Need help on which route to go

Keep the cast/dished pistons. Replace the rod nuts with ARP nuts, leave the OEM rod bolts as-is. The Edelbrock heads will bring-up the static compression to about 9.67:1 (I think the chambers are 60cc out of the box). Adjust the dynamic compression with a custom ground hydraulic flat tappet cam that closes the intake valves earlier than normal.

I'm not a big fan of push rod guided valve train, I'd recommend the pricier Yella Terra YT6321 rocker arms, but that's your call. You may want to call Tim Meyer and check what price he's getting for the Yella Terra rocker arms before you make a final decision. Its true that push rod guided valve train needs hardened push rods, studs and guide plates, but the Yella Terra rocker arms do not. So part of the additional price of the Yella Terra rocker arms is made-up by the money saved on studs, guide plates, and push rod hardening. Keep in mind that stiffer push rods are needed either way.

Save money on the damper and purchase a Power Bond damper from Tim Meyer, instead of the ATI damper (Power Bond "Race Performance" damper PB1082SS). Since you're slipping a nice steel damper on the nose of the crank, consider bolting a nice steel flywheel to the rear of the crank (check with Tim on the price & availability of the YT9902 Yella Terra steel flywheel for long-style clutches).

I would personally go for the complete refresh, i.e. rings, bearings, seals, timing set, etc. This is a good time to replace the throw-out bearing and pilot bearing too. If I can twist your arm a little, consider the tappet bore bushings to complement that nice oil pan. If you do not install tappet bore bushings, then order the push rods with a 0.040" restriction in one end. Watch the bearing clearances during mock-up assembly, target 0.0025 – 0.0030 Mains; 0.0023 – 0.0028 Rods. If the clearances are tighter than this consider installing +0.001 bearings. And finally dynamic balancing the reciprocating assembly is worth every cent.

Thanks George!
So my understanding on dished pistons was that they are prone to failure (believe it was sticky #3) and that they were performance zapping due to emissions of the day. If I am already having the bottom end worked on per your recommendation on full refresh, I thought it made sense to fix. Is your concern compression will go to high with these heads and new pistons?

The "complete refresh"/bottom end adds close to $2500 to the refresh. Are rings, seals bearings etc important in your eyes as more preventative?

Thanks
Eric

Eric, did you have any indication that the engine needed work before you pulled it? Poor performance, noises, leaks, smoking or oil consumption, anything like that? 33k miles is not much. With a known 1 owner, low mileage GTS, original std bore (?) engine, you might want to think twice about how much you do to it; I know I would. You can achieve impressive performance, improve reliability, and still preserve most of the originality with a few selected changes. Did you do compression and/or leak down tests to see if you really have any problems that need addressing?

As George said, upgrade the rod nuts, timing chain set, and damper for sure. Replace the valves if they are original, regardless of their condition; they are prone to break. A properly set up duraspark ignition should be quite adequate for street use, and is almost original. A better oil pan would be wise also.

Ultimately the choices are up to you, of course, depending on your goals and budget. Just my $0.02 worth.

Hi UFO- truthfully engine work was more of an afterthought once I had decided to paint engine area and engine/trans was pulled. Engine has zero issues that I know of but no leak down test has been done. Dad did compression test 5-6 years ago and cylinders were reading different. Engine is as it was sold 43 years ago save for the carb and intake he put on it.

I started reading on this great forum (in partiular sticky #3) and started focusing on "well since the engine is out, I may as well" fix known areas of concern (you listed many), then it shifted slightly to well I could add this part and that part and gain HP/TQ while increasing durability.

That said I by no means have a money tree. What I am solving for is while engine is out I want to address all know potential areas of concern with the 351C and boost up the power as well. There is always a point of diminishing return, any thought on what all upgrades may make on Dyno at rear wheels? I would love to get up around 350. My understanding is stock these were just over 200. Thanks!

*edit-UFO when you say you would think twice about how much is done to it, are you saying this due to it being a lower mileage 1 owner GTS and impact my proposed mods would have to value?

quote:

Originally posted by 74GTS:

... my understanding on dished pistons was that they are prone to failure ... and that they were performance zapping due to emissions of the day ...

The OEM pistons are not prone to failure at all. They are fairly sturdy for cast pistons, they have steel beams in the skirts, etc. But like any cast pistons they may crack their skirts when the engine is operated "vigorously". Cobra Jet engines were set-up to operate up to 6000 rpm; whereas the Boss 351, which had forged pistons, was set-up to operate up to 7000+ rpm.

The Ross pistons offer the advantage of having the durability of a forged piston, plus the compression afforded by flat top pistons. Other advantages include improving the cylinder wall durability due to their round skirts, plus the better sealing and lower friction afforded by thinner piston rings. Those last two things increase horsepower. Only you know how hard you plan to operate the engine in the future, or if the power improvements are worth the price of the pistons to you.

