building a 1911 from a 1.7, will my existing heads work? Options

[bradtho]

I'm thinking about taking my stock 1.7 to a 1911. Some old threads seem to suggest that you can't do this with the 1.7l heads, while others seem to suggest it's fine. Can anybody set me straight on if I would need new heads, if they'd need to be machined, or if I'm good to go?

Also, I've got 2 engines all with original german cylinders. Am I better off taking the best 4 and boring them out or going with new chinese cylinders (local shop recommends QSC). I've been thinking if I've got 4 decent ones that the OE cylinders would likely be better than the chinese stuff.

anything else I should be thinking about?

[Jake Raby]

Yes you can do this with the existing heads if you open them to a 105mm OD register like the 1.8 and 2.0 heads.

Here is an article I posted on my forums on a similar topic, lots of the info you need will be found within this article.


This topic is certainly one of the "hotter" topics of today and one that is quite misunderstood. Most people believe that machine work is involved with this conversion, but with the right components and this article it can be done with only interchangeable OEM/ stock parts.

I will break the article into two sections, one for the 1.7 stock engine with a supplement at the end of the article for the 1.8 engine, since the parts needed for each of these is only slightly different and mostly related to cylinder heads.. The 1.7 engine is the most commonly questioned engine, hence my use of it as the primary conversion base.

To convert your engine from a 1.7 to a 2 Liter Type 4:
First of all, there is nothing magical about the 2.0 case. The 1.7 case that you have has quite a few serious benefits that most people do not understand that haven't worked with these engines for most of their adult life. Things like stronger cylinder registers, better metallurgy and much more will be gone over in another article, but for now just realize that your 1.7 case (of any case code or generation) is the preferred base engine for all RAT engines, especially those making over 200 Hp.

Remember this statement:
There is NOTHING that the 1.7 case can't be used for in performance applications- in no way does the 2.0 case have superiority over the 1.7 case! This means after you make your engine into a 2.0 following this article you can feel free to take it as large as a 3 Liter engine with no challenges that wouldn't be experienced if you had started with a 2 liter case...

The 2.0 (94 or 96mm) cylinders will fit into the 1.7 or 1.8 crankcase exactly as they do the 2.0!!!! NO MACHINE WORK IS NEEDED AS ALL REGISTERS ARE THE SAME SIZE!

Now that we have that out of the way and have established that you have a solid platform to work from we are ready to get into the technical aspects of the article.

Start by disassembling your 1.7 engine completely. You will split the case and remove all components in preparation for case clean up, inspection, and reassembly as a 2 liter. When doing this note any odd wear, and if the engine had a failure that created this tear down not that cylinder and retain the parts that were scattered as they may assist with the inspection process. If the engine had any funny sounds, rattles, knocks or etc make a mental note of them and explain them to the machinist that measures the case for you as they may be tips that lead to an issue that could prove to "bite" you later on.

After disassembly you will sit aside the following components from your 1.7 engine as they will be replaced with 2.0 items to complete the conversion:

1- stock 1.7L 66mm stroke crankshaft. You will need to remove the cam drive gear, horse shoe spacer, brass dizzy drive gear, snap ring and perhaps even the woodruff key from this crank as the 2.0 unit you source may not have one. Our machine shop, or your local machine shop will have to press this assembly off the crank for you.

2-Stock 1.7 liter connecting rod set. You will not need to retain anything from these rods for the 2.0 conversion

3- cylinders/ pistons/ ring assemblies. None of this will be needed as the stock 90mm units will be replaced with a 94mm stock 2.0 arrangement, or our 96mm arrangement if you intend to take this engine to 2056ccs while you are inside it.

4- Sit your stock 1.7 cylinder heads aside as you may/ may not re-use them with the 2.0 components according to the direction you choose to go with the conversion.

Now that you have removed the components that will not be re-used with the 2.0 conversion you can concentrate on cleaning up the 1.7 case and other components that will be re-used and must be cleaned and measured to determine their integrity.

Send your case to the Type 4 Store's machine shop, or take it to a local machine shop to have it's align bore sizes compared to those found in the Bentley manual. If the case is within tolerance inspect it for odd issues, cracks, parting line pry marks and then check it's cylinder registers to determine that they do not need re-surfacing to attain the least deck height differential after 30 years of service.

NO MACHINE WORK IS NEEDED FOR YOUR 1.7 CASE TO FIT THE LARGER 2.0L COMPONENTS!!!

