Block is back from machine shop (temporarily)

[cgrey8]

OH now that you said that they were using pistons for twisted wedge heads...

There you go...different pistons and different heads on their build. I think TFS TW heads are 60.5cc chambers, not 58cc the AFR185s have. That explains why they were able to use the HR-12.

So yeah, go with the HR-14 and 1.7RRs, get the machine shop to confirm deck height and do necessary decking to get down to 8.195", use Felpro 1011-2 head gaskets, and you should be golden. You can get those head gaskets at AutoZone...although they may be special order. Expect them to be ~$40 each.

[Dave]

Chris,
Confused again. Both Summit and the info I got from Comp Cams say that the -12 is designed to be used with the 1.7/1 ratio. If you look at the -14 cam (designed for the 1.60 ratio) and use the 1.7 ratio, you come up with the same .544" lift of the -12.
Dave
Brand COMP Cams

Manufacturer's Part Number 35-320-8 - XE264HR-12
Part Type Camshafts

Product Line COMP Cams Xtreme Energy Camshafts

Summit Racing Part Number CCA-35-320-8
UPC 36584038153

Cam Style Hydraulic roller tappet
Basic Operating RPM Range 1,500-5,500
Intake Duration at 050 inch Lift 212
Exhaust Duration at 050 inch Lift 218
Duration at 050 inch Lift 212 int./218 exh.
Advertised Intake Duration 264
Advertised Exhaust Duration 270
Advertised Duration 264 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio/b] 0.544 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.544 in.
Valve Lift with Factory Rocker Arm Ratio 0.544 int./0.544 exh.
Lobe Separation (degrees) 112
Computer-Controlled Compatible Yes
Grind Number FW XE264HR-12
Valve Springs Required Yes
Quantity Sold individually.
Notes Designed to be used with 1.7 ratio roller rockers.

[cgrey8]

Yep I see that. The lobe lift and duration between these two cams is identical. The ONLY difference between these two is the lobe center angles and lobe separation.

So the short answer is BOTH can be used with 1.7RRs. I have no clue why they specifically say that on the -12, and not on the -14. I had to look at the lobe-lift values to see that these are almost identical cams hence why they are both XE264HR cams...just a slight difference on the lobe angles. But in this case, that difference in the angles is enough to affect the DCR. Nice find Dave...

[Soul]

So would I still go with the -14 or the -12? Sorry for dumb question.

[cgrey8]

Yep. The calculations are all still the same. It's just an interesting anomaly that Dave noticed about just how similar the two cams are yet the Comp descriptions are oddly different.

[Dave]

Iv'e got the -14 cam here with the valve opening/closing events but can't find them for the -122 cam anywhere on the net, not even at Comp Cams site. Anyway for giggles ran the figures I do have in Desk Top Dyno I got 445 hp and 425 lbs-ft at 6000 RPM. Shows that at even at 3000 rpm 211 hp and 443 lbs-ft torque, thats a lot of low down torque. The -14 will give a milder idle. I had to guess at the ramp rate, Chris knows better on cam design than I do.


While looking for the -12 cam card, did find this build up of a very similar 331 but with ported iron heads.


http://stangplanet.com/forum/general-mu ... 400-a.html
Dave

[cgrey8]

I found both cams on the SummitRacing website as well as on Comp. Here are the two sites for these cams:
Comp XE264HR-12 (PN: 35-320-8)

Comp XE264HR-14 (PN: 35-349-8)

[Soul]

Ok one more dumb question, I'm gonna go with the -14, should I worry about valve to piston clearance?

[cgrey8]

The short answer is you should always worry about that and test for it before bolting everything down and just assuming everything will be fine. That's the generic disclaimer that you should always expect to hear when asking this question.

That said, valve clearance issues are most often an issue when you replace stock heads with aftermarket heads, install a high lift cam, and forget that stock piston valve reliefs are only cut large enough to accommodate stock valve diameters. This is the majority of the reason people install street cams and have problems with piston/valve clearance. However if you are also installing aftermarket pistons as you'll have to do to install a stroker kit, that's not likely to be an issue since 99% of aftermarket pistons will have reliefs large enough for large 2.02"i/1.60"e aftermarket valves.

But even with proper diameter valve reliefs in the piston, there's the chance that the cam profile is just not compatible with the bottom end. There are aggressive enough cams out there that allow the piston to come up on the valve faster than the cam is closing the valve causing the piston to impact the valve head-on and bend it. This is a fairly conservative cam. It opens the valves later and closes them sooner than your typical "big" cam. So there shouldn't be any piston/valve contact events with this cam...I say SHOULDN'T. You should still check for it before bolting both heads and the entire valvetrain down to confirm everything is kosher. Cams and chains can be installed a tooth off or incorrectly and cause issues. So it is well worth the time to verify clearance on 1 cylinder before putting the engine together.

[Soul]

Ya totally going to check it, we do everything on engine assembly, just curious as we were talking decking the block to bring pistons higher and what not, Just wondering with the big valves in the AFR and all that, trying to cover bases I appreciate the help guys. Project is going to be slow for about the next 2 weeks, I'm waiting for stroker kit to come in and I have to gather the rest of the parts, I'll probably get the short block together the week of getting the stroker kit. I still need to get my motor mounts off another car and pull rest of parts.

[rojam18801]

soul... sounds like you have 10 guys helping you with this project as fast as your going. your truck will even be faster. wish i had the money for afr heads, that would drop about 75 lbs off my total weight. i got roush heads, work really good but heavy. but mine on a scale and total weight with me in it is 3030 lbs. have any of you guys weighed yours and what kind of weight do you get. with a v8 of cource....the old trucker

I wish, I've been a one man wrecking crew with about 1 day a week to work on it. Air tools speed up assemble/dissemble but Its been kicking my butt. I fought the engine (fresh pull with everything still on it) on a two wheel dolly by my self for about 100ft across the yard, talk about being tired lol.

full engine,2 wheel dolly,100 ft across yard, i'd be dead. to dam old to be doing that. old age suck's...the old trucker

[Soul]

Stroker kit is going to be in today, and hopefully rest of parts minus heads by this weekend, should have shortblock together then.