86T/AWS6

Hey guys, Im asking this question for my Dad...

He has a GM ZZ383 with fast burn heads in a 74 camaro Type LT.

The heads were factory assembled and the cam that comes in this 425hp engine is the GM 846 (222/230@.050), and im not sure on the vavle spring specs.

Anyway, he is wasting alot of bottom end with the 9" 3000 stall converter in the TH350 and he wants to move the powerband up with a bigger cam and spin it higher and obviously pick up more HP since in our opinion the motor is under cammed.

He isnt sure of a specific cam yet, probably in the cc306 to GM 847 range, but is worried about needing a hydra rev to spin it to 6500 or 7K. He doesnt want to have the spring seats machined either so would prolly be sticking to a single spring.

Whats a good valve spring for street/strip use that wont fatigue and reliably control the valves to 7K with a max lift of .600". I was suggesting behives but im no expert. The bottom end should be able to take it with a balanced forged crank and rods with hyper pistons.

Also with the fast burn heads, whats a good step in cam you guys would suggest. I think they are an awesome head and prolly flow well enough for up to 240's in duration.

Rice Killer87

Beehives are going to be the only single spring that will hold up to that lift/RPM range...your just going to have to find out if they make them in a diameter that will fit the heads your using.

Ive never used beehives myself,so if it was me I wouldnt have any problem pulling the heads off and having them machined for bigger springs and not half assing it.

86T/AWS6

to be honest im not even sure what the valve seat size is on the head, being that they are a designated GM performance head they may be a a big enough seat for better springs...not sure...just lookin for good opinion from the big engine guys on this board...you guys know who your are

1989TransAm

He needs to discuss this with a cam company or a custom cam grinder. They will tell him what springs he needs to go with the cam. That said beehives are a good way to go.

WS6T3RROR

Beehives will fit fine, you may need to go to +.050" locks and run nsa rocker arms with guideplates. It really depends on what the installed height of the spring is (valve length) and what you plan to run it with. The crane springs 99893-16 will control the cam in the motor to 6500+rpm and will also work with the 847. These are the springs that come in the crane spring kit for aluminum headed lt1's.

I cant make any other suggestions unless I know more about the engine (intake headers gears etc), and what exactly is going on with it that you dont like. What exactly are you wanting it to do.

86T/AWS6

more specs on the motor:

zz383 short block
GM fast burn heads, 205cc, 9.8:1 comp i think
Edelbrock RPM air gap dual plane intake
Holly 750cfm with vac secondaries
Hooker long tubes, jet hotted

TH350, 9" 3000 stall converter

8.5" 10 bolt with 3.73's

Mainly the motor makes power off idle to about 6000 and flattens...the converter is like a true 3000 stall before the car moves, so all that power under the 3000rpm stall is being wasted. Lookin for a cam that starts coming into the power band around 2500-3000 and that wont flatten out till 6500-7000. Basically just want to move the powerband farther up in the RPMs and spin it higher. Plus after seeing other 383 crate engines with less head make close to 500hp with a bigger cam he wants to step it up and maybe get up over 500hp, from the 425hp/465tq its rated at now.

WS6T3RROR

Whats the primary size of the headers, pipes and what mufflers are behind it. Do you have any kind of vacuum readings of the motor when its at 6000 rpm? How tall are the rear tires and how heavy is the car?

rskrause

You need to pick a cam before you can pick springs. Most factory small block heads were equipped with fairly small diameter springs - 1.200-1.300". Consequently, there is a variety of springs made in that diameter. Crane has quite a few. If the heads are aluminum, it's an easy DIY to machine the seats for a larger diameter springs. If it's an iron head, take it to a machine shop if a bigger spring is needed.

Rich

86T/AWS6

The Headers are 1 3/4" primaries, 3" collecters, 2 1/2" duals with an X pipe, feeding into 2, 2 1/2" Flowmaster 50 series mufflers...full length exhaust

Car weighs about 3400 without driver

and the tires are BFG radial T/A's, 245/60/15...which i think is about a 26" diameter.

Sorry, no vacuum readings on the motor at RPM

WS6T3RROR

I dont care for the mufflers and would suggest a switch to magnaflow stuff, get the ones with the 18" case if you want it quiet. I would also switch the intake over to a larger single plane from the rpm intake. I would say the 847 would be a good upgrade for you but I wouldnt go any bigger until I was ready to pull the heads off and have them ported, 1.6 rockers would also give you a little boost in hp. The fastburn heads imo are a bottleneck at around the 450hp level without some porting. For springs go with the crane ones I suggested earlier they are what crane recommends for use with the 847.

The wot vacuum reading was just to get an idea on if your carb is going to support the airflow required at higher hp/rpm.

86T/AWS6

Its gonna be tough to get him to switch the mufflers, remember this isnt my car lol. He likes the smooth almost indy car sound to it with that exhaust setup.

He tried the Single plane intake at first, and would prefer it but with the low profile of the stock 2nd gen hood he cant find an air cleaner to fir under it. Actually the carb barely fits with the single plane.

Ill pass on the info on the 847 and the crane springs, thank you much for that. As for the heads, i doubt ill be able to convince him to have them ported so they will prolly be left alone. Plus there isnt any very reputable porters close to our area that i know about.

Again, thanks for your help

WS6T3RROR

It only costs about $45 to send em anywhere in the us by ground. Porting the heads is the last step you need to get it up over 500hp. Until then you're just not going to gain a whole lot by going any larger with the cam, its choked now. With the right heads I have gotten over 500hp with the cam you already have.

Have him check the vacuum at high speed sometime, if its over 1.5" you can make gains with a bigger carb.

When he wants more hp later mention the mufflers to him. They sound just as good or better than the flows.

86T/AWS6

Considering the cc306 and the 847 are relatively old lobe designs, are there any of the new lobes that you would say is better? I know comp has a bunch of newer lobes, even newer than the Xtreme 224/230 i have in my car.

Ill tell him about that vacuum test next time he is out beatin on it.

again thanks alot, its appreciated

Rice Killer87

Absolutely.

Get him to call Comp or any cam company and get them to reccomend some cams which will have corresponding springs.

He can even go to www.compcams.com and download their camshaft software where you type in all your motor specs and the type of lifters you want etc. and it gives you several different cams to choose from. Pretty neat,I had it for a little while but deleted it since then.

WS6T3RROR

I cannot express how disenchanted I am with comp cams. Thier lobe designs and engineering are second to none, but thier execution and quality control are horrific. Busted springs, pressures all over the place, surface hardening that breaks through on cams, cast core roller cams, and made offshore by the cheapest bidder. Thats for somebody else.

The 846/847 may be "old tech" but i have made more hp with them since they can atually be reved up to 6700+rpm without valve crash using "old school" dual valve springs. At the same time, ignore the advertised durations and look at the lift offered for the duration against even some of the new comp stuff. The new comp stuff is going to have better duration at .200 than the older gm847 (crane) but then again most people dont get that far into analysis. The new xfi lift numbers are with 1.6 rockers so make sure you're comparing apples to apples; ie lift is stated with the same rocker ratio.

If you must have some of the newer stuff I would look at lunati's voodoo line. I have had excellent luck with them in bb mopar and bbc stuff, and recently a couple of SR sbc street engines. Excellent power drivability and quality. The voodoo lobes and cams were designed recently by Harold Brookshire who did the xe designs when they came out as well. You might even look Harold up and he would set you up with something that would work well for you. He may be hard to get ahold of though havent seen him around lately.

The most aggressive cam in the world wont make hp if it goes into valve crash before you hit max rpm.