Decided to start building a 383. Hoping to pick up a short block 350 with um.... nothing in it. Only want the block. Figured Id get a summit 383 kit. What do you guys suggest. Want to get the block ready. Fit it with some clevite 77's while saving for the kit. Will port the hell out of some alluminum l98 vette heads and match the lower TPI intake with some SlP runners and 58mm TB. Maybe an electric water pump? I don't really know where to start here. Reason for stock heads is budget. But I'll have em' milled and a 3 angel valve job done.

 

I haven't built anything smaller than 383 cubes for my own rides in over 5 years. The torque increase is WELL worth the effort. Used with a torqey TPI intake setup it will make almost big-block torque.

Pass on the 58mm TB. 52 is plenty big for even the most radical TPI, in my experience. NEVER buy a Holley TB, BTW. They are crap. I won't go into details unless you want them but they have serious problems. Of the sort you'd expect if someone designed it but never acutally tired to install it on and engine before they put it on the market. Other end of the spectrum for that is SLP throttle bodies. They are a true bolt-on with NO drawback issues. Pricey, but you won't have to second guess them.

 

get a newer style block with the one piece rear main.
if you want stronger get a truck block they are 4 bolt mains.
i am just using my stock 2 bolt block.
the internals should be balanced(probably already balanced)
get forged pistons just cause they are in there and dont cheap out on anything you will regret it if you do.

obviously get the block cleaned and bored at a well known shop.
make sure the shop is spotless then you know how clean their equipment is.
hope this helps

 

Everything I have seen about the Corvette L98 aluminum heads says the only thing they have going for them is the fact they are aluminum. You can try to port them, but beware GM's stock aluminum castings can be quite thin in areas.

I have a friend that built up an almost identical combo that you are talking about and put it into his 86 'roc. In fact, he went as far as to have 2.02 / 1.60 valves installed into his alum L98 heads. Even with all the mods he had done, it still couldn't break into the 12's. Perhaps if he could have gotten all of that torque to the ground, it could have been a different story. My 350 still pulled him on the big end.

IMHO, you would be better off saving your money and not getting a "cheap" 383 kit. The money would be better spent on AFR heads and a 350 rebuild. It will probably last longer too.

 

<<<IMHO, you would be better off saving your money and not getting a "cheap" 383 kit. The money would be better spent on AFR heads and a 350 rebuild. It will probably last longer too.>>>


dido...

 

Duely noted. They only problem I'm having is I don't understand head flow numbers, and cam spec's. That's what I really need is a set of bad *** heads, cam, and some more compression. I did just rebuild my bottom end with new crank rods and keith black flat top pistions. Also, the block is a 1 piece seal.

 

stk350, you really can't make your cylinder head choice by air flow numbers alone. If this were true, all out race heads would be the best thing you could put on a street engine. This is simply not true. Flow benches are NOT the same as engines and there are many other factors that flow benches can't measure that have an effect on how the engine runs. The flow numbers are not worthless, however, but should be used as a reference only.

The BEST way of judging cylinder heads is a comparo that is done on the same engine on a dyno. This is the most accurate way of measuring the total performance package. From what I have seen, the AFR 190/195's are arguably the best heads you can get for a street 350 or 383. Anything bigger, and you are going to lose low end power and drivablility.

According to my research, anyone that wishes to build an engine destined for street, street/strip duty is better off going with a really good set of heads like the AFR's and then selecting a cam that suits their driving needs. The nice thing here is that with the AFR's, you can run a smaller cam and still get the same performance benefits as you would with inferior heads and bigger cam but an added bonus would be that the engine would have superior drivability and get better gas milage undoubtedly.

In other words, I have TFS Twisted Wedge G1 heads on my GTA and a Comp 224/230 hyd. roller cam. While it runs ok, a similar engine with AFR heads and a 218/224 hyd roller cam would probably walk away from my car and idle better too.

 

So.... a set of $1,250.00 195cc AFR heads and a mild cam. Something along the lines a little over stock? Cool. Thanks fopr the reply Madmax350. It's posts like that that actually help people with their projects. If you don't mind. I just rebuilt my bottom end about 5,000 miles ago. Would I need to refresh? I'm planning on building a motor. Balanced blah blah blah..... Or will my bottom end benifit from another rebuild at all?

