68 Mustang Lacks Power

[captainmorgan]

I just replaced the motor in my 68 Mustang. It is a new 302 crate engine that dyno'ed at 352 HP. I also put a **** kit in the Auto transmission and installed a 2500 RPM stall convertor. It also has a new detroit locker rear with 3.55 grears. The first time I took it out I was able to spin the tires no problem. Now It just does not have any power . I adjusted the timing so that I have 36* all in by 2800 RPM. I took it out and the first time I was able to spin the tires and had full power. I tried a second time and no power again . Anyone have any ideas on want could be wrong?

Thanks

 

[jcode68]

Welcome to Stangnet. Gonna need some more information and description of the problem. When you say it has "no power", does this mean the engine bogs under heavy throttle? What other symptoms do you have? What carb and ignition system are you running?

 

[captainmorgan]

What carb and ignition system are you running?

I'm running an Edelbrock performer 750 carb and an HEI ignition.

What other symptoms do you have?

It idle's fine and seems to run fine until under load.

When you say it has "no power", does this mean the engine bogs under heavy throttle?

Yes

Thanks

 

[jcode68]

Strange if it is intermittent. Speaking from experience when I first got my new motor running, double check that you have the correct firing order for your cam. There are 2 different firing orders for the small block. I was off on a couple of plugs and although it seemed to run well at idle and would rev just fine, driving it was completely different story - no power and would run sluggish/bogged. If this engine has been running great, but just recently started with this problem, then I would start looking for things like fuel delivery problem (clogged fuel filter), vacuum leaks, fouled plugs etc.

 

[zookeeper]

Things to check also include the throttle linkage. When I first got my fastback running, I drove it conservatively for a time, then after a few miles, I stabbed the throttle and...nothing. I did a check and found it was gettng less than 1/2 throttle. A quick adjustment to the linkage and I picked up about 100 hp.

 

[captainmorgan]

Things to check also include the throttle linkage. When I first got my fastback running, I drove it conservatively for a time, then after a few miles, I stabbed the throttle and...nothing. I did a check and found it was gettng less than 1/2 throttle. A quick adjustment to the linkage and I picked up about 100 hp.

That was the first thing that I checked. It does seem like it is not getting full throttle but it is.

 

[jcode68]

Have you pulled your plugs to look at them yet? Might help to tell if it is super lean or too rich. We will need more clues to help you figure this out. Keep track of the cylinder each plug is removed from.

 

[captainmorgan]

Should I pull all of the plugs? I pulled one and it is clean. No brown at all.

 

[jcode68]

Yes, pull them all and lay them out on a piece of paper labeled with the cylinder number they came from. This way you can see if you are having problems with any particular cylinder. Report back what you find - a picture is worth a thousand words. If they are all white, then you are running very lean. This may not explain the power loss, but is good to know and something that should be addressed.