Lowering the compression of the engine did indeed zap its performance. The four basic schemes for raising compression are:

(1) flat top pistons, quench chamber heads, cams with IVC = ~70° ABDC
(2) dish top pistons, quench chamber heads, cams with IVC = ~60° ABDC
(3) flat top pistons, open chamber heads, cams with IVC = ~60° ABDC
(4) pop-up dome pistons, open chamber heads, cams with IVC = ~70° ABDC

Since you mentioned installing Edelbrock heads, the first or second schemes seem to be your choices. The second scheme saves having to purchase pistons.

quote:

Originally posted by 74GTS:

... Are rings, seals bearings etc important in your eyes as more preventative ...

Just being practical. Something to do while the engine is out of the car. You've already mentioned the compression readings were not consistent. The 40 year old crankshaft seals are bound to start leaking. I've never taken apart an OEM lower end without discovering worn bearings. The OEM timing set has nylon teeth on the cam gear. Service those things now, get them over with, and hopefully you'll never have to pull the engine again. Frankly I feel the maintenance is more necessary than Edelbrock heads ... the engine already has a decent set of heads on it.

Eric, after I hit the "post" button the other day, I see you had already responded to George, so I didn't have as much background, then as now, on your intentions. So yes, my comments were from the perspective that "it's only original once", and you are fortunate to be not far removed from that condition. There may be some resale value premium to be found in a high level of originality, certainly in the limited numbers of genuine GTS cars around. In any case, I think George would agree, there is a good bit of performance and reliability improvement to be gained with relatively simple optimization of more - or - less stock parts. Likewise, reductions of weight where possible, with better tires & brakes, can add noticeably to the overall performance.

quote:

Originally posted by UFO-LOW:

... There may be some resale value premium to be found in a high level of originality, certainly in the limited numbers of genuine GTS cars around ... I think George would agree, there is a good bit of performance and reliability improvement to be gained with relatively simple optimization of more - or - less stock parts ...

Agreed!

Appreciate the input guys and agree on trying to stay (more) original. Leaning towards keeping the heads.

Now I need to find a great engine shop in Detroit area that knows their way around a 351c

quote:

Originally posted by 74GTS:
Appreciate the input guys and agree on trying to stay (more) original. Leaning towards keeping the heads.

The 4V Cleveland heads can and will make more than adequate horsepower, I have a 391C in my car and currently building a 406C (.020 over with a 4" stroke) with no regards to originality in either build, and I do not see any reason(s) to bolt aftermarket heads.
With just minimal bowl clean up, one piece SS valves, checking/replacing guides, trued head surface,new springs and rollerized rockers, you are going to have a hard time limiting your 300 hp goal at that figure, even with a street performance hydraulic flat tappet cam you will easily surpass your 300 hp goal in a very streetable package.

You guys concerned abot leaving it stock could follow Gary Hall's ideas- on one of his go-anywhere cars, he painted a set of aluminum heads Ford Blue after first spraying them with cast-iron paint, so magnet-checks at the track stuck to them!

IMHO, two reasons to change to aluminum heads: the iron heads are 62 lbs heavier than aluminum and all that wt is far above the C.G. That means that if the engine is in the car, changing heads is a two-man job (unless your name is Godzilla!) And second, all the alloy heads run Boss-type adjustable valve trains. One can make iron heads adjustable (the 351-HO had such) but it takes some precision $$$ machining.

PM sent regarding engine builder.

I didn't even consider the weight savings, thanks for the input. Will be moving forward with the heads.

74GTS, way off-subject for this post but the possible weight savings from the engine are even more extreme if you also include the almost-mandatory aluminum intake manifold (-30 lbs over stock iron), aluminum water pump (another 8 lbs), a mini-starter (-6 lbs), and a tuner Holley that uses aluminum float bowls & metering plates in place of cast zinc (-5 lbs). I also duplicated the stock steel-plate alt/AC/idler pulley bracket in 1/4" aluminum (-16 lbs) and use a Sankyo rotary AC that is 22 lbs lighter than stock. The law of diminishing returns intrudes about this time, but I measured a whopping 120 lbs lost from our 351-C assembly.

Lightening up all areas of the Pantera has been an ongoing project for me since about 1990, and our stock-to-the-casual-eye '72 L model runs right around 2675 lbs today, licensed & ready to drive. Factory-stock was 3250 lbs on this car when I started the exercise. All this was written up in illustrated POCA Newsletter tech suggestions over the years, and free downloadable back issues (back to 1979!) are available as pdfs for members. Now, back to our regularly scheduled Forums-

Hi there ,i would run a hydralic roller instead of a flat tap,you wouldn't have to worry about oil issues and wiping the cam and lifters out not to mention the performance advantage if you using the new aluminum heads they are more efficient and have stelite seats which help with the unleaded fuel we have today,i would buy them loaded that we you have new stainless valves and PC seals for a better package we raced the Cleveland engine in NASCAR modified in the north east we always ran SS valves and bronze guides USE A GOOD HEAD GASKETwe ran a lot of compression and use to pin ours through the rocker arm stud you should not have to do that with 10:1 or less and i would run roller rockers the stamp steel ones are not what i would recommend for what its worth,my build is a Clevlor dart block C.H.I.aluminum heads Callies crank and rods Diamond pistons comp cam mechanical roller Inglese electronic fuel injection and 180 degree headers stroked to 438 cid but my choice and my hot rod