3GEN90

iTrader: (5)

Hi All:

Well, I almost have everything for my winter project for my 1990 Formula. Thanks to all who I purchased the parts from right here on ThirdGen!

I will be swapping into my 305 the following parts and want to know if I will have issues with compression, etc. and what I will need to do?

The LT1 cam is from a 97 F-Body with the following specs: 447/459 lift

The Heads are Vortec 906s that have not been milled, but have elongated shafts for the pushrods and will be using 1.6 rockers (self-aligning) The chambers match the 305 L03.

Does anyone see any issues with this combo, other than putting it into a 305?

If compression issues, any suggestions, other tan milling? Gasket type perhaps to compensate?

Also, the TBI unit will have the ultimate mods and 55lb injectors and be 46mm. The intake itself has not been decided, but want to retain the EGR.

BTW..the tranning is a WC-T5. Won't be taking it to the track, just a driver, but want to extra HP, so I won't abuse with power shifts. Don't think that will be a problem.

Thanks to all who will reply...and thanks to all for the parts!

3GEN90

iTrader: (5)

Ignore my typing and spelling mistakes.

Gallileo60

Sounds like a really cool build..I can hardly wait to hear from the pro's out there...I too am interested in building a nice 305.....Ive had several 350's, but have never really had a full tilt 305, ought to rock...good luck...

thomas1976

If I remember correct #906 heads are 350 vortec heads with 64cc chambers and do not allow over .450 lift with stock spring retainers. (LT1 cam with 1.6 is around .490)

With the thinnest 0.015 FelPro head gasket and assuming 10cc piston (not sure LO3's piston cc) gets around 8.6 CR, wich is bad.

A TPI fuel pump and a VRFPR could allow you to keep the #55 injectors by rising the fuel pressure around 25-30 psi, you will need.
EBL flash will be a must to tune and run this.

For the rest you can follow this tread for the required intake manifold, EGR plumbing, walve spring retainers, etc...

https://www.thirdgen.org/forums/tbi/...i-buildup.html

Onestly a set of 175 TFS http://www.summitracing.com/parts/TFS-30300005/, with this head gasket http://www.summitracing.com/parts/FPP-1094/ and with these springs http://www.summitracing.com/parts/CCA-981-16/ may end up costing the same as the whole vortec conversion, and be a better (and lighter) choice for your plans.

3GEN90

iTrader: (5)

Thanks!

The springs have been changed to comp springs, so that takes care of the lift.

3GEN90

iTrader: (5)

What do I need to do to get the compression up? Won't the springs take care of that?

thomas1976

If you have the right springs, you only need to make sure the valve guide to spring retainer clearence is ok for the lift of the cam with your choice of rocker arms.

To get the compression up you need cylinder heads with smaller combustion chamber or different pistons with less cc's or bigger a bore.

Here is a calculator to help you out http://www.kb-silvolite.com/calc.php?action=comp