here is my question, does this sound like it should be a descent combination for some power. in my 74vette i have...a gmpp 350 short block,edelbrock performer rpm cam,gmpp vortec heads,edelbrock performer rpm intake,holley 600 street avenger carb,crane blue full roller rocker arms,converted heads to screw in studs,hooker super comp long tube header going back to pair of flow master 40 series,B&M 3000 stall,rebuild 400 turbo,4.56 gears i just picked this up from shop on friday after months of being their and i ask shouldnt this combination at least be able to break the rear tires loose? does not feel any more powerful then did before though i am now out 5k. unsure where to go from here the only items that reused of mine were the carb(basically new when i brought it in) and mr gasket 12s electic fuel pump. is this a lost cause or am i missing something obvious.

Without the numbers on the cam and some of the other stuff i'm only guessing here but............................. Possibly you've built an engine with an awesome top end and only moderate low end. Your carb sounds good for low end but some of the other stuff sounds more like higher rpm. Does it really wake up when you spin it a little? Like maybe 5 grand on up?

cam specs are
Basic Operating RPM Range 1,500-6,500
Intake Duration at 050 inch Lift 234
Exhaust Duration at 050 inch Lift 244
Duration at 050 inch Lift 234 int./244 exh.
Advertised Intake Duration 308
Advertised Exhaust Duration 318
Advertised Duration 308 int./318 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.488 in.

less then 500 miles on it so i gotta take it easy. but cruising at 50mph pulls almost 4500rpm. i know not good for a break in. but i did hammer it once off the line and got nothing would not even break back tires loose i figured with that 4.56 rear it shouldnt be a problem. trying to figure out where i went wrong on this engine i thought for once i did everything right. To be honest my wife has an 02 WS6 and my only goal is to finally beat her i cant put into words how this irratates me, i worked on this car to get it perfect for 8 years she gets the trans am and kills me with the ac on and radio playing.

I think the super comp headers probably have big tubes, like 1 3/4 or 1 7/8", too big f/ the components. Also, 4:56 gears would work w/ a big block, but are too much f/ a small block. The engine is probably almost wound out by the time you hit the gas. But it should run alittle. Maybe the valve adj. or timing...?

Everything looks reasonable so you should be able to spin the tires pretty good. I agree w/Jim the headers are probably costing you low end torque.The 600 cfm carb will hurt your top end but not until 6 grand or so. The 3 grand converter should get you above where the headers are holding you back. The only time I have seen a situation like your is when the guy had the cam a couple of teeth off,the thing started and ran good,just didn't make any power. That's pretty tough to check w/o pulling the timing cover. Did your mech degree the cam? That's pretty much essential for what you're doing. Only other things I can think of would be ignition timing or the valves set way too tight as Jim suggested.
I would think a 4.56 would be more likely too much for a big block and pretty much spot on for a smallblock unless you wanted to run 4.88's or 5.12's. I ran a 327 with a 3 speed in front of 4.56's in a 3000 lb Studebaker and won a stoplight grand prix or two back in the 60's.
Please let us know what you find out!
Ron

Hi,
I have almost the same set up in my 74 except I have a 4speed with a 3:36 rear.
You should be able tear the tires off you Vet with that rear.
I will say this my Vet ran like crap until I found the Vac leak and then set the timing right.
The difference was like night and day.
The vac leak was internal, bad manifold causing me to run lean plus my timing was at 10 instead of 8. Another thing to ckeck if you have electronic ignition your plugs should be gapped at 41 not 35.
Doesn't take much to lose power.
Good luck,
Schoon

I'd say that the last two replies are correct, something like the timing, vacuum leak, etc. Ofcourse all the vitals need to be checked, to include reading the plugs, so that anything major should be taken care of first and then tune-up and so on... The car should run pretty well w/ what you have in it. But I have to say that, again, those are big gears f/ a small block in that 'Vette. If you're speaking 1/8 mile, then the 4:56 ratio would be the one, or very close. But f/ a (approx.) 1/4 mile, those gears are too big. The shorter stroke in the small block, as opposed to a big block, will allow you to make quicker hp, w/ those gears, you're up to the red-line f/ your cam super quick, and in a 1/4 mile, I'd say that you're wound out before the line comes up f/ you. If you had a 4 speed (over drive) automatic, then those gears would work better. I know that 6500 rpm comes quick in that car. w/ those gears. And the suggestion f/ a bigger carb IMO was correct also, and IMO an intake w/ it. What exactly are you setting the car up to do? ie; 1/4 mile or 1/8 mile? I'd say though, it sounds like you have quite a car, and w/ all you've done, and w/ the small things ironed out, I'm sure that it'll run great. I'm in NO WAY knocking your car, just don't know what you're setting it up for. Good Luck and please keep us posted.

I am thinking 3:73 gears would work best for you.
I have 4:10 gears and I am red lining just before I finish the 1/4

Schoon

I agree, it depends on what your driving demands are.
In my case I have a "long range bomber". LOL
I have 3.07s, 70 mph at 2400 to 2600 rpm.
Installed the 3 sp stick w/ overdrive.
My engine is built for mid to high rpm power band.

I agree, it depends on what your driving demands are.
In my case I have a "long range bomber". LOL
I have 3.07s, 70 mph at 2400 to 2600 rpm.
Installed the 3 sp stick w/ overdrive.
My engine is built for mid to high rpm power band.



