Need tips for putting engine together

[William B.]

Re: Need tips for putting engine together

Thank you, Duke, I didn't read the recent thread and maybe some other people missed it also. Doesn't hurt to repeat things for some us senior's and new members.

[Joe L.]

Re: Need tips for putting engine together

Joe

I like to degree a cam on #1 for street engines. This way you know where the cam timing is and you can slightly adjust for best street performance an economy. However, when building a race engine it's best to degree the cam for each cylinder. Should the cam cut be slightly off grind for one or more cylinders a slight power loss will occur and you lose the race . You would never detect this slight power loss on a street engine. I just finished building a small block street stroker using a Comp Cam and the degree on #1 was right on.

Good luck

Bill

Bill------


I have not built a huge number of engines. However, I've never yet found a cam to be out-of-spec on degreeing.

[Duke W.]

Re: Need tips for putting engine together

Thank you, Duke, I didn't read the recent thread and maybe some other people missed it also. Doesn't hurt to repeat things for some us senior's and new members.

I can't repeat the whole thread because there were many contributors. Also the OP shoud use the late big block dual valvespring/seal assemblies. This has also been thoroughly hashed out. The early valvesprings are weak and subject to breaking!

A little searching of the archives should reveal all this knowledge.

Duke

[Michael H.]

Re: Need tips for putting engine together

Bill------


I have not built a huge number of engines. However, I've never yet found a cam to be out-of-spec on degreeing.

I have a GM over the counter replacement cam for a 67 and later 435 HP that has one cyl (#6) 11* off from #1 cyl. A few others are off also but not nearly that bad.
That the result of a process used to grind a quantity of cams off of one master called "gang grindind". Several cams are ground at the same time from that master and usually the last in line is the worst.
Special order cams and competition cams are always ground one at a time so the numbers are usually accurate.
Years ago, Crane was one of the only companies that used the "one at a time" process and that was one of the reasons I always liked their cams.

I don't know if any of this is true for cams made in the last 15 years though.

[Clem Z.]

Re: Need tips for putting engine together

i installed a crane cam in a drag race engine that was a direct replacement for the cam i took out. i degreed the intake lobe to make sure it was installed on spec BUT the all exhaust lobes were off 10 degrees and the exhaust valves hit the pistons at high RPMs. crane paid me $2400 to redo the engine. check both intake and exhaust

[Michael H.]

Re: Need tips for putting engine together

i installed a crane cam in a drag race engine that was a direct replacement for the cam i took out. i degreed the intake lobe to make sure it was installed on spec BUT the all exhaust lobes were off 10 degrees and the exhaust valves hit the pistons at high RPMs. crane paid me $2400 to redo the engine. check both intake and exhaust

Yup, things like that happened from time to time. The equipment is only as good as the operator.

[Joe R.]

Re: Need tips for putting engine together

Thanks for the excellent advice, guys. I have the DVD on order. I checked with the machinist who put the short block together. He said that he ground the groove in the rear of the camshaft and used the three hole bearing. The guy who built the heads used stouter than original springs with compatible seals. I talked to the original owner a while back, she mentioned problems with valve springs breaking too. I think I will go ahead and degree the cam. It may not be absolutely necessary, but it can't hurt.

Joe

[Joel F.]

Re: Need tips for putting engine together

Joe,

Can you find the valve spring your builder used and post it here? The OEM valve springs were structurally weak and prone to breakage, but I'd caution against using a stiffer spring as it can lead to catastrophic cam failure. I think what Duke was suggesting was a stronger spring that has meets but not exceeds OEM pressure and rate.

Just my $.02

Joel

[Joe L.]

Re: Need tips for putting engine together

Thanks for the excellent advice, guys. I have the DVD on order. I checked with the machinist who put the short block together. He said that he ground the groove in the rear of the camshaft and used the three hole bearing. The guy who built the heads used stouter than original springs with compatible seals. I talked to the original owner a while back, she mentioned problems with valve springs breaking too. I think I will go ahead and degree the cam. It may not be absolutely necessary, but it can't hurt.

Joe

Joe-----


I would definitely not use "stouter" valve springs. At least, I would not use springs that were very much "stouter" than stock, ESPECIALLY if you are using a stock, flat-tappet camshaft. The original valve springs used for 1965-E69 big blocks were VERY failure-prone. However, these were discontinued 38 years ago and replaced by GM #3970627 which remain available to this very day. An engine set of these is available under GM #12371061. These are the only springs I would use with a flat tappet camshaft.

[Duke W.]

Re: Need tips for putting engine together

Joe,

Can you find the valve spring your builder used and post it here? The OEM valve springs were structurally weak and prone to breakage, but I'd caution against using a stiffer spring as it can lead to catastrophic cam failure. I think what Duke was suggesting was a stronger spring that has meets but not exceeds OEM pressure and rate.

Just my $.02

Joel

I was referring to the 3970627 dual spring/damper/seal assembly that replaced the prior failure-prone early OE single spring/damper circa 1970 in both production and service. This spring will provide excellent service with any OE big block cam.

The OP says it has a Comp Cam, which is out of my league.

I woundn't install a Comp Cam in an engine if they paid me to do so!

Duke