stock valve spring limit

[dustinmoran91]

i looked around and nobody has a clear cut answer to my question.
what is the biggest cam i can run with stock 340 valve springs?
this is a slap together motor out of parts i have laying around until i get my good motor built the right way with the right parts.
i have a 318
stock bore
cast factory flat top pistons
cast rings
'302' heads
compression should come in at 9:1 or a little more
converter will be a 2500 stall
but i need a cam and lifter set.
i dont want to spend the extra money for high dollar springs when i can get stock replacements for $50. however if anyone can also recommend a spring set that costs a just a few dollars more and wont require machine work i would go that route. i want this motor to sound awesome and intimidating at idle and i could care less about how much vacuum i pull lol.
any input and ideas will be appreciated :toothy8:

 

[Cudafever]

i looked around and nobody has a clear cut answer to my question.
what is the biggest cam i can run with stock 340 valve springs?
this is a slap together motor out of parts i have laying around until i get my good motor built the right way with the right parts.
i have a 318
stock bore
cast factory flat top pistons
cast rings
'302' heads
compression should come in at 9:1 or a little more
converter will be a 2500 stall
but i need a cam and lifter set.
i dont want to spend the extra money for high dollar springs when i can get stock replacements for $50. however if anyone can also recommend a spring set that costs a just a few dollars more and wont require machine work i would go that route. i want this motor to sound awesome and intimidating at idle and i could care less about how much vacuum i pull lol.
any input and ideas will be appreciated :toothy8:

I had/ the stock 340 valve springs with a .474 MP cam and a different set of head when 7200 with out valve flow. Now those heads had the small stem Nail head valve in them. that stock mushroom intake valve is a lot heaver and will float much much sooner.

 

[dustinmoran91]

or do you guys think it would be worth the investment to get a set of magnum heads for $60 (around here) and some pushrods. since i have to spend atleast $50 on springs anyway i could run the magnum heads that are already assembled and buy a set of pushrods and have larger valves and better flow? just a thought lol

 

[Bad Sport]

but i need a cam and lifter set.
i dont want to spend the extra money for high dollar springs when i can get stock replacements for $50.

If you need a cam and lifter set, why not just buy a comp kit? It will have cam, lifters, springs, retainers, locks, seals, everything you need. It also comes with a timing set, though I would not use it. I would go with a double roller, if you order through Comp they will substitute the double roller in for a few bucks more.

As far as just springs go you can get upgraded springs from Summit or other outlets for a little over 60 bucks.

The last thing you want is valve float.

 

[dustinmoran91]

well i already have the seals and retainers, locks, and such. a comp kit is around $450 plus shipping

 

[Bad Sport]

well i already have the seals and retainers, locks, and such. a comp kit is around $450 plus shipping

Then just order a cam and the comparable springs they recommend for it, and follow the proper breakin procedure.

 

[breakstuff]

I ran stock 318 valve springs with a factory 340 cam, .441 lift in my 318 hand grenade. At around 5300 the valves would float. I beat the crap out of that engine trying to blow it up. Ended up giving it away still purring like a kitten. LOL

 

[dustinmoran91]

Then just order a cam and the comparable springs they recommend for it, and follow the proper breakin procedure.

but the problem is, at summitracing.com all their cams say valve springs are required. i want to use stock springs to save cost. that's why i asked what the biggest cam i could run with them was. i don't want to spend hardly any money on this engine because for $150 i can pull one at the junkyard however its a 50/50 shot at whether it runs or not. all i need to buy for this engine is a $115 re-ring kit from ebay some valve springs and a cam. everything else i have besides odds and ends stuff. i would rather spend $3-400 on freshening this engine than $150 on one and have to freshen it anyway.

I ran stock 318 valve springs with a factory 340 cam, .441 lift in my 318 hand grenade. At around 5300 the valves would float. I beat the crap out of that engine trying to blow it up. Ended up giving it away still purring like a kitten. LOL

thanks! those are the answers im looking for. so now i know i can run atleast a .441 cam and be safe but im hoping someone will chime in and say i can use bigger.

there is a formula installed height-(coilbind+.060) to determine max lift allowed but i havent been able to find the stock spring specs anywhere.

 

[dustinmoran91]

also i should mention that once i build my 360 i'm going to pull this 318 out and give it to my sister in law for her duster so cheap is the goal lol

 

[Cudafever]

Does and body know what the max lift is before the stock retainer hit the valve seal?

This might be the deciding factor just as much as rpm/ valve float............

I know with the 340/360 you are pushing it if you go .500" lift and the retainer will hit the guide after that.

 

[dustinmoran91]

Does and body know what the max lift is before the stock retainer hit the valve seal?

This might be the deciding factor just as much as rpm/ valve float............

I know with the 340/360 you are pushing it if you go .500" lift and the retainer will hit the guide after that.

That is the perfect way to ask what i was thinking! Lol thank you! I think i may have been wording it to vaugely but you got it technical for me. If i could run a .480ish lift cam i would be super happy. Now i might be going backwards by asking this but with stock 1.6 rocker arms on a magnum head what lift can they handle with a stock spring? Or would it be better to port and polish the "302" heads that i have already while keeping the stock valves.