I just tore down a 350 today. I am looking at doing a 383 since I have it apart and have to buy some new parts any way. But I have some questions...

1) What carb to use for the 383?? Q-jet or that new Holley Avenger...I am using this in a Jeep and it will be for logging trails, fire roads, and snow running...Basically all around use including off camber.

2) Do I need a custom cam to run the 383?? My buddy who is building the motor for me has had to use a "custom offset" cam in each of them. I would prefer to run a regular cam to save the money. Like an Xtreme Energy.

And if you guys have any tips for headers/manifolds, oil pumps, water pumps or any of the "other stuff" I would appreciate it.

I did search and have been reading for about 3 hours.

Thanks.

Steve

I personally swear by the qjet. I hear that the avenger is good but spendy. What if you are on a hunting trip or ???? and need to get parts? Something to chew on. I have never heard about having to install an offset ground cam, but I have never built one either. I do believe the block has to be clearanced for the weights on the 400 crank. I think that any mods that you do to a 350 will work just as well on a 383.

Don't forget you need to run the 400 harmonic balancer. Also, I like the Q-jet as well. Used to run a healthy 350 in my 70C-10, and never had a problem.

I would prefer to run the Q-jet, but wasn't sure whether it would breath enough for the 383. Don't they come in a couple different sizes??

Originally posted by Kicker
I would prefer to run the Q-jet, but wasn't sure whether it would breath enough for the 383. Don't they come in a couple different sizes??



Right now, I'm running a 600cfm on my 383. It's plenty for it. Although, I want to go to a q-jet cause it'll run better on angles than the POS edelbrock performer I have now (it runs good...just bad on angles). I want to run an open element on the q-jet, but I'm not sure how it'd fit on it. Right now I'm running a 6" tall open element (I think the diameter is 18"?) with a K&N filter. It's huge and the motor likes it. I can hear it sucking in air. These motors need to be able to breathe. The exhaust system for it are headers to 2 1/2" pipe (true duals) back to 50 series flows and out.

Re: Cams. On mine, I'm running one with a cam lift : int .300, exh .307. Valve lift: int .450, exh .461

Mine has been extremly reliable and gets about 15 mpg on the highway and has plenty of power :D

I think most q jets in the 650 range. They use the same ones for small and big block in the Chevys. If you want more cfm, find one off of a 472/500 Caddy. If my memory serves me right, they are around 850, but I think that might be to much.

Yeah, I think the 850 would be a bit much as well. I want to get torque, but I don't want to starve it either...Ya know?

As far as the cam issues, you will need to grind all the heads of the rod bolts and some of the rod cap to clear the cam....even with small lift cams if you are using the 5.7" 350 rods (which are prefered), especially on rod #2 and #6, they will hit the cam and then weight match them. I had used a small base circle cam for clearance, I had used Eagle H beam rods that has 12pt. heads which did add clearance, except #'s 2 & 6, and the rods were all weight matched and I did not want to grind-check-balance-grind-check-balance the assembly just for those two rods (plus they were set and ready to run..nice pieces). So I simply had a cam ground with the same figures only in a small base circle configuration, it really was not that much more money for the piece of mind. You will then still have to clearance the oil pan rail again to clear the rod caps and nuts...I did not have to do that with the Eagle rods with their 12pt heads. You then also have to check clearance at the very bottom of the cylinders *CAUTION: do not remove to much, those are the water jackets. You want to look for about .050-.080 clearance for material expansion and stretch as it rotates. The oilpan rail and cylinder clearancing was easy to do, mostly because it was something you could see during the mock assembly, measure, and grind. You could do that while the lower end was assembled, I just used the old rods and pistons on the new stroker crank....I did use new bearings for the mock assembly which I threw out after and used fresh ones for the final assembly. Then you can fianlly get the 400 harmonic and flywheel and get everything balanced. Good luck. John

A 650 CFM would feed enough air. How many RPM's do you plan on spinning this motor. A 383 spinning 6000RPM would only require about 665CFM, and that is with 100% volumetric efficiency. A normally aspirated motor in solid running condition is apporx. 75-85% V.E. So, I think a 600 would work very well and give very good trhottle response and torque feel It does depend on your usage. John

Use a 750/ 850 Q- jet. Remember a Q-jet will only open the seconderies as much as the engine will take, it's not like a double pumper Holley.

I think that would be overkill on a trail vehicle. Why not a 600 vac. sec Holley or smaller Qjet? Keeping airflow velocity high. I know Qjets have small primaries, do the larger Qjets have larger primaries than the smaller Qjets, that may hurt his performance. I know it depends on usage but it seems as though he wants throttle response and drivability?

I have a 383 I just took out of a 74 I was running. I was very happy with the set up I was running Q-jet, Performer intake, Performer cam for the 400 (.442 lift 288*advertised duration on a 112 lobe center). I think your buddy is probably talking about a cam cut on a different lobe center, talk to him and ask him.



I used to have this motor in a 64 Elcamino and ran 14:10 in the quarter with a 600 singlefeed carb (needed a bigger carb wouldnt run over 5K) and a cam (had to recam due to amog) that was .488 lift across the board and 288* duration across the board cut on a 110 centerlobe (cut by Eddie at Camonics in North Hollywood,give him a call if he is still around). That cam came in at about 2000 RPM and pulled like mad. As soon as my Blazer is out of smog (its a 74) I am going to put that cam back in. The headers I had on that car were cheapie Hooker's.

I am looking for driveability and throttle response for sure. This is not only my play toy, it is my winter vehicle(Mustangs just don't like snow)...

I just got the new 4wheel Drive & SUV and it had GM's new 383 crate in it. It had some new custom rods made just for the 383. It was still a 5.7 rod, but had studs and nuts instead of rod bolts. They did that for durability and to make it easier to clearance the rods.

I sounds like a 600 Q-jet will be best for me.

What kind of compression are you guys running on the 383's? My buddy suggests 10:1...That's what he built the others at and they are runnign fine on pump gas. Just curious what you guys are running.

Kicker, I would keep the compression around 9:1 - 9.5:1 with iron heads. You can usually get about 10:1 - 10.5:1 with alum. heads. Cam choice also play a role in this, I am sure your running a pretty mild cam (RV/towing type cam) which builds good cylinder press. at lower rpm's and does not bleed off cyl. press. with a lot of overlap/duration. I think you could use more compression on pump gas with a more radical cam only because it bleeds off good cyl. press. at the lower rpm's with the extra overlap/duration. It really is not compression ratio, it is cylinder press that causes detonation. You would actually lose drivabilty and power with that style cam. I really do not think you are going to lose much running say 9:1 vs. 10:1, but with 9:1 you would not have to worry about detonation or having to run premium fuel all the time. I would build a solid 383, 9:1 - 9.5:1, 600CFM, and use a good torque type cam with int. duration around 200-206 and exh. around 210-214. A nice setup would be a roller cam, low duration but still offers decent lift figures. Look at the cam on the GM 383 stroker: 196I 206E dur. with .431I/.451E lift on a surprisinglt tight 109 degree lobe centerline! That motor will grunt! Just my thoughts. John

Has anyone seen any pistons that will get a 9.5:1 compression with the vortec heads?? Most I find are either 10.1 or higher.

I don't want to fork out the money for forged pistons if I can find hypereutectic at the right ratio. I can get them for about $140 a set. Forged are at least double that.

I planned on calling Comp Cams and letting them pick a nice stump pulling cam for my combo. But I do like the power they got out of the GM crate motor. Nice low down torque!!

Federal Mogul has some hypereutectic pistons that will give 9.6:1 with the Vortec 64cc heads, they are part # 602CP (the CP stands for the anti friction coating). PAW has them for $235 for a set of pistons and pins. I got mine at cost ($180) because my buddy ordered all my parts, do you know any one in the field? They are for the 5.7" rods and 3.75" stroke crank. They do have a .110 dish, but hell even some stockers have more dish than that. Theses are the pistons I had used in my 383. I think hypereutectics are the piston to use, they run a tighter fit than forged for stability and are more forgiving than cast. John

Also, with Comp Cams may I suggest the Extreme Energy 4X4 line either part # 12-231-2 or if you run E.F.I. you can use a slightly larger cam. Part # 12-325-2 would be a good choice. These would both be very torquey grinds and you would still run approx. 300-325HP with about 400-420ftlbs torque around 2000-2500rpm. John

Thanks for all the help and info.

I do appreciate it!!

I am sure I will have more questions in the very near future.

Also, no I do not have any contacts for those pistons.

