034 Chevy Bowtie Semi Finished Heads

[Pontiac310]

Whilst an old casting, does anyone have any experience with the semi finished version of the 14011034 (P/N: 10051108) Bowtie Cast Iron casting? Run an OEM iron cylinder head class (with no adding of material to ports rule) and would consider these castings if I can get my hands on a set due to the pushrod reliefs not being drilled, allowing the pushrod pinch to be opened up significantly with the offset rockers we use. We have used Bowtie Vortecs but they are prone to cracking so open to alternatives. I've read in the forums that these can flow well with full porting so I am open to considering them even though they're an old casting. Engine application is a small cube, high rpm, single carb package. Some images attached from the old Chevy Power Catalog for reference.

Chevy Bowtie Part Numbers.png

034 Semi Finished Bowtie.jpg

Thanks in advance.

[Tom68]

Do you reckon you'd ever find a set ?

Lot of work to get those unfinished low port heads useable.

Vortecs don't crack without reason do they ? something must be causing the cracking.

[mag2555]

Yes, they do crack even in plain old passenger car usage.
I would stick with the Votex heads and even go thru the expense of sending them off to get cryogenic treated.

Then the cracking issue will then stop.

The 034 casting can be ported to flow well, but when it comes down to apples to apples in terms of air flow numbers, the chambers in the vortex heads make more power out of every cfm that they do flow, plus they have a faster burn rate then the 034 casting which is another plus on there side.

[F-BIRD'88]

Are the Bowtie Vortec heads internet rumoured to be "prone to cracking". or you have used a set or 2 that have cracked on you?

The GMPP Bowtie Vortec head is a much heavier beefy er casting than the OEM L-31 truck engine 062/906 castings were.

The OEM 062/906 heads got the reputation of cracking because all the used market heads were take off heads of old abused L-31 truck engines that developed a intake gasket leak fault causing loss of coolant. thus engine overheating..
This overheating is the cause of the head cracking.
If the L-31 heads had not cracked they never would have got separated from the origional L-31 truck engine that was perfectly rebuildable if when the mileage got way up there.. The cracked heads (from overheaded engines) get ebay ed.... The good ones stay on the truck engine.
No reason to separate and sell off.
This OEM intake gasket leak was a common fault so then lots of overheated L-31 engines and thus cracked cylinder heads..
The new bought parts counter OEM L-31 062/906 Vortec heads that never seen a truck are no more crack prone than any other SBC head.
The GMPP Bowtie Vortecs are not known for being crack prone ..

The Old 034 Bowtie heads make great power when correctly ported and modded. but if you are competing against others running ported prepped GMPP bowtie Vortec heads on their engines you are going to get beat.
These make more power.

[compguy]

^^^
What F-Bird said.
If your looking for '034' Phase 2/3 iron heads, ther's some on Facebook marketplace now:
https://www.facebook.com/marketplace/it ... 39164b3f52

The latest Bowtie Vortecs are not prone to cracking. Best OEM iron head ever. However they dont make 'em anymore.

Had a set of 034 ported for all out drag racing use by a very well know porter, they wouldn't go over about 600hp, on the flow bench they got noisy.
The Bowtie large port Vortecs leave em for dead.

[mt-engines]

^^^
What F-Bird said.
If your looking for '034' Phase 2/3 iron heads, ther's some on Facebook marketplace now:
https://www.facebook.com/marketplace/it ... 39164b3f52

The latest Bowtie Vortecs are not prone to cracking. Best OEM iron head ever. However they dont make 'em anymore.

Had a set of 034 ported for all out drag racing use by a very well know porter, they wouldn't go over about 600hp, on the flow bench they got noisy.
The Bowtie large port Vortecs leave em for dead.

Then your very well known guy didn't do that great of a job.. they can make well over 600hp in the right hands. 700 hp or more in a drag racing deal.

[1980RS]

Here's my experience with 034's vs Vortec heads
034's 11.59@114mph 2.05 and 1.6 valves
062 Vortec's 10.92@120mph 1.94 and 1.5 valves

Both mildly ported and both on a flat top piston 400. Even the stock 906 Vortec's ran what the 034's did ported. Those heads ship has come and gone IMO. That's why I sold all my set of 034's I had this year.

[Old School]

Here's my experience with 034's vs Vortec heads
034's 11.59@114mph 2.05 and 1.6 valves
062 Vortec's 10.92@120mph 1.94 and 1.5 valves

Both mildly ported and both on a flat top piston 400. Even the stock 906 Vortec's ran what the 034's did ported. Those heads ship has come and gone IMO. That's why I sold all my set of 034's I had this year.

Did you remove one set of heads and install the other with everything else the same to get such a difference in et? Was the testing on the same day?

[Pontiac310]

Thanks everyone for the response. Seems like the GMPP vortecs are as good as it gets, it's a shame they didn't sell them without the pushrod reliefs machined. They do make great power for an OEM iron head but we've had 3 separate heads crack so far from ideal on that front. I believe the small port Vortecs are still available but the large ports have been disconnected per the 2022 GMPP catalogue. Although my guess is that the large ports and small ports are the same head externally just with a different core pattern for the intake runners.

[Pontiac310]

Slight typo
Large Ports Discontinued*

[1980RS]

Here's my experience with 034's vs Vortec heads
034's 11.59@114mph 2.05 and 1.6 valves
062 Vortec's 10.92@120mph 1.94 and 1.5 valves

Both mildly ported and both on a flat top piston 400. Even the stock 906 Vortec's ran what the 034's did ported. Those heads ship has come and gone IMO. That's why I sold all my set of 034's I had this year.

Did you remove one set of heads and install the other with everything else the same to get such a difference in et? Was the testing on the same day?

Testing was done on a different day. The old Bowtie heads just cannot compete with the Vortec stiff IMO. It's no different than people who ask are Vortecs better than camel hump heads, it's night and day performance difference. There are guys on this site that can get those 034's to work very well and make great power with them and I respect those guys for sure. For us little guy races though look close at the two heads as see why the Vortec's are so much better than almost every other cast iron head GM ever made. They made me a believer and I did not do a lot of work to my set, just little things.