Hi folks, my name is Kenny and I purchased my first Corvette last April. It's a 1977. It's got the stock 350/180 horse. The motor runs fine but I'm thinking somewhere down the road of installing a crate engine, for a little more umph. I've looked at all the different horsepower crate motors from GMPP, and the one I'm leaning toward is the 350/330 horse. If I went with this motor, would I have to change anything on the drive train, or will all the stock equipment hold up OK?? Would I need a stall converter or not? I know the way they measure HP has changed over the years, so I'm guessing this motor would actually give me about 100 extras horses from what I have now. I'm guessing this would be a noticable power increase from the stock motor? If anyone has installed one of these engines in their Vette, please chime in on it's performance/reliability. I'm fairly mechanically inclined, but due to my job, I really don't have the time to rebuild the stock engine, that's why I'm looking at the crates. The car will strictly be used as a weekend street cruiser. Any info appreciated. Thanks in advance.
Kenny

 

Hey Kenny, welcome aboard.
That crate motor would definately make a noticeable difference and would pretty much bolt in. The rest of the drive train is strong enough, but I think I would make sure on some things:
U-joints, differential wear, transmission, how many miles on them?
A higher than stock stall conver will effectively give you some more sli allowing higher RPM launches, if your not going to run aggressively on the street or race its not needed, but would allow some more fun factor. This would be a good oportunity to think about changing the tranny out with a 2004R, it has a better overall gear set and overdrive.
Your exhaust will need to be changed to true duals in order to let the new motor breathe
that get ya started?

 

Welcome to the Corvette Forum Kenny!

I put a GM 350/330 HO Deluxe in my '80 6 years ago and love it. It dropped right in and bolted right onto the stock bell housing. (I have a 4-speed.) It's got more than enough power for spirited cruising with all the good manners of a street engine.

I put it in with the stock exhaust at first, but it really came alive when I switched to ceramic full length headers and true dual exhaust. WOW, what a difference! If your emissions laws allow, I recommend headers to get the most out of that engine.

The Vortec heads have centerbolt valve covers and most of the wire looms attach with the valve cover bolts. Look for adapters to mount the the wire loom directly to the block to clear off the top of the valve covers.



My only gripe is that the GM intake is ugly. I tried a high temp clear coat hoping to keep the bright aluminum look, but that yellowed. Maybe powder coating or ceramic would work. I think that was discussed in another thread not too long ago.

The stock air cleaner with snorkles didn't fit, so I have been using a 3" K&N open air filter on a drop base. That sucks hot air from the engine compartment which really effects how the engine runs on hot summer days. My winter project is to build a custom intake to pull air from ahead of the radiator. (Cowl induction isn't an option on an '80 without replacing the hood with a high-rise.)

The bottom line: Go for the GM 350 HO. You won't regret it if you want a cruiser with decent performance.

 

This past summer I was deciding which engine to go with from GMPP...the 350/330hp or the 350/290hp. After talking to my mechanic and to GMPP, the 350/290hp was a "direct bolt-in"...something about the rear main seal was a 2-piece (290hp) as opposed to a 1-piece.

I went with the 290hp for several reasons:

1) I had just purchased a somewhat expensive set of chrome valve covers with the bolt pattern being on the outside...and the 330hp had center bolt pattern valve covers. And I wanted to use the new ones. I know I could have gotten an adaptor for the valve covers, but I like to keep things simple.

2) I also planned to use my 75 Vert as a cruiser/daily driver and not a racer. Oh sure, every once in a while I would pound the pavements....but that was VERY seldom...so the 40 additional HP was not an important factor.

3) Cost. At the time, the 290hp (from Summit Racing) was $1699. The 330hp was $2,599. The $600 difference for 40hp? I know the 330hp has a little more torque...but I couldn't see the difference. The other day I drove a friend of mine's '77 with 350/330hp down the street and back to see if I would notice any difference. Honestly, I noticed a little difference...especially at the higher rpms (3500-4000)...but not enough to say WOW (like driving a Z06) And NO I didn't "dog" his car..I drove it like I drive mine.

