max lift you can use before coil bind 454 oval port head [Archive] - Chevelle Tech

: max lift you can use before coil bind 454 oval port head


kingdaddycreel
Dec 13th, 03, 12:54 PM
I have a 1972 454 what is the max lift you can use before coil bind (stock diameter springs)on the big block chevy oval port head. I heard it was around 580"? Let me know......

Tom Mobley
Dec 13th, 03, 4:00 PM
I don't understand your question here. any cam that pushes them to near coil bind is going to need more spring seat pressure than they've got anyway. What are trying to do?

Tom

GRN69CHV
Dec 13th, 03, 4:42 PM
Stock springs are useless over .480 lift. It is not the travel but the spring rate is too mild. Over .520 lift you will probably also have to cut the guides for clearance. You will have to measure for sure but I found out first hand that the retainers will hit the top of the guides, crushing the valves seals and bending pushrods in the process. This was with a .550 lift cam on 69-70 "290" heads.

kingdaddycreel
Dec 13th, 03, 6:03 PM
thanks guys. I relize that the stock springs are no good for performance. But i have sucessfully ran a 559 lunati soild lift cam with them for years now. the chevelle runs 11.20s and performs quit well. I didn't even have to cut the guides.(and yes these are stock oval port heads/springs untouched) SO it can be done it is just not recomended. I was just curios to what they would take. With out finding out the hard way.

pdq67
Dec 13th, 03, 7:35 PM
Remember there are two stock, low lift spring settings here to consider.

Crane lists '65 to '98, 396 to 502, at 1.875".

Plus '80 to '95 truck, 366 to 454, at 1.828" so just be aware of this b/c both use different retainers that have a .100" height difference too!!

I don't remember why I keep wanting to say the difference in them is really 1.880" vs 1.800" so can anybody chime in here and straighten me out??

Seems like I ordered Crane's spring kit number 13308-1 and got either short springs with tall retainers or tall springs with short retainers!

And after I called them they said I needed either different springs or retainers which pissed me off AND I said so AND they said to send the whole kit back after I said their literature said the kit would work for my application, but didn't!!

JUST BEWARE!!!

pdq67

Mike Feudo
Dec 13th, 03, 7:48 PM
Unless you are the luckiest person in the world don't use the stock spring for anything.

GRN69CHV
Dec 13th, 03, 8:48 PM
kingdaddy,

.559 lift is based on lobe lift x rocker ratio and is theoretical. The .550 lift I was running that bent the pushrods was hydraulic. You have to substract the tappet clearance on a solid. If you run .020 lash you are only seeing .539 at the valve. An older Lunati Grind may have had .025 lash {net = .534 at the valve}. I would suspect a solid with .570 lift or greater {w/.020 lash}would have interference on bone stock heads. The newer style tight lash cams {.016-.018} are going to move the valves even further. Anything this close should be measured for accuracy. The older heads you were running could have been machined further down on the guides and you just didn't know it, or you could have been running close to "0" clearance and just got lucky. Take a look at all the "retrofit" cams offered by the cam manufacturers for BBC. These are all typically <.540 lift {hydraulic}.

ddeennis
Dec 14th, 03, 11:28 PM
well if you want to find out ...........you have the combo allready just go out and see how much they will take....bring your lift to max and measure between the springs with a feeler gauge and see..........measure right in the middle of the spring and shove what ever thickness you can in there all the way around making one complete circle and subtract at least .050 for coil bind there you have it for what ever lift you can go more........but you still dont know for sure what room you have left for the retainer and guide.....and if your running umbrella im sure by now they are split since they are pretty thick....ive ran a .600 solid cam on stock springs as well but i split the umbrella seals on all the exhaust side, i broke stock rockers every so often .....but the real lift was more like .580 since lash affects the lift......

any more i just cut everything down and measure. and buy the right springs.....save for alot of headaches and no more guessing........

i think you would be time ahead and money ahead if you wanted more cam to just break the heads off and go thru them and get them set up...

any more when i build i big block i have everything cut down and clearanced cause i know i will want more sooner or later.......

kingdaddycreel
Dec 17th, 03, 9:29 PM
thanks guys for all your replys. I appreciate your opinions. I have had no problems with my engine and it works great. i will leave well enough alone.

427L88
Dec 20th, 03, 6:01 AM
Sir, with one of the exhaust lobes at fill lift, eyeball the spring and measure how close the coils are to one another. I think 0.050" is OK.

SSpete67
Dec 20th, 03, 9:08 AM
I have stock springs and I'm running the Comp Cam XE274H. I called Comp Cams and asked them what was the biggest can I could run with my 396 Bored 30 over and this is what they recommended. So far I love it and haven't had any problems.