I have been thinking about buying a stroker kit and a few questions have come up, does the GM LT1 block have to be ground to clear the longer stroke? Has anybody used the LT4 cam and what is the best bet on an opti spark? I haven't got my LT1 out yet but it's close, so I haven't found what broke yet, but I'm just doing a little planning. any response would be greatly appreciated.

 

lt4 cam is going to be way too small for a 383, you'll definitely want something bigger.

clearancing the block really depends on what rotating assembly you go with. I think Eagle requires quite a bit of clearancing where other kits can sometimes get away with none.

 

I ran a Lunati 3.750" stroke crankshaft and a Lunati 5.850" rod with a previous combo.

I had no clearancing issues.

Switched to a 3.875" stroke with the same rods....I had to clearance a large amount of material.

 

What cam did you run with the 3.75 stroker crank? I called Lunati yesterday and sat on hold for over an hour and still didn't get to talk to anybody but the operator.

 

I ran a few cams with that setup. Cam selection should be based off of your likes in street manners...then come the how do the heads flow...compression...etc...

Spec wise though they were as small as 212/224 up to 236/242 with that setup. The small cams were not much slower with the heads I had.

 

I would like to keep the same RPM range that is factory, I would just like the additional torque of the stroker, after all this is one of my daily drivers and I am leaning towards a realiable torque monster, and seeing how it locked up that is a good excuse to do it. I haven't pulled the short block out yet so I don't know the extend of the damages yet.

I've got the heads off now and I think while they are off I am going to clean up the ports, and match the inake and exhaust manifolds, just take the casting out of them.

 

Just to clarify.... the stock LT4 cam is not much different than the stock LT1 cam. It just used 1.6 RR's to gain extra lift. The LT4 engine did not use the LT4 HOT cam. That is a bit larger, but was a GM aftermarket part.

 

As stated earlier, clearancing the block is dependent upon what rotating assembly you use. Mine has a Callies crank,Oliver billet steel 5.85" rods and JE pistons...There was some clearancing done but machine shops should have no problem with it...

As far as cam selection I went with a small custom from Joe Overton based on the flow of my ported LT1 heads with 2.00/1.56 valves...I wanted to have a good street/strip set up that made power to 6300...I've been told that with ported LT1 heads anything over .570" lift is a waste...My 383 originally came with a 211/219 cam from LPE which worked well, but I wanted a bit more power...I stepped up to a 226/234 with lift a hair under .570" based on Joe's recommendations...The cam is matched to the heads, to the converter, to the rear gear...If you can get that combo right you'll have tons of fun and the damn thing may surprise lots of folks with bigger cams...

You'll hear that displacement "eats up" larger cams, and thats true to an extent, but you don't want too much duration in a street car unless you want to run lots of gear and lots of converter...I have always used bigger lifts with lower durations and it seems to work well for my goals...The side benefit is that with a 6300 power band you don't put stress on the rotating assembly and with lower durations you don't go thru valve springs...My short block has remained untouched since it was built in 1995 and I'm still using the same double valve springs that LPE installed in 1995!

--Alan

 

thanks for the good info. this is the kind of things I like to hear....what works, and what "I have tried, and this is what I'm running now"

How do I get in contact with Joe Overton?

 

He's back on here sometimes, but I don't think he's doing cams anymore...

--Alan

 

So, that's why he spec'd my cam the way he did.

He's about one of the hardest guys in the world to get a hold of, but if he is still doing cams (I've heard yes and no for years now), it'd be worth it.