sluggish 451?

[Garys1969RR]

I have a 65 Belvedere thats supposed to have a 451 in it. It is a 400 block, haven't measured the stroke. Eddy Perf RPM Heads, mild cam, stock rocker gear, 9.5 to 1 C/R. 4.30 posi in the rear. It's getting 210 to 220 PSI compression on all cylinders. But this thing won't even break the tires loose in 1st gear! No smoke, timing is right. I am now thinking maybe the timing chain is off 1 tooth. If the cam was advanced 1 tooth, that would account for the high compression pressures, and the strong exhaust pulse coming out of the ex pipe. As well as the low power output. Any ideas? I plan to pull the front cover saturday and check the cam timing. Something not right here.

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My 451 in 69 RR also is getting 220 cranking pressure on all cylinders. It will fry the tires in 1st and 2nd gear. With 3.91 Posi. Runs mid 12 sec 1/4 mile.

 

[Jeremiah]

When you checked the plugs what to they look like? Also did you verify you are getting full throttle at the carb when you floor it?

Initial and total ignition timing?

With that kind of cylinder pressure it should be a stump puller. What kind of carburetor is it? Automatic or stick? If auto what converter is in it?

 

[Garys1969RR]

When you checked the plugs what to they look like? Also did you verify you are getting full throttle at the carb when you floor it?

Initial and total ignition timing?

With that kind of cylinder pressure it should be a stump puller. What kind of carburetor is it? Automatic or stick? If auto what converter is in it?

Plugs are a nice tan color. Swapped the 850 dbl pumper off of it with the 780 that ran mid 12s on my 451 RR. Same result. Then the RR ran faster when I put the 850 on it! So its not the carb. Pulled the Weiand team G and put on a Holley Street Dominator, that helped a little. Distributor has been repaired, with new reluctor and wheel. That helped. 20 degrees initial advance, and 38 total. Same as the 451 in the RR. Gonna pull the timing cover next to check cam timing.

 

[Garys1969RR]

Looks as if I found the problem. The cam was advanced about 20 degrees! Whoever assembled the engine, set up the Cloyes 3 position timing sprocket wrong. He had the keyway straight up to line up with the dot on the large cam sprocket. The crankshaft keyway should point to about the 2 o clock position at TDC, while the actual timing mark is a ways to the left. The mark he should have been aiming for was way to the left about 20 or more degrees. This timing chain set has 3 positions, straight up, or 4 degrees advanced or retarded. Easy one to mix up especially if your used to working on a Ford or Chevy.

 

[Redhorse719]

Glad that you found the problem.

 

[coloradodave]

Always nice to find the source of a problem. Makes all the hard work worth it. Hope this is your final solution. Good luck.

 

[Dennis H]

The result will be in the drive. Keep us posted.

 

[benno440]

let me know, i think i might have same problem

 

[451Mopar]

Glad you found the problem. Saturday I was helping a friend degree the cam in a 455 Olds engine. Glad we checked it, installed straight up with the "0" advance dots it was in at 117 degrees when it should have been 106 degrees. He had the Comp timing chain with +/-4 degree crank sprocket, and we found that was in crank degrees.
With the 4 degree advance crank position, we got the cam degreed at 108 degrees, the best we could do with the timing set he had.

 

[Garys1969RR]

Yes that made a huge difference! Took it for a short drive this morning, adjusted in more timing advance, and now it fries the tires in first and some what in second gear. Didn't have time to play with it much, but in the morning will do some more testing. Pretty sure this is a 9.5 to 1 C/R 451. Fairly mild cam, supposed to be 280 duration, .480" lift. Eddy Performer RPM heads. Anxious to get it to the drag strip, then can get some 1/4 mile times.

 

[Dennis H]

9.5 to 1 is friendly to pump gas and drivability. When safe, see what 3rd does.

 

[Kern Dog]

Holy crap! 20 degrees???
I had a sluggish 318 that ran really smooth but was so weak, it wouldn't even allow the car to peel out in dirt. After looking at everything outside the engine, I tore it down and checked the timing chain. It was retarded one tooth and the chain was stretched a bunch. Aftermarket chain & gears so some assclown had installed it wrong. I estimated that it was retarded by 10 degrees or more. After installing a new timing set correctly, it really felt great!

 

[GetX'd]

That's a heck of a difference. Glad you brought the beast back to life.

Is it possible for your motor to rock the dyno and then be sluggish in the car?

 

[62 Dart Convertible]

The cam was advanced about 20 degrees!

Congratulations on finding it!

Why anybody building even a half decent engine would skip degreeing the cam beggars belief. Same goes for gauging the bearing clearances. Basic stuff.

 

[Garys1969RR]

Congratulations on finding it!

Why anybody building even a half decent engine would skip degreeing the cam beggars belief. Same goes for gauging the bearing clearances. Basic stuff.

Yes its running great now! Those Eddy RPM heads really work great! You can really hear the airflow at higher RPMs. I set it up at 4 degrees advanced, and that is working well. I think the ignition timing marks must be off on the balancer. Its running best at an indicated 45 degrees total advance!

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I set it with the timing light at 38 total, and it didn't run as well as when I timed it by ear. Really burns em up at an indicated 45 advance. Has a chrome timing chain cover with a bolt on timing mark set up. I think that must be off by several degrees.

 

[62 Dart Convertible]

You can check your TDC mark with an adjustable piston stop that screws in spark plug hole.

 

[Garys1969RR]

You can check your TDC mark with an adjustable piston stop that screws in spark plug hole.

Thats a good idea! So you would screw the stop into the spark plug hole, then rotate the crankshaft until it stops, note what degree it is at? Then rotate the other direction and note the degree? I assume it should be the same distance either side of the TDC mark? Which on a stock one, is simply a small hole drilled into the tab with the marks stamped on it.

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And a piston stop is a spark plug with a rod welded onto the end?

 

[bigmanjbmopar]

Looks as if I found the problem. The cam was advanced about 20 degrees! Whoever assembled the engine, set up the Cloyes 3 position timing sprocket wrong. He had the keyway straight up to line up with the dot on the large cam sprocket. The crankshaft keyway should point to about the 2 o clock position at TDC, while the actual timing mark is a ways to the left. The mark he should have been aiming for was way to the left about 20 or more degrees. This timing chain set has 3 positions, straight up, or 4 degrees advanced or retarded. Easy one to mix up especially if your used to working on a Ford or Chevy.

This is interesting I have a 3 position crank sprocket and set mine to 4° advanced with the cam gear mark lined up with that. set my timing to around 12 initial and 35 all in and I have all kinds of romp.

Would love to see some pics of how it was ??

 

[62 Dart Convertible]

Thats a good idea! So you would screw the stop into the spark plug hole, then rotate the crankshaft until it stops, note what degree it is at? Then rotate the other direction and note the degree? I assume it should be the same distance either side of the TDC mark? Which on a stock one, is simply a small hole drilled into the tab with the marks stamped on it.

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And a piston stop is a spark plug with a rod welded onto the end?

Yep and yep!