Gary's V8 (350, 383) building thread

[1Gary]

Over 100 dyno'ed 350/383 engine combo's in this link:

http://www.ryanscarpage.50megs.com/combos1.html

Submitted for the links section also,but wanted to share with all of you so you didn't miss it.

[reaper]

Thanks for the link.
But what is with all the god stuff?

[1Gary]

Honestly I can't answer that.Just thought the info over rode that part of it in the link.

[JaxSPL]

I want combo 93 in my '89 astro.

[1Gary]

I want combo 93 in my '89 astro.

Check out combo 11.Thing is it has a lower compression ratio and still is pretty happening for a output and because of the lower compression would be more acceptable to the pump gas that is out there.One of the things I would change would be a hydro roller cam and a TBI.The cam would be that same one Lockdoc put in one of his vans.Nice part is the low RPM for torque output.You could mod a TBI to get very close to 600CFM,so with the roller cam,I would expect even more performance out of this combo.

If you take the formula for how big a intake runner should be the 195cc's are just about right for a 383.The expamle is .5 x 383 or .5 x the size of the engine.

[Mr_Roboto]

218/223 is a tiny cam for that engine. If I was going to go smaller I wouldn't do the Ramjet cam (the HT383 uses the same cam btw, if you want #s with a 383) If you look at a set of heads like the AFR195s you're talking a hell of a lot of head even with 383CID. http://www.competitionproducts.com/Elgi ... nfo/E1136/ This Elgin cam looks very nice for such and engine without getting something a bit more expensive. The other option would be a ZZ3/4 cam which is pretty stout (208/221 or thereabouts if I remember correctly) and would make a great nitrous/blower grind too because of the added exhaust duration.

[1Gary]

I am looking at how the CR,wt of the van,final gear ratio,size of the engine,size of the tires,type of induction system,what the heads and size of the intake runner and intake valve size,all relate to which cam to get.The "383" GM cam has a lobe center @ 109 which means it has a lower torque curve.I do kind of like that.

[1Gary]

While I consider building a 383 for Ole Yellar,one of the thing that I need to think about is if you have to buy a rotating assemble the is internally balanced because the externally balanced 383 needs to use a 400 flexplate.

The question is does the 400 flexplate bolt to our 700R torque converters??. And if not,I would guess the one pc seal internally balanced rotating assembles costs lots more.

Thank You for your input in advance.

[Mr_Roboto]

JMO on this get an aftermarket one. If you are using a 1 piece rear main crank you will have no choice actually because they never made a 400 crank like this. I would be buying a rotating assembly that included one if it was me. That way you're sure everything matches. It also ensures you don't get something bent/cracked/whatever. Mine was horribly cracked when I pulled it off the 4.3L.

[Rebel]

Gary..you may want to check out Skip's prices in Kingsport, Tn. I've bought several things from him in the past and you can't beat their service. Prices on some items are very good.

http://www.skipwhiteperformance.com/

I bought one of the other 65,000 volt dist. but check this out and the price.

http://www.skipwhiteperformance.com/det ... em=6500-CL

[1Gary]

Has anyone done a deep sump one pc rear seal oil pan in a Astro??.

The one one my 5.7 is really kind of beat up and I am going to want to replace it.

[1Gary]

Found this link about basic FAQ's about 383's.Hope it helps someone.

The 383 chevy is one of the most powerful engines you can build. It is also the source of many questions and a lot of confusion. This is a basic 383 information page. The info is specifically about the properties and special conditions they may require in there buildups.

What is a 383 and what do I need to build one?
A 383 is a 350 production block with a 400 production crank. The crank has some special machine work done, namely the main journals of the 400 are 2.65" and the 350's are 2.45" so they must be turned down by .200" to make the STD. 350 main bearing size. Since the 400 is externally balanced you will need a balancer and flywheel/flexplate for a 400 CID chevy motor.

Do I need special pistons?
Yes and no. The added stroke of the engine would push the piston out of the bore by .125" if you used stock 350 pistons and rods. If you run stock 350 pistons and 400 style rods you can get away without special pistons but The skirts may also hit the counterweights since the 400 crank has larger weights and is longer from the centerline outward. If you go this route you need to pay close attention to crank to piston skirt clearance.

What's with this rod thing?
The 400 uses a 5.56" long connecting rod. All other small block chevy's use a 5.7" rod. The reason for the shorter rod is GM decided not to raise the piston pin higher so they shorted the rod the appropriate length to prevent the piston from popping out. 383's can have many different rod lengths but the first ones used stock 400 rods and stock 350 pistons with relieved skirts before custom pistons were available.

Which rod is better and why?
The longer rods are better than shorter ones. For a full explanation see the rod FAQ


Will longer rods cost more or require special work?
Yes and Yes!! The longer rods themselves don't cost more but the pistons you need will raise in price. The pistons will have higher piston pin heights and will have rings higher up on the piston. In cases where a non stock rod of 6.00" or longer the pin will actually intersect with the oil ring. These will require support rails for the ring. The longer rods will also make cam to rod clearance an issue. Special grinding or clearancing of the rod bolt shoulder will be required and/or a reduced base circle camshaft will be required.

What will the block require?
The block will need to be notched in the oil pan area. The longer stroke crank will need deeper notches to clear the counter weights and rod throws.

Should I balance the motor?
Yes!!!!! Any time you change geometry from stock a balance job is neccessary. That is if you want it to live! The pistons and rods are lighter than stock 400 versions and there is too much counterweight. This will make for a lot of vibrations and that is bad for a motor.

What kind of heads do I need?
Any kind you want. A 383 takes the same cylinder heads as a 350. The 383 does like larger heads and big valves but it is not mandatory to have 2.02/1.60 valves and huge intake runners.

Do I need steam holes in these heads?
No! A 383 uses a 350 block and it has no provisions for steam holes. It also cools like a 350 so only minor cooling system upgrades are neccessary.

What is the cost of this kind of buildup?
This is a tricky question and probably the most asked one! A 383 can be very pricey. The crank will cost a pretty penny to find a used one. There are several aftermarket companies selling '383' cranks that don't require any work so said. A crank can cost anywhere from 250 to over 1800$ depending on the kind and quality of the crank you buy. Pistons also fall into this wildly ranging category. You can spend 150 on cheap cast pistons or over 500 on light forged units. The balance job can cost from 120 to 240 depending on the shop, kind of balance job and the area you live in. Block work is not too bad. The only extra is the notching and that can be from 100-175 for the work. The rods are also another area of wide variety. You can get stock reworked 400 rods with ARP bolts for 100$ and you can order the 700$ sportsman rods and so on. If you order aftermarket rods that are profiled for stroker motors you will save yourself the grinding of the rods and/or the reduced base circle cam. If you get stock rods or non profiled rods you will either have to grind them yourself or pay your shop 50-100$ for this. You will also need to do this before the motor is balanced!!! I have built them for around 1600 and as much as 10,000 so far so do some leg work and pricing!

How much power will the stock 400 crank handle?
I have used a prepped 400 crank to 700+HP I have used basically stock cranks to over 550 HP so a stock nodular iron crank is fine for most buildups. The crank is strong because of the beefier construction of the crank.

What is the red line on these motors?
The red line varies from motor to motor depending on the parts installed and work done etc... A basic short rod 383 will live to 5500 and a 5.7" rod motor will go to 6500. Motors with forged internals and special work done can of course go higher. As a basic rule of thumb you can go 1000 RPM per 10PSI of oil pressure. If you have 70 PSI you can make 6000 with a 10 PSI safety margin. This rule will affect every kind of motor. It's kinda of an either/or here. You can go as high as your oil pressure permits or the internal parts permit whichever is lower!

What size cam will I need?
Probably the second most asked question is cam sizing. This is another tricky thing to pick. Since ever single aspect of the engine and vehicle it's installed in will affect this I will just give another rule of thumb. 99% of rated ranges on products are based on the 350. If you have built a 383 you can add 10 degrees of duration to the motor and get very similar characteristics. For example; A 350 would probably have a moderate to rough idle with a 224 duration cam, measured @ .050 lift. The 383 will take a 234 duration cam to make almost the same idle and vacuum as the 350. These motors also like to breath so larger duration longer lift cams work well in them. Don't overcam! Just because you have a bigger engine don't go stuff the largest cam you can find into it. Most street engines use less than 234 degrees of duration @ .050! The motor is bigger so it will make more power with less cam so a 383 with a 214 cam will make more than a 220 duration cam 350 if all else was the same.

What intake and manifold should I use?
Intake should be a high rise aluminum and a moderate carb. The 383 likes to breath so a bigger intake manifold like the RPM or Stealth would be a better choice but the performer and action + manifolds will work. Carb also depends on application but on the street under 6000 RPM you could get away with a 650! A 750 would make more power but is the largest you should go unless you are all out racing!

Are there any special things I need to pay attention to when assembling the motor?
Yes you must check cam to rod clearance and block to rod clearance. Both should be .050" minimum! All other specks will be the same as a 350 or whatever the manufacture specifies.

Should I run a high volume oil pump?
Only if you have a deep extra capacity oil pan. I personally do not like or condone high volume oil pumps on any engine. A stock oil pan will be sucked dry by a high volume pump @ 4500 RPM under hard acceleration. I have rebuilt more than a few motors that burnt up this way.

[rlsllc]

The one thing I didn't see was why.

Can someone please explain to me what makes the 383 better, and I don't want to hear cooling issues, because I've seen many 400 motors (even a .060 over one) that cool just fine with the right radiator, thermostat, etc. I'm assuming the power output numbers or power band, area under the curve, etc is better, but havent seen numbers.

You can build a 400 without any special work. You can build a 427 small block with some extra work, and lose the 5.56" rod in the process if you choose. Very similar to a 383 build using an aftermaket rotating assembly, only with a 400 block.

Most of us would be using an aftermarket crank anyway, since one-peice-seal engines are so common, and for that matter, original 400 cranks are getting rare.

Not hate'n, just curious, and have been for some time. I will admit that when I rebuild the LT1 in my Monte Carlo, I plan to go 383, but only since the LT1 block is different.

Try'n to learn something here....

[Mr_Roboto]

The one thing I didn't see was why.

Can someone please explain to me what makes the 383 better, and I don't want to hear cooling issues, because I've seen many 400 motors (even a .060 over one) that cool just fine with the right radiator, thermostat, etc. I'm assuming the power output numbers or power band, area under the curve, etc is better, but havent seen numbers.

You can build a 400 without any special work. You can build a 427 small block with some extra work, and lose the 5.56" rod in the process if you choose. Very similar to a 383 build using an aftermaket rotating assembly, only with a 400 block.

Most of us would be using an aftermarket crank anyway, since one-peice-seal engines are so common, and for that matter, original 400 cranks are getting rare.

Not hate'n, just curious, and have been for some time. I will admit that when I rebuild the LT1 in my Monte Carlo, I plan to go 383, but only since the LT1 block is different.

Try'n to learn something here....

400 blocks are getting pretty rare is a big part of it, and they have always been perceived as a "weak" block which there is a large element of truth to. 4 bolt blocks are known for cracking in the webbing so most people run 2 bolts. They also have a rep for overheating as mentioned by you (steam holes) and they also have a weaker deck surface than a similar 350. I have seen the slips for a production block with a turbo that ran 5.65 in the 8th mile in a 3500lb cutlass so they can be made to run very fast. Then again he was also filling his coolant tank every pass too from the heads lifting even though he had deck plugs and it was done with boost. It's definitely not a feat I would want to attempt naturally aspirated with a production block due to the RPMs required.

They also never made them with 1 piece rear mains or factory roller blocks either. That being said factory roller blocks are weaker than the standard 350 blocks too from what my understanding is. Not that most people really need more than a 2 bolt cast rotating assembly engine especially if they don't intend on hitting it with any nitrous or boost. no matter what they think.

The 400 has the advantage of more CID (duh) and less valve shrouding. Then again you don't really see the Ford guys complaining when they do stuff like cram a 4" stroke crank (408W) into a block or the LSX guys doing something similar. There are actually advantages to a slightly smaller bore for a given CID namely detonation resistance, emissions and cylinder filling (Even if the valve is shrouded, for every degree of crank rotation you wind up with a larger peak piston speed.) Supposedly a 377 (350 crank/400 block) works very very well provided you're not afraid to rev the piss out of it.

An LT1 383 would be a lot of fun, not really a fan of the ignition system like most people out there though. Regardless of that it should make great power when you're done with it. Just be sure some head work and a nice cam are thrown in to it too.

[astrozam]

Gary, since you mentioned that this info comes from a link you had, could you include the link to the source of this info, please/thanks ?