Hey Guys, I am looking at rebuilding a new 455 and turbo 400 over break using some spare parts that we have. I am not satisfied with the current drivetrain, as the engine seems to have some problems as it won't pull past 4,000 RPMs and not sure how well the previous person built it and the transmission shifts are quite soft. In conversing with my Dad we are considered pulling the running drive train and keeping it aside as "Back up" and then building a more satisfying combination. This here is the "Build Thread on the car" http://www.v8buick.com/showthread.php?279311-1970-Pro-Touring-Lark We would be building a new 455 with some parts that we already have in order to keep costs down. We are planning on keeping a stock bottom end, but boring it to 0.030" and putting in some pistons that my dad has which would lead us to a 10.2:1 compression ratio. The heads will be mildly ported stock iron heads with stage one valves and springs, and the rockers and pushrods are being planned to stay stock spec. The intake would be a Edelbrock Performer RPM intake (I think) and the exhaust is cast iron manifolds (although I am looking into T/A Shorty headers). For the turbo 400 we would rebuild a short shaft turbo 400 and use a race shift kit. Just a question based in my own curiosity, does anyone know of a manual pattern shift for automatics? I have been driving a 5-speed while the Buick sits in the garage, and I think I enjoy the shift pattern more than just the ratcheting shifter. The car spends a majority of the time on the street, and uses power brakes and power steering, but will likely see autocross and strip time. I would prefer it to have a lopey sound, and obviously out perform the stock cam. The car has 4:11 gears. Thanks For Your Time Guys, -Tom
Just some additional questions/information I forgot to ask/include: T/A recommend switching to a roller set up, is that necessary? Would switching from my 67 430 heads be a good idea? I have heard that they have a high flow capacity? When I was on the phone with COMP Cams they recommended a Hydraulic Flat Tappet Cam: http://www.summitracing.com/parts/cca-96-210-4/applications Does anybody have experience with this cam? Thanks -Tom
Call Scotty Brown. He will grind you a custom cam for your build for the same price as an off the shelf unit. www.buyracingparts.com
Bumping this thread. The car will be switched to a Tremec Magnum Transmission and runs power steering and power brakes. I'm starting with a 1973 block boring it to 0.030" and putting in some hyper eutectic pistons that would lead us to a ~10.2:1 compression ratio. The heads will be 1973 iron heads with stage one valves and springs, and the rockers and pushrods are being planned to stay stock spec. The intake would be an aluminum Edelbrock intake (I think), Mallory HEI & Summit MSD for ignition, and I picked up some Shorty TA Headers. The car also has 4:11 gears. I read the Hot Rod Magazine article where they discussed various cams and intakes: https://www.hotrod.com/articles/ccrp-0906-buick-455-engine-bolt-ons/ In the article, the smaller TA-212 Cam outperformed the larger and seemingly more popular TA-413, and the authors attributed it to poor head flow (using Iron Stage 1 heads), and low compression (8.77:1). Unfortunately, I will be running about the same head flow, but I will have a higher compression ratio. Being a manual car with power steering and brakes I understand that vacuum is important, but I also like the higher RPM range and lope that a larger cam offers. Can anyone provide input, all is appreciated. The goal is to be a corner-carving streetcar, but would still want to make respectable passes at the strip!
You'll want to make sure of your compression ratio. Just because the pistons are rated at 10.2:1 doesn't mean you'll be anywhere close to that. Most pistons you buy off the shelf will sit a considerable amount down the hole at TDC. If the piston specs mention compression distance and dish cc, post that, and we can figure out what that might be. This is a pretty common mistake. Just trying to make sure you don't make it. Also, Hyper eutectic pistons do not tolerate detonation very well, so you'll want to be conservative with the ignition timing initially as you tune it.
This is a good read, http://www.empirenet.com/pkelley2/DynamicCR.html If your static compression ratio is truly 10.2:1, your Dynamic compression will be very close to 8.4 with the TA212. That is Race Gas territory. If you plan to run on pump gas, you may want to consider forged pistons, or a different cam like the TA413.
Thanks, Larry for the information, My dad has had the pistons for ~20 years but never used them, so I'm a bit hard-pressed to find statistics on them. I'll try to figure it out once I get my hands on them, get the necessary information, and get back to you. I do not plan on running race gas but on the strip would run a few gallons mixed in as cheap insurance. I appreciate the help!
Call scott brown and have a cam made for your specific applicatio . Build a camshaft that works for your motor, not what it sounds lik . Scott will tell you , i want my car to run in the 10s, but nOt sound like it. Old street racing technology.
