Engine rebuild kit questions

[86lxhatch]

I am using this rebuild kit from summit for my 306:

Sealed Power CSMHP799-311 - Federal Mogul Premium Engine Rebuild Kits

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This is my planned set up:​

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holley 600 cfm carb​

edelbrock performer rpm air gap intake​

stock C5ae 58cc heads​

roller rockers​

b303 cam​

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When I researched the kit, it showed I would get 10.13:1 comp. ratio with a 58cc head. I would like a lot of compression as this will remain a nat. aspirated motor, but was wondering if I should use the head gaskets that came with the kit, or go with a different thickness to increase my comp. ratio?​

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I would like to see around 260 rwhp, is it possible with this set up?​

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[Rick 91GT]

Pretty sure that is a Fel-Pro headgasket included which is going to be about .041" compressed, which gives a decent quench area...leave that alone. If you want to increase the compression I would mill the heads a little more. The stock heads are going to truly limt the power and your looking for about 70hp over a stock motor, I dont think that will happen with out some major cyl head work or an aftermarket head.

It says the kit is a flat top with no valve reliefs, is that true.... if so the 10.1 is correct. If you mill the heads to 56cc it will be 10.38:1

Do you already have all the parts?

 

[86lxhatch]

yes, I already have the parts. The kit said flat tops with no reliefs, but what it came with was flat tops with 4 valve reliefs...also, I haven't done anything with the heads as of yet. I found some RHS heads (used) on craigslist for $400, but I think the combustion chambers will be way to large.

 

[Rick 91GT]

What is the PT# of the piston it came with? I can tell you comp ratio. The RHS heads would be a great addition, alum or iron?

 

[86lxhatch]

pistons are summit part #

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SLP-L2488F30​

the heads are irons. I am building on a low budget, so I am looking for used parts when I can find good deals...

Still undecided on the heads though. I don't want to sink a lot of money in my current heads trying to make them perform like performance heads, when I could just keep looking to find some good, used performance heads that are ready to go. Thanks Rick for the info.

 

[Rick 91GT]

They are 2cc reliefs so your looking at 9.85:1 with a 58cc head

The RHS is a good choice

 

[86lxhatch]

Thanks for the help. Do you think that if I go with the larger heads, it'll make more power with the lower comp. ratio, or am I better off with smaller heads and more compression? This car will be used for road racing and scca events, not for drag racing.

 

[Rick 91GT]

A custom cam could take care of smoothing out the curve for the combo, b303 isnt the best choice IMO but Ive never been a bog Ford Racing cam fan. I would keep as much compression in it as you can, you culd always mill the RHS chambers down a little.

 

[Jason 302]

I ran that exact kit the first time I built my 306....the pistons stuck about +0.010 - 0.015 out of the hole because their compression height was too tall. Block had only been trued up...no material removed. So that might be something you want to check into when you factor your compression ratio.

I went with some SRP's and never looked back....much lighter.

Speed Pro's = 1.619 compression height.
SRP's = 1.600

http://www.summitracing.com/parts/SRP-138734/

 

[Rick 91GT]

He's correct in a perfect world those pistons will be .009" out of a 8.20"deck... Factory decks are all over the place, have it measured before any machine work is done. You may want to return that kit and go another route.

 

[Jason 302]

I found out when my dial gauge kept trying to fall off the deck when I turned the motor over.

 

[86lxhatch]

I measured the distance between the top of the deck and top dead center of the pistons and came up with roughly .007-.009, using a good straight edge and feeler gauges. Rick is right, the factory decks do seem to be all over the place, and nowhere near perfect. The pistons do have the valve reliefs, so I'm thinking they will be okay, so long as I don't go overbored with shaving the heads, or run a ridiculously high lift cam. I will definitely have to go with the clay method to check ptv clearance once I get some heads, but are my rough measurements in tolerance to keep building?

 

[Jason 302]

I ran those pistons with stock heads and a TFS #1 cam and didn't have any clearance problems. Running a 1.90 or 2.02 valve might be a different story though. I personally prefer the dummy valve spring method for checking PTV clearance as I think it's more accurate.

 

[Boydster]

I got my springs for checking PTV clearance from Ace Hardware. They have drawers full of all kinds of springs. All you need is one of about the same diameter, and yeah, they're nice and light but strong enuf to hold the valve closed.