basically I am about to set forth upon my 383 build for my car. I have decided that drag racing is not my thing and it is impossible for me to be half competitive and that I have way more fun just driving the car once every week or so on the street. My goal is not an all out crazy motor that will burn blazing fast honda civics (haha, sorry I make terrible jokes); but it is merely to have a *relatively reliable *(note that it is not a daily driver, I understand modified performance vehicles are never reliable) motor. I prefer a 383 because, if I understand correctly, it will tame the gm947 my motor now has and almost all of my car surge will disappear. That and I have had a great desire to have a 383 for a very long time.

currently I have ported heads with 190cc intake runner and 2" and 1.56 valves; gm847, 42lb injectors, walbro pump, exhaust and intake setup to complment the larger motor as well. I also have a t56 with spec clutch and 4.10 gears (I am planning on putting on taller drag radials so I can reuse my 15x10 prostars on the street)

I thought a *simple* 383 with components such as

cast steel crank (scat better than eagle? or is it the other way around? I can't seem to find a 3.75 stroke scat with 1 piece rear main)

scat forged i-beams: 6" or 5.7" I have read 6" is geometrically better but in a motor as simple as this I do not think it would truly make a difference

hypereutectic pistons: I have been looking at the speed-pro ring and piston sets, they seem like a pretty good deal. I am just unsure of what piston wi;; suit my motor size and cam best. I have no idea what my combustion chmaber cc is. The heads are off of a 96 model year car and were ported by Agostino racing years ago, ran in one car, blown up, repaired by me and have 7 thousandths shaved off. I am guesingg they would probably cc in the 53cc area.

I figured I would probably need a new oil pump, can reuse my main caps (require new bolts), reuse my double roller (only has five passes and one dyno pull on it), reuse my crank hub and balancer, and reuse my 140,000 mile lifters because they are still going super strong. the machine on the block would be super top notch and the cost of it is negligible (I traded services with him).

what do you guys think? things you would change? maybe a specific piston you would recommend? I do not mean for this thing to be super crazy fast, but I do expect it in the 420-430whp range.

 

I think your goals are reachable, the things I would change would be a callies crank and the compstar 6 in. rods ( I have both of these in my 383), the machining is alot better than the eagle pieces (in my opinion). I'm using Diamond pistons but I also like JE or Ross, it really depends on what you want to spend. New oil pump and I would replace the lifters just to do it, and you'll have to check the pushrod length when your done with the build up.

 

those are both very nice pieces but I am unsure about whether I really need parts that are that good for what I am trying to do. I ultimately would like to pick parts that are cost effective for what I am trying to acheive with this very simple motor.

 

I would just use hyper pistons based on your explanation of what you intend to do. I used them on my 383 and worked fine.

Get your block decked and reduce your quench.

Definitely a new oil pump.

 

The only thing I would change is to put forged pistons in it, just in case somewhere down the road you choose to try NOS and just for the piece of mind.

 

If you need to rebuild anyway, the plan to build a 383 is fine. But if you already have a short block that is in good shape, there are better ways to improve the car than simply using the same top end and making your 350 into a 383. There will not be much performance gain. Your stock rods are better than what you are thinking of buying BTW. There is no appreciable performance difference between a 6" and a 5.7" rod.

Rich

 

rskrause, what would you recommend? I am looking into this engine build because I have recently built a brand new 8.8" rear that I put a ton of work into, along with freshening up my t56 and giving it a new clutch. I figured with 138,000 hard miles a rebuild might not be a bad idea. I do know I need to diagnose a leak in the front cover and replace the rear main (transmission bell housing was covered in super thick grime, grease, and oil). my gm847/heads/cam car only put down 387whp with a severe drop in the high rpm's.

I just don't want to put a ton of work into everywhere but the motor and have too rebuild and tear the car down again in 6 months. In the last few years it has probably only spent a few months being drivable under its own power. If you recommend another route not only would I like to hear it but it probably be the direction I take. I have been on these forums for a while and recognize you as being one of the site's more experienced members in concerns to these cars. I have also seen that you are very realistic, and I think you know what I am trying to achieve. I do not want a new motor "because I want one", I simply thought it was the best route for me to take.

 

At the risk of getting flamed to death here, I want to disagree. First we need to define "performance gain".

From what he indicated for driving condition he would be under, those cubes would give him torque gain throughout his RPM band but granted unless he matches it with the correct cam, there might not be signifiant HP gains at the upper end. However it does not sound like he is looking to rev much anyway.

Everyone is different and I don't disagree with your assesment Rich because it is valid just the point on what "performance gain" is for any one of us.

Ranger, either way you go, I would just have a reputable shop put your rotating assy. together for you (assuming you have not done this work many times before) then you should be fine.

 

I see your point, at 138K it is probably getting a little tired and you want to fix the leaks. Sounds reasonable, but with due respect to the above post don't expect a large difference in performance - UNLESS it is so tired and worn out that there is poor ring seal, etc. that is causing performance loss. Kind of like the "gains" people see with a new set of plug wires, which they attribute to the brand. Of course, what is usually happening is that they are replacing a set of defective wires with good ones, often with plugs at the same time. I do acknowledge that it will make torque at lower rpm, just not a big difference in my experience.

As the above post suggests, I agree that it is often best to have the shop doing the machine work buy the parts. Or the person doing the assembly if it's different and you aren't doing it yourself. It may cost a few dollars more (or may not) but they, not you, will be responsible for everything fitting and being right. You be surprised how many people bring incompatible parts into the shop. Recently, we saw a guy with a set of rods too long for the pistons. They stuck out of the deck 0.200"!!! I have seen oil pans that wouldn't fit crossmembers, supercharger kits for a different year car that were incompatible, rings for a different bore, and so on.

