I'd like to perk up as in a mild build up. Budget is about $1,000 my stock L48 in my 78. I have a couple questions.

Vortec heads : which rockers 1.6 or 1.5 roller tip or standard?
Push Rods: Do I need new resized ones or do I have to drill, cut or chop anything on the heads??
Rockers: Self aligning or guide plates?
Edelbrock performer vortec intake: Will it fit with standard air cleaner and Qjet?

Do all the accessory holes line up with the vortec heads including A/C?

Thanks in advance!

 

Vortex heads require and different intake that may not have provisions for the stock AC and alternator.
Aftermarket aluminum heads have come down in price and they are pretty much bolt on's ! Add a set of 1:6 rockets and you have a good street runner.

 

If your changing the heads then yes it's likely you'll need different push rod lengths. Rocker geometry will dictate if you need them or not. You want the sweep of the rocker centered on the valve stem.
I used the roller tip rockers on my 350, 1.6 ratio self centering to eliminate the guide plates.
With the 1.6 ratio on vortec heads make sure you don't exceed maximum lift of the valve. I know it's restricted to something like .420" of lift stock. In fact using 1.6's may be no gain at all unless you get the heads modified to accept greater than .420" of lift.
If you can get the performer intake spread bore for a vortec then carb and air cleaner should fit fine.
Don't know about accessory holes. I would assume that it is standard if the heads have holes to start with.
check this article out.

http://www.chevyhiperformance.com/te...ds_valve_lift/

 

So here is the deal. I'm not messing with the cam. I know I can improve performance quite a bit by changing out the cam but I just don't want to completely take the the front end apart. So that's why I thought by putting 1.6 rockers it would accentuate the stock cam (I may be wrong). So I believe with a stock cam and 1.6 rockers I really shouldn't have to worry about too much lift and springs and such (Again I may wrong) thats why I'm asking.

 

go with a L82 intake, reuse the carb(maybe re-jet it, ask lairs) that way it will fit under the hood. change heads and maybe the cam, headers, larger exhaust (duals). This probably over your budget.

 

Ok, so you're changing the heads but not the cam, got it. Why vortec heads? If more valve lift is what you want the 1.6 vs 1.5 on the same cam will make little difference. Some yes, but not worth the effort of changing heads and not the cam IMO. Those heads are going to limit your lift without mods. Without changing the cam I'm not sure how much gain you'll see. Although getting a smaller chamber with the vortecs (ie 64cc) should help some.
There are some guys who have vortec heads and maybe they can chime in to let you know.

 

Basically to increase compression ratio thus theoretically more power. The Summit heads are already clearanced. Total bill just ordered with valve covers, rockers, heads, bolts, gasket's, intake = $1,146

Car already has long tube headers and true 2-1/4 duals. Next will be 100 shot of juice and I think it will give me what I'm looking for.

 

Consider advancing the cam 4 degrees, you want to at least check timing chain play by pulling off the timing cover.

 

There's little or no gain in a compression ratio change - just a few percent at most. When combined with other changes there are be more advantage...but chasing just CR isn't going to build power.


You'll see some improvement from the Vortec heads with the stock cam, and some minor improvements from the higher rocker ratio. Essentially the increase in rocker ratio gives a mild (multiply by 1.067) increase in lift and a slight effective (not actual) increase in duration as the valve opens faster and so remains open further, longer. Make sure the rockers are self-aligning, and consider using a thinner head gasket - especially if you find your stock pistons .020+ down in the hole - and pick up a little CR as well, but most importantly - far better quench.


You're leaving a fair bit of power on the table by not using a more aggressive cam profile - Vortec flow numbers are best in the midrange, and this is where a roller or near-roller profile really pays off.

 

Hello Mick,

Have you done a compression/ leak down test? If not this would be a great place to start, lets you know your not spending good money for not.
If so, rocker ratio would depend on what cam you were planing to run, with vortec heads id assume the cam would be mild enough to run 1.6, which would give a little more lift but you could run into the max lift of the vortec head, which would also bring me to have you bought the heads yet, sdpc hasvortecs that have been modified to accept higher lifts and would be the way to go even if you dont plan at this time to run that large of a cam shaft, dont paint your self into a corner. Pushrod length will need to be determined after youve installed the heads and new push rods will need to be bought.
Im not sure about the rocker style.
You can use the stock carb with the performer, but i dont think the stock cleaner will fit with out modification, some run into hood clearence issues.

I went the whole route of leaving the stock cam and changing the heads with 1.6 rockers, ended up changing the cam later. If you dont change the cam now and decide to do it later it turns out to be more work then, half the work is done when you change the intake, changing the cam is easy and would benefit the combo greatly, flat tappet cams dont cost much either, roller is the better way to go, but some times a flat tappet is all the budget allows.

 

Thanks for all the input very valuable information.

I know everyone keeps telling me to replace the cam. But to be honest if I go to the trouble of radiator, pulley, balancer, timing chain, shroud removal and all the other PIA stuff I'd be better off just yanking the motor and replacing.

So that leaves me with what I am doing. If it doesn't work, oh well I've wasted more money on other stupid things in my life. I'm just not interested in an 8-10 hour project vs. a 2-3 hour one.

From what I've read on other forums it should give a definite improvement 30% better flow numbers intake and exhaust, slightly bigger valves and there has to be a CR increase going from 76cc heads to 67 cc and a little mechanical advantage to my cam.

I'll keep you posted should be done this weekend.

All in all

 

It's not that much more work to change the cam.Worst part is getting the shroud out.After that it's pretty easy.No need to remove the hood.I did heads & ,retro roller cam swap on my L48.You'll be surprised how much difference a roller cam can make.Here's the write up:
http://forums.corvetteforum.com/c3-t...-cam-swap.html

Cost is a factor for sure but it's well worth it.

 

Either way you wont be wasting money, the vortec heads out flow the 882 by miles. I'd figure that it will take longer than 2 to 3 hours, but I might just be slow. If your not replacing the cam, 1.6 rockers added noticeable difference, but the cam swap added a lot. The gain from the compression would be 3% gain for 1 point of added compression. The added compression would allow for more camshaft duration later on.

 

Both of these really depend on the build level of the engine...sometimes the gains for a CR increase are precisely nothing for a mild engine, and the static/dynamic compression ratio thing is more suited to a racing engine than a street engine...unless you're making >= 1.4 HP/CID.

 

Nice Job! Well done.

 

Your L48 cam is the old 929 cam with 195-202 Dur. at. 050 around .390-.400 lift and was used in many small blocks since the 60's. I think you will find that a cam change would be a lot of bang for your buck even though you do not want to tackle that project right now. As stated, you will have much of the engine apart doing the head change and pulling the front engine parts to install the cam to me is easier than doing the head change with all the lifting of those heavy a$$ heads. I did a cam swap on my carbed 84 which had the worst of the worst 624 heads and I used a pretty mild 218-218 @ .050 .450 lift old school crane cam and the difference in power was amazing even with the restrictive heads. Later I installed a set of Summit/Dart cast iron large valve 72cc modern chamber heads. They have ..525 lift springs, screw in studs and were $630 shipped to my door. Even more power with heads for sure. I have no experience vortec heads but have read they are good to about .470 lift. Just some more food for thought. Good luck with your project.

 

If your going that far change the cam and timing set. The stock cam timing gear has nylon coated teeth. 90% of the Chevrolet cams I have replaced with stock timing sets had nylon teeth either missing, broken or cracked and/or excessive chain play. These would run over 100,000 miles when new if it was in the first 10 years. The nylon breaks down with age. heat, exposure to oil. These are all 30-40+ yeas old now. Timing chain failure can take out your engine.
http://forums.corvetteforum.com/c3-t...ming-gear.html

 

would some dart iron heads flow better then the vortec heads ?they would use stock gm rockers and push rods.you can find used performer intakes for $100 .a heads swap mite take more then 3 hrs .

 

Lasted best value is EQ heads - most bang for the buck - need to google this for yourself. New to me also but the IMCA guys buy'm. And they sell a street version. Take a look:https://parts.aamidwest.com/IW_Produ...TI_ITEM_SUBMIT

cardo0

 

The stock push rods might or might not be reusable depending on length needed for proper geometry. He's already bought the vortecs.