Ordered a new vortec 350, XM270hr or Hotcam??
02-13-2019, 08:32 PM
#11
These look like the proper springs for my needs. The Flat Tappet Springs I currently have from my previous setup say they are good up to 218 duration at .050.. My new cam XM270hr is 218 on the intake side and 224 exhaust so pushing it on the duration it looks like.
I'm going to call Alexs Parts tomorrow and see what the recommendation is and proceed.
02-13-2019, 08:34 PM
#12
Finally, I'm going to need to run an electric fuel pump as well as my new block is not drilled for a mechanical fuel pump like I have today. I'm thinking of ordering this pump https://www.summitracing.com/parts/crt-p4603hd/reviews/ Outside of wiring it up to power, what else do i need to do to run this safely and effectively? Relays, switches, etc?
Thanks!
Thanks!
VIP Member
02-14-2019, 06:42 AM
#15
You will need a coupler for a 1 piece rear main block. GLM sells a retro fit coupler for that swap that will work. I dont believe the newer style coupler will fit in the older bell housing.
You can wire the electric pump to an oil pressure switch so it only runs when you have at least 5psi of oil pressure.
You can wire the electric pump to an oil pressure switch so it only runs when you have at least 5psi of oil pressure.
02-14-2019, 09:34 AM
#16
You will need a coupler for a 1 piece rear main block. GLM sells a retro fit coupler for that swap that will work. I dont believe the newer style coupler will fit in the older bell housing.
You can wire the electric pump to an oil pressure switch so it only runs when you have at least 5psi of oil pressure.
You can wire the electric pump to an oil pressure switch so it only runs when you have at least 5psi of oil pressure.
02-14-2019, 11:14 AM
#17
Platinum Member
Platinum Member
iTrader: (2)
I would go with the LT4 Hotcam, stock GM Z06 beehive springs (yellow), and Comp 774 beehive retainers and 7 degree keepers. This will increase retainer clearance by a decent amount allowing .540-.550 lift without machining the guides.
When I did mine up, I used the factory self-aligning rocker arms (1.5 ratio), and had a ton of room (I was on a tight, pre-divorce, budget). Running a 1.5 rocker puts you at .492 lift. A 1.6 rocker is needed to reach the advertised .525 lift, but should have plenty of clearance if you go the above route. Most of these parts can be had pretty inexpensively making it even more attractive.
TomZ
When I did mine up, I used the factory self-aligning rocker arms (1.5 ratio), and had a ton of room (I was on a tight, pre-divorce, budget). Running a 1.5 rocker puts you at .492 lift. A 1.6 rocker is needed to reach the advertised .525 lift, but should have plenty of clearance if you go the above route. Most of these parts can be had pretty inexpensively making it even more attractive.
TomZ
02-15-2019, 06:48 AM
#19
Registered
Hot cam
I built a nice little 385 for one of my customers C18 Donzi last year and I used the LT4 hot cam kit. We started with a 2009 Mercruiser 6.2 Longblock and went from 9.0 to 9.7 on the compression, if you use the springs that come in the kit you need to cut the seat area where the spring sits because the new springs are a larger diameter. You also have to cut the valve guides down for the lift and I think we had to machine the od of the pedestals for the spring locators to fit over them Comp makes the tools specifically to do this to vortec heads and my cylinder head guy had them so it was an easy job for him. You also need to drill the pushrod holes in the head to 1/2” overall the engine came out awesome and that cam was the perfect balance for our application. His C18 picked up 12 mph on the top. And yes you will need a new flywheel and coupler and starter as well I believe the old starter had a straight across pattern for a 12” flywheel and the new flywheel will be 14” and the starter has a staggered pattern.
