High Performance GM crate engine

[dlg423]

I just purchased a GM High Performance crate engine for my 1981 coupe. Horse power is rated at 330 @ 5000rpm.

What octane and brand of gasoline should I use, brand of oll and weight? Can I use ac-delco standard plugs and plug wires or should I look for alternatives? What about break-in miles and speed limitations? This is my first post.

Thanks in advance,

 

[MrGibbly]

That GM engine has a compression ratio of 9.1:1 so it will take pump gas without any trouble but you'll have to use "the good stuff" (92 Octane or better). Of course GM recommends using AC Delco plugs, etc. but you can using pretty much anything you like (Bosch, Denso, etc.) as long as you gap 'em right. For the wires I would immediately switch to a performance wire set from MSD or Mallory. As far as oil is concerned I have always started my new cars out right away with Mobile 1. My old C3 engine is using Max Life because its got 86,000 miles on it and I'm just trying to get it by until I can afford either the engine you just bought or the Fast Burn 385. I hope that helps.

 

[AKRAY4PLAY]

i have a bunch of buddies running that motor in various vehicles. they all run 87 octane with no troubles. i would say to break the motor in on premium pump gas incase you don't have the timing set right. then you can decrease the octane unless it pings. when going down in grade, try putting 3-4 gallons in an empty tank and see if it pings. if it does, then you have enough room left in the tank to correct the problem before hurting your motor.
i like using 5W-30 for break-in. thinner oil does not stick to the cylinder walls and helps the rings seat. WATCH YOUR OIL PRESSURE ON START-UP!! make sure it is at least 30 psi. if the crank clearences are a little big, pressure will drop below the safe level. i use 10 psi oil for every 100 hp as a rule. if pressure is low, then go with a heavier weight oil like 10W-40, 15W-40, straight 30W or 20W-50 in extreme cases. you can't change your oil enough with a new motor. good filters are a must. if you can find them, AC/Delco UPF1218's are the best, but they are discontinued from GM. the rubber check valves in the drain-back holes help keep the oil pump primed on cold starts. other than that, enjoy the new motor!!! Brian

 

[Dave L.]

DD - Are you going to use your original computer controlled dist/carb set up with that engine? I'm considering that engine for my car also and would like to know what your going to do. Let me know what you think of overall performance once you get everything in order.

Thanks...Dave

 

[dlg423]

High Performance GM Crate Engine

Thanks for you post, Brian and others posting comments have been helpful, thanks to all. I was especially encouraged by your comment, Brian about the possibility of running 87 octane. I will probably go with 89 but with the cost of fuel, I was a little bit reluctant to spend the doe for 93 octane.

A brief history of my experience with this car, bought it for $10G, body and interior in excellent condition. like new. The party I bought it from was 2nd owner, millage 57,500??? The engine had a slightly rough idle so I did a carb kit and fixed a vacuum leak by replacing the cannister. The idle was still bad and now I started getting popping through the carb on exceleration with no power at all. The rough idle turned out to be a soft (or bad cam). not exactly good news. A few miles later it started knocking. I was hoping for the knock to be an oil pump rod, but no, turned out to be a rod or bearing. did a cylinder link test, wasn't good, so had to make the decision to patch up the stock 350, 190 hp or go with the High Performance Gm crate. I figured as long as I was spending hard earned money I might as well get something to show for it. I've had some problems with the GM guarentee but that a whole different topic.

 

[Fishman]

DD... I put the GM crate ZZ4 in my '78. YOU WILL LOVE the extra hp! Originally my '78 was @180 hp (L-48)... now I'm pushing double that. I had the same dilemma... fix or buy. I feel I made the right choice.
Now... don't make too many C4s and C5s feel bad :L

 

[AKRAY4PLAY]

sounds sweet! let us know how you like it and if you need any other assistence. Brian