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[deputydawg]

Engine is a stock 2001 88" carbuerated Twin cam. I have purchased an Andrews 37G set of cams with S&S gear drive kit. The manufacturers spec's say that the cams are good up to a CR of 9.5:1. I was hoping to use a S&S piston and barrel kit that has 9.7:1 CR. Is it possible the valves will hit the top of the piston or some other catastrophic event will take place? Am I tempting fate or is this slight difference acceptable? As with most of us, dependability is foremost on my mind, so I do not want to take a substantial risk with this upgrade. Also, will the addition of Harley performance heads (16953-99C) work in this upgrade? Thank you all in advance, I appreciate any help in this matter. Mark
P.S. Had great ride today, went to an HD event and pulled off a nice little burnout with the County's finest just shaking their heads Ride on!!

[nidan]

TW37 will work fine up to 9.8 , and work better with head work . There have been some that have suggested fly cutting the pistons for clearance. I ran TW31s ( same lift , different timing for higher comp) with flat tops and SE perf heads with no issues.

[rednectum]

yep, the 37 will work , some get pping at over 9.8. on your heads, save the money and use stock tc88 heads that have been worked. make sure the s&s comp ratio is when using 85 cc chambers. they may advertise comp ratio when used with their heads.

wanna save even more? dore your stock jugs and buy the SE flat tops, total piston kit and bore = $220-$250

[BillH]

Dawg -

Did this same build.  Sent the stock cylinders and heads to Short Block Charlie in AZ. He bored the stock cylinders and did some mild work on the heads, he calls it his "Scottsman" job.  With the 37g's, SE flat top's, SE lifters,Vance & Hines Ovals, Doherty PP, and a PCIII the bike makes a bunch of torque in the low and mid range, still gets decent mileage, and is very dependable.  IMHO very good results for the $$ spent.

Billh

[nidan]

SBC has a good rep as does Dewey Jelen, who has done many heads for TW 37's  http://www.deweyspegs.com/dynos.html

[BillH]

Forgot - used the Cometic .030" head gaskets also.  They give a little better squish.

Good luck.

[deputydawg]

Thanks to everyone for the help. Today I checked with two well known authorities in my area and they concurred with the prevailing thought expressed here. Now, what to do about the heads. The local shop gave a quote of 1,100.00 to trick out the heads, That ain't happening! I do have a new set of stock heads I can use if nothing else. Thanks again, Mark.

[BillH]

Dawg -

SBC - http://www.motorcyclemachine.com/scottman_pro.htm - is currently charging $495 for this service.  Check out his site, he has a good reputation for top quality work.

Billh

[deputydawg]

thanks BillH. Mark

[rednectum]

bigboyzheadporting.com also does great heads for the 37 build, as well as gmrperformance.com. also deweyspegs.com as mentioned above. none of these are even near the $1100. heck, you could buy a used car with the difference in price, and for a 37 build, i bet they all run neck and neck.

[deputydawg]

Thank you Mr. Rednectum. I have contacted one of the guys you mentioned; his dyno charts looked great. If I can near what those motors are putting out I'll be as happy as the Grampa I am in a Cheerleaders dressing room! Later, and Thanks... Mark

[Talon]

TW37 will work fine up to 9.8 , and work better with head work . There have been some that have suggested fly cutting the pistons for clearance. I ran TW31s ( same lift , different timing for higher comp) with flat tops and SE perf heads with no issues.

The lift on the 31 and 37 are the same, 0.510, but different timing. I think thats why they suggest the CR of 9.5, due to the timing, not the chance of valve clearance problems.

[GMR-PERFORMANCE]

If you are looking for a set of SBC heads i have a set of takes off from a customer. 1.940/ 1.625 valves if his site is correct. They are ported and will give you 9.7 compression. Let me know, cost would be 350 with exchange on your heads. They are in great shape black in color. They have approx 1300 miles on them.

[deputydawg]

Thanks, I went with Branch Flowmetrics here in CA. The local engine builder/drag  racer recommended them and I saw some of their work which looked great as did their dynos. Stil pricey, but I was told heads are the biggest bang for the Buck! Thanks everyone. Mark

[GMR-PERFORMANCE]

Sent you a PM.