If the case is deemed "good" you are ready to go shopping for the parts you'll need for the "conversion". Some of these items can be sourced as "used" items from Ebay or a local wrecking yard, but wise converts will source them from a reputable source like our Type 4 Store. Doing this removes guess work from the process and makes the process both quick and easy and while it is not as "cheap" we all know that you get what you pay for.

Here is your shopping list.

1-"stock" 2.0 Liter crankshaft, 71mm stroke with 50mm rod journals. Don't worry about counter weighting with this part, just find a stock crank and use it! If you source the part used you must have it inspected by someone familiar with the TIV and what issues are common to crankshafts today. Inspect all critical surfaces, journals as well as the flywheel seating surface and the crank gear key surfaces and the crank pulley hub key surfaces as these are the most problematic areas. If you want to kill the guesswork with finding a crank, just bite the bullet and click this link to add a stock crank to your shopping cart at the Type 4 Store. If you go this route we can assist you with selection of the prper bearings and etc so you want need more assistance with measurements.
http://aircooledtechnology.com/store...cat=268&page=1

2- "Stock" 2.0 liter connecting rod set. If you find these on Ebay or at a salvage yard you MUST ensure they are 2 liter rods. The 2 liter rod is 5.160" long and uses the 50mm rod bearings, it can easily be noted due to a lack of the "bump" at the outermost portion of the small end of the rod. 2.0 rods are contoured on the small end and lack the "bump" that your 1.7 rods had in this area. You will also need to ensure that your rods are a matched set as they may have came from two or more engines and could be different lengths and different weights. Have these measured to ensure their big and small ends are sized properly, else you could end up with low oil pressure or a nasty knock on your new engine converted to 2 liters. Wise converts will send these rods to be properly "rebuilt" by a Type 4 specialist, if the work is done by a local shop watch them like a hawk!

If you decide to give up looking for a used set of rods you may consider a set of the Type 4 Store's brand new, forged H beam style connecting rods. These are 300 grams lighter than stock, have real ARP bolts installed and are "stock" in every other dimension including big end/small end and overall length. They come 100% balanced, length matched and ready to be final cleaned and installed. These are standard equipment on all RAT engine kits that use the stock 2.0 crank.
Follow the link to add these to your cart at the Type 4 store.
http://aircooledtechnology.com/store...cat=366&page=1

3- Main, Connecting rod and camshaft bearings: Of course you never want to reuse engine bearings. They are designed to wear so the journals and other parts do not, don't cut corners with used bearings- thats just dumb!
The 2.0 crankshaft shares the same main bearings as your previous 1.7 liter crank did and the part number is the same, I prefer German (Kolbenschmidt) bearings and we stock a full line of stock and oversized mains in the Type 4 Store.

For the connecting rod bearings you will now use the bearings that were stock for the 2 Liter engine,(part numbers begin with "039") since you now are using the 2 liter crankshaft, which is of course the determining factor for the bearing selection. Make sure that you have the proper bearings for the crankshaft size your crank may have been ground to, you cannot "assume" what size these parts may be- you MUST have them measured! The new RAT "Extreme duty" connecting rod bearings from the Type 4 Store are a wise decision for engines that will be driven hard, or used for competition.

While you are inside the engine go ahead and replace the camshaft bearings as well since most of the time the "thrust" surfaces of these bearings are worn. These will not be altered with the 2 liter conversion as all TIV engines used the same cam bearings. You might choose our new "Extreme duty" cam bearings that eliminate premature thrust surface wear.

If you decide to purchase bearings from the Type 4 Store to eliminate guesswork, click this link and select what bearings you'll need. If you need our assistance with bearing size selection just note that on your order and one of our specialists will choose the bearings you need for you to match the other Type 4 Store components you may have selected.

4- Cylinders and pistons:

Note: The wrist pin height (compression height) of the pistons must be set up for the 2.0 liter crank and rod set, 1.7 and 1.8L parts are not compatible with the converted 2.0 parts that you now have!!! Anything that is bought for cylinders and pistons must be referenced for use with the 2.0 engine!

