Ok all you engine gurus. A friend of mine had a machine shop put a motor together for him and it is installed in his 70 Mustang. It is a 302 +.30, TRW-L2249NF pistons (high compression), Comp Cams Extreme energy with 493/500 gross lift, 262/270 duration, 218/224 duration @ .50, 110 deg separation, 351 heads, only # he can find is D00E, eddlebrock performer intake, Eddlebrock 1406 carb (600 cfm), not sure what headders, C4, stock converter, 3:25 gears. The car runs good but really has no power. It will not spin tires even when power braking it from a stop. We are about to tear it down to see what we can find but I thought I'd give you guys a shot first. Any ideas?
Timing? Maybe. Sounds like its too retarded. What is the compression? If the heads arent ported I wouldnt expect too much from the motor especially if the car is heavy. My friends 70 Mustang Mach 1 weighed 3600 LBS with a Cleveland.
My car used to not power brake at all until I changed the tranny fluid and tightened the bands. It would just keep rising in rpms all the way to 5200 but never move the tire. Now it powerbrakes like a champ. Does it sit at low rpms and refuse to throttle up or does it climb but fail to break the tires free? Personaly I would do everything I could that required little work before tearing the engine apart. Compression check it, check the plugs for lean or rich running, check timing, look in the oil for a shiney metallic film that used to be your cam, ect.
From the specs of it, the car should run pretty decent for a street car. A good ignition system which is properly setup is very important. Within that, timing and degrees of advance. What distributor is he using and is the vacuum advance working properly? Secondly, fuel delivery is key, will it fill a pint container in 10 secs out of the fuel pump while engine is being cranked via starter? Just a couple easy things to rule out first. I would tear down the motor as a very very last resort. Dan
How does it accelerate when the car is moving? If it runs well from a roll, the converter may be a little on the tight side.
Did the shop that built the engine degree in the cam? Also did they check the pushrod/rocker arm geometry. This set up was notorious for having incorrect pushrod length especially if the heads were milled. I think the converter and the performer manifold could be the culprit. Should use the RPM manifold for a little better breathing with those pistons. May have to go a little deeper in the rear to get it to the power band. So many things that have to work together to get maximum performance. If you are not running adjustable rockers, the valve lash could be to tight with the stock set up. Ran similiar set up for years and had much low end torque with the RPM manifold and a 2500 stall converter and deeper gear. Good luck and keep us informed as to the fix.
I agree with Old Guy. I would wonder about the timing and degree of the cam. That is assuming the distributor is not out of whack. Tha is assuming that there is nothing funky with the carb, it may not be getting fuel/air vapors. That is not far from my setup. My CR is around 10.5:1 with hyper flat tops. My valves are 1.94/1.6 and my cam is a XX290 by Holman Moody- 470/474 lift and 280/290 duration. Mine is supposed to be around 280-290 at the flywheel. Could his lifters be bad? Seth
I had the same problem on a similar setup when i first got mine going. It turned out that my D0OE heads had been milled, and since the rocker arms are the type that you just torque down, the valves hung open a little bit. I fixed it with a kit from PAW that converts the stock rocker arms to the adjustable type. It cost $30. Just a thought.
Thanks for all the replies. I suspected that the cam was not set properly but then you would think a compentent machine shop would know how to install a cam. He does have adjustable rockers. He is running Mallery ignition set up. The RPM does not climb when powerbraking (I forget where it stopped). The car runs very well under all conditions except it just dont have the power I thought it should. I will just have to get him over here so we can go over it.
I,ve got them at home dennis I'll post them later for you, stock and ported. I didn't realize cleveland engines weight that much more than windsors. My 70 mustang fastback weighs 3150 lbs with A/C.
As degreeing in the camshaft goes The camshaft would have to be pretty far out of sync to make it that gutless unless the chain is off one link Check the basics of the timing again like the advance curve from the mechanical advance , make sure the vacuum advance works and check the total advance . I almost forgot ..... Small block fords are famous for the vibration dampener outer ring slipping so make sure that isnt ruining your day .
another thing to consider is the earlier (69-75) 351w heads have larger intake ports than the 302 heads did. The larger ports don't like smaller engines/big cams and bottom-end torque tends to suffer some. I know this well...Just put another motor in my mustang with '75 351w heads, 1.94/1.50 undercut valves, 10.1:1 compression and a 226-228 .512" hydraulic roller, and it's dead on the bottom end for the most part. Pulls well from 3500 to about 62-6500 but the low end totally sucks. the 5-speed helps a LOT to get it up into the revs, as do the 3.73 gears. Another thing to consider is ignition timing...if it's too far retarded bottom end will be real sluggish but will pull well up top. I'd try advancing it until there is a slight ping (with regular fuel) then retard it just a bit for safety's sake. Now that being said, if the damper ring has slipped and the marks are off (which is very common) you can set the timing by ear. Warm it up, and with the engine off advance the timing just a little at a time until it starts to kick back when you try to start it. Seems to work well for most 302's. I would bet that this should help it a lot. Even our old non-adjustable valvetrain 302 with a 239 @ .050 and 9.2:1 compression would smolder the tires pretty easily. Good luck and keep us posted!