 

dido to what MadMax350 said too

if you do what mad sujested i wouldn't balance it and with a small cam you won't need to spin the motor very high(5k+) .

i have arp rod bolts, and spin my motor to 6k+ offton and is not balanced. Have been doing this for three years now and it's still togeather

 

there is absolutely nothing wrong with a good balance job, especially if you are changing components in the engine from their factory configuration. It is true that a balance job is not totally essential, but an unbalanced engine might not last as long and can cost you power, believe it or not. It is definately worth the $150-200 for the balance.

Your cam selection should be made with your vehicle application and driving habits in mind. I can tell you that I have had very good luck with the LT4 hotcam in just about every application involving not only the LT1, but the 350 TPI engine as well. It offers good idle quality and a good power band and would definately perform well with AFR heads. I would not go with anything much bigger than the hotcam in a 3500 lb street driven car using a stock torque converter and near stock gears. Again, this all depends what you want out of it.

 

I personally would look at other heads. If you have 383 ci you can run bigger runners than the AFR 190-195s and not be hurting for torque. Go with some 200-210 cc runners on some iron (budget) world castings and go with the stealth ram intake and you will make more power. The limitation of the iron casting will be weight and 1 point in compression which will be a 4% loss of power but the are a lot cheaper and it will fly. Your money will be better spent on the intake anyhow.

 

I agree, at least with the intake point, that is assuming the SteathRam will fit under your hood.

Again, heads sporting 210+ cc intake runners might be a bit much for the street. If you are not building a hi-dollar 383 that is capable of revving past 5500 on a regular basis, I would either stay away from the SteathRam or the 210+cc heads. I would not recommened doing both on a street 383 that is not built to rev.

Cast Iron heads are ok but you will have issues when it comes to compression ratio and timing. It has been well documented that most iron heads cannot take the timing and compression ratio that most aluminum heads can. Of course, this is all subject to speculation and combustion chamber design.

 

[QOUTE]
I agree, at least with the intake point, that is assuming the SteathRam will fit under your hood.

Again, heads sporting 210+ cc intake runners might be a bit much for the street. If you are not building a hi-dollar 383 that is capable of revving past 5500 on a regular basis, I would either stay away from the SteathRam or the 210+cc heads. I would not recommened doing both on a street 383 that is not built to rev.

Cast Iron heads are ok but you will have issues when it comes to compression ratio and timing. It has been well documented that most iron heads cannot take the timing and compression ratio that most aluminum heads can. Of course, this is all subject to speculation and combustion chamber design.[QOUTE]


I see your point on the rev issue, however, if you run good heads and a TPI intake that thing will be out of breath at 4000RPM. Hell my 350 L98 is out of breath at 4500 so with the additional CID of a 383 it is going to be out of air that much faster. If the stock intake is kept you may as well keep the L98 heads and have a torque motor. The heads will not do jack by themselves.
Also I don't see any reason why you can't rev to 6000 RPM on a balanced 383 with proper bearing clearance. The iron heads were simply to keep cost down, and as I mentioned a loss of power of 4% due to being a point down on compression would be noticed. But as you mentioned the combustion chamber design plays a big role too. My 98 F-150 pickup is 9 to 1 CR with aluminum heads and I have to run premium in it to avoid detination so it's not just aluminum versus iron.
The Stealth ram will fit since it is a Camaro.

 

insomniac, you are correct pertaining to the 383's airflow requirements. However, I have tried putting good heads like the Vortec and Trick Flow heads under a stock TPI intake and you will gain some top end power, although, it will not be as pronounced as with better intakes. I build up an 88 Formula about 4 years ago that sported L31 Vortec heads that were drilled and tapped to interface with the bone stock TPI intake that the car originally had. With the LT4 hotcam, that 350 engine pulled hard until about 5500 rpm, again, using the stock TPI intake.

I never said a balanced 383 wouldn't be capable of 6000rpms but a cheap 383 kit will most likely not last long if you are revving it that high on a daily basis. I am sure that a lot of money can be poured into a "cheap" 383 kit that will allow it to do this, but it is not going to last 75,000 miles without a lot of forged parts.

About the detonation issue, as I said, this all depends on combustion chamber design. Because you are talking about Ford, who knows what kind of combustion chamber design they use on their trucks let alone the timing curves and knock retard strategies that they have built into their computers. I can tell you right now that I have seen many cars of all makes with 8.5:1 compression or less that have gross detonation problems because of just carbon buildup alone, which is not entirely removed by beating on it nor by using some mechanic-in-a-can additive.