Valve spring pressure

[Ian Hill]

I run a 350 crate engine in IHRA with a hydraulic flat tappet cam shaft and lifter set. i ran regular style valve springs last year and ran the engine past the finish line to check top end rpm limits. the engine pulled no problem to 7400 rpm. Normally i was crossing at 7100. All this while running a 4.88 rear gear set and true hydraulic lifters. Now i have gone to the solid style hydraulic lifter (call it what you will), bee hive valve springs and lighter weight retainers. I put a set of 5.13's in the rear and can only pull 7200. i am running out of steam about 80-100 feet from the finish line. i have the valve springs setup for 125 lbs at the seat and 320 over the nose. i also was down 6 pounds of tire pressure from where i normally race as i thought the track was marginal.

i know that pumping up the tires will make them grow in diameter, but it will also reduce rolling resistance to the tune of almost 2 mph and .005-.007 as tested last year. i still have 30 pounds to put into the car which also will reduce top end rpm. i am at a loss for what to do to help the rpm situation without going back to the 4.88's other than shimming the valve springs for more pressure. What is normal, what is too much valve spring pressure on a hydraulic cam shaft?

thanks
Ian

[randy wilson]

it doesn't make sense. only one of three things could cause this. first, put a .030 shim under each spring and see if the extra pressure picks up rpm, second, check timing, i know it sounds simple, but double check it, third, check cam intake centerline. your car should be turning tighter not less as you know. my bet is that you don't have the spring pressure you had earlier for what ever reason.

[Mike Taylor 3601]

Did you check heads for installed spring height,to make sure your springs have that pressure and check springs to verify they are pressure they are supposed to be?
With cam & lifters broke in should be able to run around 140 seat and 375-390 open
without any problems. You don't have a hard surface lifter correct if you do you can crank
pressure on up.
You have some valve lash correct you need .003-.007 lash.
Mike Taylor 3601

[Ian Hill]

i do have .003" clearance checked hot. My timing hasn't moved, the float was happening on the first run and the next four. richening the fuel helped but slowed the car down. I am wondering if anyone has info on going from standard style springs to bee hives. can you expect to use the spring pressure set up or is it natural to have to increase spring pressure with bee hives.

Ian

[randy wilson]

there's your problem. go back to your old style springs.

[M&M Motorsports]

Changed from regular springs to beehive. I have 200 lbs seat pressure and that is good to at least 7500 rpm. Hope this helps!

[CrateCamaro]

I have tried K-Motion K-700 springs (120 @ 1.700) and the Comp Cams 941-16 (130 @ 1.750) and they both work well. I had the comp springs in at 1.700 and they seemed to do the trick with the Sherman Lifters. I ran some more lash than you so that could be something to try.I never spun my engine as high as your trying to so that could be an issue as well. 7200 max. The only time it floated the valves is when I went to a smaller tire and it tried to go through higher. I never had titanium retainers and the springs were wipped at that time so it was an unfair test. Im not a firm believer in the bee hive springs yet but im kinda thinking that they are ok if you are trying to keep the valve train weight down. Id go back to basics and just order a set of 941's and jam them in. 7500 shouldnt be a problem with 140 on the seat. Are you running EOS in your oil? Probably a good idea with big spring pressure like that. I ran the Valvoline "not for street use" 20w50...6 quarts+1 EOS and never had an issue.Camshaft was MINT when I pulled it and so were the lifters.

PS...I miss my Vortec

[Chris "drooze" Wertman]

I dont know, I know they will work in an LS, the PAC 1409's Beehive Super Stock spring is a great spring and good and stable to over 8k, if you have room you can go to a different installed height and pick up some already killer rate and pressure.

Weve had the springs to over 8500 with no float.

Maybe worth looking into to see if they will work in your motor, and thats if they are allowed I know nothing of IHRA rules.

Originally Posted by CrateCamaro

I have tried K-Motion K-700 springs (120 @ 1.700) and the Comp Cams 941-16 (130 @ 1.750) and they both work well. I had the comp springs in at 1.700 and they seemed to do the trick with the Sherman Lifters. I ran some more lash than you so that could be something to try.I never spun my engine as high as your trying to so that could be an issue as well. 7200 max. The only time it floated the valves is when I went to a smaller tire and it tried to go through higher. I never had titanium retainers and the springs were wipped at that time so it was an unfair test. Im not a firm believer in the bee hive springs yet but im kinda thinking that they are ok if you are trying to keep the valve train weight down. Id go back to basics and just order a set of 941's and jam them in. 7500 shouldnt be a problem with 140 on the seat. Are you running EOS in your oil? Probably a good idea with big spring pressure like that. I ran the Valvoline "not for street use" 20w50...6 quarts+1 EOS and never had an issue.Camshaft was MINT when I pulled it and so were the lifters.

PS...I miss my Vortec

[Ian Hill]

i am going to try another set 4.88's in the rear for this weekend, then i will creap in on the valve train. My converter slip comes out to almost 10%, so maybe my calculations on what i thought i should have been able to run is a little high. It is still my intension to see this baby turn 7500, i'll just have to wait. i run Amsoil racing 10 30 synthetic oil, should have loads of additives as far i was advised from the manuffacturer. the cam shaft looked so good from last we are reusing it this year.

Ian