Phase two bowtie heads???? [Archive] - Chevelle Tech

: Phase two bowtie heads????

Aug 28th, 04, 12:35 AM
I've had a set of phase two bowtie smallblock heads collecting dust in my basement awaiting a future project. My question is do these have hardened exhaust seats? Bob

Tom Mobley
Aug 29th, 04, 2:05 AM
Probably not since they were never sold new in an unleaded gas car. If the heads are new and never been run you can see a bluish coloration around the exhaust seats where the iron was induction hardened. if they're hardened. I sincerely doubt it on those.


Aug 29th, 04, 2:54 AM
Almost positive they will not but be, at least the ones I have seen were not but ,,,, with GM I have learned to never say never ;)

Aug 29th, 04, 6:25 AM
Quoted from the GMPP catalog...

"10134392 - Phase 2 Cast Iron Bow Tie Head
The Phase 2 Bow Tie cylinder head (casting P/N 14011034) has the highest performance potential of any cast iron Chevrolet head. It is intended for off-highway applications only. Although the Phase 2 cast iron Bow Tie cylinder head has the same casting number (14011034) as the Phase 1 head it replaced, there are several significant differences between these two heavy-duty cylinder heads. The Phase 2 cast iron Bow Tie head can be identified by its redesigned outer water jacket wall with a machined bar between the exhaust manifold flanges. (Phase 1 castings have a raised parting line between the exhaust manifold flanges.) The area around the tapped water temperature sensor hole is also machined flat on the Phase 2 head. The Phase 2 Bow Tie head has a revised combustion chamber design with a true volume of 64cc's.

The quench areas beneath the spark plugs are filled to increase compression in competition engines. The intake valve seats are machined for 2.02" diameter valves; the induction hardened exhaust valve seats are finished for 1.60" diameter valves. The intake and exhaust ports are identical in Phase 1 and Phase 2 cast iron Bow Tie heads. The 184cc intake runners will satisfy the airflow requirements of most competition engines while enhancing throttle response and mid-range torque. In unmodified form, the Phase 2 Bow Tie head will flow more air than any production cast iron small-block head. Extra-thick wall sections allow the ports to be enlarged to increase their flow capacity. The manifold heat riser passages are deleted in Phase 2 Bow Tie heads to produce a cool, dense intake charge.

Technical Notes: The valve spring pockets in cast iron Bow Tie heads are machined for up to 1.50" diameter competition valve springs. The rocker stud bosses are tapped for screw-in studs; studs and pushrod guide-plates are not included. Use GM Performance Parts studs P/N 3973416 (3/8") or P/N 3921912 (7/16") and hardened pushrod guide-plates P/N 3973418. Use 5/8" hex-head spark plugs with tapered seats and 3/8" reach. A bare casting weighs approximately 42 pounds. Valve seats are heat-treated."

Tom Mobley
Aug 29th, 04, 12:02 PM
nice post Bill. first time I've ever been wrong. smile.gif . Well, unless you ask my wife, of course.


Aug 29th, 04, 12:16 PM
Thanks Tom.
The only reason I'm familar with these heads is because we just used a set on my bro-in-law's mild 383 project. Nice package.
I might add that the "Bowtie" nickname probably refers to the bowtie symbol cast into each head in the area under the valve cover..

Aug 29th, 04, 2:57 PM
Thanks Bill,, I stand corrected & don't even have to go look them up in the catalog.

First mistake of the week but I still have plenty of time to screw up again before next weekend :D

I have an old set in the shop that were supposed to be phase II's & are 034's but now I will have to look them over a bit closer to see what they really are.

Aug 29th, 04, 11:45 PM
cool, thanks for the help. I was just wondering if I should use these or sell them off. If they would have needed hardened seats installed then that would have been a deciding factor. I guess I'll hang on to them.

Aug 29th, 04, 11:48 PM
Billscamino, how does that 383 run with the Bowtie heads? If it runs good I'd be interested in what cam, compression, and intake you use. I've also got the matching bowtie victor junior intake I was thinking of using.

Aug 30th, 04, 6:43 AM
The 383 runs good. We're in the tuning stages...had a stock HEI that we believe was laying down. Just upgraded to MSD. Plus, just purchased a 750 DP Holley.
It's a mild 383 hyper pistons, 9.7 CR, Holley Street 300-36 dual plane, XE268 cam.
Mainly a cruise night car with occasional strip visits.
Should run mid 13s.

Aug 30th, 04, 11:06 AM
I sold those heads to Bill. I ran a 13.91 at 102mph with the Bow Tie heads on 355 cubic inch mill, with 3.55 gears and a 2000 stall. My cam was way too big for the converter, and I never got the combo to ET good. It was a dog off the line. But, 102mph is pretty stout for a 355 in a car that weighs 3900 pounds with driver. I think with a better converter and traction I could have run 12's. They are pretty good heads. The only drawback is the angled spark plugs...plug access with headers is a real PITA, and a couple of the wires are prone to burn.