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Rebuilding my 350 got q's

K5Steve

K5Steve

1/2 ton status
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Aug 10, 2005
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Location
Carson city, nv.
I have done a search but everybody is doing different things.I am getting a 350 block from the machine shop for $250 all machined and ready.Now,I'm going to build it over the winter so when the engine dies I can just drop in the new one.I would like to keep the price down and I am keeping the tbi and would like to do as little ecm tuning as possible.I was thinking of some l98 heads and one of the truck cams out there.I'll probably buy one of the summit or Eagle rotating kits.I'll buy an edelbrock intake.Now I would like about 100 hp more than stock,hell,I'm even ok with stock power but may as well add some while I'm there.Would l98 heads be better than the tbi heads or should I just have the tbi's ported when the time comes?What would give more power without breaking the bank?I am thinking of spending no more than $2,000 on the whole build.The machine shop said he could use some flat top pistons and a cam to get more power But i would like to get all of your expert advise on what type of pistons ( hyper/forged)crank,cam,heads.This a daily driver and mpg's would be nice.Thank you and sorry for rambeling
 
If your looking for 100 more hp for 2000 bucks tbi will be hard to keep. Don't know much about the l98 heads but a good set of dart iron eagle platinums can be had off ebay for 759 to your door... those heads alone will add 70 hp or more. With a good cam your looking at 110 hp easy. BUT you'll need to buy a bigger tbi. I know the 454 tbi's can be bolted onto a 350 without any problems. The holley 670 cfm tbi is what I went with(basically a 454 tbi with 10 more cfm), and I will be using a prominator to tune it. You will need computer tuning... a local shop with a dyno should be able to burn you a chip for 300-400 bucks or you can do it your self(let me know if you want to burn it yourself).

Also If you get the flat tops you'll probably be stuck running 91 octane. If you don't mind running 91 then you'll be up another 20 hp. I would recomend buying a stock shortblock for around 800, the darts, a good cam, bigger tbi, and computer tuning. Your looking at 2500+ if you go that route tho.

Don't know about the l98's price range.
 
Heads/cam is where all the power is made, assuming you have a good intake and exhaust. I think the heads will be the best place to put your money followed by some long tube headers and the much needed TBI upgrades. With the 700r4 and 3.73's you'll probably want to select components that will work best with your particular setup. For example, 1 5/8" headers with an Hpipe will probably be better than 1 3/4" headers. 175cc intake runners will be better than 195cc runners. A 2500-5500rpm cam might sound cool and make more power, it won't do you much good for everyday use though if you seldom shift past 3500. Vortec heads are nice if you haven't bought an intake yet.
 
The aluminum L98 heads are great and will make gobs of torque. They weren't paticulary known for the making HP unless ported by a decent shop. Don't get me wrong though. I've belive they can be worth 40-50HP as a bolt on. They had a D-shaped exhaust port that flowed like crazy.

Things to watch out for are their small 58cc chambers and they don't have the EGR passage built into them.

If smog test aren't an issue, then you could have the EGR turned off in the chip. Flat top pistons could push the CR way up so watch out for that. Don't bother trying to get the TBI heads ported.

Kelvin
 
I have never heard of having to run 91 oct. w/flattops. I have run plenty of them on 85 (low grade in Colorado) with no side effects.

I would build a hyper flattop piston motor with an 'RV' cam. You cannot get too radical with your cam unless you have a chip burnt in a TBI setup. The TBI heads flow pretty good but not as good as Vortec's. I would not wasted my money having TBI heads ported when you can get Vortecs or Dart pretty cheap. Roller rockers will also free a little horsepower.

My engine builder in Colorado told me something about the Vortecs having a problem in colder climates because they are missing somethine that normal heads have that warms the incoming air....EGR maybe, I don't remember.
 
I don't know which pistons I'll use yet but I think I'm going with an Eagle crank for 160 from summit.I found some Scat cranks for 165 on ebay,which would be best?I have a friend who can burn a chip,He runs a stealth rammed 383 so he has been tuning his also.I can get a set of regular(non aluminum l98's for 50 bucks,that's why I ask).
 
