Mods for pump gas

[TommyK]

I have a very similar engine in my Mustang, a 1971 429 with Dove heads, 10.5 to 1 compression, it was rebuilt at a local very reputable shop. They said the heads were in good condition with no erosion, and just did a valve job. We used a Comp cam XE 273, but the rest was a stock build. We did not install hardened seats, because the car sees few miles. I run the tune with 30 degrees total timing on the distributor, and have no pinging, on pump premium.

I bought a can of octane boost, but did not need it. I say keep your DOVE heads, check your timing and go with it. The forged pistons in these engines, are very strong, and the valves have a large contact area, and run at a relatively low rpm. The Dove heads are more efficient than the D3's, equals more power.

To my knowledge (which admittedly is suspect) the only 429's which came with forged pistons were the SCJ and Boss varieties. CJ's and Thunderjets had cast pistons. Someone please correct me if this is not the case.

I am not sure what you mean by saying "The Dove heads are more efficient than the D3's..."

The DOVE and D3 heads are both closed chamber heads. By all accounts they both have the same performance potential via installation of larger valves and porting. The choice between them comes down to the compression ratio you are trying to achieve based on the piston you are working with.

 

[sm3570]

I have a very similar engine in my Mustang, a 1971 429 with Dove heads, 10.5 to 1 compression, it was rebuilt at a local very reputable shop. They said the heads were in good condition with no erosion, and just did a valve job. We used a Comp cam XE 273, but the rest was a stock build. We did not install hardened seats, because the car sees few miles. I run the tune with 30 degrees total timing on the distributor, and have no pinging, on pump premium.

I bought a can of octane boost, but did not need it. I say keep your DOVE heads, check your timing and go with it. The forged pistons in these engines, are very strong, and the valves have a large contact area, and run at a relatively low rpm. The Dove heads are more efficient than the D3's, equals more power.

To my knowledge (which admittedly is suspect) the only 429's which came with forged pistons were the SCJ and Boss varieties. CJ's and Thunderjets had cast pistons. Someone please correct me if this is not the case.

I am not sure what you mean by saying "The Dove heads are more efficient than the D3's..."

The DOVE and D3 heads are both closed chamber heads. By all accounts they both have the same performance potential via installation of larger valves and porting. The choice between them comes down to the compression ratio you are trying to achieve based on the piston you are working with.

The 429 was rebuilt in the '80s. Absent any info, I made the assumption the engine was stock. Who knows, it may have forged pistons. I haven't heard any evidence of detonation so I think I'm good to go on that front. At some point I'll probably do an engine rebuild, but it won't be anytime soon unless a mechanical problem pops up.

 

[C_andy460]

First of all the "tune" is everything. A good tune on your engine will go a long way at keeping any problems at bay. Colder plugs and a litlle richer jets and a couple degrees less advance will keep detonation away. I worked many years in auto machine shops and can tell you that hardened exhaust seats is mostly magazine hype. I have run hunderds of heads without hardened seat without any problems (on gas-LNG and LPG are different animals). The lead in the old gas may have helped the seats but caused problems because it would build up on the valves and cause them to over-heat and burn. What helps valve seat to last is to keep combustion temps down. Late model (80's) engines that were set up with low compression and lean carbs and slow advance curves produce high combustion temps, leading to seat recession. The fix was to induction harden the seats. At 9.5 to 1 and up your engine thermal effiniency goes up and over all component (pistons and heads) temps go down. Learn how to read plugs to get your tune tip top.

Andy

 

[sm3570]

I've been slowly learning this stuff. I'm still working on the interior and not driving it, but when it's road worthy I'm going to spend a bunch of time on the engine to get it just right. Thanks for the tips, it really helps.

 

[davechesnut]

i can tell you the elevation does help. i had a 69 mercury marauder with the 429 thunder jet. just kept it tuned up and it ran on 91 octane without a single issue. in the late 80's i had a friend with a 340 duster running 11:1 compression as his daily high school transportation. he would put junk 7-11 gas in that thing with no issues. i wouldnt believe it if i had not witnessed myself. not sure why but the thin air helps.