Now, you need to make a decision... You can either go to the stock 2.0 liter 94mm bore sizes and chose from either a low compression ratio set from a VW Bus, or a high compression set from a Porsche 914, both offered by the OEM supplier, Mahle. We offer these in the Type 4 Store and have the best prices on the kits that you can find.
If your engine is going into a Bus application there is no doubt about what cylinders and pistons should be used- stick with the OEM 94mm lower CR pistons so you can keep the CR below 8:1 while retaining a deck height between .040 and .060. With all bay window buses the 96mm bore size should be avoided for longevity reasons (pushing a 5,000 pound Bus isn't easy). Here is where you can find the Type 4 Store OEM piston/ cylinder kits.
http://aircooledtechnology.com/store...cat=275&page=1

If you have a Porsche 914, or VW TI conversion, or other lightweight performance application, you may choose to upgrade your engine to a 96mm bore, taking advantage of an added 85cc of engine displacement, creating a 2056cc engine. If you choose this upgrade the prices for the parts will be about the same as the smaller 94mm OEM kits and you'll get added power without sacrificing reliability or longevity. When considering this upgrade you must understand that the added displacement will necessitate a camshaft alteration to take total advantage of the added bore size (if you intend to create a thoroughly designed engine). It is possible to run the 96mm bore without making a cam swap, but we always recommend avoiding the stock camshaft to take advantage of cooler running temperatures, broader, more usable power and this could not be more true than when upgrading to the 96mm bore. Those that install the 96mm bored cylinders can expect slightly warmer temperatures, added down low power (at the loss of mid range performance)

If you choose to retain the stock camshaft I seriously recommend sticking with the 94mm bore and keeping the engine as a "Bone stock 2.0" engine. The stock camshaft demands a conservative engine combination!

The final consideration on the topic of cylinder selection will be what is planned for the cylinder heads for the converted 1.7> 2.0 engine. If you choose to keep your 1.7 heads and have them opened to 105mm register size only, with no other upgrades it would be my recommendation to retain the stock 94mm bore as the 1.7 heads cannot effectively fill the chambers of the 96mm bored engine and are just barely adequate for the 94mm bore upgrade.

If you do end up going with the 96mm bore size, do not skimp on Chinese pistons and unknown ring packages. Our Type 4 Store 96mm Keith Black piston and cylinder kits are the best value and have the best quality for street and even dual purpose "Street/ Race" engines. These arrangements don't have the issues of forged pistons on the street and are our favored choice for RAT engines. Add these to your cart if you want to continue to use Type 4 Store parts in your engine. (if you choose pistons from another supplier ensure they are for the 2 liter engine so they will have the proper wrist pin height to function with the 2.0 component upgrades you have done.
http://aircooledtechnology.com/store...cat=275&page=1

If you need further direction on which components you should choose for your application, feel free to post a question on our online forums and we'll help you make the most wise decisions possible.

5-Now more on cylinder heads:
If you are staying "Bone stock" with camshaft, lifters and etc feel free to simply have your stock 1.7L heads bored to a 105mm register size to accommodate the larger 94mm (or 96mm performance) cylinders. You should always have this work completed by a reputable Type 4 cylinder head specialist! Trusting this and any other Type 4 head related work to a local shop not seriously experienced with these cylinder heads can easily and quickly turn your engine into a failure statistic. We trust all our head work to Len Hoffman at www.haminc.biz and you should as well-

If you choose not to rebuild the heads, replace valve seats and etc the heads will need no further modifications for the 2.0 bore size to function correctly. If you are going "bone stock" skip the next paragraph of this article.

To rebuild or not??:
One reason (and perhaps the biggest) that you should rebuild the heads completely would be to remove the stock, 35+ year old sintered metal valve seats. Today we have modern materials, modern processes and 30 years of aftermarket experience to ensure the "dropped seat" issues of yesterday that plagued the Type 4 engine are eliminated. Wise engine builders will take advantage of these process when making their upgrades and you can bet the peace of mind alone will be worth the cost of the work.

