We commonly get questions on what mix of parts to use for different power outputs. Will try to cover a few here. These are mostly based for street use
Build it One step at a time. These can be done easily on a Saturday with some planning.
This is for the guy that wants to make improvements on a budget over time.
- Use a HEI distributor. Easy to install. Relatively cheap to buy, highly tuneable. Be sure to feed it with a solid 12V wire, do not use the factory distributor wire. I like to trigger a relay with the OEM wire.
- Electric fan. Free up HP and TQ by switching out that power robbing mechanical fan. Gaining 8-10HP on a 150 HP engine is a big percent.
- Head work. 25HP and TQ can be gained on a stock engine. Larger valves, Lump ports and decking the head will all aid in raising the power level. 1.94 intakes for hot street and 292, 1.84 intakes for engines expected to make 225-250 HP. Heads can be swapped in a afternoon. You can use the OEM intake/ exhaust and save money for a swap for a later date. Cams with lifts of .480 or higher would benefit from use of roller rocker arms. Something to plan on for later.
- Intake/ Exhaust. 15-20 HP gain.Can be done on a Saturday with pre planning for throttle and exhaust hookups. Offy and Clifford both make a intake that will fit under your hood. The offy being for more casual builds and the Clifford making more power at 3K and above. Both need to be water heated for best overall running.
- Cam swap. 15-30 HP gain. This is the hardest to do and may take you the weekend. Choose a cam to fit your driving and transmission. Springs need to match the cam. The balancer must be removed and later reinstalled. 194-230-250 engines, the cranks are not drilled for a installation tool to be used. We make a tool to drill and tap the crank to be able to use a installation tool. Also a good time to replace the damper.
You have to decide how you want the engine to perform. Most people are building these for pleasure but with added performance. Here is what we suggest.
The build is based around your block. So you want to be sure you have a good one.
- Clean it. There are many ways to do this.
- Magnuflux it for cracks
- Pressure check it for cracks/ leaks. You can get surprised sometimes
Hone with a TQ plate. When the head is tq’d down the bore will go out of round near the head bolts. The tq plate allows the hone to give you a round bore when head is tq’d back on.
Most street engines need 9-9.5 compression. For a 250 that equals a flat top piston. 292 equals a 18CC dish for 9.5.
Our Ross pistons have a Modern ring design, very similar to what is used in your newer daily drivers. The rings are light, low tension/ friction and can conform to your bore very nicely.
Balance the entire rotating assy.
Drill the crank snout for a 7/16-20 bolt. On 194-230-250. This will allow you to use a tool to install the balancer.
There are many to choose from. Stock/ RV/ Perf oriented units all have their place.
If you put a stock cam with 9.5 compression. The motor will suffer from detonation.
So here is a quick list to help you pick.
- Stock cam – stock compression thru 9 to 1
- RV cam - Stock compression thru 9 to 1
- HYTK cam- Stock Compression -9.25
- Thrifty cam- Stock Compression -9.5
- Mid range cam 9.5
- 320 HP cam 9.5-10
Getting good power from your inline requires you to work on improving the head.
Larger valves, Bolt in port lumps, decking and prep for screw in rockers studs are some of the ways.
Stock 1.72 and 1.5
Intakes Minimum of 1.84 – 2.02 Max
Exhaust Minimum 1.5 – 1.6 Max
For 230-250 and 292 heads the 1.84, 1.94 intakes are a good choice. Lower HP engines will benefit the most from 1.84 and high HP engines the 1.94.
Use of the “194” head will be discussed later.
Use of the bolt in lump kit will only gain intake port flow when used in conjunction with 1.84 or larger valves. When used together, the port will see a 10% increase in flow over using the larger valve by itself.
When using cams with lift of over .500 roller rockers will be a benefit. The head must be machined specifically for the roller rockers and the rocker studs used.
New guides are needed at the time of oversizing the valves. This is what centers all the work done in the port.
Decking the head is important for a great seal and for every .007 deck removed a 1CC decrease in chamber is found.
More info to follow.