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73-87 Chevy _ GMC Trucks => Performance => Topic started by: scpscpscp on January 07, 2008, 11:27:00 pm
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Replaced my 350/300hp motor in 75 Blazer with GM 350 crate motor with low horsepower 3 years ago. Thought the warranty 3 yrs vs 1 year might mean something. It did not. This thing can not get out of its way. Warranty period is now over. This is not a daily driver (1,500 miles in last 3 years) and it's normally driven around town and occasionally on the expressway. I am ready to pull the heads off and replace with the 300hp iron heads from the old motor and buy another cam which I think was the old "350/350" hydraulic cam (GM#3863151). When I put in the crate motor, I purchased a quadajet replacement from Edelbrock with the electric choke (650 or 750cfm??). I think too much carb for what I have now. I was hoping to leave the cast iron exhaust on it, the old motor had the headers and I took them off. Cast irons made it a lot easier to change plugs. This is an automatic with the NP203 in it. I have been away from this much mechanical work for 15-20 years so I know things have changed and as you can tell, this is all "old school". Any suggestions and thoughts would be greatly appreciated. Steve.
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Well do you have any specs on your crate engine? What pistons are in it? What cyl head castings you have? What's your compression ratio? What's your final drive ratio? If you're going to try and make the engine perform better headers are a must have and don't make changing the plugs that difficult. Your carb is probably fine and may just need some tuning.
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Without tearing too deep into the motor (or your pocket)...
Ramhorn headers, a good intake manifold, NGK plugs/full tune up can wake up alot of rigs. Just remember these are still BIG HEAVY rigs. Even 500+hp really doesnt make them scoot as you'd imagine.
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My cousin and I did the same thing to his new crate motor with vortec heads and a new rv cam. it blew the rings right out of the motor. This was a brand new crate motor strait from the gm delership. A engine builder told us that any crate motor you buy will have cheap parts in it,thats why they can sell them for so little. I would check into it a little further before proceeding.
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I would have to disagree on them selling crate motors with cheap parts for cheap. The are slightly more than a rebuild, but they do have a warranty. Have you ever torn one apart, it is the same stuff that came in them stock. the 300hp motors are not the same as the generic replacement either....
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My cousin and I did the same thing to his new crate motor with vortec heads and a new rv cam. it blew the rings right out of the motor. This was a brand new crate motor strait from the gm delership. A engine builder told us that any crate motor you buy will have cheap parts in it,thats why they can sell them for so little. I would check into it a little further before proceeding.
I would have to disagree on them selling crate motors with cheap parts for cheap. The are slightly more than a rebuild, but they do have a warranty. Have you ever torn one apart, it is the same stuff that came in them stock. the 300hp motors are not the same as the generic replacement either....
+1 They are the exact quality, if not higher than what was available with our trucks new(especially my '77 by leaps and bounds!)... Think of it this way when it comes to GM selling 350's for so cheap, as compared to an AfterMarket Company...
GM GEN I SBC's are using the same basic Block Design, since it first appeared in 1955, with minor change/improvement since then.. GM stopped doing any changes to the GEN I SBC back in '86, every improvement since then has been put forth with the GEN II SBC's... GM for the most part has also stopped continuing making improvements to the GEN II's, since '96/98 because of the fact that they have other designs that they want to have as much of a following with....
GM has mass produced the GEN I and GEN II's for a number of years now, so they are able to offer Short & Long Blocks at affordable prices... Currently GM is no longer producing any new GEN I SBC's, it is offering what it has left in it's inventory... When that inventory is used up, there won't be any more coming from GM... It is said that the GEN II's have already/ will soon stop production, and anything from then on will also be remaining inventory, till that is gone as well....
I got to say it is very easy for an Engine Builder to tell you that the Factory is selling junk, I mean how else is he going to stay in business selling the Junk that he bought, at an even more inflated cost to you ;)
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Where/when did you hear that Gm no longer produces the original small block?
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It is no longer a production engine. I believe 2000 was the last year
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With the introduction of the LS based engines, 1999 I think but not 100%