JC Whitney vs Summit for parts

I'd shy away from JC Whitney. Bought from them 20-30 years ago but unfortunately they're kind of like buying from Service Merchandise was at the end. Just not up to date on the latest technology/quality at the best price.
Summit is mainly high performance/racing parts.
For an engine go to PAW in California.
1-818-678-3000
www.pawengineparts.com
I buy all my engine building parts there. Engines are their specialty.
They have a 2" thick catalog that they charge for ($10.00 I think) but it's money well spent. It is absolutely loaded with information on picking parts. People ask about what cams, intakes, heads, gear etc to buy/use on their cars all the time on these forums. This catalog includes many manufacturers specs and all sorts of information and it goes from completely stock to all out racing. Instead of just listening to opinions, get your information and do your own research. This is a catalog worth buying and they have great parts and prices. I'd highly recommend them.

Once again, I agree with the above. PAW's book is the size of a phonebook. It's huge. And I paid my $10 or whatever for my catalog, and the next year, they sent me the new catalog for free!! But yeah, a great company, good parts, good people. All the information in their catalog isn't exactly credible(just because it says one thing doesn't mean that it's stamped in stone) so make sure you know what part you want and need when you order and don't go by the catalog just because it says so(I speak from experience).