Another 305 TPI build
 

Hi.

At the moment I have a 3.1L V6 in my Camaro and in the next few months I'm planning to swap it out and put a 5.0L V8 TPI in there. I'd like to fully rebuild the 305 before it is going in and I'm sharing my thoughts on the build to get some useful input from the experienced members here.

I really don't want to start another 305 vs. 350 flame, I've already read hundreds of them. :)

Here goes the plan:

Block: 1992 5.0L LB9.
Crankshaft: reuse stock.
Connecting rods: reuse stock.
Pistons: flat-top hypereutectic aluminums. (Keith Black KB229 with +5.50cc head volume)
Cylinder heads: reuse the factory 14101081 heads. A full rebuild on them with screw-in studs and new springs to support bigger lifts. Maybe a little port work also but nothing serious.
Head gasket: GM Performance 10105117 (4.0" bore, 0.028" compressed thickness)
Camshaft: still not decided but would like to go one step further from the factory one. The two cams I'm hesitating between:
Comp Cams 08-500-8 206/212 @ 0.05 .480/.488 112 LSA
Comp Cams 08-501-8 212/218 @ 0.05 .488/.495 112 LSA
Intake: stock 90-92 TPI with MAP and maybe with a little port work also.

With 58cc combustion chamber and assuming 0.020" deck clearance with 0.030" overbore and the mentioned head gasket my compression ratio would be around 9.7:1 compared to the factory 9.3:1.

It would be nice to have some input on the cam and head gasket choice, but I'm interested in all other ideas as well except the 350. :)

Thanks!

Re: Another 305 TPI build
 

I would go with an aftermarket head with better flow numbers, plus other advantages. EQ and others make much better under .500 lift flow numbers and have Vortec chambers. Most aftermarket heads already have screw in studs and use guide plates, plus super smooth "as cast" ports! I am running EQ Hybrids with 170cc intake ports and Vortec chambers. I always run quench of NO MORE than .040. My heads have 1.940 intakes and 1.5 exhausts. ZZ4 springs and GM L31 Roller cam and 1.6 full roller rockers. I used KB Hypereutectic pistons .030 over and .025 down the bore and .015 compressed gasket thickness. This is critical and any combination that gets this or a slightly smaller quench number would be fine! KB pistons use a high ring location and special ring gap is required. I would match the ports of the intake to the heads. Gasket match the runners, plenum and throttle body. Camshaft is very tough to determine, for me, the lower duration stick would be the choice. There are as many cam choices as opinions!

Re: Another 305 TPI build
 

The cam I put into my 305 TPI is a 212/212 .444"/.444" 112 LSA cam from comp cams. I think that it works pretty well in the car.

Re: Another 305 TPI build
 

I also considered aftermarket heads. The aluminum TrickFlow ones is a bit expensive for the budget that I want to spend for now. The second option was the World Products S/R. It's still around $500 and as I live far from the US that $500 will be much more until I get them at my door.

That's why I'm thinking on going with my stock heads and doing a full rebuild on them. One upgrade that I also considered for the stock heads beside the rebuild was to replace the stock 1.84" intake valves with 1.94"s to gain a little on the flow numbers. What do you think?

Re: Another 305 TPI build
 

Do you have any information on the manufacturer or some product number/grind code?

Re: Another 305 TPI build
 

I am still looking for comments on my plan. :lookhere:

Re: Another 305 TPI build
 

The cam is from Comp Cams and the grind number on it is CS 260H-12 part number 12-314-4.

Re: Another 305 TPI build
 

Thanks. Unfortunately I need a roller tappet camshaft and the 12-314-4 is a flat tappet one.

Re: Another 305 TPI build
 

I know this is an old post but I have a question regarding this cam. I have this exact cam new in the box that I bought a few years ago to put in my carbureted 305 in my 86 K10 truck. I ended up putting a 350 in the truck but I still have this cam still new in the box. Last week I bought a 1986 IROC Z28 with a stock 305 TPI and have been wondering if this camshaft will work in it with no other modifications? Would it need one of those Jet Stage 1 or possibly stage 2 computer chips or will it be fine with the stock one? What about the injectors? Will the stock ones work? I don't want to get too radical with it since I pretty much want it to appear stock but since the stock cam in the 190 hp (and I highly question that) is so small I just want to bump up the performance of what I've got under the hood. Thanks in advance! Joe