Guys,

I don't know if this is the right place to post this but I lot of you are experts on GenIII's and I need some good advice.

I am building a budget 1937 pickup street rod using a 2002 5.3l truck engine. I am planning on using the GM#12480033 ls1 hot cam in it in (0.525lift, in 271, ex 280, lsa 112) The cam came with LS6 springs I'm going to install and I'll be running the edelbrock intake with a carb and the MSD ignition.

I was working with the heads today and I can stuff a 5.7l (larger than the stock 5.3l) intake valve in the heads without modification. (I got a set of car valves on ebay) It looks like it will still fully seat on the factory machined valve seat. The valve however sits 1/32 lower at the tip when installed with the springs due to it sitting lower on the valve seat. The intake and exhaust valve tips would be at different heights. (all intakes off by 1/32)

Any advice on whether this type of thing has been done before successfully when using the truck heads or do I need a valve job to lower the seat position? Any problems I should look out for?

I am planning on bluing up the valve up to look for piston to valve contact to make sure I have clearance but what do you guys think about the combination?


Thanks, I would really appreciate any opinions!

Todd

 

We've done tons of them. You can install the 2.0" intake valve, but beware that it get's pretty shrouded by the smaller 5.3l cylinder bore. You most definitely will have to have the valves seats machined out to fit the larger valves. We normally install 1.95" dia. valves as they leave some room between the valve and cylinder bore and in all cases the valve seats get remachined to fit the larger valve. The valve tip heights are always evened out durning the valve job process. With some careful porting in the valve bowls, that engine should run strong.
Keep up posted on your progress.

Richard