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hello, i got a 1.7 and a 1.8..i want to rebuild the 1.7 because i cant line bore the mag. 1.8 case and the 1.7 is the original motor.i know the 1.8 heads have bigger valves and if i use them i need to use a 1.8 piston kit but i want at least 125-150hp..i want reliability and 50k lifespan..if i go for the big bore kit, say 96mm to 100mm do i have to use a aftermarket crank?I'm prepared to get machine work to clear the skirts, but I'm confused about crank length and rod, piston combinations..I'm needing a economical solution to my rebuild (around $2000) also what lift cam for good all around street performance and get the hp #'s I'm looking for.are the big bore kits 8:1 or less?also im going to use weber type dual carbs maybe 40mm?.if i do just put the 1.8 heads and a 1.8 cylinder kit, can i use my stock 1.7 crank and rods? i know this combo will not give me 125 but i guess i could live with just a 100hp.thanks, mike

Try here. You may need to register, but it's free.

been there but they do not offer the answers im looking for

For 100 hp you can get there with a 1911 (or close to it) which is a 96mm bore on your existing 66mm stroke crank. For 125 you need to get into a 2056 which will use the same 96mm bore, but will need a 2.0 bottom end (crank and rods) and 2.0 heads.

Cases are all interchangeable.

If I were in your situation (parts & budget), I'd send the 1.7 heads to Len Hoffman and pick up a set of 96mm pistons/cylinders (make sure you get ones for 66mm stroke, the 2.0/71mm stroke are different). Get a cam from Jake Raby or get a WebCam.

Case is aluminum, not mag. Cranks and rods are the same between 1.7 and 1.8, both 66mm stroke with 55mm journals, so pick the better one. Use whichever case is better (they are the same), get some 96mm pistons/cylinders for the 1.8, get the 1.8 heads rebuilt. 96x66 will give you 1911cc. Get a valvetrain kit from Jake Raby, or buy a web cam and lifters. Compression ratio depends on a number of factors.

Look for Brer's head rebuild thread... $650 will get you a basic head rebuild. $100 for the crank, $100 for the rods. Cam/lifters/valvetrain $350-$500. Pistons/cylinders/bearings/gaskets...

my bad, its a 75 1.8..it is mag...mike

all t4 cases are aluminum except in really odd instances

If by some weird chance you do have a mag case, ditch it and get a much stronger (and prevalent) aluminum one. If you search you can find which case numbers are mag, I sincerely doubt you have one though.

i will do a scratch and burn test. i did read somewhere that the 76-75 cases were mag.....anyone know about this change in 75..mike

Only mag Type IV cases I am aware of were European VO code. If you have one of those, your car has quite a history behind it

GC cases for 75-76 are Aluminum and yes, the VO industrial engine had a mag case.

http://www.914world.com/bbs2/index.php?showtopic=86691

There's the link for Brer's thread. =o)

If you go to Tunacan
http://www.tunacan.net/t4/

Read all about the motor, the rod ratios, all the technical info on the Type 4 motor.

If you go with bored out stock 1.8 liter cylinder (go to 96mm) you can get KB pistons that will match your rods and crank so you will end up with a 1911 motor.
130 hp from that motor with the 1.8 heads and carbs can be done with the right camshaft.
150hp from that motor will require more headwork and the right set of headers.
any more HP from that motor would not be worth it IMHO....at thatpoint I would go up to a 2056 (71mm crank and 96mm pistons) then you will get more torque (which is real power...HP is marketing)

Read the Tunacan site. Its has some great explainations on all the motor parts.

You can use any case you want to start with.

Rich

wow! 130 sounds real good...i have read alot on that site before but never could find exactly what i was looking for..im now sure of what i need and what i got. i want to THANK YOU GOOD PEOPLE for the info and advice.i guess i will stick to the factory 66mm stroke with the special 96mm 1.8 bore kit, 1.8 heads with 1.7 rockers for 911 adjusters. 42mm dual webbers/w carb. distibutor and a mild cam maybe a hot ignition too...you think i can get 125hp with that? that would be very cool and should feel nice..mike

What Webers do you have that are 42mm?

I really wouldn't expect 125 from a 1911 that's streetable. Maybe if you get it to rev real high you might get that up in the power band. But IMHO, a motor like that will be a real slouch down low (i.e. around town driving).

But, Rich and I have disagreed before.

True, we have not always agreed.
I dont expect that we will ever always agree...its car stuff.

A stock 2.0 liter motor will get to 125HP with proper tuning running Djet.
With the right headwork on a 1911 and the right camshaft, 130hp is quite attainable. You will use 40mm webers, not 44mm. The 44mm webers are to big and you will never get the motor tuned right.

A motor is just an air pump, so remember that important issue.
the restriction on these motors starts at the camshaft, so call Jake and get a good camshaft. An airpump is an airpump...no matter what the stroke is, you are pumping that same amount of air..
Your goal, should you choose to accept it, is to make your motor pump air as efficient as you possibly can. This is all done by the heads, camshaft, intake, and exhaust...dont skimp on any of those, dont guess either.

Then the heads...the 1.8 heads have more raw material to work with then the 2.0 liter heads so you will have a better chance of finding heads that have no cracks if you stick with 1.8 liter heads.
Old school racers only used the 1.8 heads due to the lack of cracks and the ability to port them out more...just more material to start with.

Spend your money on the heads, dont just throw huge valves in and expect miracles. Send them to Len...talk to Len..tell him your combo and you will get a great set of heads for that motor.
Using vendors that have experienced your motor design not only on a dyno, but in a real car is very important. It gives you more bang for the buck.

Size the valves to the optimum flow of air for the p/c set and the camshaft and you will get where you need to go with those heads.
Len and Jake will advise you correctly, and from what I have seen the prices for both are better than if you go to other vendors for the parts.

Like I said, upwards of 150 hp is where you will get a hairy and hard to maintain motor with the 66mm crank...I have driven 180HP 66mm cranked motors and while they are great race motors....they suck anywhere else...the power is to high up in the rpm range...

130 is attainable, and drivable.
Dont get to much of a camshaft...to much overlap will move the powerband up in the rpm range...it may sound cool at idle but you will need to rev it up to 3k before you can let out the clutch...that is not a fun way to drive.

Get a header. A properly tuned exhaust system is a bolt on way to make 10-30hp, depending upon the heads and camshaft you have.

Rich

ok ok thats sounds cool..i want some low end for sure, its what i like most about my 911.i like a quiet smooth exhuast, the more quiet the better but i hate the way the stock exuast looks..i love the monza quad tip set-up but know nothing about it other than its heavy as hell.the cam will be the important choice.im not going to race it.but i will not be driving it every day either.i will talk to Len...mike

Hey Mike,

Glad to see you having a plan on getting a little more power in the teener. I have a 2056 with a header(no muffler yet or it would be on the car, header that is) I am planning on getting going by mid-summer to replace my 1.8. Case has been sealed but plan on opening it up before I fire it up. Have meant to stop by your place a coupla of times but it didn't work out. Hope you and your brothers had a good holiday. When it starts to warm up we need to make a few runs with the MTFR guys.

Also, what do you think Jeff would charge to paint a coupla 914 doors?

Sorry for tha...


Ken

Ken, please feel free to stop by any time.the 914 has come a long way since you seen it last...jeff will paint your doors for whatever you think is fair..he is doing a 911 whale tail for a guy now so soon would be a good time to bring them buy while he is in mode...its good to here from you man...mike