Questions concerning lack of power after 4K

[GRM-REPR]

Do you happen to have a fuel pressure guage before the carb?

No, hadn't installed one yet, not a wild set up. I know I need to purchase one though.

I pulled a plug and it's not WHITE but it's not black, the plugs look normal to me.

In connection to what Wrath is stating about the carb getting enough air, I had thought of that last year. The original shaker hood scoop is matted to the hood, so I don't have the original air cleaner assy that drew fresh air from the outside. I had to cave in and put a Ebrock (heart shaped) filter on. I can't run anything bigger than probably 11''. It's awfully tight under the hood.

Could the problem just be the lack of incomming air to the carb? Thanks for all the responses.

[torque.hit]

The plugs could return to a normal color if you let it idle though, you wouldn't know if there was enough fuel above 4k unless you shut it off during a hard run and then checked the plugs.

[GRM-REPR]

The plugs could return to a normal color if you let it idle though, you wouldn't know if there was enough fuel above 4k unless you shut it off during a hard run and then checked the plugs.

Makes sense

[torque.hit]

Depending on the mileage of the rebuild, I'd put my money on fuel delivery or valve springs. Even when my motor had terrible timing it would still rev to 6k, just pinging the whole time.

[DurtyKurty]

I'm gonna guess too much lifter preload.

[GRM-REPR]

Well, my friend has a Holley Blue fuel pump (brand new) going to toss it in and were going to inspect and adjust the valves on Saturday. I will update then.....

[GRM-REPR]

Huhhhh.

Ok, I tossed in a new fuel pump my friend had, turns out the one I had on it had a small crack in it.

So now comes the b.s......

I followed a valve adjustment procedure to the T. I started at number 1 cyl and completed one side of the engine first before moving to the next (per instructions). After finishing, I started it, I could hear some ticking from the valve covers and I could sense a change in the exhaust note (cam didn't lope very strong). So I went back and turned each nut in about a 1/4 turn each.

I started it once again and the engine ran like crap. It sported a "bubbly" feel when I snapped the throttle linkage. So I went back AGAIN and backed each nut off 1/8 of a turn. It seemed to run better and the exhaust note sounded stronger.

However, when I went to take the car home it ran fine but when I got off the freeway, it ran like shit. The engine was somewhat surging, almost like a miss. When I went from stop to start, it felt very sputtery (sorry, best adjective I could think of). So I richend the carb a bit, seemed better but certainly not right still. When the car is cruising it feels fine, stop and start, not fine at all.

WTF did I do or didnt I do right or where do go from here. I'm pretty new to putzing with Chevy engines, especially adjusting valves and tuning carbs. Sorry to sound like an retard but naturally by adjusting valves, it would throw off the tune of the carb? It just feels way wrong.

Any help is appreciated.

Thanks.

[torque.hit]

If you set the rockers too tight, they open the valves off of their seats, killing your cranking compression.

You will probably want to reinstall the rockers. I am having trouble finding the proper procedure for you.

[GRM-REPR]

True, when I crank the engine, it feels "odd". After setting zero lash (spinning and pulling up on push rod while tightening nut), I turned each nut in 3/4's of a turn. After I had done that and started the engine, thats when it didn't sound right out of the exhaust.

This procedure I followed is the same one my friend uses successfully, don't know what I did wrong.

[GRM-REPR]

I went back and started all over again with adjusting the valves. I read two of the same articles and they explained the procedure the way I did it yesterday. I must've messed up on a couple of them because now it's super smooth. In fact the engine was never this smooth before. For all I know Engine Rebuilders didn't take good care of the rebuild because of conflicting interests.

It pulls better but it still comes up somewhat short on the high end. After getting much help here and throwing a fuel pump and valve adjustment at it, I'm really starting to lean toward the carb not getting sufficient airflow, if I didn't know any better, I'm not sure the secondaries are even opening, I never hear them. The scoop when closed over the air cleaner completely seals the air cleaner. Plus with all the engine heat rising to the top, it would almost make sense.

Thanks for all the help.

[WickedSix]

I have been trying to dig up the article from a corvette forum about valve float and hydraulic lifter preload..... but basically it is the same as what you have done but only 1/2 turn after you feel friction in the pushrod. The 3/4 comes from chevrolet and acts as a mechnical rev limiter in a sense due to causing valve float at a lower rpm.

IMHO what you need to do is start adjusting ONE thing at a time if you keep throwing a couple things at it and you fix it you'll never learn what actually fixed it.

Start by setting one of the variable ... like say timing....and then adjusting the carb until you get the best results. The leave the carb alone and adjust the timing until you get the best results..... basically you are trying to weed out what does and does not affect your problem on your engine. By being methodical you will have more insight into diagnosis for the next time.

[forest]

I went back and started all over again with adjusting the valves. I read two of the same articles and they explained the procedure the way I did it yesterday. I must've messed up on a couple of them because now it's super smooth. In fact the engine was never this smooth before. For all I know Engine Rebuilders didn't take good care of the rebuild because of conflicting interests.

It pulls better but it still comes up somewhat short on the high end. After getting much help here and throwing a fuel pump and valve adjustment at it, I'm really starting to lean toward the carb not getting sufficient airflow, if I didn't know any better, I'm not sure the secondaries are even opening, I never hear them. The scoop when closed over the air cleaner completely seals the air cleaner. Plus with all the engine heat rising to the top, it would almost make sense.

Thanks for all the help.

I would be surprized if Donny didn't do somthing right on the motor because of problems between you two. He would do the job right, just to tell you never to come back in again, he doesn't need problems that can easily be avoided. But on the other hand, everyone makes mistakes, and it would be possible that somthing got overlooked. Try adjusting the valves while it is running, and you will have GREAT results with the valve adjust, just a lil bit oily haha. :

[slow90z]

If the carb is a double pumper, why not have someone floor it with it not running, and look down the carb n make sure the secondarys open all the way...
Otherwise, by how you're describing it, it really sounds like valve float to me. And i know it isn't the distributor you got from me, because i was doing 7000+ rpm with that same hei, so that can't be it...