First off I want to say hi to everyone. Here is the situation. I am running what's left of a 1990 Blazer with a tbi 350. It is a crate engine with about 70k on it. It is a crawler with a th400 and a Atlas 4 spd t case. I put the engine in about 4 years ago at about 60k or so on it. It has long tube headers, no egr, knock sensor, or vss. Everything else is stock. Chip was burned by Howell and it does have a MSD coil. There are no cats and I did add in a heated O2. I have hammered on the engine pretty hard a few times and by that I mean smoking all 4 tires all the way up into drive and it wound up pretty good. Anyhow I started having problems with oil pressure, go figure, and it will idle at 40 cold, hit the gas it will get to around 60psi but when it gets warmed up good it will drop between 0 and 20psi at idle. Last weekend was the first time it sat long enough at low pressure to start hearing those fun engine noises. Made noise for a second untill getting back on the gas and the pressure went back up. That was early in the day and it ran fine the rest of the day. Sorry for being long winded but I wanted you to know as much info as possible. I am debating on what to do. I really don't want to spend 3 grand building the engine but I am would like to get around 350 to 375 hp out of it with good torque. If it's going to cost a pile of coin to get there it will be easier to just go with a LQ9 and a tune to get those numbers. I really like the tbi 350's and have been messing with them for quite some time but I never built one for serious power improvement. My goal would be a $2000 budget using a stock bottom end. I have been reading up on some of the threads here but really looking for spacific input for my application. What do you guys think?

Here are a couple pics of the rig it's going to be in.

 

im not to familiar with rock crawling but i assume you like 350 tbi due to torque down low the heads are bad but wasnt design for upper rpm power but more low rpm torque but i dnt think you go abover 5000 unless you smoking tires lol you can do a basic rebuild and swap the heads for vortec 350 heads that flow alot better and use a carn intake and tbi adapter you should be around your power range but again what type of power curve you want ?

 

also tbi is better for rock crawler because a carbureted car has a float and extreme angles can limit fuel delivery a tbi or fuel injection in general will always deliver as long as everything is working

 

dont they make special carbs for that reason ?


http://www.holley.com/0-90670.asp

but yea your right tho tbi would be better just do tbi ultimate mod and bore it out to 50mm etc..

also changing to carb you would have to get a lock up kit for torque conveter and change fuel pump because carb runs lower fuel pressure best to sta tbi cost effective

you can port polish swirl heads for small gain every little bit counts but prob wouldnt matter at such low rpms

 

Original poster. What kind of horsepower range you want to make that'll help in case anyone else chimes in or Zach on what kind of engine to build. I am not going to be able to help you in that area.

 

I agree that you are probably on the right track with TBI for your application. Yes, Holley makes special carbs, floats and baffles for off road applications but they were never that great. That's why every rock crawler I know runs EFI. My only concern would be your idea to use a stock bottom end. OE components and build tolerances are intended for street driven vehicles operated conservatively. The fact that your engine is having issues at 70K miles tells me that however it was built, it didn't hold up well. Unless you really wind on a SBC, it should last well more than 70K.

I would suggest that, unless you want to be doing this again in short order, you invest in the services of a good machine shop for balancing and clearancing of the bottom end and of course a good oil pump. For increased torque, you might also consider a 383 rather than the 350. Your TBI will work just fine on the stroker and you will get considerably more torque.

 

yea i agree find a good machine shop makes for less problems and hassle future

 

I want 350 to 375 hp with decent torque. When I stated stock bottom end I was referring to rebuilt but not stroked. I know a 383 would be better but I really don't want to get into all that. This is a budget build because going to a 6.0 with a tune would get me the numbers I want for under 2 grand. The engine in there now shows signs of a bad oil pump but it might be more then that. The engine has been run at severe angles with low oil pressure so if there are internal issues I really can't say it's the engines fault. I want to stay with the 350tbi due to it being simple and I know them pretty good.

 

Well to be straight up. If it is what you want and your familiar with it then it is worth rebuilding. I can find 350 TBI on craiglist all day too so that'd be a cheap option for you also.

 

That sounds good. There must be oil pan options available for your application that will help avoid loss of pressure at extreme angles.

 

You can go with a swinging pickup tube design oil pan or even a dry sump setup

 

Dry sump would be good wouldn't it? I don't know if I trust the swinging pick up tube.

 

Oil accumulator, fresh pump & bearings.

http://www.summitracing.com/parts/MOR-23930

 

Oil accumulator also very good idea.

 

just take out oil pan and and weld in sum baffles and make some one way flow gates and that should solve your problems can buy small sheet of steel and make very easy

i got the idea from these pics

the circles are the holes to put one way flow gates you can use a rupper flap of some sort and rivit it in and use paper of template

shouldnt cost more than 50 bucks

oil accumilator is a good idea too

 

Yeah, the accumulator is a good idea and we do run them on the race rigs with LS engines. I am already planning to build a new buggy with a LS but I really don't want a LS in this rig. Now let's get into the build. I have been reading alot on these engines and what can be done but there is conflicting information on the net so I only want to buy parts once. Figure on a honest 350 horse engine with a stock block, crank, rods, and pistons. Can it be done on the stock computer with a custom chip? What heads should I look at getting? I know Vortec's flow decent but can I get the numbers I want with them? What would be a good cam and should I go to a roller cam? Intake from everything I have been reading will probably be a Performer RPM unless there is a better option. What should I do as far as the tbi goes, get one that is modded or look into one from a big block? I figure this should get me a good start on what parts to get.

 

The only thing that really bothers me about all this is tuning. When it comes time to tune it I will have to seek some help. It might mean trailering to somebody close enough or seting up a meeting place and me tossing them some coin for their time and travel. I was also reading the budget build using a Vortec 350 and that could be a option. If it runs good I might just use it in the new chassis and skip the LS.

 

You can make a comfortable 350hp with the Vortec heads. I wouldn't run anything but a roller cam in any engine today. The oil companies by order of the EPA are doing away with Zinc in engine oil. Without zinc, flat tappet cams are doomed. Besides, whatever power level you can achieve with flat tappet, you will do better and with better drivability using a roller cam. As far as the intake goes, I have heard of using the Performer RPM with a TBI adapter and making good power. Sounds like a good way to go. The one thing I can absolutely recommend is a good machine shop. The cost of block prep, balancing and clearancing is about $700 and the best investment you can make.