eight
I was hoping beyer's thread would reveal some good info. Lets try again.
Discussion is only for engines to be used with TBI. No talk of carburators, or the edelbrock MPI stuff.
Here are his questions:
- Can you shave the heads to bump the compression up?
- How much compression and still safely run 91 octane?
- What is a good off-road (torque) cam for a TBI set-up motor?
Here are mine:
How much compression to run 87 octane?
How much shaving to get there?
What do you need to look for in a cam? I think you want short duration and small overlap with aggressive ramping and high lift.
Here's what I'm thinking.
9.5:1 compression.
Bored throttle body that flows 600 cfm
Larger injectors (stock tbi 350 only support 275ish hp)
Dual plane aluminum intake.
Headers to single 2.5" exhaust with glass pack (only muffler that fits)
Comp Cams 10-214-5:
256/268 duration
212/218 @.050
.477/.484 lift
42 degrees overlap
Hopeing for about 350hp, 400 lbs tq.
jeepsr4ever
- Can you shave the heads to bump the compression up? Yes
- How much compression and still safely run 91 octane? 9.8-1
- What is a good off-road (torque) cam for a TBI set-up motor? 474, 495
How much compression to run 87 octane? 9-1
How much shaving to get there? 58cc heads?
401 = 50.125 cubic inches per cylinder
401 Bore x Stroke, 4.165" x 3.68"
2.54cc in one inch
2.54 X 2.54 X 2.54
16.387 cc's in a cubic inch
3.539 cubi inches in a 58 cc head
3.552 ci left over in the combustion chamber for 8.5-1 compression
Change in volume 8.5 / 9 = 5.6% of the 58cc dome in the head
.1981 CI needs be milled away or 3.246cc's to gain .5 bump in compression
hmm a liquid test will tell you how much you will need to take off...58cc's of liquid will fill the combustion chamber on the head and to gain .5 boost in compression over 8.5-1 you will need to remove 3.246cc's which at this point tonight I cant tell you how much that would be off the head. May be around .022"
What do you need to look for in a cam? I think you want short duration and small overlap with aggressive ramping and high lift. Roller setup not good for low end torque
jeepsr4ever
We no longer suggest comp cams 256xe. After the last three engines in the shop we found that a 470 and 490 were better than the small 256
eight
What's a 470 or 490? What brand? What do you think of the 262xe?
jeepsr4ever
262 is more like it although it has more intake than I would want for a stump puller but not by much.
eight
It doesn't have to be a real low end engine. I've got plenty of reduction. But then I don't need power above 4500 rpm either. Just would like to be able to outrun scouts with LT1s and LS6s, shouldn't be too hard.
The reason I like the XE series is because they have small valve overlap. Even the 262 is only 46 degrees of overlap, where most others are 60+. The other cams I'm looking at are the Crane 863904 and 863941, and Comp 268H.
Oh and yes I have the 58cc heads.
And what brand of cams are these 4XX nymbers?
Dusty
mc.... i'll be following this too, my howards cam in the 10.2:1 edelbrock headed and fuel injected 401 hasnt met my expectations.
never mind i need to call and rattle your cage anyways :lo1l:
