# NUNZI camshaft dilemma...



## dsorochan1 (Aug 16, 2020)

Hi PontiacJim; Read tons of your posts. Appreciate your knowledge and straight-forward help to so many. Hope you could comment on my dilemma, which has seemed to get worse. Have a 1968 GTO Convert. which I bought when I was 18 years old. Seems to have a Royal Bobcat racing option, which is really whatever they had left at the time the then owner got it. Car has been sitting since about 1995. Discussed build with Nunzi Romano, since it has his 2042HL cam in it. Rebuilt .030 over many years ago, think 1983, stock parts inc. stock rods, but seems like several neat parts and work was done to the motor originally. Problem: checked oil and boosted and moved car out of storage 1996. Found later oil was like glue. Took engine out of car long ago and I got sick and motor sat on stand. Recently took it for rebuild. Have it at diesel shop where owner is an expert-in diesels. He has caught a lot with the car, but he admits that Pontiacs are not his forte'.
I found driveshaft twisted and out of balance. Straightened and balanced driveshaft. Found the crankshaft was twisted and humped 10,000's. Ended up getting Forged steel crankshaft. Nunzi insisted that I get forged rods as he said that stock rods were the big weak point in these motors, especially with Bobcat option. Said he could not convince GM for much better rods. The NUNZI camshaft is pretty well toast, some lobes worn to .278 and best was .294, which is only .441 lift, and nobody, even camshaft experts, have a master they could use to cut another camshaft very close to the NUNZI. NUNZI 2042 is 113 LSA I/E duration 301/313 @.050 I/E 232/242 I/E lift 1.5 0.460/0.470 and overlap advertised at .79 to .89 Believe ICL was 112. Car ran incredibly well with this camshaft. Had anti-pump up lifters, idled good, good vacuum even with all drum power brakes. Came with about 2300-2500 stall and posi 10-bolt rear. Even ran very well 94 octane gas, nary pings. Dynoed at 380 start torque all the way from about 2200 RPM to 5600 RPM with peak at 443 torque 4800 RPM, 413 HP peak about 4500 RPM, still have dyno sheets, except lost last 3 sheets-where they did carb. Qjet jetting and mods and more timing, etc. and figures were a bit higher. Original 3 tube headers held the HP and torque down, had to run out and get 4 tube headers before duno was finished, 1 5/8 tube headers, which I was told should have been 1 7/8 for the car, so they said the figures are about 10-20 HP and torque about 30 lower. NUNZI said that the whole car is about that camshaft and I had to get another with same exact specs. Camshaft expert who looked at camshaft said he could grind one all the same specs. except I lift 0.466 and now exhaust lift at 0.496 with 1.5 rockers, but did not say if ICL would 112 off the new master. I speculate the big thing about the camshaft may well be that it created a lower dynamic compression, and also gave time for exhaust to get out of engine properly-with the HO manifolds. Yes, head porting was done, #62 428 cast iron heads(large valves), 3-angle grind, shaved spring seats, racing springs good to I/E 0.480, roller tipped GM type rockers, better keepers, retainers. Stock single points distributor was re-curved. Different oil pan, fiberglass ram air hood, Aluminum stock intake, and stickers-rear quarter windows and on engine air cleaner. Heat riser x-over was in, but putty blocked. Use this camshaft recommended? Go to SS trunion type bearing rockers? Can I use stock Pontiac screw in 7/16 umbrella shape posts or do I need new flat racing ones? Go to 1.65 rockers and try and grind originial NUNZI camshaft down, but encounter height, push rod problems, etc? 2-3 guides were slightly loose but within specs, new guides for the 2-3 valves? If, when, dynoed, what should I bring with me to shop? Extra plugs? Purchased the repo. HO oversized exhaust manifolds and seems that they will only work with LSA cams of 112 or higher, which limits mtr. cam considerations. Please respond for conversation please?


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## Old Man Taylor (May 9, 2011)

Use this camshaft recommended? You seemed happy with the result, so get one as close to that as you can. I would be surprised if you can't find a cam grinder to do it.

Go to SS trunion type bearing rockers? You're going to have a lot of $ in the engine. If it were mine I would run roller rockers, and as a matter of fact that's what I did. 

Go to 1.65 rockers and try and grind originial NUNZI camshaft down, but encounter height, push rod problems, etc? If you're trying to keep the cam specs the same then you will want to stay with 1.5:1 rockers. It makes no sense to go to 1.65 rockers and then grind the cam down to go back to where you were. 

2-3 guides were slightly loose but within specs, new guides for the 2-3 valves? I would do all of the guides, which then requires another valve job (IMHO). If you're trying to save money anywhere I would leave well enough alone with the heads. 

By all means buy a set of forged rods.

If, when, dynoed, what should I bring with me to shop? Extra plugs? Purchased the repo. HO oversized exhaust manifolds and seems that they will only work with LSA cams of 112 or higher, which limits mtr. cam considerations. Please respond for conversation please? Take extra plugs, a socket set to tighten/loosen any bolts on the engine, a dwell meter, a timing light and some rags. As to the exhaust, you will have to use the dyno shop headers. They are set up to exit the exhaust from the shop, and they have sensors in them.

I would rather see you start from basics. What are your priorities, and what do you want the result to be?


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