Yes, I seem to remember that you have one of those engines that you had to grease the sides of to drop it into the engine compartment. LOL! You know, even w/ my 'Vette having the 350 and w/ the smog pump and lines removed, I still find that the easiest way to change the plugs is "4 from the bottom and 4 from the top." A big block in that same compartment trips me out, as the amount of clearance is next to nothing.

Yes, I seem to remember that you have one of those engines that you had to grease the sides of to drop it into the engine compartment. LOL! You know, even w/ my 'Vette having the 350 and w/ the smog pump and lines removed, I still find that the easiest way to change the plugs is "4 from the bottom and 4 from the top." A big block in that same compartment trips me out, as the amount of clearance is next to nothing.

I found that, while doing 70, if I drop to 2nd and drop the hammer she REALLY comes alive.
Haven't had to change plugs yet but it should prove to be an interesting task. LOL
We shall see......

I found that, while doing 70, if I drop to 2nd and drop the hammer she REALLY comes alive.
Haven't had to change plugs yet but it should prove to be an interesting task. LOL
We shall see......

LOL! You don't say...That 'Vette comes alive w/ that 454 in it? And w/ alittle vasaline, the plugs will slide right under the hood, and then stop, and from there you'll have to be Houdini to install the eight. LOL! In around '72, my brother bought a late '60s Sunbeam Tiger w/ a Shelby 289 in it. It had come w/ a 260 in it, same block, and my brother swapped it out f/ the 289. From the factory, there was a small hole, about 2 inches in diameter, in the front of the passenger side floor board, just below the fire-wall (where the floor pan turned up to form the fire-wall), that allowed f/ a 3/8" drive rachet to fit through to change out the rear spark plug on that side. That was the tightest engine fit in a factory design that I have ever seen, very clean and set up very well though. It was a cool car overall also, w/ the wood dash and steering wheel, basically a European style interior, but w/ an American V8 that made the car run well. My brother installed 2:88 gears in it, and w/ the 4 speed, it was a heck of a highway car. Anyway Starship, I suggest that you buy about five different brands/sets of plugs, and change the sets out after a short drive w/ each to first read the plugs and then/also see which brand runs the best in your particular car. Ofcourse that's the only way to find out for sure which brand will make your car really run to it's fullest potential. LOL! I'll send you some grease if need be. LOL! I'm sure that the changing of the plugs will be a breeze. LOL! (There is probably an easy system to that, as surely someone has figured it out by now.) :)

No clearance for grease, silicon spray on the hand should clear alright. LOL
Ya Texas, I'll look into dif plugs, but that's for another tread.
We've hijacked this one long enough. LOL

hey what was the resolution to your problem

hey terl30 forwarded this post to another forum heres the link.
hope it helps. by the way I've had this happen to me so i feel your pain. if you don't mind let us know what ended up happening.

http://forums.chevyhiperformance.com/70/8407406/car-engine/engine-rebuild/index.html

As some of the members said earlier do not overlook a vacuum leak. I have a GMPP crate long block in the Vette. I added a Weiand intake and when I fired the car up it had no power and had so much hesitation that I thought that there was an anchor attaced to the rear bumper. I put about 50 miles on the car and knew I had to do something to find the problem. I realized that I could smell burning oil fumes but it did not smoke. I took off the oil filler cap and could smell gas. I removed the intake and could see where the machined surface did not fit properly against the head surface at number 6 and 8. I had a big time vacuum leak. It was pulling mass amounts of oil fumed air into the cylinder and letting fames into the block.

Thanks everyone for all the help. I swapped out the stamped rockers for scorpion 1.5 full roller rockers(no difference),Blocked off all vacuum lines except pcv/break booster bypased everything else to elminate leak(no difference).only thing left to think of is maybe the electric fuel pump if not flowing well under a load(auto zone MR Gasket inline electric) or the powers that be just do not want me to have a faster car than my wife(02 ws6 this is THE ENTIRE reason for this build my wife cannot have a faster car than me :)

hey terl30

not only have i had a engine rebuilt that ended up never being right(86 Z\28)
i recently bought a corvette that the owner said was a recent rebuild at 400 horsepower and my little brothers stock 99 t\a smoked me in recent race. at least mine will ALWAYS be worth more! lol

so keep us informed on what your vettes outcome is


thnx
scrappy78

terl30: Have you checked fuel pressure?

It's got to be fuel, air, and/or spark/timing. Eliminate one at a time.

terl30: Have you checked fuel pressure?

It's got to be fuel, air, and/or spark/timing. Eliminate one at a time.

here is a vid of the engine starting http://www.budgetpc.org/vette/IMG_0263.MOV

was thinking of ordering a summit fuel pressure gage tonight any recomendations?

Couldn't open video. Fuel pressure would be a good check to make.

nice day outside so i decided to take her down the block for a little ride. After i got back to the garage and let sit for 2 or 3 minutes and tried to restart its as if battery was dead or dying cranked real slow and did not start. when i put it on jumper box it started right up and ran fine. the alternator is brand new and shows charging battery is 4 days old new optima so i know that is not issue. could starter be getting hot from those big a$$ headers i got on this thing? would that make it drag real hard and not want to start?

Could be but also could be a bad connection or too much advance. Don't know what the engine parameters are. I'd check all the primary 12V and ground connections. Also see what the voltage does while it's cranking. Use a meter as the gauge isn't that accurate.