other details would be greatly appreciated. I am going to put it in my 64 lemans someday. Thanks.

[TinjunTribe]

Use your stock heads!!!........ I just got a set of Eagle H-beams from Butler for 425.00........they also dished a set of TRW pistons to have 15cc total dish (to work with my #62 heads.....which have advertised 72cc chambers, but measured 75cc), in my +.040 400 will arrive at 9.46:1 compression ratio. The cost to dish all 8 pistons was only $100.00! Butler told me a total of 20cc could be dished into a TRW (speed pro) piston.

[Will]

Originally Posted by #1WideTrak

....
Thanks for the input Will! I think I will go with the RAIII heads then, if dished pistons aren't that big of a deal. When you call out that spec cam, are you still thinking in terms of a roller?

To be honest, I was thinking flat hydraulic, but a hydro roller with those specs would be a torque monster.

Robert's suggestion for a wider LSA to keep overlap down has some merit, but honestly, a hydro roller 224/232 @ .050" on a 112 LSA will make plenty of vacuum for power brakes. It will have more "attitude" at idle than what Robert has suggested and I guess there's a little bit of my personal preference rubbing off there. I like a musclecar to sound like a musclecar.

A slightly wider LSA will help with engine breathing given that you will be running the RA manifolds. Even the 3" outlet versions won't "tune" like a header will, so a wider LSA is called for. Personally, I wouldn't go over 114 as you'll be giving up some midrange torque, so you'll just have to decide which internet car geek you think makes the most sense.

Originally Posted by #1WideTrak

Regarding the 60' comment, I am used to seeing LS1 F-bodies cutting sub 2.0s and blowing up the rears. Granted, that's the M6 cars, but at the same time, with my T/As, I consider a 2.0 a fair 60' (especially when I had to work them down from 2.2+ on street tires), so that's all I would expect to squeeze out of the Land Yaht!

Sub 2.0 60' isn't easy on street tires, granted. I credit the rather large 305/50-15s I have on the back of my Formula along with the Coan 11" 3200 stall converter with making the decent 60 footers I was able to pull off possible.

As to what you saw happening to the F-bodies - pay them no mind. They have super-wimpy little 7.5" rearends in them. All the serious F-body racers I know upgrade to 12 bolts or 9" rears ASAP. I'll never understand why GM put those pathetic, weak-ass rearends in those cars when they were still making the relatively bulletproof 8.5" 10-bolt. It's funny, the '00 S-10 ZR2 truck I had, with a 4.3L V6 had the 8.5" rear in it...

Your GP should have an 8.5" rear in it and as long as it's in good shape it will easily withstand mid 12s on street tires and 1.8 second 60' times - IF you can get traction that good.

This also brings up another important part of the equation - spend some money on a good converter! A high quality converter with an appropriate stall speed will make a huge difference in how your vehicle performs. Don't listen to people who say you can't or shouldn't run as much as 3000 stall on the street with tall rear gears. They've never run a custom converter before. A converter like the ones Continental, Hughes, Coan, and others make will act very close to a stock converter in normal driving yet allow the engine to easily flash up into it's powerband when you nail the gas. Such a converter will be very well coupled below it's stall speed and thus require only minimal throttle opening to accelerate away from a stop or to increase speed while driving in traffic, just like a stock converter, but when you lay your foot into it the engine will rev up and the car will move out like you wouldn't believe. People who are afraid to run more than 2200-2400 stall on the street apparently only have experience with the junk B&M sells, and I feel sorry for them as they're really missing out on a good bit of performance (FUN).

Good luck!

[#1WideTrak]

I appreciate everyone's replies. All are noted. I'll post back when I work out more details. It may be a few weeks, but I'll check back in with updates eventually!!! (while checking out other threads in the meantime!)

[1971WARBIRD]

Originally Posted by mth

Hello guys, I was reading the posts and hoped that you can tell me a few things. I just bought a 69 428 from another member and I was wanting to know a few things about this motor and you guys look to know alot about 428s. My block is a yh code 089746 and the #s at the back of the block are 9792968. It is a complete motor with #46 heads and the 4 bbl intake. I think i heard that they made 3 variations from 360-390 hp ca anyone tell me what this motor is and any other details would be greatly appreciated. I am going to put it in my 64 lemans someday. Thanks.

this is a great starting point for a build up.your block should be a 2bolt main(67-68were 4 bolt),and 376-390hp were 4 bolt,yours is a 360hp.the 46 heads should be small valve and press in stud,not the best for high performance.the intake is as good as it gets for stock,same as raIII 400 intake.your 2 bolt block with some good rods,pistons,and a set of good flowing heads and you have a great street setup.i always wanted to do a 428 for the street as it has great hp,but a little less torque than a 455,so it might be easier to hook on street tires.good deal,should work great in your 64.

