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#1
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Where to start? 428+030, roller cam, what heads?
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 |
#2
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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 |
#3
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#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.
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69 Grand Prix 428 H.O. loaded "J" 11.51 @ 116 |
#4
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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.
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65 Catalina sedan. Allen Thomas Performance 495. KRE Heads at 310cfm ported by SD Performance, ProSystems Dominator carb on ported Victor intake, P-Dude custom grind hydraulic roller, MSD ignition, 3.50 Moser/Ford rear. F-Glass front bumper by son Rob, rear by the old man and joint effort for trunk lid. 3950# w/driver. Best of 9.5761/139 on 175 shot, 6.01 /114 in 1/8. |
#5
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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. Quote:
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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!
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Brent '72 GP '88 GTA '01 T/A http://www.WideTrackDrive.com Others have caught on. But they haven't caught up. |
#6
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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
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69 Grand Prix 428 H.O. loaded "J" 11.51 @ 116 |
#7
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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... Last edited by Z Code 400; 07-01-2007 at 09:32 PM. |
#8
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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? - Quote:
Good luck with your build, whichever route you go!
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---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
#9
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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!
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Brent '72 GP '88 GTA '01 T/A http://www.WideTrackDrive.com Others have caught on. But they haven't caught up. |
#10
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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. Quote:
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!
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---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
#11
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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!)
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Brent '72 GP '88 GTA '01 T/A http://www.WideTrackDrive.com Others have caught on. But they haven't caught up. |
#12
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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. |
#13
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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!
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SJM |
#14
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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.
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#15
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FREEDOM ISN'T FREE BUT WORTH FIGHTING FOR |
#16
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Rods Pistons
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.
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#17
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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. |
#18
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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.
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#19
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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.
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#20
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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. |
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