Gt40p With Xe270hr-14 And 1.7 Comp Rockers?

JasonFOXBOD · Mar 15, 2016

I have GT40P heads with Alex part .550 lift springs and valves converted to 3/8 stud and I am looking at the XE270HR-14 cam and I already have the Comp 1.7 rocker kit RP1450-16. I know the XE270HR-12 shows for use with 1.7's but want to get the 114 LSA cam rather than the 112 LSA. I also know PTV must be checked but curious to know if anyone has any experience with this combo. Since I have the 1.7's I would like to use them. Ant suggestions?

I won GT40P heads and 1.7's, want to use the XE270HR-14 with heads and rockers.

JasonFOXBOD · Mar 15, 2016

meant to say

I own the GT40P heads and 1.7's, want to use the XE270HR-14 which I do not have yet with heads and rockers.

1990 GT stock rebuilt bottom end, NA, gt40 tubular intake and 70 MM throttle body with 75MM mass air w/ cold air intake and 24 Lb. injectors

FoxMustangLvr · Mar 15, 2016

Why not call the cam manufacturer and ask them? Typically they are the ones that will help you decide on the right cam, springs, and best rear gears for the application.

What work has been done to the heads? Were they milled down at all?

I'm sure somebody will chime in with an answer.

JasonFOXBOD · Mar 15, 2016

I did speak with a tech at AmericanMuscle and he said either cam XE270HR-12 OR XE270HR-14 will work with 1.7's. Getting a second opinion.
The heads have not been milled just Alex parts .550 lift springs and valves with 3/8 stud conversion.

hoopty5.0 · Mar 15, 2016

Will the cam work with the spring pressures that you have? I had to sell my Alex parts springs a while back because they were too light for the cam I wanted to use.

JasonFOXBOD · Mar 15, 2016

Alex parts advertises them to support up to .550 and the cam with 1.7's should get me to .544 I think. Newer version is .560 but I have the older version at .550 max. Just got off the phone with Comp and tech said 1.7's can be use with the XE270HR-14 but of course PTV clearance must be checked. He said the XE270HR-12 was simply spec with 1.7 which is why they say to be used with 1.7's. I guess I am going with my original plan to get the XE270HR-14 which should give me more of a buffer for PTV clearance.
Which alex springs and cam did you use that gave you problems? Thanks for chiming in Hoopty, you've helped me in the past and I appreciate it.

FoxMustangLvr · Mar 16, 2016

JasonFOXBOD said:
Alex parts advertises them to support up to .550 and the cam with 1.7's should get me to .544 I think. Newer version is .560 but I have the older version at .550 max. Just got off the phone with Comp and tech said 1.7's can be use with the XE270HR-14 but of course PTV clearance must be checked. He said the XE270HR-12 was simply spec with 1.7 which is why they say to be used with 1.7's. I guess I am going with my original plan to get the XE270HR-14 which should give me more of a buffer for PTV clearance.
Which alex springs and cam did you use that gave you problems? Thanks for chiming in Hoopty, you've helped me in the past and I appreciate it.

I'm glad you called Comp and talked to them which is the right thing to do. I wouldn't trust AM to give me tech advice outside of simple bolt ons (if that). I've have called them and LMR in the past and have had people guessing on the other side of the phone. Always go straight to the MFR or study up on the forums like you are now.

Good luck

hoopty5.0 · Mar 16, 2016

JasonFOXBOD said:
Alex parts advertises them to support up to .550 and the cam with 1.7's should get me to .544 I think. Newer version is .560 but I have the older version at .550 max. Just got off the phone with Comp and tech said 1.7's can be use with the XE270HR-14 but of course PTV clearance must be checked. He said the XE270HR-12 was simply spec with 1.7 which is why they say to be used with 1.7's. I guess I am going with my original plan to get the XE270HR-14 which should give me more of a buffer for PTV clearance.
Which alex springs and cam did you use that gave you problems? Thanks for chiming in Hoopty, you've helped me in the past and I appreciate it.

All good. While the lift may be supported, the open and closed pressures may be too light as they were in my case. This will cause valve float and P to V contact is bad news bears. The comp website should have specs for that cam with required spring pressures. Make sure that the springs meet or exceed those numbers and you'll be in good shape. I had a crane 2031 which is a pretty mild cam relatively speaking and it was too much for those springs.

FoxMustangLvr · Mar 16, 2016

I'm sure you've been on their site but here is all the recommendations from Comp cams for the cam you chose....
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1054&sb=0

You can call them and double check that the springs they recommend are OK to be used with a 1.7 rr.

A5literMan · Mar 16, 2016

I will also add that in my experience comp tends to be on the "tight" side of spring rates. I would use their recommendations as a minimum requirement. Like Hoopty said above...not enough spring is going to be a big problem. I don't think your springs are enough for that cam. It's really to close to know without actually checking after you have the parts. I'd either go one step lower with profile or check into a spring upgrade or buy the cam and check.

JasonFOXBOD · Mar 19, 2016

Thanks everyone. I have looked at the cam card and I got cam quest from comp cams which suggested the cam I chose as the first option. I planned on having the machine shop check the heads because all the work was do e when I got the heads. I'll have the springs checked and pick up new ones if required.
One thing I am not exactly clear on is the use of guide plates. Cam card says guide plates but rocker instructions says do not use guide plates. I thought to ask right after I hung up with comp so I'll call them again. And yes, this I my first build.

JasonFOXBOD · Apr 28, 2016

UPDATE - Went with the Comp Cams XE264HR-14 and taking my block and heads to machine shop tomorrow.

Gt40p With Xe270hr-14 And 1.7 Comp Rockers?

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