I recently installed a 383 in my '90 Jimmy. It is running Vortec heads, Fed-Mogual pistons, Scat crank & 5.7 rods, LT1 roller cam, a Eldlebrock MPFI system, and Edlebrock headers. It is a daily driver and runs on mid-range pump gas(it would run on regular if the timing was backed off a little). The FI offers instant throttle response and it has great low-end torque.

I would reccomend the SCAT crank. They are suppose to be good up to 8k fairly cheap and let you use the 350 balancer/flexplate you already have. They also potentially save you the cost of grinding down the 400 crank's mains. As cj8scrambled said go for a cam with lower duration, higher lift, and lower overlap. I believe the vortec heads are only good to 0.48 though. Good luck.


Charlo


P.S. If you can clerance it the 6.0 rods are supposed to give more torque, but the cost or replacing them and the pistons may be too much.

True on the Vortec max lift of .480, unless you change springs. But on a DD and trail rig big lifts not all too important..for the gain. And, yes the SCAT cranks do let you ext or int bal, for ext you use the 400 flex/flywheel and harmonic. For int. you would have to use mallory (heavy metal) which can get costly. The ext. bal is fine...look at all the BBC's that were ext bal. Oh, and the 6" rods do get a bit costly and are better rod angles (less friction with piston loads on the cyl wall) but the gain is small and the ring lands on the piston are closer to the the crown...thinner more susceptible to breakage with any detonation. John

Found some Federal Mogul Hypereutectic Pistons that are 9.35:1 and only cost $14.99 each. but they are listed for the 350. Are they the same as a 383 piston???

Anyone have experience with these?? Also, does anyone know who makes these for them??

No/sort of, they will only work with the 400 rods which are 5.5" will work but not ideal. Increased friction and loading/scuffing against cyl. wall. I believe Fed Mogul is a parent company...? John

Just curious...

I know at my old job we used to make a lot of stuff for them. I know they make some of their own stuff, but I am pretty sure most is out sourced.

I was thinking with the 6" rods and pistons you can save a lot of weight since you gotta buy new ones anyways get lighter ones, maybe even enough to avoid a heavy metal ballance which would also save the cost of a 400 flex/flywheel and harmonic balancer for some one who has a 350 already like kicker. But I am smog guy so I have to squeeze all I can get. I can see why most people would go 400 w/ 5.7s. But I would rather have the longer rod which delays peek piston speed until later in the stroke when the intake valve is open further. These effects are furthered by larger lift cam with steeper ramps such as a roller cam. Reduced piston-bore wear, greater mechanical linkage effeciancy, and better volumetric effeciancy are all postives of the longer rods, but as cj8 pointed out they come at a heavy price. I have been building a 383 with vortec heads but as you can see have chosen a different route.

Charlo

Charlo,
I agree with the long rod theory and understand it. That would be ideal but I also understand form reading his post that there is a cost factor behind this project. I am sure he would, hell I would, do things differently if cost was not an issue.

I had read an article on a "different" (sort of..just not all too common) approach to building a motor. It was a short stroke/long rod/large bore setup. They had used a 400 block with a 327 crank (short stroke) and they used long 6.3" rods (Ford 300 inline six rods..machined slightly) and they had aluminum heads with a compression ratio of 11:1..on 87 octane pump!! It put out something like 400 and about 450ftlbs torque....all with a mild stock roller cam. Now one would think that with a stock cam that builds good low speed cyl. press. that that cam would not work with that high of a compression ratio...because it would not bleed of press. via overlap/duration and it be crazy with detonation on pump gas. No matter what they did it would not detonate! What this long rod/short stroke arrangement did was to increase dwell time of the piston being at topdead on compression, with the ignition (power stroke) firing and the piston "hanging out" at a longer dwell time the "explosive" power stroke forces were greater...more "push" on the piston, overall a more efficient combustion process. Like I said this was not entirely "different", NASCAR has been doing this for sometime.....short stroke/longrod arrangement. I will try and find a link to that article! John

Yes guys...There is a cost limit involved in this for sure. I have to build this motor, get my nex axles, do the SOA, and then hte little stuff. SO I can't built the monster I would if I had money to spare.

Otherwise I would have forged everything with aluminum heads and so on. But that is not in the forecast for this project.

