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 air gap
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 2600 stall
rebuild 400 turbo
4.56 gears

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.

Cylinder Head Style Assembled
Cylinder Head Material Cast iron
Cylinder Head Finish Natural
Combustion Chamber Volume (cc) 64
CNC-Machined Combustion Chamber No
Intake Runner Volume (cc) 170cc
CNC-Machined Intake Runner No
CNC-Machined Exhaust Runner No
Intake Port Location Standard
Exhaust Port Shape Square
Exhaust Port Location Standard
Spark Plug Style Straight
Intake Valves Included Yes
Intake Valve Diameter (in) 1.940 in.
Exhaust Valves Included Yes
Exhaust Valve Diameter (in) 1.500 in.
Valve Springs Included Yes
Outside Diameter of Outer Spring (in) 1.250 in.


This combination is directly what edelbrock recomended for performer rpm power package(of course with edelbrock carb not holley) the gmpp
heads were same specs as edelbrock aluminum heads just cast iron and 800 or so $ cheaper.

I cant even break the rear tires loose with this combination although the idle is awesome. when it is hot after driving a few minutes very slow and hard to start almost like dead battery even though battery is two weeks old. unsure where to go from here being it is a vacuum secondary carb when i open throtle without running i only see front jets opening. unsure what to check now...

 

too much cam

 

http://www.carcraft.com/projectbuild...all/index.html

Have you seen this

 

This is the performer RPM power pack from edelbrock i consulted them to make sure the right parts were ordered. Obviously they cant support Holley carbs so i was wondering if this could be a problem. I just need some help on what to check the engine is 9.25compression and with 64cc heads it should make 390hp so 330ish or so to rear. now that is substanitally more then the stock l48 and that would break the rear tire loose. I paid an exremly large amount of money to have this engine built and would just like some help. If no one know has any idea could you please let me know where to go or who to call. I am scared to call back the shop as i only have 160miles and was told under no circumstances to go over 50 or get on it for 500 miles. but after being away from me for 6months i was so excited to get it back i had to hammer it just once....

 

Sounds like you may have some carb and timing issues,the stock L48 should have no problem spinning those rear wheels with those 4:56 gears.As for your engine builder's break in advice,toss it.After the fluids are up to temp,drive as you intend to use it,just keep the rpms and load to a reasonable level.

 

Well since you've already got the package we just need to get it tuned as best as we can. Definitely not the cam I would have used and the heads are OK. Not sure if they spank the Edelbrocks..but they are OK.

Need to start with a compression test. You don't have enough compression to make that cam really work well in the first place and we need to verify that at least it's installed right.

Next...what valvesprings are on those heads? Can they handle that cam? Hyd cams don't RPM that well anyway, but need decent springs to get close.

Intake is fine.
How big are those headers?

The carb is also not what I would use on it, but it can be made to work OK. This setup is begging for at least a 650...preferably a 750 DP Holley. Even a 600 DP would do OK...but the dual plane will like the bigger carbs and your gearing will make it easy.

You won't see the rear barrels open. Mash the pedal to the floor (engine off) and then see if you can manually open the rear barrels at the linkage...either on the driver's side where the little slot and link is or on the right side where the diaphragm assy operates the rear barrels. Just want to make sure the linkage moves free and no gasket is holding it closed. Make sure choke is opening all the way. If not it will hold rear barrels closed. Often a problem with regular chokes and headers.

If nothing else you will likely need a spring change in the vacuum can. Either get a quick change kit from Holley to make it easy and/or get the springs from Holley to let you tune. Start with lightest spring and see what happens.

What is total and base timing set at? Need to be in the 32-34* total area (no vacuum advance) and all you can get at idle. Maybe 18-20* with no vacuum hooked up.

Definitely need to find out what the electrical problem is. Low voltage isn't going to allow the ignition to do its job.

That will get you started. With your converter and gears you should have some incredible seat of the pants acceleration out of this thing even with the mis matched combo of parts. We just need to get it set up right.

JIM

 

What distrib. are You using? What is Your timing at? How was the engine broke in? Is there any popping noises from exhaust or intake? This should easily break the tires loose even with the original L48 motor. Be patient and You will figure it out with the help of this Forum.

 

i am using the stock distributor with a protronix insert to convert to hei so i could keep the tach drive. it is set at 14 degress as per edelbrock recomendation.I used the edelbrock springs that came in the cam kit.The headers are Hooker Headers #520-2456
Competition Headers
1955-82 Corvette 265-400
1-5/8" x 24" Primary Tubes
3" Collector
High Temp Black Paintfrom jegs. i am not sure how the engine was broke in after being at shop since march on oct 17th i got a call and said it was ready for pickup.im sure if i wouldnt have paid all up front they might have got it done quicker. The carb linkang on side will open secondaries when i push the down with a screwdriver. I did run out of money towards the end and had to use a cheaper autozone electric fuel pump...edelbrock told me to make sure the rockers were only adjusted 1/4 turn not 1/2 or 1 turn. if they did this wrong could it make a difference?? i appreciate the help on all this guys i have had a 84/86/97/98 and now this 74 and i tell you why wife calls me the corvette jinx i love them but they sure HATE ME. the 84 was first and most problomatic of all the 86 had ton of electrical problems the 97 was broken everywhere and the 98 ran perfect but i got hit by some dumb kid before the temp tags even expired so i thought it would be cheaper and less problematic to get a early 70's WITH NO computer euipment at all. To be honest i just want for once to be able to take my wife's 2002 ws6 it is bone stock and has run circles around everything i have owned.........childish i know but im 37 and finally am sucessful enough to start reliving lost days of youth :-)

 

my little yellow 74 at a local show

 

When I worked at a PD the cars that were babied during the break in period ran like dogs the rest of the time that we had them. The ones that were driven as we would normally drive them always seemed to have more power and were more reliable. Ford later told us to break them in as we would be normally using them. Once we did that they all performed better.

 

well i only did that for the first 160 or so miles now it is parked until i figure out this issue better to park it than chance breaking messing something. Then i want to paint dual black strips down the street................

 

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Also here is a vid of me starting it up it does sound good just no power.

 

i was gonna try readjusting rocker arms tonight i was told i need to go to earch rocker arm and loosen it until i head a clatter then slowly tighten until it stops then bump it 1/4 turn. is this right? is it ok to stick a piece of cardboard so oil doesnt splash everywhere.