"New" guy

**Fast355** · 04-20-2017

Originally Posted by retorq

That is certainly promising information!

My buddy ran one in a Vortec head 350 tbi in a 1995 C1500 that was lifted on 32" tall tires. Had a 4L80E that came from a 6.5 diesel. Even with the stock 1,000 rpm diesel stall speed and 3.73s it ran well. Had an edelbrock victor jr 2bbl intake on it as well. It lagged a little on a WOT hit from a stop but it would run 0-60 in 1st gear. Once it got a little rpm built up it pulled HARD. He ran the MAF TBI 4L60E ECU code that Adam over on Thirdgen.org wrote.

**Queencityspeed** · 04-22-2017

I've done a lot of builds similar to yours but with carbs on them. I cant see why it wouldn't work great in a Tahoe with a Holley TBI on it. I think it would like a slightly higher stall. ( like the S-10 converter) I've never tuned a Holley TBI so keep us informed. I have one coming up soon.

**1project2many** · 04-22-2017

When presented with high lift / shorter duration or low lift / longer duration for EFI, a good general rule is to pick lift if possible. The cam recommended by the tuner may not be all that different from the HOT cam. It's got less lift and slightly more duration. The difference in ICL (1 degree) could disappear in manufacturing. The HOT cam has fairly mild ramps and I'm betting the Lunati version is the same. I'd have no problem running the HOT cam.

And I think your tuner would choke if told I'm using a 302 with a smaller cam in a Suburban. My truck has 3.42's and it tows a trailer. I originally built the engine with an LT4 stock cam for an S10 Blazer but changed to the Marine cam before the engine was installed. Short stroke engines tend to like smaller cams.

The HOT cam has little overlap and makes strong and steady vacuum. In a heavy truck with an automatic it will prefer a looser converter. If you're in an area with lots of hills you might tune for faster unlock of TCC on the highway and let the converter work for you. You might also tune for 4 -> 3 downshifts at lower throttle angle.

Put the biggest dang cooler you can on that transmission. The trans will be expected to shift and in some cases a looser converter generates more heat.

Do your prep work on that Holley TBI. I don't know how old it is but you need to be sure you have it in good shape before tuning begins. Understand what injectors are installed, make sure the throttles close properly, and make sure the IAC works.

**retorq** · 04-24-2017

Originally Posted by 1project2many

When presented with high lift / shorter duration or low lift / longer duration for EFI, a good general rule is to pick lift if possible. The cam recommended by the tuner may not be all that different from the HOT cam. It's got less lift and slightly more duration. The difference in ICL (1 degree) could disappear in manufacturing. The HOT cam has fairly mild ramps and I'm betting the Lunati version is the same. I'd have no problem running the HOT cam.And I think your tuner would choke if told I'm using a 302 with a smaller cam in a Suburban. My truck has 3.42's and it towns a trailer. I originally built the engine with an LT4 stock cam for an S10 Blazer but changed to the Marine cam before the engine was installed. Short stroke engines tend to like smaller cams. The HOT cam has little overlap and makes strong and steady vacuum. In a heavy truck with an automatic it will prefer a looser converter. If you're in an area with lots of hills you might tune for faster unlock of TCC on the highway and let the converter work for you. You might also tune for 4 -> 3 downshifts at lower throttle angle. Put the biggest dang cooler you can on that transmission. The trans will be expected to shift and in some cases a looser converter generates more heat.Do your prep work on that Holley TBI. I don't know how old it is but you need to be sure you have it in good shape before tuning begins. Understand what injectors are installed, make sure the throttles close properly, and make sure the IAC works.

I assume you mean pick higher lift, less duration, right?There are only small differences in the cams, I will be running 1.6 stainless full roller rockers on this setup. The lift/duration of the Lunati are quoted at 1.5, the Hot Cam numbers are quoted with 1.6 already I believe. There is some math to see exactly how close they are. I've seen others running the LT4 Hot Cam with Vortec heads in 350s, even wit TBI induction so my philosophy is, if they can do it so can I! Just the time it takes to get it there is the issue. My tuner would choke if he knew I was here lol!I'm one step ahead on the trans cooler. I have new lines and a big x large B+M plate style cooler ready to go in, just waiting to pull the engine to have full access to everything in there. The trans was rebuild a few years ago, 5 pinion GM planetaries, GM turbolator steels, upgraded band with matching clutches, Superior shift correction kit, Transgo plate, turlon balls, Sonnax .500 boost valve, Sonnax input drum reinforcement kit, Sonnax "Smart" shell, 36 element sprag, new electronics, deep cast AL pan with the correct filter. I do have a higher stall converter but it's been a few years since that was ordered, I am not sure what exactly it is. I do know with the current engine config I can hold it to about 2000/2100rpms and not much more. Worst case scenario, since I don't have to get a new cam and TBI unit, I can throw a few bucks at a name brand verified high stall convertor if needed. :DThanks for your thoughts, they have certainly helped.

**1project2many** · 04-24-2017

Yes, as a general rule, when faced with two cams that offer similar performance for EFI, opt for more lift instead of greater duration.

Increasing rocker ratio increases duration at .050" as the lift is achieved sooner in cam rotation and does not come again for a greater number of degrees. So GM cam would show less at 1.5 while Lunati would show more at 1.6.

Sounds like the trans has been in good hands. Lotsa $$ in those parts but sometimes that's the only way to keep a '60E together.

My tuner would choke if he knew I was here lol!

Well, not everything we suggest here agrees with what pro tuners and magazines say. And in all fairness a conservative tuner would suggest a path that is most likely to promise success for both the customer and the tuner. As always, YMMV.

**Fast355** · 04-25-2017

The Lunati cam has slightly less advertised duration, the same duration at .050, but more lift and slightly faster ramp rates. It also has 1° more advance built in. The GM Hotcam drops in on a 109° ICL and the Lunati a 108°. The difference in performance would be pretty negligable between the two. The Lunati has .536/.536" lift with 1.6s. I bought the Lunati cam dirt cheap when Lunati was clearancing them a couple of years ago. They were ssomething like $80.00 shipped.

**1project2many** · 04-25-2017

The Lunati has .536/.536" lift with 1.6s.

Interesting. But are we talking about the same cams? The Lunati numbers currently published for the 20080660 mentioned above show a dual pattern cam with 279/287 advertised duration and .477"/ .502" lift with 1.6 rockers.

http://www.lunatipower.com/ProductGr...?id=261&cid=59
https://www.summitracing.com/parts/lun-20080660

Lunati's 20120120 looks like it is a good match for the GM HOT cam:
http://www.lunatipower.com/Product.aspx?id=3161&gid=337