Running a manual gear box like an overdrive Tremec opens up a whole lot more flexibility with cam selection, as you control the driving rpm range. Depending on which ratio box you have, you can run a more radical cam with a tighter lobe center than with an automatic. (Back in the day, Mopar offered different factory profiles between stick and auto cars.) On a T56 Magnum close ratio model, rpms don't drop as much between the 1st 4 gear shifts and the .8 overdrive is great for top end pulls and the .63 will loaf the interstates at 70 mph, so you have more gear options than others to play with. As you may know from my recent "Sick Speed " build, I run a more radical TA 308S solid cam with my T56 Magnum on the street. It works better than it did with the full manual shift TH400 with high stall, and is way more fun to drive. Don't be afraid of a slightly rougher profile. The engine rpm can be better controlled manually better in just about all driving conditions. That said, my cam is not for your engine build, unless you get better flowing aftermarket heads, bottom end, compression, valve train, oiling, etc . I would ensure your static compression is around a true 9.5 -10ish ( don't think it is) and run at least a T/A 413 or equivalent with your 4.11 combination. Scott Brown also knows his stuff. Tom
Hi Larry, We found the old box of pistons, and they are Sterling Performance Pistons (Part Number H392NP). The box has a copyright sticker from 1989, but when I look up the part number it brings me to SpeedPro https://www.summitracing.com/parts/stl-h392np-40 (Sterling Performance & Speed Pro are both owned by Federal-Mogul). What's weird is that the summit page says the bore is 4.35 rather than 4.34075 as is listed on the box, but the rest of the listing matches (455, Hypereutectic, dish with 4 valve reliefs, etc.) If I use that listing: The compression height is 1.985 in. The piston height is: +23.00cc If I can't trust the listing, how do I measure those parameters? I'm a little lost when it comes to measuring when a piston is in the hole, or what the deck clearance is but I read on the forums that 0.02" was viable, although I know zero-decking is also a thing. I also assumed that 1973 heads had a 70 cc cylinder head volume and used Felpro 1125 head gaskets. Hi Tom, I can actually pick between these two sets of ratios, but I was assuming the 2.97 with a 4.11 rear would have trouble putting the power down and would make first gear really short. What are your thoughts? 2.66, 1.78, 1.30, 1.00, 0.80, 0.63 2.97, 2.10, 1.46, 1.00, 0.80, 0.63 In all, I apologize that I'm a little confused, but I am grateful for the help you all are providing! Once I solidify an SCR, I will reach out to Scotty regarding a camshaft. I also moved my start date up three months for work (graduating in June and will be starting work as well) so I am eyeballing TA Stage 1 SEs with the extra money I'll make, but haven't committed to it at the time.
Those are .030 over 455 pistons.The stock bore is 4.3125. They would actually be 4.3425 despite what it says on the box. The stock deck height of a 455 is 10.57. What you do is take 1/2 stroke, add the rod length, and the compression distance together. That would be 3.9/2 + 6.6 + 1.985 = 10.535. 10.57 - 10.535 = .035. So theoretically, these pistons will be .035" in the hole. 1973 heads are listed as 71cc. They usually cc bigger than that. My 70 Stage1 heads were actually 72cc.
Hi Jim, I know the link online is different, but it was the only part number match I could find (these pistons have been sitting in a box for 30 years. So I'm hoping that the dish/valve relief and compression height are similar/same even if the bore is different. Thanks, Thomas
Thanks Larry! That's great information and insight. We are planning on decking the block down at a local machine shop so we may reduce the deck clearance bringing us back up a little bit in compression.
Ok. Just a little added info........if you deck the block too far you will need to cut the intake or heads on the intake side to get a good seal. I understand you "have" these pistons. But from what you say you want to do a forged pistons will be a better choice. And you can get them with taller compression height to not have to cut the block as much. Higher rpms came and stk heads and power brakes..........dont add up either. Stk heads wont do well with much over .500 lift.........and will need some guide clearance work much over that lift numbers either. B4 setting you budget find out what having the stk heads worked over will run........any more I'm seeing machine shops getting half the cost of aluminum heads ir even more to redo old stk iron heads.........and most ppl cant port iron heads to the point where aluminum ones flow out ofvthe box .....plus the aluminum heads will have smaller cc helping your compression ratio. I love the 308s cam......but there is no way it will run power brakes and you will need roller rockers to handle the .600lift and the pressures the spring require. There are a few things that truely need worked out on paper b4 you start spending money on your project. 68 big port heads only flow a few % more in stk form......so dont get hung up on them
Tom, the compression height is measured from the piston pin center line to the top of the piston. Measure a piston and see. You can also measure the valve relief cc if you want. There are probably youtube videos on how to do it, and it isn't expensive at all.
Good luck w the build and plan wisely. I actually have a 73 455+.040 and small valve bowl ported heads. Pistons .035 in hole. I would have decked block had I known before these specs. Using that comp cam too and edelbrock performer. But contact Scott brown as advised and get a cam to match your combo. Sounds like fun.
An update. We run an aluminum intake Edelbrock intake on top. It's likely quite similar to the warmed-over 455s that have graced this board for years, as a 462 with higher compression, a TA 413 Cam, and Stage 1 valved heads. Double Roller billet timing gear. Degreed @ 113.5 with +4 A 0.030 bored over Buick 455 Stage1 (462 displacement) aligned honed, decked, balanced, and blueprinted. Compression calculations from the machinist indicate 10.0 to 1 My dad really liked the idea of a stage one valve Iron head, so he ported and polished heads before sending them to the machine shop to have larger Stage1 intake valves & springs installed. Head machine work included surfacing, valve guides, and unshrouded valve pockets. I know there was a lot of push to get aluminum heads and forged pistons, but he had been dreaming about this engine for years, and using the parts we had was good for the budget. we Picked up the TA Performance shorty headers from the powder coating dude last week as well. They were a never-installed Craigslist score....1-7/8” primaries, 3” collectors. Exits similar to stock manifolds. Supposedly 25-30 HP gain over stock manifolds on 400-500 HP combinations. Hopefully, we are somewhere in that power range.
