Thread: 305 h.o. build

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What is the best cam to put in a 91 305 h.o. from a 91 z28 Camaro have a 650 etelbrock carb

Welcome to the site, it's nice to see you here. Your question as it is, leaves more questions than answers. Are you trying to accomplish something more than stock?

Actually to be honest, I think you'd be better off by doing an upgrade to a 350, it should bolt right in and no one would know. Don't forget the old adage, "there's no substitute for cubic inches"..

Welcome to CHR!

The lil’ ol’ 305 is often thought of as a red-headed step child of the small block family. Primarily due to its small bore (3.736”) and the corresponding stock heads that have small valves and overall anemic breathing characteristics. This engine can be brought to life and I have built several 305 roller cam combinations that produce respectable horsepower and torque numbers. That said, if yours in in need a rebuild, I’d recommend finding a junkyard 350 roller as there really is no substitute for cubic inches.

If you believe the engine to be in good shape internally and a compression test shows 130 per cylinder or better, you can get some good results with top end bolt-on components. I would discourage you from a “cam only” upgrade as the stock heads are really tapped out with the stock cam profile. The good news is that Trick Flow Specialties makes a great head for the 305 – part number TFS-30310006 - that has longer runners, bigger valves and allows for greater lift. It’s especially well suited to the 1991 305 as they were 9.3:1 compression ratio stock with a 62cc chamber. The new heads are 56cc and will result in a bit more compression that will act favorably. Key in installation is to use a Fel-Pro .039” gasket (FEL-17020) as it is specifically designed for the 305. It will show as a marine application – but is fine for your build. Use new head bolts as the originals will stretch and twist when you remove them. Install some long tube headers and Flowmaster 40 series mufflers to allow good exhale.

Now you can select a cam. I like the Comp Cam part number 08-422-8 here. Advertised intake duration is 270, exhaust is 276. Duration at 050 inch lift is 218 /224 which will still provide good street manners. The lift is .495/.502 (another reason to ditch factory heads). If your lifters are okay – reuse them but new rockers and nuts would be a prudent investment. I like the Comp Cams 1417-12. They come with new balls and nuts for less than $150.

Top this with a Performer RPM (or Weiand Street Warrior – kind of pricy) and your 650 Edelbrock with a good open element air cleaner and you’ll have a winner with 150 more horsepower and 50 lb. ft. of torque that you will definitely feel in the seat of your pants.

Have fun and let us know what you’re working on.

Best,
Glenn

Thank you i have worked on cars my whole life just never took one this far i am redoing the top half of the moter putting it in my s10 truck needed some more towin power got a new boat just want it to run good and last a wile any suggestions are very appreciated

Getting heads redone will that be ok with my applications it is a h.o. from 91 z28

The 305 stock heads (typically 624 and 416 casting numbers) have 1.84/1.50 valve combination and small combustion chambers. The stock springs on 305 heads are good for about .375” lift. They are a limiting factor.

The Trick Flow are 1.94/1.50 units with an enhanced combustion chamber and larger intake runners that provide a 25% increase in flow (245 cfm versus the stock 190). They also handle .480 lift.

Am I seeing where you may be taking a fuel injected engine out of a Z28 and putting it in a S10 but with a carb??Whats your plan for intake and ignition ????ECM????

Originally Posted by jerry clayton

Am I seeing where you may be taking a fuel injected engine out of a Z28 and putting it in a S10 but with a carb??Whats your plan for intake and ignition ????ECM????

Good catch there Jerry - If the engine was a TBI/TPI (which almost all were by 1991) the distributor will need to be considered when going to a carb. MSD Street Fire HEI distributor or similar will allow you to bypass pretty near everything and have a one wire hookup (12 volt  source to the B+ terminal of the distributor cap) to fire off. Tachometer hooks to the TACH terminal on the cap.

Kudos to Glenn for his good work, but using a 305 for towing is still a bad idea in my opinion. 350's are almost free any more and spending any amount of money on 305 heads just seems foolish to me.

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Thanks, Tech - and I didn't see his S-10/towing idea until after I posted (for some reason I thought it was going back into the Camaro....) I agree about the 350 - especially in a truck - and if it were me I'd build a stroker - but sometimes people need or want to build what they have. Hopefully he will think about this and if he does opt to keep the 305 it will perform a lot better than it did in the Camaro.

Yea. Wanted to go 350 but done got 305 its not a big boat i am gettin distributor biger springs on heads gettin a comp .050 cam on a somewhat tite budget thankes for all your coments