Aluminum heads or full roller valvetrain? - Page 2 - Chevelle Tech
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post #16 of 33 (permalink) Old Apr 20th, 19, 11:34 AM
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Re: Aluminum heads or full roller valvetrain?

Invest in the heads...the entire combo will run better with the same setup plus cut 20-30 pounds.

I've only used AFR's and yes $$, but they have worked wonderfully without issue.

Think Lingenfelter used to say a great heads and small cam will still perform, but a big cam in old heads will be a dog.
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post #17 of 33 (permalink) Old Apr 20th, 19, 1:18 PM
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Re: Aluminum heads or full roller valvetrain?

Quote:
Originally Posted by 427L88 View Post
Kerry, correct me if I am wrong, but you can only give Vortecs so much cam. I would NOT spend the dime on a custom roller setup with limited heads. To wit, you cant get .520 lift out of them, right? therefore : HEADS.
True 427L88, but with a bit more lift, and the right timing events, there can be a lot of power, especially over the single pattern he is running now.

Look what Chris says in this thread, and that power gain is over a cam with a proper intake/exh duration split.

https://www.chevelles.com/forums/13-...m-upgrade.html
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post #18 of 33 (permalink) Old Apr 20th, 19, 1:30 PM
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Re: Aluminum heads or full roller valvetrain?

Quote:
Originally Posted by gnicholson View Post
to be honest i would prob tune what you have 1st have you tried tuning the carb and ignition advance curve? the right flat tappet cam would pick it up some.
^^^^^ This Guy gets it^^^^^ You need to crawl before you scoot on your A$$, then learn to walk then run. Spending time tuning will pay off with Big Rewards. And you will learn a lot about your car & engine combo. I spent one race season just tuning my car. I picked up over 5 tenths and never got into the engine. As asked in a prior question, whats the trap r.p.m.? And as suggested a change to a decent solid lifter cam would be my choice too.

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post #19 of 33 (permalink) Old Apr 20th, 19, 10:08 PM
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Re: Aluminum heads or full roller valvetrain?

Vortecs are better than old stock iron stuff but sometimes people give them way too much credit.
The guys getting good times/#s out of them are sinking lots of $, they arent buying them from summit bolting them on and making lots of power.
If youre open to a vortec intake Afr makes a killer 190 head. Probably out of budget just saying..

Careful about buying cheap budget heads even with a name. Too many out there with junk valves/springs..its just not possible to get a great head for cheap.
If you got to have iron vortecs ck out EQ

I dont think they are worth (gm) sticking larger valves porting etc unless you can diy. Traditional porting methods may have you going backwards on those.

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post #20 of 33 (permalink) Old Apr 21st, 19, 4:00 PM Thread Starter
BH
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Re: Aluminum heads or full roller valvetrain?

Thanks for the input everybody!

The car is consistent. I want to chase more often. I don't *think* it spins. It doesn't feel like it, and I would think I would see it on my time slips.

I believe the converter is around 3300 stall, but I'm not 100% on that. The TH350 has a band delete and a shift kit. I'm not really sure what the trap RPM is but I'm thinking it's up around 5000. Let's do the math!

According to Hoosier, my slicks have an 87.5" circumference, which means that the car travels 87.5" / 4.11 = 21.3" per engine revolution.

103 miles / hour * 1 revolution / 21.3 inches * 12 inches / foot * 5280 foot / mile * 1 hour / 60 minutes = 5100 RPM which sounds about right. I'm pretty sure the shift light (5000 RPM) comes on just before I hit the finish.

For the folks who have suggested shifting higher, I'll give it a shot but I'm skeptical. In the past the car has nosed over after 5000 RPM, particularly in 1st gear. I can shift anywhere from 4000-5000 and it will run basically the same times. If I hold on any longer, it slows down. That's one of the main reasons I'm considering the valvetrain. I don't think I can spin much faster on my hydraulic flat-tappet cam. It does still pull pretty hard in 3rd after the finish line though.

As 427L88 mentioned, I may be limited in the total lift I can go to with the Vortecs. They're advertised as max lift of .475 and I'm already running .480. I'm not sure if they can be machined a bit for some additional clearance. Anybody have any experience with that?

I'm definitely not against leaving the engine alone and working on the suspension, though I'm not really sure where to start in that regard. Shocks? In the back I've got boxed control arms and racing springs, but that's about as far as I've gone in the suspension department.
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post #21 of 33 (permalink) Old Apr 21st, 19, 4:14 PM Thread Starter
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Re: Aluminum heads or full roller valvetrain?

One other question: what specifically are you talking about when you say "tuning the carb and ignition advance curve"? I don't think I have an ignition advance curve.
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post #22 of 33 (permalink) Old Apr 21st, 19, 5:07 PM
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The Vortec heads can have beehive springs installed and handle more lift without any modifications.
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post #23 of 33 (permalink) Old Apr 22nd, 19, 8:42 PM
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Re: Aluminum heads or full roller valvetrain?

Quote:
Originally Posted by BH View Post
Thanks for the input everybody!

It does still pull pretty hard in 3rd after the finish line though.
I've always run faster when all 3 gear changes are maid around the 330 ft clock. Pulling hard past the finish line should tell you something.

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post #24 of 33 (permalink) Old Apr 22nd, 19, 11:00 PM
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Re: Aluminum heads or full roller valvetrain?

do you have your timing locked out?generally vortec heads like 32 to 34 degrees total. have you ever tried to change main jets and note what if anychange was made to trap speed and incremental times. reading plugs if you do it correctly can help you but the ultimate guage is the speed on your time slip. make sure the floats are set go up 2 sizes on the main jets and make a pass. try to make sure the air is close to the same and the car is cooled to the same temp etc. be consistent and keep a log book. if you go with a roller cam you will have to pull the heads to machine the guides if you havent done this allready. upping the valve sizes and good porting work will pick it up some. get the car where it will make power to 6500 plus will help et especially if you gear it. cam gear and tuning should put you in the high 11s
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post #25 of 33 (permalink) Old Apr 23rd, 19, 9:10 AM
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Re: Aluminum heads or full roller valvetrain?

Not sure what but you have problem with your set up. Might be the heads and intake Like people have said tune on it. The reason I say there is an problem is back around 1990 I had 1980 Z28 black with T roofs 350 with 350 trans. Car had about 40000 miles on it. I put on cheapy headers Dart II heads Holley Strip dom intake Holley 650 double pump carburetor. Cam was hydraulic flat tappet with Rhoads lifters 500 300 cam. Had a 3500 stall 4.11 gear and 29.5 x 9 slick. Car was 3800 lbs and went the best of 12.63. Don't remember MPH. Shortblock was as GM assembled it. So take my weight to yours in your car it would be right at 12.0 or 12.1s. Plus the way things have improved in the 30 yrs since I did that. The top e d was all box stock with just jetting in carb. So you either have a terrible combination or way out of tune. But sounds like the heads and intake might be holding you back. My guy like the Flotek heads. He says with Chad Sper is a great source for the dollars. Good luck and go heads intake first.

RH
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post #26 of 33 (permalink) Old Apr 23rd, 19, 10:10 AM
 
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Re: Aluminum heads or full roller valvetrain?

This is a flat top 355 with a set of Dart IRON SHP 165 heads and one of my GTA Semi Customs. Nothing fancy, just a good solid piece.
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Why is it we never have time or money to do it the right way in the beginning but we always have time and money to do it over again?
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post #27 of 33 (permalink) Old Apr 23rd, 19, 10:25 AM
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Re: Aluminum heads or full roller valvetrain?

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Originally Posted by cstraub View Post
This is a flat top 355 with a set of Dart IRON SHP 165 heads and one of my GTA Semi Customs. Nothing fancy, just a good solid piece.
Thank you cstraub. I wasn't bashing or trying to be a d!nk. Just a mild combination with some time into though is all you need. Heck a guy from my shop did a 30 over 327. 3000 stall stall 3.73. Motor is 10 to 1. He ported the double bump heads and gm alum intake. He used a comp hydraulic roller XE282 and in a 1967 Nova for a girl he knows it runs right at 12.00. She drives it all over with usually an issue and looks stock with headers. But that is maybe 100 lbs lighter then this guy. Guy from shop who drives it at the track is 6 6 and 380lbs.

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post #28 of 33 (permalink) Old Apr 23rd, 19, 3:59 PM
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Re: Aluminum heads or full roller valvetrain?

Cstraub can you elaborate more?(cam, headwork?) Nice 350.

BH I had the same problem wiht an old 350/Isky 280 tried everything in the book..it was the valvesprings. Shoulda spun up well past 6 but around 5k felt like somoenes letting off the gas. No missing, nothing just.....well nada.
Head place put some pioneer Z/28 springs in that broke often..replaced them only to find they werent set up right. Was young and naive didnt know any better. Built a bigger motor to "fix" it. lol
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post #29 of 33 (permalink) Old Apr 23rd, 19, 7:10 PM
 
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Re: Aluminum heads or full roller valvetrain?

Quote:
Originally Posted by cuisinartvette View Post
Cstraub can you elaborate more?(cam, headwork?) Nice 350.

BH I had the same problem wiht an old 350/Isky 280 tried everything in the book..it was the valvesprings. Shoulda spun up well past 6 but around 5k felt like somoenes letting off the gas. No missing, nothing just.....well nada.
Head place put some pioneer Z/28 springs in that broke often..replaced them only to find they werent set up right. Was young and naive didnt know any better. Built a bigger motor to "fix" it. lol
.520/.520
221/235
108 LSA

Dart SHP 165's with a 3 angle valve job. Morel 5372. Dual plane intake. I believe a 750 carb. Flat top piston.

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post #30 of 33 (permalink) Old Apr 23rd, 19, 7:41 PM
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Re: Aluminum heads or full roller valvetrain?

Quote:
Originally Posted by cstraub View Post
.520/.520
221/235
108 LSA

Dart SHP 165's with a 3 angle valve job. Morel 5372. Dual plane intake. I believe a 750 carb. Flat top piston.
I wonder how much power you would give up to make that LSA 112 ?

LOL that cam idles a bit too rough for me

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