Scat makes a good product, I used Eagle in my Ford 347 stroker, just because I got the best deal on them. If I had a choice at the same price I would pick Scat. What is wrong with you stock crank?

Also make sure that the price on the crank is for a 1 piece rear main crank.....that is assuming that you engine is a 1 piece. 86 and up are one piece.
 
Nothing is wrong with the stock one.I just kinda need it to drive the truck till the new motor is done:DYeah it's for a 1 piece.I know which pieces to get but not too sure on types of pistons.
 
I would just go with a hypereutectic piston, with moly rings. You are not building a hot rod, just a good stout motor. I think all mine had Sealed Power pistons....whatever EPW put in there kits.
 
Scat, Eagle or stock cranks will work just fine. With the L98's you'll need a small dished piston unless you're willing to have a 11.1+ CR. To run that high a CR you'll need stuff like zero decking and reall tight quinch. I'm guessing you'll need something around -12cc to -18cc D-cups to keep the CR around 9.8/10.5 ish.

Hmm D-cups, I love that ;)

Get the best rods you can afford and a set of KB pistons and you should be all set.

The stock springs that come on those heads will have to be trashed if you're talking about cam with some lift. I think the stock retainers/rotators have to go also along with the non hardened guide plates. Unless you're planning on running stock rockers and crap?

Did you buy a roller block?

cya

KM
 
I haven't bought the block yet.I was thinking of going with a roller block though.A friend of mine has an l98 block for cheap.I don't want the high compression so I will have to do some calculating.Would an l98 block work ok?I will swap in a tpi sooner or later also.
 
No biggie on the mains.It won't be a racer or hard core wheeler so I think a 2 bolt main would be ok.That's probably what's in it now.I just want the truck to have more grunt.I climb a mountain to work everyday so more power is good.I can get the l98 block and heads for about 150 and then I need them machined,or I could just go with the same kinda block that's in it now(non roller)machined for 250.
 
I'm not 100% sure about what I'm about to say, but I'm sure others will chime in if I'm wrong.

I think TBI Blazers had 4 bolt main roller blocks! They just didn't get the roller cam and lifters. So with that said, you may be able to......

JFYI

KM
 
I have heard that these blocks were roller but didn't have the cam and chain.If so then I'll probably stick with the same type block.I have to yank the intake to replace the gasket this weekend so I'll check to see if it is a roller block.
 
Sticking with a roller block is your best bet, sounds like you have a couple of options for this.

*Iron* L98 heads don't have the compression that the AL's do, 64 vs 58, so you could run flattops with the Iron L98's likely without problem. However, changing heads invariably means the timing is going to be nowhere near correct, and burning a chip is the only way to get something like that optimal.

You might check thirdgen.org, a roller cam out of an L98 car off of ebay might be a pretty decent bump up from a TBI truck cam, while still being no problem for the injection setup.
 
I am thinking of just going with vortecs once I get the bottom end done.I'll get the new intake once it's time to drop in.
 
Have fun with that. :)

Vortecs are a waste compared to the other aftermarket heads out there that do the same thing, but with better parts that will allow you more flexibility in a build, or in the future. They are good heads, but they are very limited "stock" as to cam, intake selection,etc.

I've got a set, they are pretty neat, but IMO all the issues I had to deal with could have been avoided by going with some darts, AFR's, etc. Some are pretty pricey, some are not much more than beefed up Vortecs will cost you.
 
I was looking at the Darts so that is a possibility.I don't want to spend a lot on heads so I will be limited.Now on the crank,Should I go internally or externally balanced?
 
Roller rockers will free up 20 hp or so but its all high rpm hp. You'll probably never see the gains unless your above 4500 where the stock hei falls on its face.

When you said flat tops I thought you meant 10:1... don't know why but I guess thats what i get for posting while intoxicated.

PWI
 
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