i have a 66, 327/300hp/4 speed/3.36 rear/wide ratio trans convertible, my buddy just took me for a ride in his 66,327/350hp/close ratio/3.70 rear convertible. there is no comparison with the acceleration of the two cars, his jerks your head right off your shoulders in second and third gears and mine is sluggish(but runs and shifts well), should there be such a difference between two 327 cars, does the 350 hp package and rear end differences make such a difference, why would my car be so sluggish? he then let me drive his C5, talk about heaven on earth! that's the most powerful and best handling car this novice has ever been in, joe t
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Re: 66 performance
Joe - there are lots of variables here, such as are both engines built stock or not, etc. Assuming they are, I have a 67 L79 327/350HP with wide ratio transmission and a 3.55 rear (I am temporarily dropping a 4.11 in it for a while, since it is my around town light to light driver!). It will nail you back pretty hard in 2nd and 3rd, when you wind it up to 6000rpm (I scare myself sometimes and it is the original block). It will spin the skins when powershifting, or I should say chirp. I am anticipating a lot more with the 4.11 rear onboard. However, 3.36 with a base motor small block would drop the acceleration a bit, so it is probably about right, and without know what if any engine mods are there, it's hard to judge...Craig -
Well, a couple of thoughts...
1) You should go through your car and give it a complete tune-up, using a chassis dyno if you have access in your area. When I say complete, I mean check and or replace points, plugs, wires, etc., plus check all internal and external carb adjustments, and check distributor vacuum and centrifugal advance curves. You should also check cam timing, a problem like a worn chain can take the edge off your power.
2) Wide vs close ratio trans, "low vs high" rear. About 20 years ago I switched my daily ride from 3.00:1 to 3.50:1. Felt like I replaced the engine! Come to think of it, my 3.73:1 V8 Mountaineer goes pretty good at a stoplight, for a station wagon! Just remember, 3.90 or 4.11 gears feel great in town, but can be a real pain on the highway.Comment
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Re: 66 performance
It's tough to say from your description whether there is anything "wrong" with your engine, but SHP engines create more of a visceral difference than the horsepower differences might indicate. The 300 HP engine has more torque/power below 3500 revs, but this will only be noticeable up to 3500 in first gear or about 30 MPH. The two gearing combinations you listed have the same OVERALL ratios in first through third, so once you're over 3500 in first gear on a WOT accleration run the L79 will feel considerably stronger because of it's greater power in the upper half of the rev range and it's abililty to rev higher.
These old engines have a lot of mechanical systems that are critical to good operation such as the mechanical and centrifugal advance systems and carburetors, so you would be well advised to thoroughly check these systems for proper operation and compliance with specifications.
Dyno pulls can also be a good indicator of overall engine condition. A good 300 HP engine should pull about 200 RWHP at 4500, and a good L-79 should be approach 250 at 5500.
DukeComment
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Re: 66 performance
As Duke says the 300 is stronger up to about 3500 rpm. If yours isn't, I'd start with the complete tune-up including checking the distributor curve. I've seen many of the old distributors come up way short of the factory prescribed curve and that will contribute a lot to the sluggish feeling. A well tuned 300 is quite strong off the line up to 30mph or so. Aftert that the 350 will take over.Bill Clupper #618Comment
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Re: 66 performance
Joe -
I have exactly the same combination you do, and I'm very happy with it (after a proper and complete tune-up, including factory-spec carb and complete rebuild/re-curve of the distributor); does everything I want it to do. I've had the L-79 combination you describe as well, and yes, there's quite a difference with tall gearing when it starts to howlComment
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