I am very pleased I installed the 290hp. Hope this helps in any way...Good Luck.

Oh, one more thing...the warranty on a GMPP is FANTASTIC! (24mon/50,000miles). Initially I had some problems with the valve guide seals...took it into a GM dealer, they verified my information and fixed the problem with no fuss/no muss. Got it back that same day.

 

I have the 330 hp in a 63 nova and have been very pleased. I think the only mod to go in your vette would be the water pump. The 330 comes with a long water pump and I believe the vette needs a short version.
Good luck with your project.

 

Thanks for the responses. The previous owner had already installed headers, so I've got a set of those. My current engine also has an Edelbrock intake. I'm thinking I could reuse that on the crate engine if I get the stripped down version. Anyway, it's great to know people seem to be having great luck with these engines. Once I decide which engine to go with and have it delivered, I'll be back with a zillion questions for you guys. Thanks again,
Kenny

 

the only real issue will be the temp sensor may need to be relocated not sure how the 77 is on my 75 the stock sensor was wrong thread size for the newer head some poeple put it in the intake i did not like that idea so i searched around and found that the 82 sensor is the right thread and the right connector works on mine then new starter and water pump

 

Try Phoenix Engines...They have a bunch of options and I just bought a 350-355 hp from them which is a turn key motor for my 71 for $3500. This includes everything but the starter and alternater. Take a look on there website phoenixengines.com.

Good Luck

 

In one of my cars (not a Vette), I had a GMPP 350HO/330 hp engine installed with Edelbrock EFI..awesome engine. I do have to admit for a car that I simply use to cruise in it seems a bit overpowered.

A close friend with a '66 Vette installed a GMPP 350/290 and absolutely loves it. It's strictly a cruiser and he couldn't be more happy with it. The tired engine he took out of the was a 327/250 so the difference was quite noticeable to him.

 

If you have an existing Edelbrock intake on your stock engine and want to reuse it, you won't be able to use it on the GMPP 350/330 HO engine because of the Vortec heads. That intake is not compatible with the Vortec bolt pattern. That intake is compatible with the 350/290 engine as the heads are the older style 76cc heads and that bolt pattern.

 

If your 77 L48 was NEW and tested & rated same method as NEW crate motors are ... a new 77 L48 would make about 250 HP ... so you'd probably be looking at a difference of about 80 HP w/ 330HP 350HO.

Both TurnKey & DELUXE 350HO comes with small 153T flexplate for automatic. Pretty sure OE 77C3 has larger 168T regardless if auto or 4spd. Dunno if yours auto or man? Your 77 flex/fw will NOT fit those motors. If you have an auto then it's cheap to buy a new flexplate ... but new flywheel a good bit more $.

If it were mine I'd definately prefer the crates with vortec heads over the old style heads on 290hp. I'd probably prefer Base 350 HO p/n 12486041 ... it does NOT have any of the following: flex/fw, intake manifold, distributor, water pump, harmonic damper. Use your distributor & damper & carb ... but buy an intake, waterpump, flex/fw.

-edit- ... I've got f/s for under $100 ... a good used plain lowrise satin intake for vortec heads that'll fit under a low vette hood & has both spreadbore& squarebore carb pad ... EMAIL (no pm!) thru this forum only if serious. This'll fit 77 w/ 350HO crate.

 

The absolute best bang for the buck is the YearOne 350ci/400hp engine for 3000.00. do a search on this and other forums more then a couple installed and everyone seems happy. i'm getting mine from them.

No reason to spend 6 grand on a weekend motor. also i saw where you can get the 290hp gm motor for like 1800.00, some bolt ons and its 330hp for lets them 3k


http://www.yearone.com/serverfiles/f...crate&SM=2&SC=

rich

 

A lot depends on your budget and what you want to use it for. Both the 290 and 330 horse engines from GMPP are great engines. Remember, no matter how much power you have, someone has more then you!