found this cam cheap on cl. any reason it wouldnt work in an 87 lg4? stock carb, heads, etc. the cam is hydraulic flat tappet and requires 9:1 compression
http://www.trickflow.com/partdetail....=TFS-K31401000

 

Personally, I wouldn't go from roller to flat tappets. So, that's strike #1. Whether your '87 LG4 has roller lifters has been the subject of great debate in another thread, so I guess you'd have to verify that first.

On the outside chance that your engine has flat tappets now, then it may be okay. You will need all new lifters (does it come with lifters?). And, it's quite a bit of cam for an otherwise stock engine - I wouldn't do it with stock, unmodified exhaust, for instance. A higher stall torque converter would help avoid dog-like symptoms off the line as well.

 

it has the exhaust taken care of. This isnt the first thread youve talked about a different TQ with a cam swap, could you point me to some more information on that topic? does it have to do with the powerband of the cam?

 

Yes. Your cubic inches are static. Therefore all you can do to make more power is shift your torque curve higher in the RPMs. Horsepower is how fast you spin torque, and it helps to think of torque as linked to displacement (more accurately, to air flow, but displacement is still a big determining factor). So if you can only make a peak 250 lb ft of torque, then you can set your engine up to make that 250 lb ft at 2000 RPM, but if you set your engine up to make that 250 lb ft at 4000 RPM, your horsepower will double in the process, because hp is torque x RPM. This is why diesels make enough torque to pull the earth through its orbit, but have very very low hp numbers compared to their torque numbers.

Almost every single performance mod people make (heads, larger ports, larger cams, larger headers, bigger intakes etc) serves the primary purpose of shifting the power band higher in the RPM range. This is why it's important to make sure all of your parts match each other, because all it takes is one piece in the chain that isnt optimized for the same RPM range to cripple all of it.

This is why people always say go to a 350. With a 350 you make more torque. So you can shift your power band higher than you can with a 305 and make more peak power, but the amount of torque you're making at the low end will be hte same as the 305. Does that make sense? LS1's are better because they just flow massive amounts of air per cubic inch. They can shift their power bands insanely high for that reason and still have enough low end to keep it streetable.

This isnt really what you asked, but I think it's good to have some theoretical understanding of what's going on.

A larger cam helps optimize the airflow a higher RPM at the expense of bad airflow at lower RPM. If you've ever heard a top level NASCAR engine or any ridiculously fast street/strip car with a big cam, what you're hearing at idle is the engine misfiring and making barely enough power to keep itself running. As the cams get larger they have to increase the idle speed just to make sure the engine can turn its own parts because it's so inefficient at flowing air at low RPMs. But hte tradeoff is they can make their peak torque numbers at 6000+ RPM and have a usable rpm range from 4000-8000 RPM where that torque multiplies by that RPM to make GOBS of horsepower. As a side note, compression ratio is another very important factor here, but I'm not going go into that right now, but the larger the cam the more compression you need to run it.

 

makes a lot of sense. thank you very much