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350 or 388 that is the question

sandawgk5

sandawgk5

3/4 ton status
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My 350 is gettin kinda tired with 180,000 miles so my question is should I just rebuild it as a 350 or should I go ahead and punch and stroke it to 388. Second has anyone built a 388 and been able to use the edelbrock tbi to multi-port conversion. The reason is I live in the wonderful tree hugging state of California and I have to keep it smog legal (should bought the diesel I was looking at instead). Also does anyone make a -24 cc dome piston to use with a 3.8 stroke crank and 5.7 rods? Compression reasons.

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hands down stroke it, just keep the same pistons but get a 3.80 crank I believe which will give you a 383 if your worried about that, the down low power will be much greater than the 350 /forums/images/graemlins/thumb.gif
 
Any guesses what I chose to do? /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif

Check KB Pistons...I know when I was looking for pistions, they had a 12cc (what I used) and 18cc dish. They might have a 24cc. /forums/images/graemlins/thinking.gif

If the bores will clean up at 0.030 over, then do that. No sense going to the max right off the bat. /forums/images/graemlins/thumb.gif
 
That is what i am trying to do but with the computer controlled crap I need to keep the compression to 9.3 which is stock I have done some research and I dont think I can go any higher and have the computer like it.
 
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just keep the same pistons but get a 3.80 crank

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In order to do that, you will require the use of the short 5.565" 400 rods, which isn't the ideal combination, but it is doable. Depending on the deck of the block, the 3.80 stroke crank, rather than the 3.75, might push the piston out of the bore a bit. /forums/images/graemlins/thinking.gif
 
should i just buy teh gm performance parts partial 383 and install that with my heads, cam and injection with all smog swapped over would that still pass emissions visually or is the block a pre 87?
 
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I need to keep the compression to 9.3 which is stock

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What heads are you going to use? /forums/images/graemlins/thinking.gif
 
If you want to be smog legal and use the Edelbrock TBI to Multiport. I think it would be best to keep it a 350.
If you want more power. You can always get Vortec heads and the TBI to MPFI kit that fits Vortec heads. Edelbrock claims these produce a 265 hp bolt on with headers. These are susposed smog legal in Calif also. They have a CARB #

If you stroke your 350 and do any performance mods you may need a custom chip to get by smog. Plus some mods to the TB Also it is wise stay away from domed pistions. They raise the compression ratio up way more than the computer can handle. TBI does best with compression ratios under 9.5 to one. You can get that with flat tops and stock heads.

BTW if you want 9.3 to 1 CR. Just put on Vortec heads and use the stock dished pistons. That will also pass smog no problem.
 
i was thinking about the edelbrock aluminum centerbolt head. They are 50 state legal and are matched with their MPFI conversion. But they are pricey. They also run the stock 60cc combustion chamber.
 
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Also it is wise stay away from domed pistions.

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He asked about -24cc pistons, which would mean dished. /forums/images/graemlins/thumb.gif The pistons that I spoke of are dished as well. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
 
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i was thinking about the edelbrock aluminum centerbolt head. They are 50 state legal and are matched with their MPFI conversion. But they are pricey. They also run the stock 60cc combustion chamber.

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You sure have your numbers correct. With the 60cc chamber, you will need a 24cc dish to get a 9.3:1 comp ratio like you mentioned. I ran that through my calculator, and with a 0.041" thick head gasket, 0.004 deck height, 4.166 gasket bore etc etc, you'll get 9.342:1.

What is the factory dish on the pistions? Edelbrock's site says that 60cc is the factory size chamber. Hmm.... /forums/images/graemlins/thinking.gif /forums/images/graemlins/thinking.gif
 
Yep thats what I got those are the pistons I have to run if I stroke it out with a 3.75 crank. If I dont stroke it I dont have to change pistons at all other than for how much I take out of the cylinders
 
Make sure the multi point conversion is legal for california...reason I am saying is because I want the pro flo multi point setup that converts from a carbed set up and it's not california legal.
 
I checked and the tbi to mpfi is 50-state legal. There is a web site run by the state that list all oe numbers for aftermarket equipment but i cant remember the address right now.
 
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I checked and the tbi to mpfi is 50-state legal. There is a web site run by the state that list all oe numbers for aftermarket equipment but i cant remember the address right now.

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Please find it if you can, I would really appreciate it. I am looking into swapping out my heads and fuel system out for better stuff like I should have when I built the motor /forums/images/graemlins/tongue.gif and add headers but It's hard to distinguish which ones are legal for all my AIR pump crap. I could really use a list. I wan't the Pro flow multi port system, AFR aluminum heads and a very good set of headers like doug thorleys. /forums/images/graemlins/thumb.gif
 
Thanks for the link. Looks like I'm screwed because Almost all the chevy truck modifications are for 87' and newer or 79' and earlier. Seems the government doesn't want us tinkering with mid 80's carbed trucks which is incredibly stupid because you would think they would support from carb to FI conversions because FI is so much better. Just plain stupid. /forums/images/graemlins/frown.gif /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif
 
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was thinking about the edelbrock aluminum centerbolt head. They are 50 state legal and are matched with their MPFI conversion. But they are pricey. They also run the stock 60cc combustion chamber.

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First of all the stock chamber on TBI heads is 76cc not 60cc.
I am not a big fan of running alu heads on a truck engine. I know many people here will dissagree with me but I just dont like it.
They are great for a street car that you may take out to the strip on the weekends but on a truck all I have heard about is longevity problems with Alu heads. Namely valve spring seat wear and blown head gaskets. If you just want a truck to go fast they would be great. But if it is a DD/ 4x4 trail rig. I would go with Cast iron heads.
I mean, the truck weighs 5000+ pounds what the hell is 30 or 40 lbs of - weight going to save you? It sure aint going to lower your ET any
You can get cast iron heads that floe the same or better for a lot less money
To me Alu heads on a heavy truck are just a waste of money.

Look into Vortecs or World SR TorquerII heads either one will pass smog and be a great head for TBI. Of the two I perfer the World Torquers.
They come in 76 cc or 67cc center bolt design, look like stock heads, flow real good, and dont need the special vortec manifold. You bolt on an aftermarket intake and the stock or bigger CFM TBI, good computer grind cam and you can be putting out around 300 hp And still should be able to make smog.
 
I am building a 388 via .060 over and 3.75 crank. Your engine with 180,000 probably needs cylinder work. My engine with 160,000 had ring ridges so big I had to sleeve a couple cylinders. Oh with your 3.80 crank, dont go over 5500 RPMs, the long stroke is very stressful. Long rods would help that out if you got the cash. I just got 5.7 cause 6.0 were about $150 more.
 
ya I was thinking about the long throw also, but prolly just gonna go .030 over use the stock crank or a stock stroke crank depending on the condition of mine. It might not make uber power but it is temporary. My wife just told me when we get a tow rig she wants it to go offroad only, therefore 496 will be going in cause smog not an issue. /forums/images/graemlins/thumb.gif With the vortec heads edelbrock also makes a 50 state legal MPFI setup to replace TBI with the vortec patern.
 
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