I currently have a 68 GS400. I am thinking of shelving my numbers matching 400. I was going to put in a '68 430... but it sold to someone else. Is there a preference of a 430 or 455? From what I have read, it seems that the stock 430 has more horsepower and better fuel economy over a stock 455??? Is this true??? Also, what years of 430 or 455 would interchange with my '68? Please... If anyone knows of an 'inexpensive' 430 or 455 in the upper midwest, please let me know! I would also like to find a 3.42 posi to gear it! Thanks in advance, Gil Mpls. MN 763-434-7900 :TU:
There are more speed parts for a 455. A 430 may be cheaper but has some head cracking issues. Anyone who tells you that a 430 makes more power needs to look around and see what block is being built for street engines and strip engnes. With only a few exceptions it is the 455.
Any 400,430,455 is a direct bolt in.They all have the same outer dimensions and accessory provisions(motor mounts,exhaust manifolds,waterpumps...etc).If you can,I would try for the 455.Like Jim said more speed oriented parts are made for the 455. Pat
It all depends on what you want to do. If High performance isn't an issue, A 430 from a 67-69 riv or electra might be easier to find and in good condition with low miles - there's one here locally from a 69 electra with 67,000 miles on it for $400 (So the ad says) and its been in the local trader paper for weeks. Alot of people won't just throw an unknown motor into their car and end up having machine work done....new water pump and timing cover and gear/chain....cam bearings and a new cam....main bearings....rings....valve job....etc.etc.etc. If you're doing all this the thinking is you might as well go 455 because its all the same parts (costwise and machine work wise....) and you get more power when you're done. Also note - you won't be able to use the aluminum Stage1 heads on a 400/430 as the valves are too big for the cyl. bores. Additionally - some of the big car motors used center sump oil pans instead of the GS's rear sump. You'll have to either get another rear sump pan or use your existing one (Swap them). Have you tried a "Wanted" post ?? Searched out the local Buick guys near you ?? you never know what might turn up
Hey Gil.It looks like your not far from Jim Weise`s TSP.You can`t get a much better lead than that.I would consider 455 if you want to play!!Later,Tony.
I have asked a few Buick engine builders and have been told that a 430 can benefit from stage 1 valves and a 400 cannot.
430 Vs 455 There are pros and cons to both. It depends on what you want to do with the car and whether you're going to work on the motor or just stick it in stock. Any big block Buick will bolt right into your car in place of the 400. I have a '74 455 block in my '68 with ported '70 heads, forged Speed Pro (now TRW) pistons and the stock 400 intake, timing cover, cast exhaust manifolds, and accessories. I did this for the extra cubes and because it was cheaper than rebuilding the 400. I still have the 400 crated up in case it comes time to put the car back to original. My car went from a mid 15 second dog (400 was really toast) to a low 13 second stock appearing car that I can drive anywhere. Gas mileage didn't change much - I get 12 mpg on the highway. As far as 430 vs 455 comparison - The 430 in stock condition oils the rocker arms through pressurized oil passages in the rocker shafts. This was changed in the 455 to lube through the lifters and pushrods to rovide longer rocker life. Later 455 blocks (maybe 74 and up) had better oiling through larger oil galleries. You can drill out the earlier blocks, just like you can retrofit to the newer style lifters and pushrods. Some early 430 heads featured "big ports" - maybe 10% larger on the intake side. You can get pre-egr 455 heads to flow the same with porting. 1973 and up egr heads are not as easy to get flow from, and the combustion chambers are larger leading to lower compression. It's possible that your stock 400 came with these heads. There's a list of big port casting numbers on atlantabuick.com. All BBB cranks are the same - 400, 430, 455 have cast nodular iron cranks with the same dimensions. Stock 430 motors would have higher compression than later 455's leading to higher horsepower but also higher octane requirements. Forged pistons are a custom deal for the 430 as far as I know (unless you can find old NOS someplace). Forged 455 pistons are available again - they were scarce for a while. The 430 will have thicker cylinder walls and more meat between the bores for head gasket sealing, say if you wanted to crank up boost with a power adder. You can use most of the parts from your 400 if you want (heads intake carb starter timing cover water pump accessories etc.) and keep it stock appearing. You have to be careful mixing early and late accessory drive stuff - the water pumps are shorter on the early cars and pullies don't line up with newer parts. Get cracking! Your car will be more fun with more motor.