As far as the hp your car put down, I see you are in Scottsdale. If it was tested there, that is higher altitude and often hot, right? That means the air density might have been quite low when tested if it was local. You need to either use corrected numbers or at least compare with similar cars under similar conditions. If it is truly lower than it should be, the usual culprit is something wrong in the valvetrain or bad plugs. Other ignition issues could also be a cause. A severe drop at high rpm is usually valvetrain related. Sometimes the tune is way off.

In terms of specific parts, I am not real familiar with the GM 847 cam but I assume it is going to want some compression. Especially if you drive in thin air, you are going to want to choose the static CR with air density and the cam in mind to maximize your performance. Oh yeah, that's another reason people often notice a performance gain going to 383 from a 350 - they typically end up with more compression. There will be about a quarter point gain if nothing else changes going to a 383. That is enough to make a difference, especially in a cammed car. You will be fine with a HE piston. Speed Pro is a good brand. Don't skimp on rings. I'd look for a static CR in the 10.8-11:1 range assuming low air density and premium fuel. If you know guys with that cam in your area, see what they are running and how it is working. You can't pick the pistons until you have CC'd the heads and know what your deck is going to be. Choosing the correct CR is pretty important.

Rich

 

My opinion is that a LOT of the " strokers make more lowend and are better street motors because of it" is largely excuses made by guys who put together mediocre or weak motors.

Yes is all is done equally a stroker will make a little more lowend, BUT if a 350/355 is done well they make plenty enough to make street traction a challenge, done well a 355 can and has made more torque than the average stroker. One example of a 355 that gets tken to 7500 on the strip makes 385tq at 3400rpms and opeaks at 418tq at 5000rpms that is torque comparable to most strokers but in a high rpm 355. The average power put down is what makes it fly.

Before doing a budget stroker poorly do some reading and consider doing a 355 well, price will be similar, just take the saving from not having to buy a crank and such and put it into the topend, results will be better if you choose well.

 

the elevation here is something around 1200' and it does get very hot (110+plus for a few months each year). I have already figured out that I need a higher compression to work with the cam I have. the GM847 cam is a 234/242 at .050 and 296/304 at .004. I remember when I was considering a rebuild a long time ago I think I came up with needing a -5cc dish to get the right dcr, but I really was only guessing at 52cc for my combustion chambers.

The shop that will be doing the is going to advise me on the parts I need. The deal I have worked out with them is I buy the parts at their discount and get the machine work free/extreme discount as well. I am very confident in them and know they do excellent work. I have have a great relationship with them for the past nine months. I am going to have them assemble the short block as well. I have done it before and feel confident, but for this situation I prefer if it gets put together right the first time, rather than blowing something up and redoing it.

In concern to my low dyno results I think it is tune related, I can barely get my car to idle as it sits right now, and it surges so bad when I try to pull out of the garage it is nearly uncontrollable.

rskrause, would you recommend using stock reconditioned rods for my application? I am going to call the owner of the shop today and speak with him, when I last spoke with him he had stated that he prefered not reusing them but I am sure I can convince otherwise.

 

Give me a PM and I can see what I can help you with on the tune. I am currently tuning my 383 setup now and have a similar sized cam so similar issues will be had by you.

Maybe shoot by and plug in my computer to your PCM sometime.

 

I do believe that the 94 model cars use the GM "pink" rods. A lot of GM folks swear by them. if you know for a fact that you are never going to use a power adder those rods will be fine for you. However if you do plan or think you may use nitrous or a blower in the future an I-beam forged rod would be the absolute least I'd go with. The 5.7" rod is fine with a 383 as well. I run the forged Eagle crank and H-beam 5.7" rods in my set up.

As far as the rods go my brother runs his re-used 1994 "pink" rods on his heads/cam 355 with a 175 shot of nitrous without a problem. He runs the speed pro forged pistons for the nitrous but a good set of Hyp. pistons will be fine for a non-power adder car.

All said for what you want I'd go with a 11.1:1 CR stock reconditioned "pink" rods and the Hyp. pistons with a scat 3.75" stroke crank. Be sure the folks you have doing your short block balance the flywheel with the rotating assembly/Hub and balancer included.

The GM 847 cam is great but I'm sure there is a custom gind out there that can suite your set up a little better. Also new lifter such as the LS7 lifters would be a GREAT idea at this stage. DO NOT skimp on the lifters and springs as those two things can completely kill you over 5900 rpm if not done correctly. I recomend the LS7 lifters and the PAC 1518 springs set up optimally for the cam you go with. Don't just slap them in at 1.8" installed height and be done with it. Generally a little bit tighter seat presure is great and will help out in the upper rpms being sure to stay away from coil bind at max lift.

As a word of encouragement my brother who has a 355 big nitrous cam likes to drive my 383 around on the street much more. He says it has much more torque and throttle response down low while driving while his 355 has to rev up before hitting the same torque levels.

Hope this helps.....G/L!

 

as much as I would like to say "yeah I will throw a 100 shot on it!" I know realistically it will never happen. I would have a hard time parting money for something I would use once a year, and my significant other thinks that I would kill myself with it

i already have the flywheel off and just recently resurfaced, pulling those other parts off are no problem. maybe using the stock rods aren't such a bad idea. I just wonder if mine are still strong after 20 or thirty drag strip passes to 6.7k rpm

 

With 138K on the rods I would consider replacing them. The stock GM rods (either the earlier "pink" rods or the newer PM rods) are great. But by the time they are reconditioned and magnafluxed, it is not economical. I don't know much about cheaper rods, so I can't really advise which ones to buy.

Rich