I just got the 77 back on the road after 4 year body off restoration. The engine build was guided by Mako, BK Broiler, and others on this forum and lots of reading and studying. I spared little expense to build what I thought was a good engine. I thought it would be torquey strong motor, and I guess truth is, that its strong, especially when you get it up in the RPM, but I thought it would pin me back in the seat and break tires loose when I pushed the pedal down. Now to be fair, so far, I haven't pushed it past 3500 RPM, so maybe I just need to nail it, but I was hoping for more without doing that.....maybe I should have stroked it to 383 like original plan. Here is the build:

- New GM ZZ4 short block
- AFR 180cc Heads, 65cc Chamber 10:1 Compression (015 gasket)
- GM Factory Hydraulic Roller Lifter system
- Comp Cam Extreme Energy XR270 Roller Cam (218/224, .500 lift, 110 LSA)
- Comp Cam Ultra Pro Magnum Steel Roller Rockers
- Edelbrock RPM intake
- Quadrajet rebuilt by Lars (with the above engine specs)
- DUI Performance HEI Distributor (timed to 35 degrees)
- Stainless Works 1-5/8 inch long tube headers / 2-1/2 mandrel bent exhaust system
- Borg T-10 Rebuilt Original 4-speed transmission with 3:55 differential; New Spec Stage II Clutch

I guess I am looking for any comments. Did I expect too much, or what could be wrong?

 

Well, tho the changes you made to the engine and exhaust don't mean much to this old fellow..Sounds like you took great pains to put together good components that complement one another.
You didn't mention clutch/pressure plate changes-upgrades..
FWIW. I'M not certain exactly WHY you feel like performance has much if anything to do with burning rubber..
Assume on a new engine there's some breaking in period..Have you done a simple 0-60 mph time from standing start?.
How does the car feel when you drive it../?
It's not set up for a 1/4 miler that'll run in the low 12's..but it is a fine build sounds like and a tribute to many hours and dollars of effort..
May not blow the doors off many current cars of lesser lineage..(WHO would you be impressing and WHY?)
BUT it's yours..and your work has not only brought it back..but enhanced it..
So from one older fellow..relax.enjoy..Run good gas with No ethanol..Jim

 

3500 ain't even opening the carb. up.
step on it. if you only Dyno a motor after a rebuild to 3500 rpm,
would not give satisfying results either.
good machine shops nail it ... right after assemble on the dyno.

 

should be a fairly strong street motor... get a few miles on it and turn it loose ...you can 't tell at 3500 rpm.. you're no where near peak power ... STAND ON IT! Your secondaries aren t even opening yet.. the primaries are tiny.

 

Make sure the secondaries are opening. You may have to adjust the throttle cable (or bend the pedal rod) to achieve enough travel to open them.

 

Three answers all alike in 1 minute. maybe we're correct!

 

Sounds like you want big block torque out of your ZZ4 having not taken it past 3,500 rpm. Are you open to taking it into a shop to get tuned and dyno'd? They're gonna rev it past 3,500 for sure

 

It certainly ought to run decent. That's easy 12 sec material in parts. Something is out of whack on tune, secondaries etc. But yes...definitely need to rev it some.

From a roll with similar small blocks I usually push in the clutch and rev it to about 5000-6000 and dump the clutch again. This gets the tires spinning a little and lets it begin a climb back up to RPM.

But as mentioned...a mild 350 is just going to do so much.

JIM

 

Well a dyno tune is really all thats left to do. U will be surprised how much a few degrees of adv timing makes. And a dyno is a tool to optimize that and fueling.

Sorry if this sounds like a lot more money but if u shop around u should be able to find a dyno shop that tunes carbs. Carb engine cars really don't have to hold RPM and can use WOT pulls which should be faster/less dyno time.

Good luck and let us know what you find. BTW I think u have a good combo there now u need to tune it which takes patience instead of parts.

 

Thanks for the responses so far. Yes, I want to get it on a chassis dyno. Anyone know a good one in the western Pennsylvania / Ohio / West Virginia area? I was wondering if anyone does decent dyno work at Corvette Carlisle?

I have to add that throttle response is awesome, Lars did a great job on the carb, it has no bog, very quick on the throttle, no flat spots. And yes, I am getting full throttle, and the secondaries are opening mechanically.....I just have not stomped it yet to see what happens when they do going down the road. And now that I am past 500 miles on it, I feel okay on stomping it. Maybe all the doubt will disappear once I do that. I know that from 2500-3500 its accelerating good, so I suspect the 3500 -5000 is going to feel good. But I have to be honest, I am also approaching higher speeds on the car carefully, since I am not a trained driver AND the last thing I want to do is lose control of it. So far at 75 mph the car is solid, no vibrations, and stable.

Most of my "disappointment" is probably just comes from my resistance / fear to pushing the motor to where the power really is. I need to get over that, don't I? I probably am more a guy who likes big block torque, and I almost started with a 383 build for that reason. But at the time, I thought about all the pluses and minuses, and the factory ZZ4 short block pushed me to just build a solid 350.

In the end, as long as I am tuned correctly, I will be happy with what I have.

 

I just want to make sure I have the right parts, like I thought I did, and then, get it tuned where it needs to be. I am going to need help with that.

 

I believe that recipe is not going to come on really strong until after that 3500 you have been taking it to,

Food for thought, my 69 automatic unknown rear gear, 383 built by a known race engine builder didn't have any low end torque to speak of didn't come on until 4K and then hit like an afterburner, ( I love saying afterburner ) and yeah, it pushed you back in the seat, but didn't really like spinning a 265 50, and cruising around it felt crappy, it would have been way better with a stick.

I didn't like the engine I wasn't gonna be taking it to the strip to rev the heck out of it and for the way I used the car the power band was all wrong,

I swapped it for a mild 454 it will put you in the seat, it will melt the tires if I didn't get off it, ( spinning aint winning ) and it rumbles through the side pipes that you can feel standing next to it and just has to be uber fast right? no, The 383 would have ran a lower ET in the 1320 but that wasn't where I drive.

I believe you will be happy with your build if you do not mind getting into the throttle.....

 

Generally the smaller the SBC, the more you gotta wind it up to get the power. Are you using the stock GM roller lifters or aftermarket pieces?

 

Factory OEM GM roller lifters.

 

Check out Back Street Performance in Medina, OH. They are who I go to for all my customers LS tuning and they run the mobile dyno for the race events at Mid-Ohio. Very knowledgeable group of guys and do great tuning.

 

Lean on it and break the rings in......it will make more power once it is sealed up.
Is this a four speed car?
That is an easy 400+ horsepower setup......
Get it to a dyno and dial it in.......

Good luck

Jebby

 

It will probably feel a little lazy below 3500RPM. I spent a lot of money on my 427ci and took it to a chassis dyno a week after I put it together and spun it up to 7000RPM.

You are not even spinning it up enough to seat the rings. Take it out and rev it up to at least 5000RPM and report back your feelings.

From the parts list it is not going to be a screaming small block but tuned properly it could be enough to keep you happy

 

You need to get the rpm up on that thing - your cam is just starting to work at 3500 rpm, and the carb secondaries aren't even close to opening up at 3500. We usually start our dyno pulls on a new engine at 3500. Take that thing out and hammer it through 1st and 2nd gears with some WOT runs through 5500 rpm - you need to do that to get the rings seated. Only then will you have a feel for what it's going to run like. Heck, 3500 is just above normal cruise rpm...

 

Yes, rebuilt factory rebuilt Borg T-10, with 3:55 differential. Based on the desktop dynos I accessed, I thought it would be 400 HP. Thanks for the input.

 

Will do.