[sd389421]

There was a 428+.030 over dyno tested with a iron intake, cast KRE heads, and a 236/236 HR.

Search under the race section "428 dyno results". There is alot of good info. Engine made apporx. 500 hp and 520 ft.lbs of torque.

[BruceWilkie]

Your GP will hook up a lot easier than any F body. FWIW my sons near stock 64 Bonneville 389 with regular 235/70-15 radials 3.08 gears and NO posi or suspension work 60 fts 1.90's. Your GP isnt quite as heavy in the rear but it wont be too hard to go sub 2.0 sixties.

[mth]

Thanks for the info warbird. I have found out that the block is drilled and tapped for 4 bolt mains so I am going to put them in when I do the motor. Also Will has said that the heads are good and easily converted to the big valves and screw in studs. My concern is the cr is 10.5:1 stock will this be a problem with 91 octane fuel in california? Also should I have this motor balanced & blueprinted? Any thoughts appreciated I have never owned a pontiac and have heard these motors are different from the chevys.

[PONTIAC DUDE]

Originally Posted by #1WideTrak

I just got word back that my 428 block ('69 YH 2-bolt main) took a 30 overbore to clean up. I have had this block and miscellaneous parts for too many years, but I am finally ready for a build up. I have #12 Ram Air III heads that are supposed to be untouched minus a possible milling. I have a '66 421 crank, too.

I have decided I want to go with a roller cam setup, and I was beginning to sway towards a set of aluminum heads (Edelbrock or Kauffman). I started having grand thoughts of higher compression with aluminum heads and their out of the box flow capability.

On the other hand, I am one cheap person, and I hate for stuff to sit around with no purpose. I am really thinking to make use of the Ram Air III heads, but stick with a roller cam.

I know the 428 + 72 CC chambers (max CC, if they're untouched) is going to yield high compression, so dished pistons are required. Years ago someone told me to stay away from dished pistons saying going away from a flat top will cost me "quench." Just recently someone said, "No, dished pistons will begin to give you a semi-hemi chamber."

I've just got to decide what route to take for the heads. I was curious if a set of dished 428 + 030 pistons have a great enough price that the money spent over flat top pistons would be better spent on going with aluminum heads.

My goal is to have a solid (maybe low) 13 second ET and 100-105 mph trap speed '72 Grand Prix using a 200R and stock rear gears (3.08 or 3.23) that still has tame street manners. It weighs 4200 lbs with me in it.

I prefer to run Ram Air (repro) manifolds over headers. I think that alone detours me from the Edelbrock heads. ?

I figure up to 105 mph trap with 4200 lbs will require about 380 hp. 100 mph will need about 330 hp. I am so far out of the loop on Pontiac Power, I am not sure what I can get with a tame combo that will idle similar to stock. I know the roller setup should give me more power while staying tame over most standard cams.

In haste, I bought a set of Harland Sharp 1.65 rockers many years ago, and chickened out installing them when I read I might have to open the holes for clearance. They were to be strictly bolt-ons without pulling heads. I'd like to put them to use if they are feasible with the right roller cam.

Even though the GP is just a weekend toy, I want to run no more than 93 octane pump gas. I may drive it up to the T/A Nats or Norwalk in the future.

I've thought about Eagle rods, but really don't know much about them. I always liked the idea of a 428 over a 455 for more rev capability with the shorter stroke.

Any advice is appreciated.
Brent

If ya use the E-heads you can use a standard flatop piston but have a better flowing head (280 cfm plus) to take advantage of a faster ramp roller cam. And later when ya want even more power you can port them to 325 cfm plus without offset rocker arms. You also have the choice of a hyd roller with less noise that would put your combo into the 12's easily and still drive anywhere . Still maintaining great vacuum. As far as rods, even the Proline rods will sell cheaper then the Pontiac Eagle type out there will handle 600hp easily. If ya go up on my website you will see great reults I have had with the 428. I compare the 428 Pontiac to the 472 chevy. Thes best of both worlds. Bigger bore with the right stroke. Also a good rod ratio.