Head knowledge needed

[screamin_eagle]

take a look at the #4 intake factory cast heads completely redone ported and larger valves. factory valve springs shouldn't they have held up to an rv cam? anyway what are some good springs to go with?

[PrinsGMC]

I would go with z-28 springs, they are rather inexpensive and can definately hold there own. Your headwork sound about what I did on my corvette and I used Z-28 springs.

[Sport/Truck]

Your cam company should recommend a spring for the cam you are using.

[screamin_eagle]

the cam is manufactured by general motors. Now that i think of it 350 four bolt bored 30 over forged flat tops and the heads I mentioned what cam would be best for the most power?

[chevydog66]

Cam choice would also depend on carb and intake as well.

[RACINJASON22]

we need more info. What you have and What your after performance wise

[screamin_eagle]

I've got an edelbrock performer intake no carb except about twenty quadra junks in various arangements. I'm thinking there has got to be a proven set up of some sort. I have nothing installed on the top half of the engine so at this point anything goes.

[screamin_eagle]

350 four bolt fresh from the machince shop bored 30 over forged flat top pistons nitrous safe rings. I want this damn thing to scream and not chuck valve springs or anything else.

[RACINJASON22]

Comp-Cams 268h real good choice. get a kit with springs and lifters and there you go. you can opt for a rebuild of one of your Q-Jet's or go 600 but not over 650 aftermarket edl,holley ect. It still depends how you are gonna drive your truck you don't want to build for all kinds of top end then expect to have a daily driver freindly truck.

[Robznob11]

well im kinda confused, how come you have all this major head work like porting and larger valves but your running cheap springs and you don't even have roller rockers, makes me wonder if some one or machiene shop might have got to you. I hope you know a little about porting becuas from my experiance most machiene shops will take advantage of some one that does not know.. they will generaly will pawn off a set of heads that are hogged out or have been cut a little to much in the short side radius witch will leave you with a head that flows worse than a stock casting, they also will shine up a port real well to make it look good but not really cut them out like they are suppost to be. just for every ones knolage only the exh side should look shiney you want the int side to have a little texture to it, to relly pick a good set up you first need to know like they said what you intend to do with the truck, best bet is to get some flow numbers for your heads and call any cam company and tell them the specs of your motor like intake style hedder size comp ratio and gear ratios also helps to know tire size and weight of truck then they will give you a cam recomendation that will put down the most power in the band you intend to use the truck for, 2500--4000 for a daily driver and 4000 up for a street strip truck, remember if you go big you will need a stall converter and if you run a hi stall on the street you will heat up the tranny in stop and go traffic that means beefing up with coolers or burning them up all the time, so dont over do it you will likley enjoy an medioker cam better than that lopy boy that falls on its face when you punch it good luck and have fun

[basketcase]

Now there is a question you will get as many opinions on as replies. What are the specs of the cam you have now? Also I agree that the Z28 valve spring recommendation. These are the old 302 springs with the part number ending in 142 and a very good basic performance spring for all around use. They were designed to be used with the old 140 service package Z optional cam which was rather radical but they are not so stiff as to cause problems with excessive wear on a street cam.

As with any flat tappet cam with stronger valve springs today you need to use an oil that still has the proper anti wear addatives in it. Modern oil for the current crop of roller cammed and low emisions engines just doesn't do the job on flat tappets. Use Shell Rotella T or Mobile Delvac deisel oil to protect that cam.

Tom

[screamin_eagle]

i bought the engine in this condition has a thousand miles on it maybe. the heads look perfect except for that spring. thanks for the advice all just want this thing ready come summer. the old crate I'm running now is getting tired.

[68C15]

where is Ankeny? in Sioux City is a place called Northern Auto Parts. they sell cheap due to a large volume.
http://northernautoparts.com/
http://www.northernautoparts.com/Pro...tModelId=13787

[RetroSBK]

Never run stock valve springs.... Ever...

Always spring for the extra money to fit a real set...

Why??

OE valve springs will lose 10% seat pressure within 100 miles of being started, 25% within 1000 miles. 25%!!!! The reduction in seat pressure is HUGE! Think of the poor valve, when the cam lobe hits the lifter, the valve BOUNCES off the rocker arm..

Ive watched this on a Spintron, its WILD, and what leads to most of the rocker arm failure you see... reduction is seat pressure

Most OE springs go into coil bind with anything over stock life, so even with stock lift, you cant shim the spring to increase the seat pressure. no room.

Also, one thing to think about... if you have a motor that is assembled, and has sat for a few years, it needs new valve springs. Several of them have been held open, non stop for that entire time, ruining the spring.

I just took a peek on ebay, and you can get a set for $60, including retainers and keepers... I dont know this guy, and cant vouch for him, its just an example...

http://cgi.ebay.com/ebaymotors/600-L...QQcmdZViewItem

60 bucks shouldnt be a stretch! Its only 3 lap dances!!

Will

[basketcase]

Those specs are very close to what I used.

Tom

[RetroSBK]

If you were using stock old valves... welll... cant help you there, if you had new ones... keep reading

While you were building the heads, did you ...

check for coil bind at max lift?

What was the residual lift at max cam lift?

Did you actually CHECK the seat pressure at preloaded height, and what was it?

Check the seat pressure at actual max lift?

What rocker arm ratio did you have?

What was the pushrod length?

check the others for damage?

Was the head broken off at the keeper grove? maybe have the broken piece??


Will