Cory1970

Please post your set up with a comp xe 274, or similar. I am running 350 with an xe 274 flat tappet, 10.3 : 1, double hump heads (ported), Air Gap RPM (port matched to heads), Demon 650 speed demon, and hooker side pipes with spiral baffels.


Dyno numbers or sheets Please

I am paying 900 bucks for the heads to be rebuilt, ported, and the manifold to be matched.... let me know what you think....

Guru_4_hire

Probably want to scrap the iron heads for compression that high. 900 + 60 will get you a nice set of edelbrock RPMs.

otherwise I would be concerned about detonation.

but here ya go(from compcams website)
http://www.compcams.com/Technical/Dy...74H-10_001.asp

Cory1970

I have been running these heads for a while with no detonation problems. My valve seals and guides went bad, so i am considering porting the intake and heads while they are off the motor. Is 900 for a full rebuild (bigger valves, new guides, seals, locks,) and port job to the heads and intake too much? The guy seems to know what he is doing and he is porting the heads to match my cam. What do you think?

Matt Gruber

buy new heads

Cory1970

Will out of the box vortec or iron eagles flow as well as a set well ported double humps and a ported air gap rpm intake?...... vortecs and an intake from Scoggin-Dickey cost $950... plus I need new rockers and valve covers.... Iron eagles are 900 or so... but I still don't get a ported intake .... Maybe some used vortecs or Iron eagles would work..... for the price the ported double humps still look good... more suggestions???

Matt Gruber

canfield $950

mandm1200

GMPP has released 2 new sets of Vortec Bowtie heads in addition to the L31 heads.
PN 25534371 (bare) and PN 25534431 (complete) larger ports
PN 25534351 (bare) and PN 25534421 (complete) smaller ports

The new heads are different and allow the use of regular valve covers. I don't know if self aligning rockers are needed or if they come with guide plates. You may be able to use your intake as it has both the new and the old bolt pattern. These Vortecs, like the L31 style, have raised intake ports which may require a new intake to match. The standard L31 Vortec heads essentially outflowed everything in their class including the aluminum heads. One of the magazines has a web article where they compared a bunch of heads. The new heads cost considerably more. Another advantage of the new style is that they allow for a higher lift cam without changing springs.

Will the L31 Vortec outflow ported double humps? I don't know. As for the the machine shop porting them for the particuliar, that sounds like BS. The Scoggins kits include new rockers, head bolt, intake bolts, and gaskets; however you will still need new center bolt valve covers. Obviously the new Vortec setup will cost more. If I had a choice of staying with ported old heads or going to the L31's, I would go for the L31 setup.

Cory1970

what about hood clearance problems with vortec heads??? Anyone know what the flow number are with these "new" vortecs with bigger ports??

Matt Gruber

@.500"
462 221/139
L31 vortec 239/160
canfield 258/190

Corey_68

No doubt about it.

79VetteMike

I'm going to go out on a limb here, but you should get new heads.
I have aluminum Pro Toplines. They are a very nice head. I've heard that Canfields are very nice heads too.

BKbroiler

No hood clearance problems with Vortecs and Edelbrock Performer on my 77.

mandm1200

The Canfields are considerable better at .400 lift and above. The Vortecs have a 170cc intake port while the Canfields are 195cc. A choice has to be made on port size as well as flow.
Here is a link to compare heads, http://chevyhiperformance.com/techarticles/41598/ .
Note that the Vortec and Canfield are in different categories. Check the flow numbers of the little Vortec heads and compare them to the others in its category. If you read between the lines not only do they flow well, but with the small intake port they will have great velocity. When picking heads, there is more to it than just flow. Bigger heads that flow more may not be better for a street car. It's like choosing the right cam. A longer duration (310*) and higher lift (> .600") cam does not make it a better cam if most of the driving in done a 2000-3000rpms. An engine works best when all the parts compliment each other.

1970-Bronze

With a 70' and a standard hood, your going to have clearence issues with the air cleaner if you go with the Air Gap.

I ended up using the EPS cause there just wasn't enough space.

page62

There's more to life than flow numbers and dyno results. There have been LONG discussions about this very topic (just ask Dep). What are you trying to accomplish overall?

And yes, get new heads. Double hump heads are overhyped. New technology such as high-swirl combustion chambers have made them truly obsolete.

Cory1970

I am running double humps now with a Air Gap and it fits. Are you saying it will not fit with Canfeilds or Vortecs?

Cory1970

Does anyone have experience with Canfields???

Cory1970

ttt

munday

Of course new tech heads will be better, but iron heads can be made to flow quite well. Valve size can make a difference and I might be concerned with that. If iron heads sucked, no one would sell them and only alums would be on the market.

Empatho