The stock 1.7 heads are great performers for small displacement engines up to 2056cc, they have the smallest ports of all TIV heads, but that makes for extreme port velocity and insane torque and extreme drive ability, especially at low revs with the proper camshaft package. The ports of the 1.7L head are slightly crippled by the super small valve sizes offered in the stock heads from the factory, these were fine for the 90mm 1.7L bore, but now that bore has been added, as well as stroke they won't cut it. When having valve seats replaced during your rebuild process you can take advantage of all new valve train components and increasing the valve sizes to 42mm intake and 36mm exhaust will help to optimize those awesome ports and won't cost much more at all than a bone stock rebuild with a valve seat swap/ update and you'll be stuck with OEM quality stock sized valves. Choosing a RAT valve train package will guarantee that you can upgrade your heads with the proper, compatible parts that will optimize performance and will help create a really broad power band for the best usable power, plus you get extreme duty parts. Go here for more information and view our camshaft and valve train presentation for the most information on these engineered arrangements. http://aircooledtechnology.com/store/home.php?cat=328

"Other heads" that can be used with the 1.7>2.0 conversion:
Now that you have upgraded to the 94mm cylinders (or 96mm) you are no longer limited to the small 100mm OD registered heads of the 1.7 engine. This means you can bolt on a set of 1.8 or 2.0 heads and if you go this route you won;t need to do ANY machine work to the heads at all for them to match perfectly to the 2.0 cylinders.

Ultimately I feel the best heads for these 2.0 conversions come from the 1.8L engine. These have the largest stock valves of any OEM head and the lack of machine work that is necessary make them a bit cheaper, especially for guys that are choosing to work on a budget, keeping as much "stock" as possible. Of course you should have any head completely rebuilt with new seats added- If you choose 1.8L heads you can keep the valve sizes stock at 41X34, or you can upgrade the components to 42X36 (my favorite valve sizes for small displacement engines) and use our modern parts for the job.

The 2.0 Bus or 914 heads are also worthy units, but most of them must have repair work made because the Bus heads come from overworked engines that have been pushing 5,000 pounds for 30+ years. We stay away from rebuilding any heads that came from a Bus engine as most have irreparable damage or damage that will cost more than the heads are worth to repair. The 2.0 914 heads are the only real "Porsche" heads found on the Type 4 engine. They feature 3 stud intake manifolds, the largest chambers and their own spark plug location. These are the most rare heads and also the heads that have the weakest combustion chambers, 95% of the time they are cracked and require machine work and a full rebuild. They are the most expensive heads to work with- period. They will make the most power of any stock head, due to the plug location, valve sizes and combustion chambers but the performance comes with a cost.

So, that pretty much wraps it up for the conversion of the 1.7 engine>>a 2.0 engine. As you can see the process is quite simple with all parts simply bolting into place with the proper interchangeable components and the only machine work you'll need to have done is the head registers of the 1.7 cylinder heads opened up, if you decide to utilize them on the 2.0 engine.

If I were completing a 1.7> 2.0 conversion for my personal car, this is what I'd do:
-Select a good used 2 liter crank
-Select new H beam connecting rods
-Swap the stock cam for a 9500 series RAT camshaft, matching lifters and basic valve train kit
-Bolt on RAT KB 96mm cylinders and pistons, set up at 8:1 CR
-Have Len Hoffman (www.haminc.biz) totally rebuild a set of 1.8L cylinder heads, using the components from the RAT valve train kit. This could be completed for 1500-2,000.00 more than likely and the engine would make a solid 110-115 HP, run for 100K miles and be very reliable. An engine of this size won't benefit from head work, so just keep the ports stock and drive it!

The main things you must consider is what the intent of the engine is and how much you want to spend to do the conversion. It is quite possible to complete this conversion using 95% used parts from a donor 2.0 engine, only replacing bearings and you'd probably do the entire conversion for 500 bucks- but that is not wise given the age and service life of many components today. Remember that cutting corners and doing things half assed is never smart and WILL come back to haunt you with the Type 4 engine.

Read this portion if you have a 1.8L engine as your base for the 2.0 conversion:

Since you have a 1.8 L engine the process for you is more simple as your stock cylinder heads can easily be retained and will slide right onto the 94mm cylinders of the 2.0L engine, since the OD is the same @ 105mm. Since your bore size of the 1800 engine is 93mm, these heads will easily be adequate for the larger 94mm (or 96mm) bore of the 2.0 conversion.

What this means for you is you'll follow all the directives above for the 1.7 engine, but you'll pay no attention to the information concerning 1.7L heads, since you already have the more superior, 1.8L heads on your base engine.

All other information referring to the 1.7L engine including the list of components needed and etc also pertains to 18>> 2.0 conversions.

I hope this article removes some of the mystery related to the 1.7/ 1.8 engines and converting them into a 2.0 engine. Please feel free to post any questions on this topic here on the forums for further clarification by our team.

This post has been edited by Jake Raby: Aug 23 2011, 12:11 AM