Kicker that is why I suggested the approach I did, I understand the $$ factor. Building it with external bal. would be fine and the 400 fly/flexplate and harmonic are not all too expensive, you don't need a SFI approved Fluidampr, I ran a $80 Pioneer 400 harmonic and have been very happy with it. Now I see Jeg's has a 400 ext. bal. for $65. They have Eagle stroker cranks kits that include the following: Their 5140 I beam rods 5.7", cast steel 3.75 crank, Keith Black hypereutectic pistons, moly rings, rod and main bearings, harmonic bal and flexplate all for $1149.99 for a two piece rear seal or $1179.99 for the one piece. That is for the inverted pistons that give 9.7:1 with the 64cc Vortec heads. The only other thing you would be looking at would be the machining. Price it out, the only additional parts here I see are the rods which you don't really need if you have the 350 rods already, but it may save $$ on the machining of the rods. Like I said with those Eagle rods and a small base circle cam you do not have to clearance the rods at all. All you have to do is clearance the blocks oil pan rail and the bottoms of the cyl. which you can do your self and save on the machine shops labor.

Check them out:

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=27152&prmenbr=361

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=27153&prmenbr=361

If your looking for budget stuff check out www.enginekits.com . They have 383 kits with flex/flywheel balanced for $670.

Thanks Charlo, Kicker take a look there are deals out there and sometimes people just need to point them out. They do have a rotating assembly "kit" that runs a 10.8:1 ratio but maybe they can put something else together for you, like sustituting the pistons to get the comp ratio down. John

John, I more than appreciate all the info and help you have given.

I picked up a cast Eagle crank off Ebay for $209 including shipping. That's $80 less than Jegs.

My rods I have now are brand new. They are copies of the Eagle SIR rods. They are made by CAT. I think they are part of Prowler. Nice rods either way.

Just searching for the right pistons now.

Flexplate's and dampners are pretty cheap so those are not much of a problem to me.

After that, I just need to find a Q-jet and then pick the cam. That will be it for all teh "major" parts.

Kicker, I am sure there are other sources out there. But here are a couple from the PAW catalog. Keith Black HyperE part # KB-135 and KB-102 are both 18cc D cup and give 9.7:1 with 64cc heads. the 135's are priced at $352 with moly rings. The 102's are only offered with Speed Pro rings at $405. The only other ones in the PAW acatlog that fit your criteria were the HyperE by Fed Mogul Part # 602CP and they were $235 pistons and pins only...no rings. And they too were 9.6:1 ratio. Again, ask around for piston sets that will give you the desired comp. ratio. Good luck and have fun. John

For anyone interested in that article with the "destroked" 400 you can find it at airflowresearch.com. It was their aluminum heads they used.

As far as that JEG's rotating assembly goes, im building a 383 right now with the $899 kit. The only differenct between it an the other kit that listed at 1149-1179 is the pistons. I have 74cc AFR heads unlike your vortecs. If you really wanted to pinch a penny or two you could order the 899 one and deck your block .010-.025, depending on the desired compression ratio, and run a thinner head gasket. Chance are if you are gonna build a decent motor with your old block you need to have it "square decked" anyways. So you could pick up some more compression by gettin the machinist to take it down a little farter. If you end up with too much compression you can run a fatter head gasket. Normal compression thickness is somewhere around .035. You can get gaskets conciderably thinner and up to .060 thick. My machinist said that for every .010 of an inch you take off on a motor like the one im building you can count on half of a point in compression. I got my block square decked to .010 and it should bring my compression ratio to 10.2:1 give or take. Im gonna use a lil thicker head gasket to get the compression down. Gotta cc my combustion chamber to find out what its really at.

Thanks slowJEEP for the AirFlowResearch tip, it is located under "articles" and click on "the 350 Engine Chevrolet Should Have Built". I knew that is who put together the destroked 400 and was looking for a direct link...but that works! Also, that is a good point about decking the block, I had decked my block when I built it but that was just to make sure it was a true 90 deg "V". That is one way to inrcease comp ratio when using larger chambered heads. But I believe he already has the Vortec heads at 64cc, so decking would be bad but using a thicker head gasket may get him to the desired comp ratio if he does not find the pistons to match what he needs! Thanks. John

On the q-jet, rochester only made 750 and 800 cfm as far as I know. (there is a 850 cfm edelbrock one, but it would be a bit big, and costs about $550). A stock 350 came with a 750 cfm q-jet.