Reply With QuoteI'll be watching this closely. I'm feeling a 468 BBC is in my near future.
Im trying to learn more about BBC's. Im getting the urge to get rid of the Olds.
I hear about different Generation blocks. Whats the difference between the different generation's.
What is the difference in a tall and short deck block.
What type block is the Merlins base on?
If I start looking for a block, what should I look for?
Any other info that may be of benefit to me would be appreciated.
[ October 16, 2003, 01:32 PM: Message edited by: Taylorman ]
I'll be watching this closely. I'm feeling a 468 BBC is in my near future.
Ill start,although you would be better off posting in the gearheads section.Good call on getting rid of the olds,it will make a great boat anchor.Here is what i can contribute:
-The different gen. blocks all have slightly updated features and minor casting changes, oiling,cooling,fuel pumps, bolt patterns, and were mave a different times, save your self the trouble and go with the the mark iv,parts are very available and they are proven.
-The differense in the tall vs, short decks is the deck height.The deck is where the heads meet the block. On a tall deck it will be .400 taller than a standard or short deck, obviously you need a to take that tall deck into consideration and need to compensate for that extra .400 deck height.In my motor we are putting in a .400 long carillo rod in it.you also will have intake manifold issues if you go with one of these tall decks or sometimes they are called "truck" blocks(at first used in older trucks)since you have the taller deck that moves the heads farther away from eachother and you will need a "tall deck" manifold made for this or you can run the tall deck spacers to take up the space.either way is fine.Dont be scared of these blocks, they are still very good.
-Im not sure what the merlin is based on, but i do know they are quite a bit better than the old gm blocks,the gm flaws have been fixed on these blocks. If you can find one, that has not been machined to death, id grab it..Keep in mind merlins are not the only good aftermarket block available, there are many others like the GM bowties and my favorite, the dart block, normal gm blocks are good too, either way you will be fine up to around 700-800 horse, then it may be better to upgrade since you have all that money in parts invested and a dart block is only 2000 bucks more
-what to look for? well if your looking at bare blocks, i would not buy anything until you sonic check it. This check means you send ultrasonic waves into the block to see how thick the cylinders are.Generally the merlins and other aftermarket blocks are pretty thick and are good to go to the machine shop a few times.But i would still check them if they are anything but standard bore, it only costs 60 bucks and is cheap insurance.If your looking at a gm block i wouldnt touch anything that is .060 over or more,they are just starting get pretty thin at that point. Let me know if you need the guys a number to have this check done, or if you need a block, i know where a few good ones are.If your buying a motor that is already built and been ran for a while, generally dont expect much.
Im sure i missed a few things, but others will chime in im sure. Good luck.
[ October 17, 2003, 09:59 AM: Message edited by: cs19 ]
For a jet boat a 4 bolt block is recomended with mainstuds, the 1970s blocks will generally accept a .100 overbore and we regularly bore them to + .125 to + .140 if they pass the sonic test. The machineshop you select is AT LEAST as important as what parts you use! Most shops don't understand or have never run a jet boat/motor, avoid them like the plague! The parts are similar, the clearances different, the cam/head/carb combo along with the oiling system are quite different. Too much to go into here. Find out who is fast,who's stuff lasts,and who builds comparable stuff to what you are trying to get built. Ask for references,deal with someone local who has a reputation to protect,go to several shops and see whats up, does the shop do all their own machinework,or are they just an assembler? AN ASSEMBLER IS NOT AN ENGINE BUILDER!!! If things don't work out on your engine, a he said/she said finger pointing session will surely follow. If you don't see $200,000+ of machine equipment,RUN! And finally,don't ask the owner to ***** his prices or you will get what you deserve. Thats just my opinion and I may be wrong. TIMINATOR
cs19:
-Im not sure what the merlin is based on, but i do know they are quite a bit better than the old gm blocks. If you can find one, that has not been machined to death, id grab it..Keep in mind merlins are not the only good aftermarket block available, there are many others like the bowties and my favorite, the dart block, gm blocks are good too, Good information CS19. I was told that my 572 is a Bowtie talldeck. I always assumed that bowtie and GM (chevy) blocks were one in the same. I didn't realize that they were made by an aftermarket company. Do you have any more info on who makes them? Are they still making them? thanks.
Sorry about that, i made it sound like a bowtie is an aftermarket company that manufactures blocks.The bowtie is still a gm block but its a block built for high perf applications, sounds like you have a good block,check your casting numbers too see which one you really have.If its a bowtie your stoked.
[ October 17, 2003, 10:02 AM: Message edited by: cs19 ]
He finally sees the light talk to Jack he knows his shit.and wheres my dam pictures.
[ October 17, 2003, 05:09 AM: Message edited by: matt1 ]
The light is still far away. They pictures are in my image gallery jackass. Dont you have some stringers to replace. Get to work and off the computer.
Taylorman,
next time you are in Houston give me a buzz. I know a guy in Spring that deals with BBC all the time. he builds engines for NHRA cars, circle track cars etc and has people all around the country sending him engines. He probably has a block for you also. he has built several marine engines also. He has about 50 years experience in the business and has built SEVERAL race winning engines including the Top Alcohol dragster engine in his son's car (notice picture below). he is from the country and builds engines in his shop behind his house but has some the same high dollar equipment that everyone else does. He will also warrantee an engine. If you ever want to go meet the guy and talk to him let me know. He is a fountain of knowledge and not to far away from your inlaws house. PM me for more details if interested in have a backwards ass, garage floor engine building, country ****, plumber hook you up. Known the guy for about 10 years now, no complaints (he only does machine work for me) but I have seen many of the engines he builds perform ON THE TRACK and they are great. Good luck and good choice to quit beating the dead horse.
Omega
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