Couple years back I purchased a 1973 Buick Riviera minus engine and transmission. Yesterday I purchased a 1973 455 complete with transmission. The compression varied widely between the cylinders so at bare minimum I'm going to re-ring. The research I have done shows that the 73 455 runs 8.5-1 compression and puts out only 250hp. My question is what do I need to do up my compression to at least 9.5-1? Le to get the horsepower back up into the mid threes? I have built Chevy & Ford engines to whatever specs I wanted but I'm really having problems finding out how to build this Buick motor. Please help. Thank y'all in advance!
You need to do more then just re-ring because you can not safely mill those heads enough to pick up a full point of compression! So it's pistons also as part of the rebuild or different heads with smaller chambers.
If it will still stay a standard bore, some 70 pistons and cut the block .020 and the heads the same amount
First, the HP figure is SAE net, not the gross HP rating that was used prior to 1972, so it isn’t as bad as you think. Second, yes, advertised static compression was 8.5:1, but it is lower than that. As mentioned, you will need to change the pistons. Part of the problem is the stock pistons can sit as much as .050” down in the hole at TDC. Fortunately, we have some customizable piston options that weren’t available in the past. You can order Autotec or Diamond pistons that you can specify with different compression heights and valve reliefs/dish volumes. That enables you to really dial in the static compression you need for the cam you want to run. Altering the compression height makes the piston sit even with the deck and then you can play with dish volume to get the compression where you want it. You can PM Jim Weise and he can set you up with the right pistons. If I was you, I would just bite the bullet and do a rebuild while you are at it, but your budget might preclude that.
You could clean up the heads say .010" and use .027" cometic gaskets, will pick up about .7 in compression.
Thank each of you for your responses. I kind of expected to have to change the Pistons to recover the compression but had not found many options. Before this thread I had spoken only to Summit and things were looking bleak! Please keep the options coming. Once again, thank you!
I have not measured but assume the length is the same since the year make and model of the vehicle that donated the engine is the same as mine. I also know mine originally had a 455 Turbo 400 combo which is what I purchased.
If it is the same year, make and model you should be OK. There can be a difference in the location of the sump.
This will give you an idea of what is available today. This thread talks about 470 and 482 engine pistons, but I would give Jim a call and see what he can do for you. Sumitt and Jegs will only have off the shelf pistons which will sit below deck. The 470 and 480 combos involve replacing the rods and offset grinding the crank to get more stroke, you don't have to do that, but it is an option. http://www.v8buick.com/index.php?threads/new-470-482-piston-options.324745/ http://www.v8buick.com/index.php?th...ences-similarities.327964/page-2#post-2747442
You could also have the deck milled .030" and the heads milled .030" with the mentioned thinner gaskets to be able to reuse the pistons that came out of the engine to get your compression up where you want it. But that's about $300 of milling work and then you will need to get new shorter pushrods so another around $100 and the thinner gaskets as mentioned are more than the $40 Fel-Pro blue head gaskets are. With the all of the milling and thinner gaskets the intake may no longer fit so it or the intake mounting surface on the heads may need corrective milling so the intake fits. But you won't need to rebalance which would be around $150 to $200 depending on your local machine shop pricing. If you find good used '70 pistons as mentioned make sure the crank is rebalanced to those pistons. There is also an economy 482 BBB option if you're interested in that as well which would use 5.4L Ford aftermarket rods, AutoTec pistons and a stroked crank.
The 71 455 I have in my car was rated at 8.5:1. It was actually about 8.2:1 with Felpro blue head gaskets. This past summer, I pulled the motor and replaced the stock 71 pistons with the TA 1607 cast "10:1" pistons and a set of the steel shim head gaskets. The 1607 pistons have a slightly taller compression height. My compression is now right at 9.5:1. Not sure you could use the steel shim gaskets on a 73, but maybe a set of the thinnest Cometics might get you around 9:1 or maybe a little more with the 1607 pistons. But truthfully, you'd be better off with the custom set of Autotec's and just the regular old Felpro blue headgaskets to get your compression up without having to mill anything more than a cleanup pass on your block. That way, your intake wouldn't need milling to correct the fit and you wouldn't need to take more than a cleanup pass on the heads, either. If I end up having to pull my engine apart again for some reason, that's probably what I'll end up doing.
can't use the .020" shim gaskets on later blocks due to their oval shaped water jackets on the head surface. the .027" cometics are ok.
I had felpro 1125 head gaskets on my 73 Going to cometics and milling heads. Have sealed power pistons L2353F. .040
I have a u-code 455 in my "73 Gran Sport. You wouldn't believe the difference that can be made with some super tuning the low compression engine. Better cam timing, carb jetting and tuning, higher output ign. and tuning, the engine really wakes up.
Great news Pascoe. Having my heads gone thru and milled. And .027 thick gaskets for my 73 engine in my 70.
Hey gentlemen, I've taken the heads to the shop for a valve job. I am keeping the original bore but replacing the Ring. There looks to be a little bit of wear on the camshaft. Since I'm in this far I was wanting to buy a new cam and I was wondering do any of you have recommendations for which cam I should use to get a little more performance out of an otherwise stock rebuild? Thank all of you!
I like the Herbert cam for a '73 stocker. Cam Grind Type:HYDRAULIC FLAT TAPPET CAMS Application: BUICK V8 67-76 400-430-455 Brand Code: Herbert Performance Cams Dur Int-Exh: 265/275 Dur @ .050 Int-Exh: 215/230 Lift 1.5 - 1.5 Int/Exh: 470/505 Lobe Center: 112
Go to the TA Performance website ( http://www.taperformance.com/ ) and download their catalog. Open the downloaded catalog to pages 60-61 for a list of available cams and the descriptions of each one of them. Would be a good idea to also call them up and ask for their recommendation. They know their products very well.
